[IMP] compiler: add support for t-for directive

This commit adds support for the `t-for` whose syntax and usage is
similar to the syntax of the for..of loop in JS (and in fact it compiles
to a for..of loop). This looping construct supports looping on arbitrary
iterables and destructuring assignments, which would be difficult to
support in a backward compatible manner on the existing t-foreach
directive.

doc/reference/app.md

@@ -117,7 +117,7 @@ const { loadFile, mount } = owl;
 Dev mode activates some additional checks and developer amenities:
 
 - [Props validation](./props.md#props-validation) is performed
-- [t-foreach](./templates.md#loops) loops check for key unicity
+- [t-for and t-foreach](./templates.md#loops) loops check for key unicity
 - Lifecycle hooks are wrapped to report their errors in a more developer-friendly way
 - onWillStart and onWillUpdateProps will emit a warning in the console when they
   take longer than 3 seconds in an effort to ease debugging the presence of deadlocks

doc/reference/templates.md

@@ -61,7 +61,7 @@ For reference, here is a list of all standard QWeb directives:
 | `t-out`                        | [Outputting value, possibly without escaping](#outputting-data) |
 | `t-set`, `t-value`             | [Setting variables](#setting-variables)                         |
 | `t-if`, `t-elif`, `t-else`,    | [conditionally rendering](#conditionals)                        |
-| `t-foreach`, `t-as`            | [Loops](#loops)                                                 |
+| `t-for/t-of`, `t-foreach/t-as` | [Loops](#loops)                                                 |
 | `t-att`, `t-attf-*`, `t-att-*` | [Dynamic attributes](#dynamic-attributes)                       |
 | `t-call`                       | [Rendering sub templates](#sub-templates)                       |
 | `t-debug`, `t-log`             | [Debugging](#debugging)                                         |
@@ -372,6 +372,24 @@ Like conditions, `t-foreach` applies to the element bearing the directive’s at
 
 is equivalent to the previous example.
 
+Owl also has another pair of directives that can be used for looping that allow
+destructuring the contents of the loop item: `t-for` and `t-of`, which behaves
+much like `for..of` in javascript:
+
+```xml
+<t t-for="[left, right]" t-of="[['a', 1], ['b', 2], ['c', 3]]" t-key="left">
+    <p><t t-esc="left"/>: <t t-esc="right"/></p>
+</t>
+```
+
+will be rendered as:
+
+```xml
+<p>a: 1</p>
+<p>b: 2</p>
+<p>c: 3</p>
+```
+
 An important difference should be made with the usual `QWeb` behaviour: Owl
 requires the presence of a `t-key` directive, to be able to properly reconcile
 renderings.
@@ -380,8 +398,9 @@ renderings.
 and maps, it will expose the key of the current iteration as the contents of the
 `t-as`, and the corresponding value with the same name and the suffix `_value`.
 
-In addition to the name passed via t-as, `t-foreach` provides a few other useful
-variables (note: `$as` will be replaced with the name passed to `t-as`):
+In addition to the name passed via t-as, `t-foreach` (but not `t-for`) provides
+a few other useful variables (note: `$as` will be replaced with the name passed
+to `t-as`):
 
 - `$as_value`: the current iteration value, identical to `$as` for arrays and
   other iterables, but for objects and maps, it provides the value (where `$as`
@@ -393,10 +412,9 @@ variables (note: `$as` will be replaced with the name passed to `t-as`):
   (equivalent to `$as_index + 1 == $as_size`), requires the iteratee’s size be
   available
 
-These extra variables provided and all new variables created into the `t-foreach`
-are only available in the scope of the `t-foreach`. If the variable exists outside
-the context of the `t-foreach`, the value is copied at the end of the foreach
-into the global context.
+These variables and all new variables created inside`t-foreach` and `t-for` are
+only available inside of the loop. If a variable existed outside the context of
+the loop, the assignment will affect the outer variable.
 
 ```xml
 <t t-set="existing_variable" t-value="false"/>
@@ -408,7 +426,7 @@ into the global context.
     <!-- existing_variable and new_variable now true -->
 </p>
 
-<!-- existing_variable always true -->
+<!-- existing_variable still true -->
 <!-- new_variable undefined -->
 ```
 
@@ -471,18 +489,11 @@ are all equivalent:
 </t>
 ```
 
-If there is no `t-key` directive, Owl will use the index as a default key.
-
-Note: the `t-foreach` directive only accepts arrays (lists) or objects. It does
-not work with other iterables, such as `Set`. However, it is only a matter of
-using the `...` javascript operator. For example:
-
-```xml
-<t t-foreach="[...items]" t-as="item">...</t>
-```
-
-The `...` operator will convert the `Set` (or any other iterables) into a list,
-which will work with Owl QWeb.
+The `t-key` directive is mandatory, and as mentioned should represent the object's
+identity. You may be tempted to use the loop index as a key, but keep in mind that
+this is only correct if items in the loop cannot be reordered. If this is not the
+case, using the index as the key can lead to bugs that are difficult to find, so
+use the index as the key only if you are sure items cannot be reordered.
 
 ### Sub Templates
 

docs/owl.js

@@ -82,6 +82,67 @@ function toggler(key, child) {
 
 // Custom error class that wraps error that happen in the owl lifecycle
 class OwlError extends Error {
+}
+// Maps fibers to thrown errors
+const fibersInError = new WeakMap();
+const nodeErrorHandlers = new WeakMap();
+function _handleError(node, error) {
+    if (!node) {
+        return false;
+    }
+    const fiber = node.fiber;
+    if (fiber) {
+        fibersInError.set(fiber, error);
+    }
+    const errorHandlers = nodeErrorHandlers.get(node);
+    if (errorHandlers) {
+        let handled = false;
+        // execute in the opposite order
+        for (let i = errorHandlers.length - 1; i >= 0; i--) {
+            try {
+                errorHandlers[i](error);
+                handled = true;
+                break;
+            }
+            catch (e) {
+                error = e;
+            }
+        }
+        if (handled) {
+            return true;
+        }
+    }
+    return _handleError(node.parent, error);
+}
+function handleError(params) {
+    let { error } = params;
+    // Wrap error if it wasn't wrapped by wrapError (ie when not in dev mode)
+    if (!(error instanceof OwlError)) {
+        error = Object.assign(new OwlError(`An error occured in the owl lifecycle (see this Error's "cause" property)`), { cause: error });
+    }
+    const node = "node" in params ? params.node : params.fiber.node;
+    const fiber = "fiber" in params ? params.fiber : node.fiber;
+    if (fiber) {
+        // resets the fibers on components if possible. This is important so that
+        // new renderings can be properly included in the initial one, if any.
+        let current = fiber;
+        do {
+            current.node.fiber = current;
+            current = current.parent;
+        } while (current);
+        fibersInError.set(fiber.root, error);
+    }
+    const handled = _handleError(node, error);
+    if (!handled) {
+        console.warn(`[Owl] Unhandled error. Destroying the root component`);
+        try {
+            node.app.destroy();
+        }
+        catch (e) {
+            console.error(e);
+        }
+        throw error;
+    }
 }
 
 const { setAttribute: elemSetAttribute, removeAttribute } = Element.prototype;
@@ -1542,68 +1603,6 @@ function remove(vnode, withBeforeRemove = false) {
     vnode.remove();
 }
 
-// Maps fibers to thrown errors
-const fibersInError = new WeakMap();
-const nodeErrorHandlers = new WeakMap();
-function _handleError(node, error) {
-    if (!node) {
-        return false;
-    }
-    const fiber = node.fiber;
-    if (fiber) {
-        fibersInError.set(fiber, error);
-    }
-    const errorHandlers = nodeErrorHandlers.get(node);
-    if (errorHandlers) {
-        let handled = false;
-        // execute in the opposite order
-        for (let i = errorHandlers.length - 1; i >= 0; i--) {
-            try {
-                errorHandlers[i](error);
-                handled = true;
-                break;
-            }
-            catch (e) {
-                error = e;
-            }
-        }
-        if (handled) {
-            return true;
-        }
-    }
-    return _handleError(node.parent, error);
-}
-function handleError(params) {
-    let { error } = params;
-    // Wrap error if it wasn't wrapped by wrapError (ie when not in dev mode)
-    if (!(error instanceof OwlError)) {
-        error = Object.assign(new OwlError(`An error occured in the owl lifecycle (see this Error's "cause" property)`), { cause: error });
-    }
-    const node = "node" in params ? params.node : params.fiber.node;
-    const fiber = "fiber" in params ? params.fiber : node.fiber;
-    if (fiber) {
-        // resets the fibers on components if possible. This is important so that
-        // new renderings can be properly included in the initial one, if any.
-        let current = fiber;
-        do {
-            current.node.fiber = current;
-            current = current.parent;
-        } while (current);
-        fibersInError.set(fiber.root, error);
-    }
-    const handled = _handleError(node, error);
-    if (!handled) {
-        console.warn(`[Owl] Unhandled error. Destroying the root component`);
-        try {
-            node.app.destroy();
-        }
-        catch (e) {
-            console.error(e);
-        }
-        throw error;
-    }
-}
-
 function makeChildFiber(node, parent) {
     let current = node.fiber;
     if (current) {
@@ -3008,8 +3007,8 @@ function prepareList(collection) {
             values = keys;
         }
         else {
-            values = Object.values(collection);
-            keys = Object.keys(collection);
+            values = Object.keys(collection);
+            keys = Object.values(collection);
         }
     }
     else {
@@ -4347,18 +4346,18 @@ class CodeGenerator {
         }
         this.addLine(`for (let ${loopVar} = 0; ${loopVar} < ${l}; ${loopVar}++) {`);
         this.target.indentLevel++;
-        this.addLine(`ctx[\`${ast.elem}\`] = ${keys}[${loopVar}];`);
+        this.addLine(`ctx[\`${ast.elem}\`] = ${vals}[${loopVar}];`);
         if (!ast.hasNoFirst) {
             this.addLine(`ctx[\`${ast.elem}_first\`] = ${loopVar} === 0;`);
         }
         if (!ast.hasNoLast) {
-            this.addLine(`ctx[\`${ast.elem}_last\`] = ${loopVar} === ${keys}.length - 1;`);
+            this.addLine(`ctx[\`${ast.elem}_last\`] = ${loopVar} === ${vals}.length - 1;`);
         }
         if (!ast.hasNoIndex) {
             this.addLine(`ctx[\`${ast.elem}_index\`] = ${loopVar};`);
         }
         if (!ast.hasNoValue) {
-            this.addLine(`ctx[\`${ast.elem}_value\`] = ${vals}[${loopVar}];`);
+            this.addLine(`ctx[\`${ast.elem}_value\`] = ${keys}[${loopVar}];`);
         }
         this.define(`key${this.target.loopLevel}`, ast.key ? compileExpr(ast.key) : loopVar);
         if (this.dev) {
@@ -5548,20 +5547,11 @@ function compile(template, options = {}) {
     const codeGenerator = new CodeGenerator(ast, { ...options, hasSafeContext });
     const code = codeGenerator.generateCode();
     // template function
-    try {
-        return new Function("app, bdom, helpers", code);
-    }
-    catch (originalError) {
-        const { name } = options;
-        const nameStr = name ? `template "${name}"` : "anonymous template";
-        const err = new OwlError(`Failed to compile ${nameStr}: ${originalError.message}\n\ngenerated code:\nfunction(app, bdom, helpers) {\n${code}\n}`);
-        err.cause = originalError;
-        throw err;
-    }
+    return new Function("app, bdom, helpers", code);
 }
 
 // do not modify manually. This file is generated by the release script.
-const version = "2.2.4";
+const version = "2.2.3";
 
 // -----------------------------------------------------------------------------
 //  Scheduler
@@ -5994,6 +5984,6 @@ TemplateSet.prototype._compileTemplate = function _compileTemplate(name, templat
 export { App, Component, EventBus, OwlError, __info__, blockDom, loadFile, markRaw, markup, mount, onError, onMounted, onPatched, onRendered, onWillDestroy, onWillPatch, onWillRender, onWillStart, onWillUnmount, onWillUpdateProps, reactive, status, toRaw, useChildSubEnv, useComponent, useEffect, useEnv, useExternalListener, useRef, useState, useSubEnv, validate, validateType, whenReady, xml };
 
 
-__info__.date = '2023-08-02T06:20:03.634Z';
-__info__.hash = '8f9ad98';
+__info__.date = '2023-07-20T06:05:29.796Z';
+__info__.hash = 'b1a3b32';
 __info__.url = 'https://github.com/odoo/owl';

docs/playground/samples/todo_app/todo_app.js

@@ -43,6 +43,10 @@ class TaskList {
         }
     }
 
+    toggleTask(task) {
+        task.isCompleted = !task.isCompleted;
+    }
+
     toggleTask(id) {
         const task = this.tasks.find(t => t.id === id);
         task.isCompleted = !task.isCompleted;
@@ -57,7 +61,7 @@ class TaskList {
     clearCompleted() {
         const tasks = this.tasks.filter(t => t.isCompleted);
         for (let task of tasks) {
-            this.deleteTask(task.id);
+            this.deleteTask(task);
         }
     }
     

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "@odoo/owl",
-  "version": "2.2.4",
+  "version": "2.2.3",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@odoo/owl",
-  "version": "2.2.4",
+  "version": "2.2.3",
   "description": "Odoo Web Library (OWL)",
   "main": "dist/owl.cjs.js",
   "module": "dist/owl.es.js",

src/common/owl_error.ts

@@ -1,4 +0,0 @@
-// Custom error class that wraps error that happen in the owl lifecycle
-export class OwlError extends Error {
-  cause?: any;
-}

src/compiler/code_generator.ts

@@ -18,6 +18,7 @@ import {
   ASTTCallBlock,
   ASTTEsc,
   ASTText,
+  ASTTFor,
   ASTTForEach,
   ASTTif,
   ASTTKey,
@@ -29,7 +30,7 @@ import {
   Attrs,
   EventHandlers,
 } from "./parser";
-import { OwlError } from "../common/owl_error";
+import { OwlError } from "../runtime/error_handling";
 
 type BlockType = "block" | "text" | "multi" | "list" | "html" | "comment";
 const whitespaceRE = /\s+/g;
@@ -471,6 +472,8 @@ export class CodeGenerator {
         return this.compileTIf(ast, ctx);
       case ASTType.TForEach:
         return this.compileTForeach(ast, ctx);
+      case ASTType.TFor:
+        return this.compileTFor(ast, ctx);
       case ASTType.TKey:
         return this.compileTKey(ast, ctx);
       case ASTType.Multi:
@@ -894,20 +897,20 @@ export class CodeGenerator {
     }
     this.addLine(`for (let ${loopVar} = 0; ${loopVar} < ${l}; ${loopVar}++) {`);
     this.target.indentLevel++;
-    this.addLine(`ctx[\`${ast.elem}\`] = ${keys}[${loopVar}];`);
+    this.addLine(`ctx[\`${ast.elem}\`] = ${vals}[${loopVar}];`);
     if (!ast.hasNoFirst) {
       this.addLine(`ctx[\`${ast.elem}_first\`] = ${loopVar} === 0;`);
     }
     if (!ast.hasNoLast) {
-      this.addLine(`ctx[\`${ast.elem}_last\`] = ${loopVar} === ${keys}.length - 1;`);
+      this.addLine(`ctx[\`${ast.elem}_last\`] = ${loopVar} === ${vals}.length - 1;`);
     }
     if (!ast.hasNoIndex) {
       this.addLine(`ctx[\`${ast.elem}_index\`] = ${loopVar};`);
     }
     if (!ast.hasNoValue) {
-      this.addLine(`ctx[\`${ast.elem}_value\`] = ${vals}[${loopVar}];`);
+      this.addLine(`ctx[\`${ast.elem}_value\`] = ${keys}[${loopVar}];`);
     }
-    this.define(`key${this.target.loopLevel}`, ast.key ? compileExpr(ast.key) : loopVar);
+    this.define(`key${this.target.loopLevel}`, compileExpr(ast.key));
     if (this.dev) {
       // Throw error on duplicate keys in dev mode
       this.helpers.add("OwlError");
@@ -954,6 +957,46 @@ export class CodeGenerator {
     return block.varName;
   }
 
+  compileTFor(ast: ASTTFor, ctx: Context): string {
+    let { block } = ctx;
+    if (block) {
+      this.insertAnchor(block);
+    }
+    block = this.createBlock(block, "list", ctx);
+    this.target.loopLevel++;
+    this.addLine(`ctx = Object.create(ctx);`);
+    // Throw errors on duplicate keys in dev mode
+    if (this.dev) {
+      this.define(`keys${block.id}`, `new Set()`);
+    }
+    this.define(`c_block${block.id}`, "[]");
+    const index = `i${this.target.loopLevel}`;
+    this.addLine(`let ${index} = ${0};`);
+    const binding = compileExpr(ast.binding);
+    this.addLine(`for (${binding} of ${compileExpr(ast.iterable)}) {`);
+    this.target.indentLevel++;
+    this.define(`key${this.target.loopLevel}`, compileExpr(ast.key));
+    if (this.dev) {
+      // Throw error on duplicate keys in dev mode
+      this.helpers.add("OwlError");
+      this.addLine(
+        `if (keys${block.id}.has(String(key${this.target.loopLevel}))) { throw new OwlError(\`Got duplicate key in t-for: \${key${this.target.loopLevel}}\`)}`
+      );
+      this.addLine(`keys${block.id}.add(String(key${this.target.loopLevel}));`);
+    }
+    const subCtx = createContext(ctx, { block, index });
+    this.compileAST(ast.body, subCtx);
+    this.addLine(`${index}++;`);
+    this.target.indentLevel--;
+    this.target.loopLevel--;
+    this.addLine(`}`);
+    if (!ctx.isLast) {
+      this.addLine(`ctx = ctx.__proto__;`);
+    }
+    this.insertBlock("l", block, ctx);
+    return block.varName;
+  }
+
   compileTKey(ast: ASTTKey, ctx: Context): string | null {
     const tKeyExpr = generateId("tKey_");
     this.define(tKeyExpr, compileExpr(ast.expr));

src/compiler/index.ts

@@ -2,7 +2,7 @@ import type { TemplateSet } from "../runtime/template_set";
 import type { BDom } from "../runtime/blockdom";
 import { CodeGenerator, Config } from "./code_generator";
 import { parse } from "./parser";
-import { OwlError } from "../common/owl_error";
+import { OwlError } from "../runtime";
 
 export type Template = (context: any, vnode: any, key?: string) => BDom;
 

src/compiler/inline_expressions.ts

@@ -1,4 +1,4 @@
-import { OwlError } from "../common/owl_error";
+import { OwlError } from "../runtime/error_handling";
 
 /**
  * Owl QWeb Expression Parser

src/compiler/parser.ts

@@ -1,4 +1,4 @@
-import { OwlError } from "../common/owl_error";
+import { OwlError } from "../runtime/error_handling";
 
 // -----------------------------------------------------------------------------
 // AST Type definition
@@ -26,6 +26,7 @@ export const enum ASTType {
   TCallBlock,
   TTranslation,
   TPortal,
+  TFor,
 }
 
 export interface ASTText {
@@ -104,7 +105,15 @@ export interface ASTTForEach {
   hasNoLast: boolean;
   hasNoIndex: boolean;
   hasNoValue: boolean;
-  key: string | null;
+  key: string;
+}
+
+export interface ASTTFor {
+  type: ASTType.TFor;
+  iterable: string;
+  binding: string;
+  body: AST;
+  key: string;
 }
 
 export interface ASTTKey {
@@ -183,6 +192,7 @@ export type AST =
   | ASTTCall
   | ASTTOut
   | ASTTForEach
+  | ASTTFor
   | ASTTKey
   | ASTComponent
   | ASTSlot
@@ -230,6 +240,7 @@ function parseNode(node: Node, ctx: ParsingContext): AST | null {
   return (
     parseTDebugLog(node, ctx) ||
     parseTForEach(node, ctx) ||
+    parseTFor(node, ctx) ||
     parseTIf(node, ctx) ||
     parseTPortal(node, ctx) ||
     parseTCall(node, ctx) ||
@@ -531,6 +542,36 @@ function parseTForEach(node: Element, ctx: ParsingContext): AST | null {
   };
 }
 
+function parseTFor(node: Element, ctx: ParsingContext): AST | null {
+  if (!node.hasAttribute("t-for")) {
+    return null;
+  }
+  const binding = node.getAttribute("t-for")!;
+  node.removeAttribute("t-for");
+  const iterable = node.getAttribute("t-of") || "";
+  node.removeAttribute("t-of");
+  const key = node.getAttribute("t-key");
+  if (!key) {
+    throw new OwlError(
+      `"Directive t-for should always be used with a t-key!" (expression: t-for="${binding}" t-of="${iterable}")`
+    );
+  }
+  node.removeAttribute("t-key");
+  const body = parseNode(node, ctx);
+
+  if (!body) {
+    return null;
+  }
+
+  return {
+    type: ASTType.TFor,
+    iterable,
+    binding,
+    body,
+    key,
+  };
+}
+
 function parseTKey(node: Element, ctx: ParsingContext): AST | null {
   if (!node.hasAttribute("t-key")) {
     return null;

src/runtime/app.ts

@@ -1,8 +1,7 @@
 import { version } from "../version";
 import { Component, ComponentConstructor, Props } from "./component";
 import { ComponentNode } from "./component_node";
-import { nodeErrorHandlers, handleError } from "./error_handling";
-import { OwlError } from "../common/owl_error";
+import { nodeErrorHandlers, OwlError, handleError } from "./error_handling";
 import { Fiber, RootFiber, MountOptions } from "./fibers";
 import { Scheduler } from "./scheduler";
 import { validateProps } from "./template_helpers";

src/runtime/blockdom/block_compiler.ts

@@ -1,4 +1,4 @@
-import { OwlError } from "../../common/owl_error";
+import { OwlError } from "../error_handling";
 import { attrsSetter, attrsUpdater, createAttrUpdater, setClass, updateClass } from "./attributes";
 import { config } from "./config";
 import { createEventHandler } from "./events";

src/runtime/component_node.ts

@@ -1,8 +1,7 @@
 import type { App, Env } from "./app";
 import { BDom, VNode } from "./blockdom";
 import { Component, ComponentConstructor, Props } from "./component";
-import { fibersInError } from "./error_handling";
-import { OwlError } from "../common/owl_error";
+import { fibersInError, OwlError } from "./error_handling";
 import { Fiber, makeChildFiber, makeRootFiber, MountFiber, MountOptions } from "./fibers";
 import { clearReactivesForCallback, getSubscriptions, reactive, targets } from "./reactivity";
 import { STATUS } from "./status";

src/runtime/error_handling.ts

@@ -1,7 +1,11 @@
-import { OwlError } from "../common/owl_error";
 import type { ComponentNode } from "./component_node";
 import type { Fiber } from "./fibers";
 
+// Custom error class that wraps error that happen in the owl lifecycle
+export class OwlError extends Error {
+  cause?: any;
+}
+
 // Maps fibers to thrown errors
 export const fibersInError: WeakMap<Fiber, any> = new WeakMap();
 export const nodeErrorHandlers: WeakMap<ComponentNode, ((error: any) => void)[]> = new WeakMap();

src/runtime/event_handling.ts

@@ -1,6 +1,6 @@
 import { filterOutModifiersFromData } from "./blockdom/config";
 import { STATUS } from "./status";
-import { OwlError } from "../common/owl_error";
+import { OwlError } from "./error_handling";
 
 export const mainEventHandler = (data: any, ev: Event, currentTarget?: EventTarget | null) => {
   const { data: _data, modifiers } = filterOutModifiersFromData(data);

src/runtime/fibers.ts

@@ -1,7 +1,6 @@
 import { BDom, mount } from "./blockdom";
 import type { ComponentNode } from "./component_node";
-import { fibersInError } from "./error_handling";
-import { OwlError } from "../common/owl_error";
+import { fibersInError, OwlError } from "./error_handling";
 import { STATUS } from "./status";
 
 export function makeChildFiber(node: ComponentNode, parent: Fiber): Fiber {

src/runtime/index.ts

@@ -55,7 +55,7 @@ export {
   onError,
 } from "./lifecycle_hooks";
 export { validate, validateType } from "./validation";
-export { OwlError } from "../common/owl_error";
+export { OwlError } from "./error_handling";
 
 export const __info__ = {
   version: App.version,

src/runtime/lifecycle_hooks.ts

@@ -1,6 +1,5 @@
 import { getCurrent } from "./component_node";
-import { nodeErrorHandlers } from "./error_handling";
-import { OwlError } from "../common/owl_error";
+import { nodeErrorHandlers, OwlError } from "./error_handling";
 
 const TIMEOUT = Symbol("timeout");
 function wrapError(fn: (...args: any[]) => any, hookName: string) {

src/runtime/portal.ts

@@ -1,7 +1,7 @@
 import { onMounted, onWillUnmount } from "./lifecycle_hooks";
 import { BDom, text, VNode } from "./blockdom";
 import { Component } from "./component";
-import { OwlError } from "../common/owl_error";
+import { OwlError } from "./error_handling";
 
 const VText: any = text("").constructor;
 

src/runtime/reactivity.ts

@@ -1,5 +1,5 @@
 import type { Callback } from "./utils";
-import { OwlError } from "../common/owl_error";
+import { OwlError } from "./error_handling";
 
 // Special key to subscribe to, to be notified of key creation/deletion
 const KEYCHANGES = Symbol("Key changes");

src/runtime/template_helpers.ts

@@ -4,7 +4,7 @@ import { html } from "./blockdom/index";
 import { isOptional, validateSchema } from "./validation";
 import type { ComponentConstructor } from "./component";
 import { markRaw } from "./reactivity";
-import { OwlError } from "../common/owl_error";
+import { OwlError } from "./error_handling";
 import type { ComponentNode } from "./component_node";
 
 const ObjectCreate = Object.create;
@@ -75,8 +75,8 @@ function prepareList(collection: unknown): [unknown[], unknown[], number, undefi
       keys = [...(<Iterable<unknown>>collection)];
       values = keys;
     } else {
-      values = Object.values(collection);
-      keys = Object.keys(collection);
+      values = Object.keys(collection);
+      keys = Object.values(collection);
     }
   } else {
     throw new OwlError(`Invalid loop expression: "${collection}" is not iterable`);

src/runtime/template_set.ts

@@ -3,7 +3,7 @@ import { comment, createBlock, html, list, multi, text, toggler } from "./blockd
 import { getCurrent } from "./component_node";
 import { Portal, portalTemplate } from "./portal";
 import { helpers } from "./template_helpers";
-import { OwlError } from "../common/owl_error";
+import { OwlError } from "./error_handling";
 
 const bdom = { text, createBlock, list, multi, html, toggler, comment };
 

src/runtime/utils.ts

@@ -1,4 +1,4 @@
-import { OwlError } from "../common/owl_error";
+import { OwlError } from "./error_handling";
 export type Callback = () => void;
 
 /**

src/runtime/validation.ts

@@ -1,4 +1,4 @@
-import { OwlError } from "../common/owl_error";
+import { OwlError } from "./error_handling";
 import { toRaw } from "./reactivity";
 
 type BaseType =

src/version.ts

@@ -1,2 +1,2 @@
 // do not modify manually. This file is generated by the release script.
-export const version = "2.2.4";
+export const version = "2.2.3";

tests/__snapshots__/reactivity.test.ts.snap

@@ -353,7 +353,7 @@ exports[`Reactivity: useState useless atoms should be deleted 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(Object.keys(ctx['state']));;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`id\`] = k_block2[i1];
+      ctx[\`id\`] = v_block2[i1];
       const key1 = ctx['id'];
       c_block2[i1] = withKey(comp1({id: ctx['id']}, key + \`__1__\${key1}\`, node, this, null), key1);
     }

tests/compiler/__snapshots__/event_handling.test.ts.snap

@@ -72,7 +72,7 @@ exports[`t-on can bind handlers with empty object (with non empty inner string)
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(['someval']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`action\`] = k_block2[i1];
+      ctx[\`action\`] = v_block2[i1];
       ctx[\`action_index\`] = i1;
       const key1 = ctx['action_index'];
       const v1 = ctx['activate'];
@@ -142,7 +142,7 @@ exports[`t-on handler is bound to proper owner, part 2 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList([1]);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`value\`] = k_block1[i1];
+      ctx[\`value\`] = v_block1[i1];
       const key1 = ctx['value'];
       let hdlr1 = [ctx['add'], ctx];
       c_block1[i1] = withKey(block2([hdlr1]), key1);
@@ -189,11 +189,11 @@ exports[`t-on handler is bound to proper owner, part 4 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList([1]);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`value\`] = k_block1[i1];
+      ctx[\`value\`] = v_block1[i1];
       ctx[\`value_first\`] = i1 === 0;
-      ctx[\`value_last\`] = i1 === k_block1.length - 1;
+      ctx[\`value_last\`] = i1 === v_block1.length - 1;
       ctx[\`value_index\`] = i1;
-      ctx[\`value_value\`] = v_block1[i1];
+      ctx[\`value_value\`] = k_block1[i1];
       const key1 = ctx['value'];
       c_block1[i1] = withKey(callTemplate_1.call(this, ctx, node, key + \`__1__\${key1}\`), key1);
     }
@@ -348,7 +348,7 @@ exports[`t-on t-on modifiers (native listener) t-on with prevent modifier in t-f
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['projects']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`project\`] = k_block2[i1];
+      ctx[\`project\`] = v_block2[i1];
       const key1 = ctx['project'];
       const v1 = ctx['onEdit'];
       const v2 = ctx['project'];

tests/compiler/__snapshots__/misc.test.ts.snap

@@ -33,7 +33,7 @@ exports[`misc complex template 1`] = `
     ctx = Object.create(ctx);
     const [k_block4, v_block4, l_block4, c_block4] = prepareList(ctx['batch'].slot_ids.filter(_slot=>_slot.build_id.id&&!_slot.trigger_id.manual&&(ctx['options'].trigger_display[_slot.trigger_id.id])));;
     for (let i1 = 0; i1 < l_block4; i1++) {
-      ctx[\`slot\`] = k_block4[i1];
+      ctx[\`slot\`] = v_block4[i1];
       const key1 = ctx['slot'].id;
       c_block4[i1] = withKey(comp1({class: ctx['slot_container'],slot: ctx['slot']}, key + \`__1__\${key1}\`, node, this, null), key1);
     }
@@ -42,7 +42,7 @@ exports[`misc complex template 1`] = `
     ctx = Object.create(ctx);
     const [k_block6, v_block6, l_block6, c_block6] = prepareList([1,2,3,4]);;
     for (let i1 = 0; i1 < l_block6; i1++) {
-      ctx[\`x\`] = k_block6[i1];
+      ctx[\`x\`] = v_block6[i1];
       const key1 = ctx['x'];
       c_block6[i1] = withKey(block7(), key1);
     }
@@ -51,7 +51,7 @@ exports[`misc complex template 1`] = `
     ctx = Object.create(ctx);
     const [k_block8, v_block8, l_block8, c_block8] = prepareList(ctx['commit_links']);;
     for (let i1 = 0; i1 < l_block8; i1++) {
-      ctx[\`commit_link\`] = k_block8[i1];
+      ctx[\`commit_link\`] = v_block8[i1];
       const key1 = ctx['commit_link'].id;
       let b10,b11,b12,b13;
       let attr5 = \`/runbot/commit/\${ctx['commit_link'].commit_id}\`;
@@ -99,11 +99,11 @@ exports[`misc global 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList([4,5,6]);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`value\`] = k_block2[i1];
+      ctx[\`value\`] = v_block2[i1];
       ctx[\`value_first\`] = i1 === 0;
-      ctx[\`value_last\`] = i1 === k_block2.length - 1;
+      ctx[\`value_last\`] = i1 === v_block2.length - 1;
       ctx[\`value_index\`] = i1;
-      ctx[\`value_value\`] = v_block2[i1];
+      ctx[\`value_value\`] = k_block2[i1];
       const key1 = ctx['value'];
       let txt1 = ctx['value'];
       const b4 = block4([txt1]);
@@ -223,7 +223,7 @@ exports[`misc other complex template 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['projects']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`project\`] = k_block2[i1];
+      ctx[\`project\`] = v_block2[i1];
       const key1 = ctx['project'].id;
       let hdlr1 = [ctx['selectProject'](ctx['project']), ctx];
       let txt2 = ctx['project'].name;
@@ -263,7 +263,7 @@ exports[`misc other complex template 1`] = `
       ctx = Object.create(ctx);
       const [k_block15, v_block15, l_block15, c_block15] = prepareList(ctx['categories']);;
       for (let i1 = 0; i1 < l_block15; i1++) {
-        ctx[\`category\`] = k_block15[i1];
+        ctx[\`category\`] = v_block15[i1];
         const key1 = ctx['category'].id;
         let attr6 = ctx['category'].id;
         let prop1 = new Boolean(ctx['category'].id==ctx['options'].active_category_id);
@@ -284,7 +284,7 @@ exports[`misc other complex template 1`] = `
       ctx = Object.create(ctx);
       const [k_block18, v_block18, l_block18, c_block18] = prepareList(ctx['triggers']);;
       for (let i1 = 0; i1 < l_block18; i1++) {
-        ctx[\`trigger\`] = k_block18[i1];
+        ctx[\`trigger\`] = v_block18[i1];
         const key1 = ctx['trigger'].id;
         let b20;
         if (!ctx['trigger'].manual&&ctx['trigger'].project_id===ctx['project'].id&&ctx['trigger'].category_id===ctx['options'].active_category_id) {

tests/compiler/__snapshots__/qweb_memory.test.ts.snap

@@ -12,7 +12,7 @@ exports[`memory t-foreach does not leak stuff in global scope 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList([3,2,1]);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`item\`] = k_block2[i1];
+      ctx[\`item\`] = v_block2[i1];
       ctx[\`item_index\`] = i1;
       const key1 = ctx['item_index'];
       c_block2[i1] = withKey(text(ctx['item']), key1);

tests/compiler/__snapshots__/t_call.test.ts.snap

@@ -440,11 +440,11 @@ exports[`t-call (template calling) recursive template, part 2 2`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['node'].children||[]);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`subtree\`] = k_block2[i1];
+      ctx[\`subtree\`] = v_block2[i1];
       ctx[\`subtree_first\`] = i1 === 0;
-      ctx[\`subtree_last\`] = i1 === k_block2.length - 1;
+      ctx[\`subtree_last\`] = i1 === v_block2.length - 1;
       ctx[\`subtree_index\`] = i1;
-      ctx[\`subtree_value\`] = v_block2[i1];
+      ctx[\`subtree_value\`] = k_block2[i1];
       const key1 = ctx['subtree_index'];
       ctx = Object.create(ctx);
       ctx[isBoundary] = 1;
@@ -495,11 +495,11 @@ exports[`t-call (template calling) recursive template, part 3 2`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['node'].children||[]);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`subtree\`] = k_block2[i1];
+      ctx[\`subtree\`] = v_block2[i1];
       ctx[\`subtree_first\`] = i1 === 0;
-      ctx[\`subtree_last\`] = i1 === k_block2.length - 1;
+      ctx[\`subtree_last\`] = i1 === v_block2.length - 1;
       ctx[\`subtree_index\`] = i1;
-      ctx[\`subtree_value\`] = v_block2[i1];
+      ctx[\`subtree_value\`] = k_block2[i1];
       const key1 = ctx['subtree_index'];
       ctx = Object.create(ctx);
       ctx[isBoundary] = 1;
@@ -553,11 +553,11 @@ exports[`t-call (template calling) recursive template, part 4: with t-set recurs
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['node'].children||[]);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`subtree\`] = k_block2[i1];
+      ctx[\`subtree\`] = v_block2[i1];
       ctx[\`subtree_first\`] = i1 === 0;
-      ctx[\`subtree_last\`] = i1 === k_block2.length - 1;
+      ctx[\`subtree_last\`] = i1 === v_block2.length - 1;
       ctx[\`subtree_index\`] = i1;
-      ctx[\`subtree_value\`] = v_block2[i1];
+      ctx[\`subtree_value\`] = k_block2[i1];
       const key1 = ctx['subtree_index'];
       ctx = Object.create(ctx);
       ctx[isBoundary] = 1;
@@ -813,11 +813,11 @@ exports[`t-call (template calling) t-call with t-set inside and outside 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['list']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`v\`] = k_block2[i1];
+      ctx[\`v\`] = v_block2[i1];
       ctx[\`v_first\`] = i1 === 0;
-      ctx[\`v_last\`] = i1 === k_block2.length - 1;
+      ctx[\`v_last\`] = i1 === v_block2.length - 1;
       ctx[\`v_index\`] = i1;
-      ctx[\`v_value\`] = v_block2[i1];
+      ctx[\`v_value\`] = k_block2[i1];
       const key1 = ctx['v_index'];
       setContextValue(ctx, \\"val\\", ctx['v'].val);
       ctx = Object.create(ctx);
@@ -880,11 +880,11 @@ exports[`t-call (template calling) t-call with t-set inside and outside. 2 2`] =
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['list']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`v\`] = k_block2[i1];
+      ctx[\`v\`] = v_block2[i1];
       ctx[\`v_first\`] = i1 === 0;
-      ctx[\`v_last\`] = i1 === k_block2.length - 1;
+      ctx[\`v_last\`] = i1 === v_block2.length - 1;
       ctx[\`v_index\`] = i1;
-      ctx[\`v_value\`] = v_block2[i1];
+      ctx[\`v_value\`] = k_block2[i1];
       const key1 = ctx['v_index'];
       setContextValue(ctx, \\"val\\", ctx['v'].val);
       ctx = Object.create(ctx);

tests/compiler/__snapshots__/t_for.test.ts.snap

@@ -0,0 +1,670 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`t-for destructuring array items 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block1 = [];
+    let i1 = 0;
+    for ([ctx['key'],ctx['value']] of Object.entries({a:1,b:2})) {
+      const key1 = ctx['key'];
+      const b3 = text(\`(\`);
+      const b4 = text(ctx['key']);
+      const b5 = text(\`: \`);
+      const b6 = text(ctx['value']);
+      const b7 = text(\`)\`);
+      c_block1[i1] = withKey(multi([b3, b4, b5, b6, b7]), key1);
+      i1++;
+    }
+    return list(c_block1);
+  }
+}"
+`;
+
+exports[`t-for destructuring array items: rest 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block1 = [];
+    let i1 = 0;
+    for ([ctx['head'],...ctx['tail']] of [[1,2,3],[4,5,6]]) {
+      const key1 = ctx['head'];
+      const b3 = text(\`(\`);
+      const b4 = text(ctx['head']);
+      const b5 = text(\`;\`);
+      const b6 = text(ctx['tail']);
+      const b7 = text(\`)\`);
+      c_block1[i1] = withKey(multi([b3, b4, b5, b6, b7]), key1);
+      i1++;
+    }
+    return list(c_block1);
+  }
+}"
+`;
+
+exports[`t-for destructuring object items 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block1 = [];
+    let i1 = 0;
+    for ({k:ctx['k'],v:ctx['v']} of [{k:'a',v:1},{k:'b',v:2}]) {
+      const key1 = ctx['k'];
+      const b3 = text(\`(\`);
+      const b4 = text(ctx['k']);
+      const b5 = text(\`: \`);
+      const b6 = text(ctx['v']);
+      const b7 = text(\`)\`);
+      c_block1[i1] = withKey(multi([b3, b4, b5, b6, b7]), key1);
+      i1++;
+    }
+    return list(c_block1);
+  }
+}"
+`;
+
+exports[`t-for destructuring object items: rest 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block1 = [];
+    let i1 = 0;
+    for ({k:ctx['k'],v:ctx['v']} of [{k:'a',v:1},{k:'b',v:2}]) {
+      const key1 = ctx['k'];
+      const b3 = text(\`(\`);
+      const b4 = text(ctx['k']);
+      const b5 = text(\`: \`);
+      const b6 = text(ctx['v']);
+      const b7 = text(\`)\`);
+      c_block1[i1] = withKey(multi([b3, b4, b5, b6, b7]), key1);
+      i1++;
+    }
+    return list(c_block1);
+  }
+}"
+`;
+
+exports[`t-for does not pollute the rendering context 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['item'] of [1]) {
+      const key1 = ctx['item'];
+      c_block2[i1] = withKey(text(ctx['item']), key1);
+      i1++;
+    }
+    const b2 = list(c_block2);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`t-for iterate on items (on a element node) 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  let block3 = createBlock(\`<span><block-text-0/></span>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['item'] of [1,2]) {
+      const key1 = ctx['item'];
+      let txt1 = ctx['item'];
+      c_block2[i1] = withKey(block3([txt1]), key1);
+      i1++;
+    }
+    const b2 = list(c_block2);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`t-for iterate, Map param 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block1 = [];
+    let i1 = 0;
+    for ([ctx['key'],ctx['value']] of ctx['map']) {
+      const key1 = ctx['key'];
+      const b3 = text(\` [\`);
+      const b4 = text(ctx['key']);
+      const b5 = text(\`: \`);
+      const b6 = text(ctx['value']);
+      const b7 = text(\`] \`);
+      c_block1[i1] = withKey(multi([b3, b4, b5, b6, b7]), key1);
+      i1++;
+    }
+    return list(c_block1);
+  }
+}"
+`;
+
+exports[`t-for iterate, Set param 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block1 = [];
+    let i1 = 0;
+    for (ctx['item'] of ctx['set']) {
+      const key1 = ctx['item'];
+      c_block1[i1] = withKey(text(ctx['item']), key1);
+      i1++;
+    }
+    return list(c_block1);
+  }
+}"
+`;
+
+exports[`t-for iterate, generator param 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block1 = [];
+    let i1 = 0;
+    for (ctx['item'] of ctx['gen']()) {
+      const key1 = ctx['item'];
+      c_block1[i1] = withKey(text(ctx['item']), key1);
+      i1++;
+    }
+    return list(c_block1);
+  }
+}"
+`;
+
+exports[`t-for iterate, iterable param 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block1 = [];
+    let i1 = 0;
+    for (ctx['item'] of ctx['map'].values()) {
+      const key1 = ctx['item'];
+      c_block1[i1] = withKey(text(ctx['item']), key1);
+      i1++;
+    }
+    return list(c_block1);
+  }
+}"
+`;
+
+exports[`t-for nested destructuring 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block1 = [];
+    let i1 = 0;
+    for ([ctx['key'],{left:ctx['left'],right:ctx['right']}] of Object.entries(ctx['obj'])) {
+      const key1 = ctx['key'];
+      const b3 = text(\`(\`);
+      const b4 = text(ctx['key']);
+      const b5 = text(\`: [\`);
+      const b6 = text(ctx['left']);
+      const b7 = text(\`, \`);
+      const b8 = text(ctx['right']);
+      const b9 = text(\`])\`);
+      c_block1[i1] = withKey(multi([b3, b4, b5, b6, b7, b8, b9]), key1);
+      i1++;
+    }
+    return list(c_block1);
+  }
+}"
+`;
+
+exports[`t-for simple iteration (in a node) 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['item'] of [3,2,1]) {
+      const key1 = ctx['item'];
+      c_block2[i1] = withKey(text(ctx['item']), key1);
+      i1++;
+    }
+    const b2 = list(c_block2);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`t-for simple iteration 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block1 = [];
+    let i1 = 0;
+    for (ctx['item'] of [3,2,1]) {
+      const key1 = ctx['item'];
+      c_block1[i1] = withKey(text(ctx['item']), key1);
+      i1++;
+    }
+    return list(c_block1);
+  }
+}"
+`;
+
+exports[`t-for simple iteration with two nodes inside 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  
+  let block3 = createBlock(\`<span>a<block-text-0/></span>\`);
+  let block4 = createBlock(\`<span>b<block-text-0/></span>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block1 = [];
+    let i1 = 0;
+    for (ctx['item'] of [3,2,1]) {
+      const key1 = ctx['item'];
+      let txt1 = ctx['item'];
+      const b3 = block3([txt1]);
+      let txt2 = ctx['item'];
+      const b4 = block4([txt2]);
+      c_block1[i1] = withKey(multi([b3, b4]), key1);
+      i1++;
+    }
+    return list(c_block1);
+  }
+}"
+`;
+
+exports[`t-for t-call with body in t-for in t-for 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { isBoundary, withDefault, setContextValue, withKey } = helpers;
+  const callTemplate_1 = app.getTemplate(\`sub\`);
+  
+  let block1 = createBlock(\`<div><block-child-0/><span>[<block-text-0/>][<block-text-1/>][<block-text-2/>]</span></div>\`);
+  let block6 = createBlock(\`<span><block-text-0/></span>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    ctx[isBoundary] = 1
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['a'] of ctx['numbers']) {
+      const key1 = ctx['a'];
+      ctx = Object.create(ctx);
+      const c_block4 = [];
+      let i2 = 0;
+      for (ctx['b'] of ctx['letters']) {
+        const key2 = ctx['b'];
+        ctx = Object.create(ctx);
+        ctx[isBoundary] = 1;
+        setContextValue(ctx, \\"c\\", 'x'+'_'+ctx['a']+'_'+ctx['b']);
+        c_block4[i2] = withKey(callTemplate_1.call(this, ctx, node, key + \`__1__\${key1}__\${key2}\`), key2);
+        ctx = ctx.__proto__;
+        i2++;
+      }
+      ctx = ctx.__proto__;
+      const b4 = list(c_block4);
+      let txt1 = ctx['c'];
+      const b6 = block6([txt1]);
+      c_block2[i1] = withKey(multi([b4, b6]), key1);
+      i1++;
+    }
+    ctx = ctx.__proto__;
+    const b2 = list(c_block2);
+    let txt2 = ctx['a'];
+    let txt3 = ctx['b'];
+    let txt4 = ctx['c'];
+    return block1([txt2, txt3, txt4], [b2]);
+  }
+}"
+`;
+
+exports[`t-for t-call with body in t-for in t-for 2`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(\` [\`);
+    const b3 = text(ctx['a']);
+    const b4 = text(\`] [\`);
+    const b5 = text(ctx['b']);
+    const b6 = text(\`] [\`);
+    const b7 = text(ctx['c']);
+    const b8 = text(\`] \`);
+    return multi([b2, b3, b4, b5, b6, b7, b8]);
+  }
+}"
+`;
+
+exports[`t-for t-call without body in t-for in t-for 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  const callTemplate_1 = app.getTemplate(\`sub\`);
+  
+  let block1 = createBlock(\`<div><block-child-0/><span>[<block-text-0/>][<block-text-1/>][<block-text-2/>]</span></div>\`);
+  let block6 = createBlock(\`<span><block-text-0/></span>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['a'] of ctx['numbers']) {
+      const key1 = ctx['a'];
+      ctx = Object.create(ctx);
+      const c_block4 = [];
+      let i2 = 0;
+      for (ctx['b'] of ctx['letters']) {
+        const key2 = ctx['b'];
+        c_block4[i2] = withKey(callTemplate_1.call(this, ctx, node, key + \`__1__\${key1}__\${key2}\`), key2);
+        i2++;
+      }
+      ctx = ctx.__proto__;
+      const b4 = list(c_block4);
+      let txt1 = ctx['c'];
+      const b6 = block6([txt1]);
+      c_block2[i1] = withKey(multi([b4, b6]), key1);
+      i1++;
+    }
+    ctx = ctx.__proto__;
+    const b2 = list(c_block2);
+    let txt2 = ctx['a'];
+    let txt3 = ctx['b'];
+    let txt4 = ctx['c'];
+    return block1([txt2, txt3, txt4], [b2]);
+  }
+}"
+`;
+
+exports[`t-for t-call without body in t-for in t-for 2`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { isBoundary, withDefault, setContextValue } = helpers;
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    ctx[isBoundary] = 1
+    setContextValue(ctx, \\"c\\", 'x'+'_'+ctx['a']+'_'+ctx['b']);
+    const b2 = text(\` [\`);
+    const b3 = text(ctx['a']);
+    const b4 = text(\`] [\`);
+    const b5 = text(ctx['b']);
+    const b6 = text(\`] [\`);
+    const b7 = text(ctx['c']);
+    const b8 = text(\`] \`);
+    return multi([b2, b3, b4, b5, b6, b7, b8]);
+  }
+}"
+`;
+
+exports[`t-for t-for in t-for 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['number'] of ctx['numbers']) {
+      const key1 = ctx['number'];
+      ctx = Object.create(ctx);
+      const c_block3 = [];
+      let i2 = 0;
+      for (ctx['letter'] of ctx['letters']) {
+        const key2 = ctx['letter'];
+        const b5 = text(\` [\`);
+        const b6 = text(ctx['number']);
+        const b7 = text(ctx['letter']);
+        const b8 = text(\`] \`);
+        c_block3[i2] = withKey(multi([b5, b6, b7, b8]), key2);
+        i2++;
+      }
+      ctx = ctx.__proto__;
+      c_block2[i1] = withKey(list(c_block3), key1);
+      i1++;
+    }
+    const b2 = list(c_block2);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`t-for t-for in t-foreach 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { prepareList, withKey } = helpers;
+  
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['numbers']);;
+    for (let i1 = 0; i1 < l_block2; i1++) {
+      ctx[\`number\`] = v_block2[i1];
+      const key1 = ctx['number'];
+      ctx = Object.create(ctx);
+      const c_block3 = [];
+      let i2 = 0;
+      for (ctx['letter'] of ctx['letters']) {
+        const key2 = ctx['letter'];
+        const b5 = text(\` [\`);
+        const b6 = text(ctx['number']);
+        const b7 = text(ctx['letter']);
+        const b8 = text(\`] \`);
+        c_block3[i2] = withKey(multi([b5, b6, b7, b8]), key2);
+        i2++;
+      }
+      ctx = ctx.__proto__;
+      c_block2[i1] = withKey(list(c_block3), key1);
+    }
+    const b2 = list(c_block2);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`t-for t-for with t-if inside (no external node) 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  
+  let block3 = createBlock(\`<span><block-text-0/></span>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block1 = [];
+    let i1 = 0;
+    for ({id:ctx['id'],text:ctx['text']} of ctx['elems']) {
+      const key1 = ctx['id'];
+      let b3;
+      if (ctx['id']<3) {
+        let txt1 = ctx['text'];
+        b3 = block3([txt1]);
+      }
+      c_block1[i1] = withKey(multi([b3]), key1);
+      i1++;
+    }
+    return list(c_block1);
+  }
+}"
+`;
+
+exports[`t-for t-for with t-if inside 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  let block4 = createBlock(\`<span><block-text-0/></span>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for ({id:ctx['id'],text:ctx['text']} of ctx['elems']) {
+      const key1 = ctx['id'];
+      let b4;
+      if (ctx['id']<3) {
+        let txt1 = ctx['text'];
+        b4 = block4([txt1]);
+      }
+      c_block2[i1] = withKey(multi([b4]), key1);
+      i1++;
+    }
+    const b2 = list(c_block2);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`t-for t-foreach in t-for 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { prepareList, withKey } = helpers;
+  
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['number'] of ctx['numbers']) {
+      const key1 = ctx['number'];
+      ctx = Object.create(ctx);
+      const [k_block3, v_block3, l_block3, c_block3] = prepareList(ctx['letters']);;
+      for (let i2 = 0; i2 < l_block3; i2++) {
+        ctx[\`letter\`] = v_block3[i2];
+        const key2 = ctx['letter'];
+        const b5 = text(\` [\`);
+        const b6 = text(ctx['number']);
+        const b7 = text(ctx['letter']);
+        const b8 = text(\`] \`);
+        c_block3[i2] = withKey(multi([b5, b6, b7, b8]), key2);
+      }
+      ctx = ctx.__proto__;
+      c_block2[i1] = withKey(list(c_block3), key1);
+      i1++;
+    }
+    const b2 = list(c_block2);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`t-for t-key on t-for 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  let block3 = createBlock(\`<span/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['thing'] of ctx['things']) {
+      const key1 = ctx['thing'];
+      c_block2[i1] = withKey(block3(), key1);
+      i1++;
+    }
+    const b2 = list(c_block2);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`t-for throws error if invalid loop expression 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  let block3 = createBlock(\`<span/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['item'] of ctx['abc']) {
+      const key1 = ctx['item'];
+      const tKey_1 = ctx['item'];
+      c_block2[i1] = withKey(block3(), tKey_1 + key1);
+      i1++;
+    }
+    const b2 = list(c_block2);
+    return block1([], [b2]);
+  }
+}"
+`;

tests/compiler/__snapshots__/t_foreach.test.ts.snap

@@ -12,7 +12,7 @@ exports[`t-foreach does not pollute the rendering context 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList([1]);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`item\`] = k_block2[i1];
+      ctx[\`item\`] = v_block2[i1];
       const key1 = ctx['item'];
       c_block2[i1] = withKey(text(ctx['item']), key1);
     }
@@ -35,7 +35,7 @@ exports[`t-foreach iterate on items (on a element node) 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList([1,2]);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`item\`] = k_block2[i1];
+      ctx[\`item\`] = v_block2[i1];
       const key1 = ctx['item'];
       let txt1 = ctx['item'];
       c_block2[i1] = withKey(block3([txt1]), key1);
@@ -58,9 +58,9 @@ exports[`t-foreach iterate on items 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList([3,2,1]);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`item\`] = k_block2[i1];
+      ctx[\`item\`] = v_block2[i1];
       ctx[\`item_index\`] = i1;
-      ctx[\`item_value\`] = v_block2[i1];
+      ctx[\`item_value\`] = k_block2[i1];
       const key1 = ctx['item'];
       const b4 = text(\` [\`);
       const b5 = text(ctx['item_index']);
@@ -87,9 +87,9 @@ exports[`t-foreach iterate, Map param 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['value']);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`item\`] = k_block1[i1];
+      ctx[\`item\`] = v_block1[i1];
       ctx[\`item_index\`] = i1;
-      ctx[\`item_value\`] = v_block1[i1];
+      ctx[\`item_value\`] = k_block1[i1];
       const key1 = ctx['item_index'];
       const b3 = text(\` [\`);
       const b4 = text(ctx['item_index']);
@@ -115,9 +115,9 @@ exports[`t-foreach iterate, Set param 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['value']);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`item\`] = k_block1[i1];
+      ctx[\`item\`] = v_block1[i1];
       ctx[\`item_index\`] = i1;
-      ctx[\`item_value\`] = v_block1[i1];
+      ctx[\`item_value\`] = k_block1[i1];
       const key1 = ctx['item_index'];
       const b3 = text(\` [\`);
       const b4 = text(ctx['item_index']);
@@ -145,9 +145,9 @@ exports[`t-foreach iterate, dict param 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['value']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`item\`] = k_block2[i1];
+      ctx[\`item\`] = v_block2[i1];
       ctx[\`item_index\`] = i1;
-      ctx[\`item_value\`] = v_block2[i1];
+      ctx[\`item_value\`] = k_block2[i1];
       const key1 = ctx['item_index'];
       const b4 = text(\` [\`);
       const b5 = text(ctx['item_index']);
@@ -174,9 +174,9 @@ exports[`t-foreach iterate, generator param 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['gen']());;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`item\`] = k_block1[i1];
+      ctx[\`item\`] = v_block1[i1];
       ctx[\`item_index\`] = i1;
-      ctx[\`item_value\`] = v_block1[i1];
+      ctx[\`item_value\`] = k_block1[i1];
       const key1 = ctx['item_index'];
       const b3 = text(\` [\`);
       const b4 = text(ctx['item_index']);
@@ -202,9 +202,9 @@ exports[`t-foreach iterate, iterable param 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['map'].values());;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`item\`] = k_block1[i1];
+      ctx[\`item\`] = v_block1[i1];
       ctx[\`item_index\`] = i1;
-      ctx[\`item_value\`] = v_block1[i1];
+      ctx[\`item_value\`] = k_block1[i1];
       const key1 = ctx['item_index'];
       const b3 = text(\` [\`);
       const b4 = text(ctx['item_index']);
@@ -232,9 +232,9 @@ exports[`t-foreach iterate, position 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(Array(5));;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`elem\`] = k_block2[i1];
+      ctx[\`elem\`] = v_block2[i1];
       ctx[\`elem_first\`] = i1 === 0;
-      ctx[\`elem_last\`] = i1 === k_block2.length - 1;
+      ctx[\`elem_last\`] = i1 === v_block2.length - 1;
       ctx[\`elem_index\`] = i1;
       const key1 = ctx['elem'];
       let b4,b5,b6,b7,b8,b9;
@@ -268,7 +268,7 @@ exports[`t-foreach simple iteration (in a node) 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList([3,2,1]);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`item\`] = k_block2[i1];
+      ctx[\`item\`] = v_block2[i1];
       const key1 = ctx['item'];
       c_block2[i1] = withKey(text(ctx['item']), key1);
     }
@@ -288,7 +288,7 @@ exports[`t-foreach simple iteration 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList([3,2,1]);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`item\`] = k_block1[i1];
+      ctx[\`item\`] = v_block1[i1];
       const key1 = ctx['item'];
       c_block1[i1] = withKey(text(ctx['item']), key1);
     }
@@ -310,7 +310,7 @@ exports[`t-foreach simple iteration with two nodes inside 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList([3,2,1]);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`item\`] = k_block1[i1];
+      ctx[\`item\`] = v_block1[i1];
       const key1 = ctx['item'];
       let txt1 = ctx['item'];
       const b3 = block3([txt1]);
@@ -339,20 +339,20 @@ exports[`t-foreach t-call with body in t-foreach in t-foreach 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['numbers']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`a\`] = k_block2[i1];
+      ctx[\`a\`] = v_block2[i1];
       ctx[\`a_first\`] = i1 === 0;
-      ctx[\`a_last\`] = i1 === k_block2.length - 1;
+      ctx[\`a_last\`] = i1 === v_block2.length - 1;
       ctx[\`a_index\`] = i1;
-      ctx[\`a_value\`] = v_block2[i1];
+      ctx[\`a_value\`] = k_block2[i1];
       const key1 = ctx['a'];
       ctx = Object.create(ctx);
       const [k_block4, v_block4, l_block4, c_block4] = prepareList(ctx['letters']);;
       for (let i2 = 0; i2 < l_block4; i2++) {
-        ctx[\`b\`] = k_block4[i2];
+        ctx[\`b\`] = v_block4[i2];
         ctx[\`b_first\`] = i2 === 0;
-        ctx[\`b_last\`] = i2 === k_block4.length - 1;
+        ctx[\`b_last\`] = i2 === v_block4.length - 1;
         ctx[\`b_index\`] = i2;
-        ctx[\`b_value\`] = v_block4[i2];
+        ctx[\`b_value\`] = k_block4[i2];
         const key2 = ctx['b'];
         ctx = Object.create(ctx);
         ctx[isBoundary] = 1;
@@ -408,20 +408,20 @@ exports[`t-foreach t-call without body in t-foreach in t-foreach 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['numbers']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`a\`] = k_block2[i1];
+      ctx[\`a\`] = v_block2[i1];
       ctx[\`a_first\`] = i1 === 0;
-      ctx[\`a_last\`] = i1 === k_block2.length - 1;
+      ctx[\`a_last\`] = i1 === v_block2.length - 1;
       ctx[\`a_index\`] = i1;
-      ctx[\`a_value\`] = v_block2[i1];
+      ctx[\`a_value\`] = k_block2[i1];
       const key1 = ctx['a'];
       ctx = Object.create(ctx);
       const [k_block4, v_block4, l_block4, c_block4] = prepareList(ctx['letters']);;
       for (let i2 = 0; i2 < l_block4; i2++) {
-        ctx[\`b\`] = k_block4[i2];
+        ctx[\`b\`] = v_block4[i2];
         ctx[\`b_first\`] = i2 === 0;
-        ctx[\`b_last\`] = i2 === k_block4.length - 1;
+        ctx[\`b_last\`] = i2 === v_block4.length - 1;
         ctx[\`b_index\`] = i2;
-        ctx[\`b_value\`] = v_block4[i2];
+        ctx[\`b_value\`] = k_block4[i2];
         const key2 = ctx['b'];
         c_block4[i2] = withKey(callTemplate_1.call(this, ctx, node, key + \`__1__\${key1}__\${key2}\`), key2);
       }
@@ -475,12 +475,12 @@ exports[`t-foreach t-foreach in t-foreach 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['numbers']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`number\`] = k_block2[i1];
+      ctx[\`number\`] = v_block2[i1];
       const key1 = ctx['number'];
       ctx = Object.create(ctx);
       const [k_block3, v_block3, l_block3, c_block3] = prepareList(ctx['letters']);;
       for (let i2 = 0; i2 < l_block3; i2++) {
-        ctx[\`letter\`] = k_block3[i2];
+        ctx[\`letter\`] = v_block3[i2];
         const key2 = ctx['letter'];
         const b5 = text(\` [\`);
         const b6 = text(ctx['number']);
@@ -509,7 +509,7 @@ exports[`t-foreach t-foreach with t-if inside (no external node) 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['elems']);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`elem\`] = k_block1[i1];
+      ctx[\`elem\`] = v_block1[i1];
       const key1 = ctx['elem'].id;
       let b3;
       if (ctx['elem'].id<3) {
@@ -536,7 +536,7 @@ exports[`t-foreach t-foreach with t-if inside 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['elems']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`elem\`] = k_block2[i1];
+      ctx[\`elem\`] = v_block2[i1];
       const key1 = ctx['elem'].id;
       let b4;
       if (ctx['elem'].id<3) {
@@ -564,7 +564,7 @@ exports[`t-foreach t-key on t-foreach 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['things']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`thing\`] = k_block2[i1];
+      ctx[\`thing\`] = v_block2[i1];
       const key1 = ctx['thing'];
       c_block2[i1] = withKey(block3(), key1);
     }
@@ -587,7 +587,7 @@ exports[`t-foreach throws error if invalid loop expression 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['abc']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`item\`] = k_block2[i1];
+      ctx[\`item\`] = v_block2[i1];
       ctx[\`item_index\`] = i1;
       const key1 = ctx['item'];
       const tKey_1 = ctx['item_index'];
@@ -614,7 +614,7 @@ exports[`t-foreach with t-memo 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['items']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`item\`] = k_block2[i1];
+      ctx[\`item\`] = v_block2[i1];
       const key1 = ctx['item'].id;
       const memo1 = [ctx['item'].x];
       const vnode1 = cache[key1];;

tests/compiler/__snapshots__/t_key.test.ts.snap

@@ -58,7 +58,7 @@ exports[`t-key t-key directive in a list 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['beers']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`beer\`] = k_block2[i1];
+      ctx[\`beer\`] = v_block2[i1];
       const key1 = ctx['beer'].id;
       let txt1 = ctx['beer'].name;
       c_block2[i1] = withKey(block3([txt1]), key1);

tests/compiler/__snapshots__/t_ref.test.ts.snap

@@ -105,7 +105,7 @@ exports[`t-ref refs in a loop 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['items']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`item\`] = k_block2[i1];
+      ctx[\`item\`] = v_block2[i1];
       const key1 = ctx['item'];
       const tKey_1 = ctx['item'];
       const v1 = ctx['item'];

tests/compiler/__snapshots__/t_set.test.ts.snap

@@ -335,6 +335,99 @@ exports[`t-set t-set evaluates an expression only once 1`] = `
 }"
 `;
 
+exports[`t-set t-set outside modified in t-for 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { isBoundary, withDefault, setContextValue, withKey } = helpers;
+  
+  let block1 = createBlock(\`<div><block-child-0/><p>EndLoop: <block-text-0/></p></div>\`);
+  let block3 = createBlock(\`<p>InLoop: <block-text-0/></p>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    ctx[isBoundary] = 1
+    setContextValue(ctx, \\"iter\\", 0);
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['val'] of ['a','b']) {
+      const key1 = ctx['val'];
+      let txt1 = ctx['iter'];
+      c_block2[i1] = withKey(block3([txt1]), key1);
+      setContextValue(ctx, \\"iter\\", ctx['iter']+1);
+      i1++;
+    }
+    ctx = ctx.__proto__;
+    const b2 = list(c_block2);
+    let txt2 = ctx['iter'];
+    return block1([txt2], [b2]);
+  }
+}"
+`;
+
+exports[`t-set t-set outside modified in t-for increment-after operator 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { isBoundary, withDefault, setContextValue, withKey } = helpers;
+  
+  let block1 = createBlock(\`<div><block-child-0/><p>EndLoop: <block-text-0/></p></div>\`);
+  let block3 = createBlock(\`<p>InLoop: <block-text-0/></p>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    ctx[isBoundary] = 1
+    setContextValue(ctx, \\"iter\\", 0);
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['val'] of ['a','b']) {
+      const key1 = ctx['val'];
+      let txt1 = ctx['iter'];
+      c_block2[i1] = withKey(block3([txt1]), key1);
+      setContextValue(ctx, \\"iter\\", ctx['iter']++);
+      i1++;
+    }
+    ctx = ctx.__proto__;
+    const b2 = list(c_block2);
+    let txt2 = ctx['iter'];
+    return block1([txt2], [b2]);
+  }
+}"
+`;
+
+exports[`t-set t-set outside modified in t-for increment-before operator 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { isBoundary, withDefault, setContextValue, withKey } = helpers;
+  
+  let block1 = createBlock(\`<div><block-child-0/><p>EndLoop: <block-text-0/></p></div>\`);
+  let block3 = createBlock(\`<p>InLoop: <block-text-0/></p>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    ctx[isBoundary] = 1
+    setContextValue(ctx, \\"iter\\", 0);
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['val'] of ['a','b']) {
+      const key1 = ctx['val'];
+      let txt1 = ctx['iter'];
+      c_block2[i1] = withKey(block3([txt1]), key1);
+      setContextValue(ctx, \\"iter\\", ++ctx['iter']);
+      i1++;
+    }
+    ctx = ctx.__proto__;
+    const b2 = list(c_block2);
+    let txt2 = ctx['iter'];
+    return block1([txt2], [b2]);
+  }
+}"
+`;
+
 exports[`t-set t-set outside modified in t-foreach 1`] = `
 "function anonymous(app, bdom, helpers
 ) {
@@ -351,7 +444,7 @@ exports[`t-set t-set outside modified in t-foreach 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(['a','b']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`val\`] = k_block2[i1];
+      ctx[\`val\`] = v_block2[i1];
       const key1 = ctx['val'];
       let txt1 = ctx['iter'];
       c_block2[i1] = withKey(block3([txt1]), key1);
@@ -381,7 +474,7 @@ exports[`t-set t-set outside modified in t-foreach increment-after operator 1`]
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(['a','b']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`val\`] = k_block2[i1];
+      ctx[\`val\`] = v_block2[i1];
       const key1 = ctx['val'];
       let txt1 = ctx['iter'];
       c_block2[i1] = withKey(block3([txt1]), key1);
@@ -411,7 +504,7 @@ exports[`t-set t-set outside modified in t-foreach increment-before operator 1`]
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(['a','b']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`val\`] = k_block2[i1];
+      ctx[\`val\`] = v_block2[i1];
       const key1 = ctx['val'];
       let txt1 = ctx['iter'];
       c_block2[i1] = withKey(block3([txt1]), key1);
@@ -441,7 +534,7 @@ exports[`t-set t-set should reuse variable if possible 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['list']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`elem\`] = k_block2[i1];
+      ctx[\`elem\`] = v_block2[i1];
       ctx[\`elem_index\`] = i1;
       const key1 = ctx['elem_index'];
       let txt1 = ctx['v'];
@@ -454,6 +547,35 @@ exports[`t-set t-set should reuse variable if possible 1`] = `
 }"
 `;
 
+exports[`t-set t-set should reuse variable if possible: for..of 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { isBoundary, withDefault, setContextValue, withKey } = helpers;
+  
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  let block3 = createBlock(\`<div><span>v<block-text-0/></span></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    ctx[isBoundary] = 1
+    setContextValue(ctx, \\"v\\", 1);
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['elem'] of ctx['list']) {
+      const key1 = ctx['elem_index'];
+      let txt1 = ctx['v'];
+      setContextValue(ctx, \\"v\\", ctx['elem']);
+      c_block2[i1] = withKey(block3([txt1]), key1);
+      i1++;
+    }
+    const b2 = list(c_block2);
+    return block1([], [b2]);
+  }
+}"
+`;
+
 exports[`t-set t-set with content and sub t-esc 1`] = `
 "function anonymous(app, bdom, helpers
 ) {

tests/compiler/t_for.test.ts

@@ -0,0 +1,317 @@
+import {
+  renderToBdom,
+  renderToString,
+  snapshotEverything,
+  TestContext,
+  makeTestFixture,
+} from "../helpers";
+import { mount, patch } from "../../src/runtime/blockdom";
+
+snapshotEverything();
+
+// -----------------------------------------------------------------------------
+// t-for
+// -----------------------------------------------------------------------------
+
+describe("t-for", () => {
+  test("simple iteration", () => {
+    const template = `<t t-for="item" t-of="[3, 2, 1]" t-key="item"><t t-esc="item"/></t>`;
+    expect(renderToString(template)).toBe("321");
+  });
+
+  test("simple iteration with two nodes inside", () => {
+    const template = `
+      <t t-for="item" t-of="[3, 2, 1]" t-key="item">
+        <span>a<t t-esc="item"/></span>
+        <span>b<t t-esc="item"/></span>
+      </t>`;
+    const expected =
+      "<span>a3</span><span>b3</span><span>a2</span><span>b2</span><span>a1</span><span>b1</span>";
+    expect(renderToString(template)).toBe(expected);
+  });
+
+  test("destructuring array items", () => {
+    const template = `<t t-for="[key, value]" t-of="Object.entries({ a: 1, b: 2 })" t-key="key">(<t t-esc="key"/>: <t t-esc="value"/>)</t>`;
+    expect(renderToString(template)).toBe("(a: 1)(b: 2)");
+  });
+
+  test("destructuring array items: rest", () => {
+    const template = `<t t-for="[head, ...tail]" t-of="[[1, 2, 3], [4, 5, 6]]" t-key="head">(<t t-esc="head"/>;<t t-esc="tail"/>)</t>`;
+    expect(renderToString(template)).toBe("(1;2,3)(4;5,6)");
+  });
+
+  test("destructuring object items", () => {
+    const template = `<t t-for="{ k, v }" t-of="[{ k: 'a', v: 1 }, { k: 'b', v: 2 }]" t-key="k">(<t t-esc="k"/>: <t t-esc="v"/>)</t>`;
+    expect(renderToString(template)).toBe("(a: 1)(b: 2)");
+  });
+
+  test("destructuring object items: rest", () => {
+    const template = `<t t-for="{ k, v }" t-of="[{ k: 'a', v: 1 }, { k: 'b', v: 2 }]" t-key="k">(<t t-esc="k"/>: <t t-esc="v"/>)</t>`;
+    expect(renderToString(template)).toBe("(a: 1)(b: 2)");
+  });
+
+  test("nested destructuring", () => {
+    const template = `<t t-for="[key, {left, right}]" t-of="Object.entries(obj)" t-key="key">(<t t-esc="key"/>: [<t t-esc="left"/>, <t t-esc="right"/>])</t>`;
+    expect(
+      renderToString(template, {
+        obj: {
+          a: { left: 1, right: 2 },
+          b: { left: 3, right: 4 },
+        },
+      })
+    ).toBe("(a: [1, 2])(b: [3, 4])");
+  });
+
+  test("t-key on t-for", async () => {
+    const template = `
+        <div>
+          <t t-for="thing" t-of="things" t-key="thing">
+            <span/>
+          </t>
+        </div>`;
+
+    const fixture = makeTestFixture();
+
+    const vnode1 = renderToBdom(template, { things: [1, 2] });
+    mount(vnode1, fixture);
+    let elm = fixture;
+    expect(elm.innerHTML).toBe("<div><span></span><span></span></div>");
+    const first = elm.querySelectorAll("span")[0];
+    const second = elm.querySelectorAll("span")[1];
+
+    const vnode2 = renderToBdom(template, { things: [2, 1] });
+    patch(vnode1, vnode2);
+
+    expect(elm.innerHTML).toBe("<div><span></span><span></span></div>");
+    expect(first).toBe(elm.querySelectorAll("span")[1]);
+    expect(second).toBe(elm.querySelectorAll("span")[0]);
+  });
+
+  test("simple iteration (in a node)", () => {
+    const template = `
+        <div>
+          <t t-for="item" t-of="[3, 2, 1]" t-key="item"><t t-esc="item"/></t>
+        </div>`;
+    expect(renderToString(template)).toBe("<div>321</div>");
+  });
+
+  test("iterate on items (on a element node)", () => {
+    const template = `
+        <div>
+          <span t-for="item" t-of="[1, 2]" t-key="item"><t t-esc="item"/></span>
+        </div>`;
+    const expected = `<div><span>1</span><span>2</span></div>`;
+    expect(renderToString(template)).toBe(expected);
+  });
+
+  test("iterate, Map param", () => {
+    const template = `
+      <t t-for="[key, value]" t-of="map" t-key="key">
+        [<t t-esc="key"/>: <t t-esc="value"/>]
+      </t>`;
+    const expected = ` [a: 1]  [b: 2]  [c: 3] `;
+    const context = {
+      map: new Map([
+        ["a", 1],
+        ["b", 2],
+        ["c", 3],
+      ]),
+    };
+    expect(renderToString(template, context)).toBe(expected);
+  });
+
+  test("iterate, Set param", () => {
+    const template = `
+      <t t-for="item" t-of="set" t-key="item">
+        <t t-esc="item"/>
+      </t>`;
+    const expected = `123`;
+    const context = { set: new Set([1, 2, 3]) };
+    expect(renderToString(template, context)).toBe(expected);
+  });
+
+  test("iterate, iterable param", () => {
+    const template = `
+      <t t-for="item" t-of="map.values()" t-key="item">
+        <t t-esc="item"/>
+      </t>`;
+    const expected = `123`;
+    const context = {
+      map: new Map([
+        ["a", 1],
+        ["b", 2],
+        ["c", 3],
+      ]),
+    };
+    expect(renderToString(template, context)).toBe(expected);
+  });
+
+  test("iterate, generator param", () => {
+    const template = `
+      <t t-for="item" t-of="gen()" t-key="item">
+        <t t-esc="item"/>
+      </t>`;
+    const expected = `123`;
+    const context = {
+      *gen() {
+        yield 1;
+        yield 2;
+        yield 3;
+      },
+    };
+    expect(renderToString(template, context)).toBe(expected);
+  });
+
+  test("does not pollute the rendering context", () => {
+    const template = `
+        <div>
+          <t t-for="item" t-of="[1]" t-key="item"><t t-esc="item"/></t>
+        </div>`;
+    const context = { __owl__: {} };
+    renderToString(template, context);
+    expect(Object.keys(context)).toEqual(["__owl__"]);
+  });
+
+  test("t-for in t-for", () => {
+    const template = `
+        <div>
+          <t t-for="number" t-of="numbers" t-key="number">
+            <t t-for="letter" t-of="letters" t-key="letter">
+              [<t t-esc="number"/><t t-esc="letter"/>]
+            </t>
+          </t>
+        </div>`;
+
+    const context = { numbers: [1, 2, 3], letters: ["a", "b"] };
+    const expected = "<div> [1a]  [1b]  [2a]  [2b]  [3a]  [3b] </div>";
+    expect(renderToString(template, context)).toBe(expected);
+  });
+
+  test("t-for in t-foreach", () => {
+    const template = `
+        <div>
+          <t t-foreach="numbers" t-as="number" t-key="number">
+            <t t-for="letter" t-of="letters" t-key="letter">
+              [<t t-esc="number"/><t t-esc="letter"/>]
+            </t>
+          </t>
+        </div>`;
+
+    const context = { numbers: [1, 2, 3], letters: ["a", "b"] };
+    const expected = "<div> [1a]  [1b]  [2a]  [2b]  [3a]  [3b] </div>";
+    expect(renderToString(template, context)).toBe(expected);
+  });
+
+  test("t-foreach in t-for", () => {
+    const template = `
+        <div>
+          <t t-for="number" t-of="numbers" t-key="number">
+            <t t-foreach="letters" t-as="letter" t-key="letter">
+              [<t t-esc="number"/><t t-esc="letter"/>]
+            </t>
+          </t>
+        </div>`;
+
+    const context = { numbers: [1, 2, 3], letters: ["a", "b"] };
+    const expected = "<div> [1a]  [1b]  [2a]  [2b]  [3a]  [3b] </div>";
+    expect(renderToString(template, context)).toBe(expected);
+  });
+
+  test("t-call without body in t-for in t-for", () => {
+    const context = new TestContext();
+    const sub = `
+        <t>
+          <t t-set="c" t-value="'x' + '_' + a + '_'+ b" />
+          [<t t-esc="a" />]
+          [<t t-esc="b" />]
+          [<t t-esc="c" />]
+        </t>`;
+
+    const main = `
+        <div>
+          <t t-for="a" t-of="numbers" t-key="a">
+            <t t-for="b" t-of="letters" t-key="b">
+              <t t-call="sub" />
+            </t>
+            <span t-esc="c"/>
+          </t>
+          <span>[<t t-esc="a" />][<t t-esc="b" />][<t t-esc="c" />]</span>
+        </div>`;
+
+    context.addTemplate("sub", sub);
+    context.addTemplate("main", main);
+
+    const ctx = { numbers: [1, 2, 3], letters: ["a", "b"] };
+    const expected =
+      "<div> [1] [a] [x_1_a]  [1] [b] [x_1_b] <span></span> [2] [a] [x_2_a]  [2] [b] [x_2_b] <span></span> [3] [a] [x_3_a]  [3] [b] [x_3_b] <span></span><span>[][][]</span></div>";
+    expect(context.renderToString("main", ctx)).toBe(expected);
+  });
+
+  test("t-call with body in t-for in t-for", () => {
+    const context = new TestContext();
+    const sub = `
+        <t>
+          [<t t-esc="a" />]
+          [<t t-esc="b" />]
+          [<t t-esc="c" />]
+        </t>`;
+
+    const main = `
+        <div>
+          <t t-for="a" t-of="numbers" t-key="a">
+            <t t-for="b" t-of="letters" t-key="b">
+              <t t-call="sub" >
+                <t t-set="c" t-value="'x' + '_' + a + '_'+ b" />
+              </t>
+            </t>
+            <span t-esc="c"/>
+          </t>
+          <span>[<t t-esc="a" />][<t t-esc="b" />][<t t-esc="c" />]</span>
+        </div>`;
+
+    context.addTemplate("sub", sub);
+    context.addTemplate("main", main);
+
+    const ctx = { numbers: [1, 2, 3], letters: ["a", "b"] };
+    const expected =
+      "<div> [1] [a] [x_1_a]  [1] [b] [x_1_b] <span></span> [2] [a] [x_2_a]  [2] [b] [x_2_b] <span></span> [3] [a] [x_3_a]  [3] [b] [x_3_b] <span></span><span>[][][]</span></div>";
+    expect(context.renderToString("main", ctx)).toBe(expected);
+  });
+
+  test("throws error if invalid loop expression", () => {
+    const test = `<div><t t-for="item" t-of="abc" t-key="item"><span t-key="item"/></t></div>`;
+    expect(() => renderToString(test)).toThrow("ctx.abc is not iterable");
+  });
+
+  test("t-for with t-if inside", () => {
+    const template = `
+        <div>
+          <t t-for="{ id, text }" t-of="elems" t-key="id">
+            <span t-if="id lt 3"><t t-esc="text"/></span>
+          </t>
+        </div>`;
+    const ctx = {
+      elems: [
+        { id: 1, text: "a" },
+        { id: 2, text: "b" },
+        { id: 3, text: "c" },
+      ],
+    };
+    expect(renderToString(template, ctx)).toBe("<div><span>a</span><span>b</span></div>");
+  });
+
+  test("t-for with t-if inside (no external node)", () => {
+    const template = `
+          <t t-for="{ id, text }" t-of="elems" t-key="id">
+            <span t-if="id lt 3"><t t-esc="text"/></span>
+          </t>`;
+    const ctx = {
+      elems: [
+        { id: 1, text: "a" },
+        { id: 2, text: "b" },
+        { id: 3, text: "c" },
+      ],
+    };
+    expect(renderToString(template, ctx)).toBe("<span>a</span><span>b</span>");
+  });
+});

tests/compiler/t_foreach.test.ts

@@ -110,7 +110,7 @@ describe("t-foreach", () => {
       <t t-foreach="value" t-as="item" t-key="item_index">
         [<t t-esc="item_index"/>: <t t-esc="item"/> <t t-esc="item_value"/>]
       </t>`;
-    const expected = ` [0: a 1]  [1: b 2]  [2: c 3] `;
+    const expected = ` [0: 1 a]  [1: 2 b]  [2: 3 c] `;
     const context = {
       value: new Map([
         ["a", 1],

tests/compiler/t_set.test.ts

@@ -122,6 +122,19 @@ describe("t-set", () => {
     expect(renderToString(template, { list: ["a", "b"] })).toBe(expected);
   });
 
+  test("t-set should reuse variable if possible: for..of", () => {
+    const template = `
+        <div>
+          <t t-set="v" t-value="1"/>
+          <div t-for="elem" t-of="list" t-key="elem_index">
+              <span>v<t t-esc="v"/></span>
+              <t t-set="v" t-value="elem"/>
+          </div>
+        </div>`;
+    const expected = "<div><div><span>v1</span></div><div><span>va</span></div></div>";
+    expect(renderToString(template, { list: ["a", "b"] })).toBe(expected);
+  });
+
   test("t-set with content and sub t-esc", () => {
     const template = `
         <div>
@@ -232,6 +245,22 @@ describe("t-set", () => {
     );
   });
 
+  test("t-set outside modified in t-for", async () => {
+    const template = `
+      <div>
+        <t t-set="iter" t-value="0"/>
+        <t t-for="val" t-of="['a','b']" t-key="val">
+          <p>InLoop: <t t-esc="iter"/></p>
+          <t t-set="iter" t-value="iter + 1"/>
+        </t>
+        <p>EndLoop: <t t-esc="iter"/></p>
+      </div>
+    `;
+    expect(renderToString(template)).toBe(
+      "<div><p>InLoop: 0</p><p>InLoop: 1</p><p>EndLoop: 2</p></div>"
+    );
+  });
+
   test("t-set outside modified in t-foreach increment-after operator", async () => {
     const template = `
       <div>
@@ -248,6 +277,22 @@ describe("t-set", () => {
     );
   });
 
+  test("t-set outside modified in t-for increment-after operator", async () => {
+    const template = `
+      <div>
+        <t t-set="iter" t-value="0"/>
+        <t t-for="val" t-of="['a','b']" t-key="val">
+          <p>InLoop: <t t-esc="iter"/></p>
+          <t t-set="iter" t-value="iter++"/>
+        </t>
+        <p>EndLoop: <t t-esc="iter"/></p>
+      </div>
+    `;
+    expect(renderToString(template)).toBe(
+      "<div><p>InLoop: 0</p><p>InLoop: 0</p><p>EndLoop: 0</p></div>"
+    );
+  });
+
   test("t-set outside modified in t-foreach increment-before operator", async () => {
     const template = `
       <div>
@@ -264,6 +309,22 @@ describe("t-set", () => {
     );
   });
 
+  test("t-set outside modified in t-for increment-before operator", async () => {
+    const template = `
+      <div>
+        <t t-set="iter" t-value="0"/>
+        <t t-for="val" t-of="['a','b']" t-key="val">
+          <p>InLoop: <t t-esc="iter"/></p>
+          <t t-set="iter" t-value="++iter"/>
+        </t>
+        <p>EndLoop: <t t-esc="iter"/></p>
+      </div>
+    `;
+    expect(renderToString(template)).toBe(
+      "<div><p>InLoop: 0</p><p>InLoop: 1</p><p>EndLoop: 0</p></div>"
+    );
+  });
+
   test("t-set can't alter from within callee", async () => {
     const context = new TestContext();
     const sub = `<div><t t-esc="iter"/><t t-set="iter" t-value="'called'"/><t t-esc="iter"/></div>`;

tests/components/__snapshots__/basics.test.ts.snap

@@ -492,7 +492,7 @@ exports[`basics list of two sub components inside other nodes 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].blips);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`blip\`] = k_block2[i1];
+      ctx[\`blip\`] = v_block2[i1];
       const key1 = ctx['blip'].id;
       const b4 = comp1({}, key + \`__1__\${key1}\`, node, this, null);
       const b5 = comp2({}, key + \`__2__\${key1}\`, node, this, null);
@@ -1084,7 +1084,7 @@ exports[`basics updating a component with t-foreach as root 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['items']);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`item\`] = k_block1[i1];
+      ctx[\`item\`] = v_block1[i1];
       const key1 = ctx['item'];
       c_block1[i1] = withKey(text(ctx['item']), key1);
     }
@@ -1135,7 +1135,7 @@ exports[`basics widget after a t-foreach 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(Array(2));;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`elem\`] = k_block2[i1];
+      ctx[\`elem\`] = v_block2[i1];
       ctx[\`elem_index\`] = i1;
       const key1 = ctx['elem_index'];
       c_block2[i1] = withKey(text(\`txt\`), key1);
@@ -1282,7 +1282,7 @@ exports[`t-out in components can render list of t-out  1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].items);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`item\`] = k_block2[i1];
+      ctx[\`item\`] = v_block2[i1];
       const key1 = ctx['item'];
       const b4 = text(ctx['item']);
       const b5 = safeOutput(ctx['item']);

tests/components/__snapshots__/concurrency.test.ts.snap

@@ -13,7 +13,7 @@ exports[`Cascading renders after microtaskTick 1`] = `
     ctx = Object.create(ctx);
     const [k_block4, v_block4, l_block4, c_block4] = prepareList(ctx['state']);;
     for (let i1 = 0; i1 < l_block4; i1++) {
-      ctx[\`elem\`] = k_block4[i1];
+      ctx[\`elem\`] = v_block4[i1];
       const key1 = ctx['elem'].id;
       c_block4[i1] = withKey(text(ctx['elem'].id), key1);
     }
@@ -34,7 +34,7 @@ exports[`Cascading renders after microtaskTick 2`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['state']);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`elem\`] = k_block1[i1];
+      ctx[\`elem\`] = v_block1[i1];
       const key1 = ctx['elem'].id;
       c_block1[i1] = withKey(comp1({id: ctx['elem'].id}, key + \`__1__\${key1}\`, node, this, null), key1);
     }
@@ -1901,7 +1901,7 @@ exports[`t-foreach with dynamic async component 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['list']);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`arr\`] = k_block1[i1];
+      ctx[\`arr\`] = v_block1[i1];
       ctx[\`arr_index\`] = i1;
       const key1 = ctx['arr_index'];
       let b3;

tests/components/__snapshots__/error_handling.test.ts.snap

@@ -950,7 +950,7 @@ exports[`can catch errors catching error, rethrow, render parent  -- a main comp
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(Object.values(ctx['state'].cps));;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`cp\`] = k_block1[i1];
+      ctx[\`cp\`] = v_block1[i1];
       const key1 = ctx['cp'].id;
       const v1 = ctx['this'];
       const v2 = ctx['cp'];
@@ -1029,7 +1029,7 @@ exports[`can catch errors catching in child makes parent render 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(Object.entries(ctx['this'].elements));;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`elem\`] = k_block1[i1];
+      ctx[\`elem\`] = v_block1[i1];
       const key1 = ctx['elem'][0];
       const v1 = ctx['this'];
       const v2 = ctx['elem'];

tests/components/__snapshots__/event_handling.test.ts.snap

@@ -117,7 +117,7 @@ exports[`event handling objects from scope are properly captured by t-on 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['items']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`item\`] = k_block2[i1];
+      ctx[\`item\`] = v_block2[i1];
       const key1 = ctx['item'];
       const v1 = ctx['onClick'];
       const v2 = ctx['item'];
@@ -158,7 +158,7 @@ exports[`event handling t-on with handler bound to dynamic argument on a t-forea
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['items']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`item\`] = k_block2[i1];
+      ctx[\`item\`] = v_block2[i1];
       const key1 = ctx['item'];
       const v1 = ctx['onClick'];
       const v2 = ctx['item'];

tests/components/__snapshots__/props.test.ts.snap

@@ -11,7 +11,7 @@ exports[`.alike suffix in a list 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['state'].elems);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`elem\`] = k_block1[i1];
+      ctx[\`elem\`] = v_block1[i1];
       const key1 = ctx['elem'].id;
       const v1 = ctx['this'];
       const v2 = ctx['elem'];
@@ -106,7 +106,7 @@ exports[`basics arrow functions as prop correctly capture their scope 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['items']);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`item\`] = k_block1[i1];
+      ctx[\`item\`] = v_block1[i1];
       const key1 = ctx['item'].val;
       const v1 = ctx['onClick'];
       const v2 = ctx['item'];

tests/components/__snapshots__/slots.test.ts.snap

@@ -2140,7 +2140,7 @@ exports[`slots slot in t-foreach locations 2`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['props'].list);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`elem\`] = k_block1[i1];
+      ctx[\`elem\`] = v_block1[i1];
       ctx[\`elem_index\`] = i1;
       const key1 = ctx['elem_index'];
       let txt1 = ctx['elem'];
@@ -2430,7 +2430,7 @@ exports[`slots slots are rendered with proper context, part 2 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].users);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`user\`] = k_block2[i1];
+      ctx[\`user\`] = v_block2[i1];
       const key1 = ctx['user'].id;
       const ctx1 = capture(ctx);
       const b7 = comp1({to: '/user/'+ctx['user'].id,slots: markRaw({'default': {__render: slot1.bind(this), __ctx: ctx1}})}, key + \`__1__\${key1}\`, node, this, null);
@@ -2478,7 +2478,7 @@ exports[`slots slots are rendered with proper context, part 3 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].users);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`user\`] = k_block2[i1];
+      ctx[\`user\`] = v_block2[i1];
       const key1 = ctx['user'].id;
       setContextValue(ctx, \\"userdescr\\", 'User '+ctx['user'].name);
       const ctx1 = capture(ctx);
@@ -2625,7 +2625,7 @@ exports[`slots slots in t-foreach and re-rendering 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(Array(2));;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`n\`] = k_block2[i1];
+      ctx[\`n\`] = v_block2[i1];
       ctx[\`n_index\`] = i1;
       const key1 = ctx['n_index'];
       const ctx1 = capture(ctx);
@@ -2674,14 +2674,14 @@ exports[`slots slots in t-foreach in t-foreach 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['tree']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`node1\`] = k_block2[i1];
+      ctx[\`node1\`] = v_block2[i1];
       const key1 = ctx['node1'].key;
       let txt1 = ctx['node1'].value;
       const b4 = block4([txt1]);
       ctx = Object.create(ctx);
       const [k_block6, v_block6, l_block6, c_block6] = prepareList(ctx['node1'].nodes);;
       for (let i2 = 0; i2 < l_block6; i2++) {
-        ctx[\`node2\`] = k_block6[i2];
+        ctx[\`node2\`] = v_block6[i2];
         const key2 = ctx['node2'].key;
         const ctx1 = capture(ctx);
         c_block6[i2] = withKey(comp1({slots: markRaw({'default': {__render: slot1.bind(this), __ctx: ctx1}})}, key + \`__1__\${key1}__\${key2}\`, node, this, null), key2);
@@ -2731,7 +2731,7 @@ exports[`slots slots in t-foreach with t-set and re-rendering 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(Array(2));;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`n\`] = k_block2[i1];
+      ctx[\`n\`] = v_block2[i1];
       ctx[\`n_index\`] = i1;
       const key1 = ctx['n_index'];
       setContextValue(ctx, \\"dummy\\", ctx['n_index']);
@@ -2881,11 +2881,11 @@ exports[`slots t-slot in recursive templates 1`] = `
     ctx = Object.create(ctx);
     const [k_block3, v_block3, l_block3, c_block3] = prepareList(ctx['items']);;
     for (let i1 = 0; i1 < l_block3; i1++) {
-      ctx[\`item\`] = k_block3[i1];
+      ctx[\`item\`] = v_block3[i1];
       ctx[\`item_first\`] = i1 === 0;
-      ctx[\`item_last\`] = i1 === k_block3.length - 1;
+      ctx[\`item_last\`] = i1 === v_block3.length - 1;
       ctx[\`item_index\`] = i1;
-      ctx[\`item_value\`] = v_block3[i1];
+      ctx[\`item_value\`] = k_block3[i1];
       const key1 = ctx['item'].name;
       let b5,b6;
       if (!ctx['item'].children.length) {

tests/components/__snapshots__/t_call.test.ts.snap

@@ -415,11 +415,11 @@ exports[`t-call t-call in t-foreach and children component 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(['a','b','c']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`val\`] = k_block2[i1];
+      ctx[\`val\`] = v_block2[i1];
       ctx[\`val_first\`] = i1 === 0;
-      ctx[\`val_last\`] = i1 === k_block2.length - 1;
+      ctx[\`val_last\`] = i1 === v_block2.length - 1;
       ctx[\`val_index\`] = i1;
-      ctx[\`val_value\`] = v_block2[i1];
+      ctx[\`val_value\`] = k_block2[i1];
       const key1 = ctx['val'];
       c_block2[i1] = withKey(callTemplate_1.call(this, ctx, node, key + \`__1__\${key1}\`), key1);
     }

tests/components/__snapshots__/t_for.test.ts.snap

@@ -0,0 +1,493 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`list of components components in a node in a t-for  1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  const comp1 = app.createComponent(\`Child\`, true, false, false, [\\"item\\"]);
+  
+  let block1 = createBlock(\`<div><ul><block-child-0/></ul></div>\`);
+  let block3 = createBlock(\`<li><block-child-0/></li>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['item'] of ctx['items']) {
+      const key1 = 'li_'+ctx['item'];
+      const b4 = comp1({item: ctx['item']}, key + \`__1__\${key1}\`, node, this, null);
+      c_block2[i1] = withKey(block3([], [b4]), key1);
+      i1++;
+    }
+    const b2 = list(c_block2);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`list of components components in a node in a t-for  2`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<div><block-text-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let txt1 = ctx['props'].item;
+    return block1([txt1]);
+  }
+}"
+`;
+
+exports[`list of components crash on duplicate key in dev mode 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { OwlError, withKey } = helpers;
+  const comp1 = app.createComponent(\`Child\`, true, false, false, []);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const keys1 = new Set();
+    const c_block1 = [];
+    let i1 = 0;
+    for (ctx['item'] of [1,2]) {
+      const key1 = 'child';
+      if (keys1.has(String(key1))) { throw new OwlError(\`Got duplicate key in t-for: \${key1}\`)}
+      keys1.add(String(key1));
+      const props1 = {};
+      helpers.validateProps(\`Child\`, props1, this);
+      c_block1[i1] = withKey(comp1(props1, key + \`__1__\${key1}\`, node, this, null), key1);
+      i1++;
+    }
+    return list(c_block1);
+  }
+}"
+`;
+
+exports[`list of components crash on duplicate key in dev mode 2`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(\`\`);
+  }
+}"
+`;
+
+exports[`list of components crash when using object as keys that serialize to the same string 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { OwlError, withKey } = helpers;
+  const comp1 = app.createComponent(\`Child\`, true, false, false, []);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const keys1 = new Set();
+    const c_block1 = [];
+    let i1 = 0;
+    for (ctx['item'] of [{},{}]) {
+      const key1 = ctx['item'];
+      if (keys1.has(String(key1))) { throw new OwlError(\`Got duplicate key in t-for: \${key1}\`)}
+      keys1.add(String(key1));
+      const props1 = {};
+      helpers.validateProps(\`Child\`, props1, this);
+      c_block1[i1] = withKey(comp1(props1, key + \`__1__\${key1}\`, node, this, null), key1);
+      i1++;
+    }
+    return list(c_block1);
+  }
+}"
+`;
+
+exports[`list of components crash when using object as keys that serialize to the same string 2`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(\`\`);
+  }
+}"
+`;
+
+exports[`list of components list of sub components inside other nodes 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  const comp1 = app.createComponent(\`SubComponent\`, true, false, false, []);
+  
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  let block3 = createBlock(\`<div><block-child-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['blip'] of ctx['state'].blips) {
+      const key1 = ctx['blip'].id;
+      const b4 = comp1({}, key + \`__1__\${key1}\`, node, this, null);
+      c_block2[i1] = withKey(block3([], [b4]), key1);
+      i1++;
+    }
+    const b2 = list(c_block2);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`list of components list of sub components inside other nodes 2`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<span>asdf</span>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    return block1();
+  }
+}"
+`;
+
+exports[`list of components order is correct when slots are not of same type 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { capture, markRaw } = helpers;
+  const comp1 = app.createComponent(\`Child\`, true, true, false, []);
+  
+  let block2 = createBlock(\`<div>A</div>\`);
+  
+  function slot1(ctx, node, key = \\"\\") {
+    let b2;
+    if (!ctx['state'].active) {
+      b2 = block2();
+    }
+    return multi([b2]);
+  }
+  
+  function slot2(ctx, node, key = \\"\\") {
+    return text(\`B\`);
+  }
+  
+  function slot3(ctx, node, key = \\"\\") {
+    return text(\`C\`);
+  }
+  
+  return function template(ctx, node, key = \\"\\") {
+    const ctx1 = capture(ctx);
+    return comp1({slots: markRaw({'a': {__render: slot1.bind(this), __ctx: ctx1, active: !ctx['state'].active}, 'b': {__render: slot2.bind(this), __ctx: ctx1, active: true}, 'c': {__render: slot3.bind(this), __ctx: ctx1, active: ctx['state'].active}})}, key + \`__1\`, node, this, null);
+  }
+}"
+`;
+
+exports[`list of components order is correct when slots are not of same type 2`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { callSlot, withKey } = helpers;
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block1 = [];
+    let i1 = 0;
+    for (ctx['slotName'] of ctx['slotNames']) {
+      const key1 = ctx['slotName'];
+      const slot1 = (ctx['slotName']);
+      c_block1[i1] = withKey(toggler(slot1, callSlot(ctx, node, key1 + \`__1__\${key1}\`, slot1, true, {})), key1);
+      i1++;
+    }
+    return list(c_block1);
+  }
+}"
+`;
+
+exports[`list of components reconciliation alg works for t-for in t-for 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  const comp1 = app.createComponent(\`Child\`, true, false, false, [\\"blip\\"]);
+  
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['section'] of ctx['state'].s) {
+      const key1 = ctx['section'];
+      ctx = Object.create(ctx);
+      const c_block3 = [];
+      let i2 = 0;
+      for (ctx['blip'] of ctx['section'].blips) {
+        const key2 = ctx['blip'];
+        c_block3[i2] = withKey(comp1({blip: ctx['blip']}, key + \`__1__\${key1}__\${key2}\`, node, this, null), key2);
+        i2++;
+      }
+      ctx = ctx.__proto__;
+      c_block2[i1] = withKey(list(c_block3), key1);
+      i1++;
+    }
+    const b2 = list(c_block2);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`list of components reconciliation alg works for t-for in t-for 2`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<div><block-text-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let txt1 = ctx['props'].blip;
+    return block1([txt1]);
+  }
+}"
+`;
+
+exports[`list of components reconciliation alg works for t-for in t-for, 2 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  const comp1 = app.createComponent(\`Child\`, true, false, false, [\\"row\\",\\"col\\"]);
+  
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  let block3 = createBlock(\`<p><block-child-0/></p>\`);
+  let block5 = createBlock(\`<p><block-child-0/></p>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['row'] of ctx['state'].rows) {
+      const key1 = ctx['row'];
+      ctx = Object.create(ctx);
+      const c_block4 = [];
+      let i2 = 0;
+      for (ctx['col'] of ctx['state'].cols) {
+        const key2 = ctx['col'];
+        const b6 = comp1({row: ctx['row'],col: ctx['col']}, key + \`__1__\${key1}__\${key2}\`, node, this, null);
+        c_block4[i2] = withKey(block5([], [b6]), key2);
+        i2++;
+      }
+      ctx = ctx.__proto__;
+      const b4 = list(c_block4);
+      c_block2[i1] = withKey(block3([], [b4]), key1);
+      i1++;
+    }
+    const b2 = list(c_block2);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`list of components reconciliation alg works for t-for in t-for, 2 2`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<div><block-text-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let txt1 = ctx['props'].row+'_'+ctx['props'].col;
+    return block1([txt1]);
+  }
+}"
+`;
+
+exports[`list of components simple list 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  const comp1 = app.createComponent(\`Child\`, true, false, false, [\\"value\\"]);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block1 = [];
+    let i1 = 0;
+    for (ctx['elem'] of ctx['state'].elems) {
+      const key1 = ctx['elem'].id;
+      c_block1[i1] = withKey(comp1({value: ctx['elem'].value}, key + \`__1__\${key1}\`, node, this, null), key1);
+      i1++;
+    }
+    return list(c_block1);
+  }
+}"
+`;
+
+exports[`list of components simple list 2`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<span><block-text-0/></span>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let txt1 = ctx['props'].value;
+    return block1([txt1]);
+  }
+}"
+`;
+
+exports[`list of components sub components rendered in a loop 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  const comp1 = app.createComponent(\`Child\`, true, false, false, [\\"n\\"]);
+  
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['number'] of ctx['state'].numbers) {
+      const key1 = ctx['number'];
+      c_block2[i1] = withKey(comp1({n: ctx['number']}, key + \`__1__\${key1}\`, node, this, null), key1);
+      i1++;
+    }
+    const b2 = list(c_block2);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`list of components sub components rendered in a loop 2`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<p><block-text-0/></p>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let txt1 = ctx['props'].n;
+    return block1([txt1]);
+  }
+}"
+`;
+
+exports[`list of components sub components with some state rendered in a loop 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  const comp1 = app.createComponent(\`Child\`, true, false, false, []);
+  
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['number'] of ctx['state'].numbers) {
+      const key1 = ctx['number'];
+      c_block2[i1] = withKey(comp1({}, key + \`__1__\${key1}\`, node, this, null), key1);
+      i1++;
+    }
+    const b2 = list(c_block2);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`list of components sub components with some state rendered in a loop 2`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<p><block-text-0/></p>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let txt1 = ctx['state'].n;
+    return block1([txt1]);
+  }
+}"
+`;
+
+exports[`list of components switch component position 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  const comp1 = app.createComponent(\`Child\`, true, false, false, [\\"key\\"]);
+  
+  let block1 = createBlock(\`<span><block-child-0/></span>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['c'] of ctx['clist']) {
+      const key1 = ctx['c'];
+      c_block2[i1] = withKey(comp1({key: ctx['c']}, key + \`__1__\${key1}\`, node, this, null), key1);
+      i1++;
+    }
+    const b2 = list(c_block2);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`list of components switch component position 2`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<div><block-text-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let txt1 = ctx['props'].key;
+    return block1([txt1]);
+  }
+}"
+`;
+
+exports[`list of components t-for with t-component, and update 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { withKey } = helpers;
+  const comp1 = app.createComponent(\`Child\`, true, false, false, [\\"val\\"]);
+  
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const c_block2 = [];
+    let i1 = 0;
+    for (ctx['n'] of [0,1]) {
+      const key1 = ctx['n'];
+      c_block2[i1] = withKey(comp1({val: ctx['n']}, key + \`__1__\${key1}\`, node, this, null), key1);
+      i1++;
+    }
+    const b2 = list(c_block2);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`list of components t-for with t-component, and update 2`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<span><block-text-0/><block-text-1/></span>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let txt1 = ctx['state'].val;
+    let txt2 = ctx['props'].val;
+    return block1([txt1, txt2]);
+  }
+}"
+`;

tests/components/__snapshots__/t_foreach.test.ts.snap

@@ -14,7 +14,7 @@ exports[`list of components components in a node in a t-foreach  1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['items']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`item\`] = k_block2[i1];
+      ctx[\`item\`] = v_block2[i1];
       const key1 = 'li_'+ctx['item'];
       const b4 = comp1({item: ctx['item']}, key + \`__1__\${key1}\`, node, this, null);
       c_block2[i1] = withKey(block3([], [b4]), key1);
@@ -51,7 +51,7 @@ exports[`list of components crash on duplicate key in dev mode 1`] = `
     const [k_block1, v_block1, l_block1, c_block1] = prepareList([1,2]);;
     const keys1 = new Set();
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`item\`] = k_block1[i1];
+      ctx[\`item\`] = v_block1[i1];
       const key1 = 'child';
       if (keys1.has(String(key1))) { throw new OwlError(\`Got duplicate key in t-foreach: \${key1}\`)}
       keys1.add(String(key1));
@@ -87,7 +87,7 @@ exports[`list of components crash when using object as keys that serialize to th
     const [k_block1, v_block1, l_block1, c_block1] = prepareList([{},{}]);;
     const keys1 = new Set();
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`item\`] = k_block1[i1];
+      ctx[\`item\`] = v_block1[i1];
       const key1 = ctx['item'];
       if (keys1.has(String(key1))) { throw new OwlError(\`Got duplicate key in t-foreach: \${key1}\`)}
       keys1.add(String(key1));
@@ -125,7 +125,7 @@ exports[`list of components list of sub components inside other nodes 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].blips);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`blip\`] = k_block2[i1];
+      ctx[\`blip\`] = v_block2[i1];
       const key1 = ctx['blip'].id;
       const b4 = comp1({}, key + \`__1__\${key1}\`, node, this, null);
       c_block2[i1] = withKey(block3([], [b4]), key1);
@@ -191,7 +191,7 @@ exports[`list of components order is correct when slots are not of same type 2`]
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['slotNames']);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`slotName\`] = k_block1[i1];
+      ctx[\`slotName\`] = v_block1[i1];
       const key1 = ctx['slotName'];
       const slot1 = (ctx['slotName']);
       c_block1[i1] = withKey(toggler(slot1, callSlot(ctx, node, key1 + \`__1__\${key1}\`, slot1, true, {})), key1);
@@ -214,13 +214,13 @@ exports[`list of components reconciliation alg works for t-foreach in t-foreach
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].s);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`section\`] = k_block2[i1];
+      ctx[\`section\`] = v_block2[i1];
       ctx[\`section_index\`] = i1;
       const key1 = ctx['section_index'];
       ctx = Object.create(ctx);
       const [k_block3, v_block3, l_block3, c_block3] = prepareList(ctx['section'].blips);;
       for (let i2 = 0; i2 < l_block3; i2++) {
-        ctx[\`blip\`] = k_block3[i2];
+        ctx[\`blip\`] = v_block3[i2];
         ctx[\`blip_index\`] = i2;
         const key2 = ctx['blip_index'];
         c_block3[i2] = withKey(comp1({blip: ctx['blip']}, key + \`__1__\${key1}__\${key2}\`, node, this, null), key2);
@@ -263,12 +263,12 @@ exports[`list of components reconciliation alg works for t-foreach in t-foreach,
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].rows);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`row\`] = k_block2[i1];
+      ctx[\`row\`] = v_block2[i1];
       const key1 = ctx['row'];
       ctx = Object.create(ctx);
       const [k_block4, v_block4, l_block4, c_block4] = prepareList(ctx['state'].cols);;
       for (let i2 = 0; i2 < l_block4; i2++) {
-        ctx[\`col\`] = k_block4[i2];
+        ctx[\`col\`] = v_block4[i2];
         const key2 = ctx['col'];
         const b6 = comp1({row: ctx['row'],col: ctx['col']}, key + \`__1__\${key1}__\${key2}\`, node, this, null);
         c_block4[i2] = withKey(block5([], [b6]), key2);
@@ -308,7 +308,7 @@ exports[`list of components simple list 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['state'].elems);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`elem\`] = k_block1[i1];
+      ctx[\`elem\`] = v_block1[i1];
       const key1 = ctx['elem'].id;
       c_block1[i1] = withKey(comp1({value: ctx['elem'].value}, key + \`__1__\${key1}\`, node, this, null), key1);
     }
@@ -344,7 +344,7 @@ exports[`list of components sub components rendered in a loop 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].numbers);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`number\`] = k_block2[i1];
+      ctx[\`number\`] = v_block2[i1];
       const key1 = ctx['number'];
       c_block2[i1] = withKey(comp1({n: ctx['number']}, key + \`__1__\${key1}\`, node, this, null), key1);
     }
@@ -381,7 +381,7 @@ exports[`list of components sub components with some state rendered in a loop 1`
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].numbers);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`number\`] = k_block2[i1];
+      ctx[\`number\`] = v_block2[i1];
       const key1 = ctx['number'];
       c_block2[i1] = withKey(comp1({}, key + \`__1__\${key1}\`, node, this, null), key1);
     }
@@ -418,7 +418,7 @@ exports[`list of components switch component position 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['clist']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`c\`] = k_block2[i1];
+      ctx[\`c\`] = v_block2[i1];
       const key1 = ctx['c'];
       c_block2[i1] = withKey(comp1({key: ctx['c']}, key + \`__1__\${key1}\`, node, this, null), key1);
     }
@@ -455,7 +455,7 @@ exports[`list of components t-foreach with t-component, and update 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(Array(2));;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`n\`] = k_block2[i1];
+      ctx[\`n\`] = v_block2[i1];
       ctx[\`n_index\`] = i1;
       const key1 = ctx['n_index'];
       c_block2[i1] = withKey(comp1({val: ctx['n_index']}, key + \`__1__\${key1}\`, node, this, null), key1);

tests/components/__snapshots__/t_key.test.ts.snap

@@ -13,7 +13,7 @@ exports[`t-key t-foreach with t-key switch component position 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['clist']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`c\`] = k_block2[i1];
+      ctx[\`c\`] = v_block2[i1];
       const key1 = ctx['c'];
       const tKey_1 = ctx['key1'];
       c_block2[i1] = withKey(comp1({key: ctx['c']+ctx['key1']}, tKey_1 + key + \`__1__\${key1}\`, node, this, null), tKey_1 + key1);

tests/components/__snapshots__/t_model.test.ts.snap

@@ -196,7 +196,7 @@ exports[`t-model directive in a t-foreach 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`thing\`] = k_block2[i1];
+      ctx[\`thing\`] = v_block2[i1];
       const key1 = ctx['thing'].id;
       const bExpr1 = ctx['thing'];
       const expr1 = 'f';
@@ -223,7 +223,7 @@ exports[`t-model directive in a t-foreach, part 2 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`thing\`] = k_block2[i1];
+      ctx[\`thing\`] = v_block2[i1];
       ctx[\`thing_index\`] = i1;
       const key1 = ctx['thing_index'];
       const bExpr1 = ctx['state'];
@@ -251,7 +251,7 @@ exports[`t-model directive in a t-foreach, part 3 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['names']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`name\`] = k_block2[i1];
+      ctx[\`name\`] = v_block2[i1];
       ctx[\`name_index\`] = i1;
       const key1 = ctx['name_index'];
       const bExpr1 = ctx['state'].values;
@@ -485,7 +485,7 @@ exports[`t-model directive t-model with dynamic number values on select options
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].options);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`o\`] = k_block2[i1];
+      ctx[\`o\`] = v_block2[i1];
       const key1 = ctx['o'].value;
       let attr1 = ctx['o'].value;
       let attr2 = bValue1 === ctx['o'].value;
@@ -586,7 +586,7 @@ exports[`t-model directive t-model with dynamic values on select options in fore
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['options']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`v\`] = k_block2[i1];
+      ctx[\`v\`] = v_block2[i1];
       const key1 = ctx['v'];
       let attr1 = ctx['v'];
       let attr2 = bValue1 === ctx['v'];
@@ -613,7 +613,7 @@ exports[`t-model directive t-model with radio button group in t-foreach 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['options']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`opt\`] = k_block2[i1];
+      ctx[\`opt\`] = v_block2[i1];
       const key1 = ctx['opt'];
       let prop1 = new String((ctx['opt']) === 0 ? 0 : ((ctx['opt']) || \\"\\"));
       let attr1 = ctx['opt'];

tests/components/__snapshots__/t_on.test.ts.snap

@@ -16,7 +16,7 @@ exports[`t-on t-on expression captured in t-foreach 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['arr']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`val\`] = k_block2[i1];
+      ctx[\`val\`] = v_block2[i1];
       const key1 = ctx['val'];
       const v1 = ctx['otherState'];
       const v2 = ctx['iter'];
@@ -43,7 +43,7 @@ exports[`t-on t-on expression in t-foreach 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].values);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`val\`] = k_block2[i1];
+      ctx[\`val\`] = v_block2[i1];
       ctx[\`val_index\`] = i1;
       const key1 = ctx['val'];
       let txt1 = ctx['val_index'];
@@ -75,7 +75,7 @@ exports[`t-on t-on expression in t-foreach with t-set 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].values);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`val\`] = k_block2[i1];
+      ctx[\`val\`] = v_block2[i1];
       ctx[\`val_index\`] = i1;
       const key1 = ctx['val'];
       setContextValue(ctx, \\"bossa\\", ctx['bossa']+'_'+ctx['val_index']);
@@ -106,7 +106,7 @@ exports[`t-on t-on method call in t-foreach 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].values);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`val\`] = k_block2[i1];
+      ctx[\`val\`] = v_block2[i1];
       ctx[\`val_index\`] = i1;
       const key1 = ctx['val'];
       let txt1 = ctx['val_index'];
@@ -196,7 +196,7 @@ exports[`t-on t-on on components and t-foreach 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(['John','Raoul','Gérald']);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`name\`] = k_block1[i1];
+      ctx[\`name\`] = v_block1[i1];
       const key1 = ctx['name'];
       const v1 = ctx['this'];
       const v2 = ctx['name'];
@@ -493,7 +493,7 @@ exports[`t-on t-on when first component child is an empty component 2`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['props'].list);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`c\`] = k_block1[i1];
+      ctx[\`c\`] = v_block1[i1];
       ctx[\`c_index\`] = i1;
       const key1 = ctx['c_index'];
       let txt1 = ctx['c'];

tests/components/__snapshots__/t_out.test.ts.snap

@@ -17,7 +17,7 @@ exports[`components in t-out simple list 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList([1,2]);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`n\`] = k_block1[i1];
+      ctx[\`n\`] = v_block1[i1];
       const key1 = ctx['n'];
       ctx[\`blabla\`] = new LazyValue(value1, ctx, this, node, key1);
       c_block1[i1] = withKey(safeOutput(ctx['blabla']), key1);

tests/components/error_handling.test.ts

@@ -20,7 +20,7 @@ import {
   useLogLifecycle,
   nextAppError,
 } from "../helpers";
-import { OwlError } from "../../src/common/owl_error";
+import { OwlError } from "../../src/runtime/error_handling";
 
 let fixture: HTMLElement;
 

tests/components/style_class.test.ts

@@ -1,4 +1,4 @@
-import { OwlError } from "../../src/common/owl_error";
+import { OwlError } from "../../src/runtime/error_handling";
 import { App, Component, mount, onMounted, useState, xml } from "../../src";
 import { makeTestFixture, nextAppError, nextTick, snapshotEverything } from "../helpers";
 

tests/components/t_for.test.ts

@@ -0,0 +1,391 @@
+import { App, Component, mount, onMounted, useState, xml } from "../../src/index";
+import {
+  makeTestFixture,
+  nextAppError,
+  nextTick,
+  snapshotEverything,
+  useLogLifecycle,
+} from "../helpers";
+
+snapshotEverything();
+
+let originalconsoleWarn = console.warn;
+let mockConsoleWarn: any;
+
+let fixture: HTMLElement;
+
+beforeEach(() => {
+  fixture = makeTestFixture();
+  mockConsoleWarn = jest.fn(() => {});
+  console.warn = mockConsoleWarn;
+});
+
+afterEach(() => {
+  console.warn = originalconsoleWarn;
+});
+
+describe("list of components", () => {
+  test("simple list", async () => {
+    class Child extends Component {
+      static template = xml`<span><t t-esc="props.value"/></span>`;
+    }
+
+    class Parent extends Component {
+      static template = xml`
+            <t t-for="elem" t-of="state.elems" t-key="elem.id">
+                <Child value="elem.value"/>
+            </t>`;
+      static components = { Child };
+
+      state = useState({
+        elems: [
+          { id: 1, value: "a" },
+          { id: 2, value: "b" },
+        ],
+      });
+    }
+
+    const parent = await mount(Parent, fixture);
+    expect(fixture.innerHTML).toBe("<span>a</span><span>b</span>");
+    parent.state.elems.push({ id: 4, value: "d" });
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<span>a</span><span>b</span><span>d</span>");
+
+    parent.state.elems.pop();
+
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<span>a</span><span>b</span>");
+  });
+
+  test("components in a node in a t-for ", async () => {
+    class Child extends Component {
+      static template = xml`<div><t t-esc="props.item"/></div>`;
+      setup() {
+        useLogLifecycle();
+      }
+    }
+
+    class Parent extends Component {
+      static template = xml`
+              <div>
+                  <ul>
+                      <t t-for="item" t-of="items" t-key="'li_'+item">
+                          <li>
+                              <Child item="item"/>
+                          </li>
+                      </t>
+                  </ul>
+              </div>`;
+      static components = { Child };
+
+      setup() {
+        useLogLifecycle();
+      }
+
+      get items() {
+        return [1, 2];
+      }
+    }
+
+    await mount(Parent, fixture);
+    expect(fixture.innerHTML).toBe(
+      "<div><ul><li><div>1</div></li><li><div>2</div></li></ul></div>"
+    );
+    expect([
+      "Parent:setup",
+      "Parent:willStart",
+      "Parent:willRender",
+      "Child:setup",
+      "Child:willStart",
+      "Child:setup",
+      "Child:willStart",
+      "Parent:rendered",
+      "Child:willRender",
+      "Child:rendered",
+      "Child:willRender",
+      "Child:rendered",
+      "Child:mounted",
+      "Child:mounted",
+      "Parent:mounted",
+    ]).toBeLogged();
+  });
+
+  test("reconciliation alg works for t-for in t-for", async () => {
+    class Child extends Component {
+      static template = xml`<div><t t-esc="props.blip"/></div>`;
+    }
+
+    class Parent extends Component {
+      static template = xml`
+        <div>
+            <t t-for="section" t-of="state.s" t-key="section">
+                <t t-for="blip" t-of="section.blips" t-key="blip">
+                  <Child blip="blip"/>
+                </t>
+            </t>
+        </div>`;
+      static components = { Child };
+      state = { s: [{ blips: ["a1", "a2"] }, { blips: ["b1"] }] };
+    }
+
+    await mount(Parent, fixture);
+    expect(fixture.innerHTML).toBe("<div><div>a1</div><div>a2</div><div>b1</div></div>");
+  });
+
+  test("reconciliation alg works for t-for in t-for, 2", async () => {
+    class Child extends Component {
+      static template = xml`<div><t t-esc="props.row + '_' + props.col"/></div>`;
+    }
+
+    class Parent extends Component {
+      static template = xml`
+        <div>
+          <p t-for="row" t-of="state.rows" t-key="row">
+            <p t-for="col" t-of="state.cols" t-key="col">
+                <Child row="row" col="col"/>
+              </p>
+            </p>
+        </div>`;
+      static components = { Child };
+      state = useState({ rows: [1, 2], cols: ["a", "b"] });
+    }
+
+    const parent = await mount(Parent, fixture);
+    expect(fixture.innerHTML).toBe(
+      "<div><p><p><div>1_a</div></p><p><div>1_b</div></p></p><p><p><div>2_a</div></p><p><div>2_b</div></p></p></div>"
+    );
+    parent.state.rows = [2, 1];
+    await nextTick();
+    expect(fixture.innerHTML).toBe(
+      "<div><p><p><div>2_a</div></p><p><div>2_b</div></p></p><p><p><div>1_a</div></p><p><div>1_b</div></p></p></div>"
+    );
+  });
+
+  test("sub components rendered in a loop", async () => {
+    class Child extends Component {
+      static template = xml`<p><t t-esc="props.n"/></p>`;
+    }
+
+    class Parent extends Component {
+      static template = xml`
+        <div>
+          <t t-for="number" t-of="state.numbers" t-key="number" >
+            <Child n="number"/>
+          </t>
+        </div>`;
+      static components = { Child };
+
+      state = useState({ numbers: [1, 2, 3] });
+    }
+    await mount(Parent, fixture);
+
+    expect(fixture.innerHTML).toBe(`<div><p>1</p><p>2</p><p>3</p></div>`);
+  });
+
+  test("sub components with some state rendered in a loop", async () => {
+    let n = 1;
+
+    class Child extends Component {
+      static template = xml`<p><t t-esc="state.n"/></p>`;
+      state: any;
+      setup() {
+        this.state = useState({ n });
+        n++;
+      }
+    }
+
+    class Parent extends Component {
+      static template = xml`
+        <div>
+          <t t-for="number" t-of="state.numbers" t-key="number">
+            <Child/>
+          </t>
+        </div>`;
+      static components = { Child };
+
+      state = useState({
+        numbers: [1, 2, 3],
+      });
+    }
+    const parent = await mount(Parent, fixture);
+
+    parent.state.numbers = [1, 3];
+    await nextTick();
+    expect(fixture.innerHTML).toBe(`<div><p>1</p><p>3</p></div>`);
+  });
+
+  test("list of sub components inside other nodes", async () => {
+    // this confuses the patching algorithm...
+    class SubComponent extends Component {
+      static template = xml`<span>asdf</span>`;
+    }
+    class Parent extends Component {
+      static template = xml`
+      <div>
+          <div t-for="blip" t-of="state.blips" t-key="blip.id">
+              <SubComponent />
+          </div>
+      </div>`;
+      static components = { SubComponent };
+      state = useState({
+        blips: [
+          { a: "a", id: 1 },
+          { b: "b", id: 2 },
+          { c: "c", id: 4 },
+        ],
+      });
+    }
+    const parent = await mount(Parent, fixture);
+    expect(fixture.innerHTML).toBe(
+      "<div><div><span>asdf</span></div><div><span>asdf</span></div><div><span>asdf</span></div></div>"
+    );
+    parent.state.blips.splice(0, 1);
+    await nextTick();
+    expect(fixture.innerHTML).toBe(
+      "<div><div><span>asdf</span></div><div><span>asdf</span></div></div>"
+    );
+  });
+
+  test("t-for with t-component, and update", async () => {
+    class Child extends Component {
+      static template = xml`
+          <span>
+            <t t-esc="state.val"/>
+            <t t-esc="props.val"/>
+          </span>`;
+      state = useState({ val: "A" });
+      setup() {
+        onMounted(() => {
+          this.state.val = "B";
+        });
+      }
+    }
+    class Parent extends Component {
+      static components = { Child };
+      static template = xml`
+          <div>
+            <t t-for="n" t-of="[0, 1]" t-key="n">
+              <Child val="n"/>
+            </t>
+          </div>`;
+    }
+
+    await mount(Parent, fixture);
+    expect(fixture.innerHTML).toBe("<div><span>A0</span><span>A1</span></div>");
+
+    await nextTick(); // wait for changes triggered in mounted to be applied
+    expect(fixture.innerHTML).toBe("<div><span>B0</span><span>B1</span></div>");
+  });
+
+  test("switch component position", async () => {
+    const childInstances = [];
+    class Child extends Component {
+      static template = xml`<div t-esc="props.key"></div>`;
+      setup() {
+        childInstances.push(this);
+      }
+    }
+
+    class Parent extends Component {
+      static components = { Child };
+      static template = xml`<span>
+        <t t-for="c" t-of="clist" t-key="c">
+          <Child key="c"/>
+        </t>
+      </span>`;
+
+      clist = [1, 2];
+    }
+
+    const parent = await mount(Parent, fixture);
+    expect(fixture.innerHTML).toBe("<span><div>1</div><div>2</div></span>");
+    parent.clist = [2, 1];
+    parent.render();
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<span><div>2</div><div>1</div></span>");
+    expect(childInstances.length).toBe(2);
+  });
+
+  test("crash on duplicate key in dev mode", async () => {
+    const consoleInfo = console.info;
+    console.info = jest.fn();
+    class Child extends Component {
+      static template = xml``;
+    }
+
+    class Parent extends Component {
+      static template = xml`
+        <t t-for="item" t-of="[1, 2]" t-key="'child'">
+          <Child/>
+        </t>
+      `;
+      static components = { Child };
+    }
+
+    const app = new App(Parent, { test: true });
+    const mountProm = expect(app.mount(fixture)).rejects.toThrow(
+      "Got duplicate key in t-for: child"
+    );
+    await expect(nextAppError(app)).resolves.toThrow("Got duplicate key in t-for: child");
+    await mountProm;
+    console.info = consoleInfo;
+    expect(mockConsoleWarn).toBeCalledTimes(1);
+  });
+
+  test("crash when using object as keys that serialize to the same string", async () => {
+    const consoleInfo = console.info;
+    console.info = jest.fn();
+    class Child extends Component {
+      static template = xml``;
+    }
+
+    class Parent extends Component {
+      static template = xml`
+        <t t-for="item" t-of="[{}, {}]" t-key="item">
+          <Child/>
+        </t>
+      `;
+      static components = { Child };
+    }
+
+    const app = new App(Parent, { test: true });
+    const mountProm = expect(app.mount(fixture)).rejects.toThrow(
+      "Got duplicate key in t-for: [object Object]"
+    );
+    await expect(nextAppError(app)).resolves.toThrow("Got duplicate key in t-for: [object Object]");
+    await mountProm;
+    console.info = consoleInfo;
+    expect(mockConsoleWarn).toBeCalledTimes(1);
+  });
+
+  test("order is correct when slots are not of same type", async () => {
+    class Child extends Component {
+      static template = xml`
+          <t t-slot="{{ slotName }}" t-for="slotName" t-of="slotNames" t-key="slotName"/>
+      `;
+      get slotNames() {
+        return Object.entries(this.props.slots)
+          .filter((entry: any) => entry[1].active)
+          .map((entry) => entry[0]);
+      }
+    }
+
+    class Parent extends Component {
+      static template = xml`
+        <Child>
+          <t t-set-slot="a" active="!state.active"><div t-if="!state.active">A</div></t>
+          <t t-set-slot="b" active="true">B</t>
+          <t t-set-slot="c" active="state.active">C</t>
+        </Child>
+      `;
+      static components = { Child };
+      state = useState({ active: false });
+    }
+
+    const parent = await mount(Parent, fixture);
+    expect(fixture.textContent).toBe("AB");
+    parent.state.active = true;
+    await nextTick();
+    expect(fixture.textContent).toBe("BC");
+  });
+});

tests/helpers.ts

@@ -19,7 +19,7 @@ import { helpers } from "../src/runtime/template_helpers";
 import { TemplateSet, globalTemplates } from "../src/runtime/template_set";
 import { BDom } from "../src/runtime/blockdom";
 import { compile } from "../src/compiler";
-import { OwlError } from "../src/common/owl_error";
+import { OwlError } from "../src/runtime/error_handling";
 
 const mount = blockDom.mount;
 

tests/misc/__snapshots__/portal.test.ts.snap

@@ -18,7 +18,7 @@ exports[`Portal Add and remove portals 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['portalIds']);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`portalId\`] = k_block1[i1];
+      ctx[\`portalId\`] = v_block1[i1];
       const key1 = ctx['portalId'];
       const ctx1 = capture(ctx);
       c_block1[i1] = withKey(comp1({target: '#outside',slots: {'default': {__render: slot1.bind(this), __ctx: ctx1}}}, key + \`__1__\${key1}\`, node, ctx, Portal), key1);
@@ -47,7 +47,7 @@ exports[`Portal Add and remove portals on div 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['portalIds']);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`portalId\`] = k_block1[i1];
+      ctx[\`portalId\`] = v_block1[i1];
       const key1 = ctx['portalId'];
       const ctx1 = capture(ctx);
       c_block1[i1] = withKey(comp1({target: '#outside',slots: {'default': {__render: slot1.bind(this), __ctx: ctx1}}}, key + \`__1__\${key1}\`, node, ctx, Portal), key1);
@@ -77,7 +77,7 @@ exports[`Portal Add and remove portals with t-foreach 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['portalIds']);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`portalId\`] = k_block1[i1];
+      ctx[\`portalId\`] = v_block1[i1];
       const key1 = ctx['portalId'];
       let txt1 = ctx['portalId'];
       const ctx1 = capture(ctx);
@@ -109,7 +109,7 @@ exports[`Portal Add and remove portals with t-foreach and destroy 1`] = `
     ctx = Object.create(ctx);
     const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['portalIds']);;
     for (let i1 = 0; i1 < l_block1; i1++) {
-      ctx[\`portalId\`] = k_block1[i1];
+      ctx[\`portalId\`] = v_block1[i1];
       const key1 = ctx['portalId'];
       let txt1 = ctx['portalId'];
       const ctx1 = capture(ctx);
@@ -142,7 +142,7 @@ exports[`Portal Add and remove portals with t-foreach inside div 1`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['portalIds']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`portalId\`] = k_block2[i1];
+      ctx[\`portalId\`] = v_block2[i1];
       const key1 = ctx['portalId'];
       let txt1 = ctx['portalId'];
       const ctx1 = capture(ctx);
@@ -429,7 +429,7 @@ exports[`Portal conditional use of Portal with child and div 2`] = `
     ctx = Object.create(ctx);
     const [k_block2, v_block2, l_block2, c_block2] = prepareList([1]);;
     for (let i1 = 0; i1 < l_block2; i1++) {
-      ctx[\`elem\`] = k_block2[i1];
+      ctx[\`elem\`] = v_block2[i1];
       const key1 = ctx['elem'];
       const ctx1 = capture(ctx);
       c_block2[i1] = withKey(comp1({target: '#outside',slots: {'default': {__render: slot1.bind(this), __ctx: ctx1}}}, key + \`__1__\${key1}\`, node, ctx, Portal), key1);
@@ -479,7 +479,7 @@ exports[`Portal conditional use of Portal with child and div, variation 2`] = `
     ctx = Object.create(ctx);
     const [k_block3, v_block3, l_block3, c_block3] = prepareList([1]);;
     for (let i1 = 0; i1 < l_block3; i1++) {
-      ctx[\`elem\`] = k_block3[i1];
+      ctx[\`elem\`] = v_block3[i1];
       const key1 = ctx['elem'];
       const ctx1 = capture(ctx);
       c_block3[i1] = withKey(comp1({target: '#outside',slots: {'default': {__render: slot1.bind(this), __ctx: ctx1}}}, key + \`__1__\${key1}\`, node, ctx, Portal), key1);

tests/misc/portal.test.ts

@@ -1,4 +1,4 @@
-import { OwlError } from "../../src/common/owl_error";
+import { OwlError } from "../../src/runtime/error_handling";
 import {
   App,
   Component,

tools/devtools/src/devtools_app/store/store.js

@@ -899,7 +899,7 @@ function keepEnvLit(details) {
       alreadyMet.add(details.env.children[i].name);
     } else {
       let lastElement = details.env.children[i];
-      while (lastElement.children.at(-1)?.name === "[[Prototype]]") {
+      while (lastElement.children.at(-1).name === "[[Prototype]]") {
         for (const [index, child] of lastElement.children.entries()) {
           if (index < lastElement.children.length - 1) {
             if (!alreadyMet.has(child.name)) {