[IMP] qweb: the t-slot directive is now dynamic

It is useful for some kind of components to be able to use a completely
dynamic slot expression.

doc/reference/slots.md

@@ -25,6 +25,8 @@ some sub template, but still be the owner. For example, a generic dialog compone
 will need to render some content, some footer, but with the parent as the
 rendering context.
 
+Slots are inserted with the `t-slot` directive:
+
 ```xml
 <div t-name="Dialog" class="modal">
   <div class="modal-title"><t t-esc="props.title"/></div>
@@ -62,7 +64,9 @@ This is deprecated and should no longer be used in new code.
 
 ## Reference
 
-Default slot: the first element inside the component which is not a named slot will
+### Default Slot
+
+The first element inside the component which is not a named slot will
 be considered the `default` slot. For example:
 
 ```xml
@@ -77,7 +81,9 @@ be considered the `default` slot. For example:
 </div>
 ```
 
-Default content: slots can define a default content, in case the parent did not define them:
+### Default content
+
+Slots can define a default content, in case the parent did not define them:
 
 ```xml
 <div t-name="Parent">
@@ -94,3 +100,12 @@ Rendering context: the content of the slots is actually rendered with the
 rendering context corresponding to where it was defined, not where it is
 positioned. This allows the user to define event handlers that will be bound
 to the correct component (usually, the grandparent of the slot content).
+
+### Dynamic Slots
+
+The `t-slot` directive is actually able to use any expressions, using string
+interplolation:
+
+```xml
+ <t t-slot="{{current}}" />
+```

src/qweb/extensions.ts

@@ -1,4 +1,5 @@
 import { VNode } from "../vdom/index";
+import { INTERP_REGEXP } from "./compilation_context";
 import { QWeb } from "./qweb";
 
 /**
@@ -228,8 +229,9 @@ QWeb.addDirective({
   priority: 80,
   atNodeEncounter({ ctx, value, node, qweb }): boolean {
     const slotKey = ctx.generateID();
+    const valueExpr = value.match(INTERP_REGEXP) ? ctx.interpolate(value) : `'${value}'`;
     ctx.addLine(
-      `const slot${slotKey} = this.constructor.slots[context.__owl__.slotId + '_' + '${value}'];`
+      `const slot${slotKey} = this.constructor.slots[context.__owl__.slotId + '_' + ${valueExpr}];`
     );
     ctx.addIf(`slot${slotKey}`);
     let parentNode = `c${ctx.parentNode}`;

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

@@ -220,6 +220,25 @@ exports[`t-slot directive default slot work with text nodes 1`] = `
 }"
 `;
 
+exports[`t-slot directive dynamic t-slot call 1`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"__template__1\\"
+    let utils = this.constructor.utils;
+    let scope = Object.create(context);
+    let h = this.h;
+    let c10 = [], p10 = {key:10,on:{}};
+    let vn10 = h('button', p10, c10);
+    extra.handlers['click__11__'] = extra.handlers['click__11__'] || function (e) {if (!context.__owl__.isMounted){return}utils.getComponent(context)['toggle'](e);};
+    p10.on['click'] = extra.handlers['click__11__'];
+    const slot12 = this.constructor.slots[context.__owl__.slotId + '_' + (scope['current'].slot)];
+    if (slot12) {
+        slot12.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: c10, parent: extra.parent || context}));
+    }
+    return vn10;
+}"
+`;
+
 exports[`t-slot directive multiple roots are allowed in a default slot 1`] = `
 "function anonymous(context, extra
 ) {

tests/component/slots.test.ts

@@ -1,4 +1,4 @@
-import { Component, Env } from "../../src/component/component";
+import { Component, Env, mount } from "../../src/component/component";
 import { QWeb } from "../../src/qweb/qweb";
 import { xml } from "../../src/tags";
 import { useState, useRef } from "../../src/hooks";
@@ -1085,4 +1085,37 @@ describe("t-slot directive", () => {
 
     expect(fixture.innerHTML).toBe("<div><div><p>Ablip</p><div><p>Bblip</p></div></div></div>");
   });
+
+  test("dynamic t-slot call", async () => {
+    class Toggler extends Component {
+      static template = xml`<button t-on-click="toggle"><t t-slot="{{current.slot}}"/></button>`;
+      current = useState({ slot: "slot1" });
+      toggle() {
+        this.current.slot = this.current.slot === "slot1" ? "slot2" : "slot1";
+      }
+    }
+
+    class Parent extends Component {
+      static template = xml`
+        <div>
+          <Toggler>
+            <t t-set-slot="slot1"><p>slot1</p><span>content</span></t>
+            <t t-set-slot="slot2"><h1>slot2</h1></t>
+          </Toggler>
+        </div>`;
+      static components = { Toggler };
+    }
+    await mount(Parent, { target: fixture });
+    expect(fixture.innerHTML).toBe("<div><button><p>slot1</p><span>content</span></button></div>");
+
+    fixture.querySelector<HTMLElement>("button")!.click();
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div><button><h1>slot2</h1></button></div>");
+
+    fixture.querySelector<HTMLElement>("button")!.click();
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div><button><p>slot1</p><span>content</span></button></div>");
+
+    expect(env.qweb.templates[Toggler.template].fn.toString()).toMatchSnapshot();
+  });
 });