feat(ivy): add support for attributes on ng-content nodes (#21935)

By adding attributes on the <ng-content> element template authors
can decide how content should be re-projected (or, in other words:
which selectors should match re-projected content).

PR Close #21935

packages/core/src/render3/instructions.ts

@@ -15,9 +15,9 @@ import {LQueries} from './interfaces/query';
 import {LView, LifecycleStage, TData, TView} from './interfaces/view';
 
 import {LContainerNode, LElementNode, LNode, LNodeFlags, LProjectionNode, LTextNode, LViewNode, TNode, TContainerNode, InitialInputData, InitialInputs, PropertyAliases, PropertyAliasValue,} from './interfaces/node';
-import {assertNodeType, assertNodeOfPossibleTypes} from './node_assert';
+import {assertNodeType} from './node_assert';
 import {appendChild, insertChild, insertView, appendProjectedNode, removeView, canInsertNativeNode} from './node_manipulation';
-import {isNodeMatchingSelector} from './node_selector_matcher';
+import {matchingSelectorIndex} from './node_selector_matcher';
 import {ComponentDef, ComponentTemplate, ComponentType, DirectiveDef, DirectiveType} from './interfaces/definition';
 import {RElement, RText, Renderer3, RendererFactory3, ProceduralRenderer3, ObjectOrientedRenderer3, RendererStyleFlags3} from './interfaces/renderer';
 import {isDifferent, stringify} from './util';
@@ -1222,33 +1222,16 @@ export function projectionDef(index: number, selectors?: CssSelector[]): void {
   let componentChild = componentNode.child;
 
   while (componentChild !== null) {
-    if (!selectors) {
-      distributedNodes[0].push(componentChild);
-    } else if (
-        (componentChild.flags & LNodeFlags.TYPE_MASK) === LNodeFlags.Element ||
-        (componentChild.flags & LNodeFlags.TYPE_MASK) === LNodeFlags.Container) {
-      // Only trying to match selectors against:
-      // - elements, excluding text nodes;
-      // - containers that have tagName and attributes associated.
-
-      if (componentChild.tNode) {
-        for (let i = 0; i < selectors !.length; i++) {
-          if (isNodeMatchingSelector(componentChild.tNode, selectors ![i])) {
-            distributedNodes[i + 1].push(componentChild);
-            break;  // first matching selector "captures" a given node
-          } else {
-            distributedNodes[0].push(componentChild);
-          }
-        }
+    // execute selector matching logic if and only if:
+    // - there are selectors defined
+    // - a node has a tag name / attributes that can be matched
+    if (selectors && componentChild.tNode) {
+      const matchedIdx = matchingSelectorIndex(componentChild.tNode, selectors !);
+      distributedNodes[matchedIdx].push(componentChild);
     } else {
       distributedNodes[0].push(componentChild);
     }
 
-    } else if ((componentChild.flags & LNodeFlags.TYPE_MASK) === LNodeFlags.Projection) {
-      // we don't descend into nodes to re-project (not trying to match selectors against nodes to
-      // re-project)
-      distributedNodes[0].push(componentChild);
-    }
     componentChild = componentChild.next;
   }
 
@@ -1291,9 +1274,16 @@ function appendToProjectionNode(
  * @param nodeIndex
  * @param localIndex - index under which distribution of projected nodes was memorized
  * @param selectorIndex - 0 means <ng-content> without any selector
+ * @param attrs - attributes attached to the ng-content node, if present
  */
-export function projection(nodeIndex: number, localIndex: number, selectorIndex: number = 0): void {
+export function projection(
+    nodeIndex: number, localIndex: number, selectorIndex: number = 0, attrs?: string[]): void {
   const node = createLNode(nodeIndex, LNodeFlags.Projection, null, {head: null, tail: null});
+
+  if (node.tNode == null) {
+    node.tNode = createTNode(null, attrs || null, null, null);
+  }
+
   isParent = false;  // self closing
   const currentParent = node.parent;
 

packages/core/src/render3/node_selector_matcher.ts

@@ -114,3 +114,16 @@ export function isNodeMatchingSelector(tNode: TNode, selector: CssSelector): boo
 
   return false;
 }
+
+/**
+ * Checks a given node against matching selectors and returns
+ * selector index (or 0 if none matched);
+ */
+export function matchingSelectorIndex(tNode: TNode, selectors: CssSelector[]): number {
+  for (let i = 0; i < selectors.length; i++) {
+    if (isNodeMatchingSelector(tNode, selectors[i])) {
+      return i + 1;  // first matching selector "captures" a given node
+    }
+  }
+  return 0;
+}

packages/core/test/render3/content_spec.ts

@@ -812,7 +812,7 @@ describe('content projection', () => {
      * Descending into projected content for selector-matching purposes is not supported
      * today: http://plnkr.co/edit/MYQcNfHSTKp9KvbzJWVQ?p=preview
      */
-    it('should not match selectors on re-projected content', () => {
+    it('should not descend into re-projected content', () => {
 
       /**
        *  <ng-content select="span"></ng-content>
@@ -878,6 +878,66 @@ describe('content projection', () => {
               '<child><grand-child><span>in child template</span><hr><span>parent content</span></grand-child></child>');
     });
 
+    it('should match selectors on ng-content nodes with attributes', () => {
+
+      /**
+       * <ng-content select="[card-title]"></ng-content>
+       * <hr>
+       * <ng-content select="[card-content]"></ng-content>
+       */
+      const Card = createComponent('card', function(ctx: any, cm: boolean) {
+        if (cm) {
+          pD(0, [[[['', 'card-title', ''], null]], [[['', 'card-content', ''], null]]]);
+          P(1, 0, 1);
+          E(2, 'hr');
+          e();
+          P(3, 0, 2);
+        }
+      });
+
+      /**
+       * <card>
+       *  <h1 card-title>Title</h1>
+       *  <ng-content card-content></ng-content>
+       * </card>
+       */
+      const CardWithTitle = createComponent('card-with-title', function(ctx: any, cm: boolean) {
+        if (cm) {
+          pD(0);
+          E(1, Card);
+          {
+            E(3, 'h1', ['card-title', '']);
+            { T(4, 'Title'); }
+            e();
+            P(5, 0, 0, ['card-content', '']);
+          }
+          e();
+          Card.ngComponentDef.h(2, 1);
+          r(2, 1);
+        }
+      });
+
+      /**
+       * <card-with-title>
+       *  content
+       * </card-with-title>
+       */
+      const App = createComponent('app', function(ctx: any, cm: boolean) {
+        if (cm) {
+          E(0, CardWithTitle);
+          { T(2, 'content'); }
+          e();
+        }
+        CardWithTitle.ngComponentDef.h(1, 0);
+        r(1, 0);
+      });
+
+      const app = renderComponent(App);
+      expect(toHtml(app))
+          .toEqual(
+              '<card-with-title><card><h1 card-title="">Title</h1><hr>content</card></card-with-title>');
+    });
+
     it('should match selectors against projected containers', () => {
 
       /**