feat(language-service): add services to support editors (#12987)

modules/@angular/language-service/src/html_path.ts

@@ -0,0 +1,72 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {Attribute, Comment, Element, Expansion, ExpansionCase, Node, Text, Visitor, visitAll} from '@angular/compiler/src/ml_parser/ast';
+
+import {AstPath} from './ast_path';
+import {inSpan, spanOf} from './utils';
+
+export class HtmlAstPath extends AstPath<Node> {
+  constructor(ast: Node[], public position: number) { super(buildPath(ast, position)); }
+}
+
+function buildPath(ast: Node[], position: number): Node[] {
+  let visitor = new HtmlAstPathBuilder(position);
+  visitAll(visitor, ast);
+  return visitor.getPath();
+}
+
+export class ChildVisitor implements Visitor {
+  constructor(private visitor?: Visitor) {}
+
+  visitElement(ast: Element, context: any): any {
+    this.visitChildren(context, visit => {
+      visit(ast.attrs);
+      visit(ast.children);
+    });
+  }
+
+  visitAttribute(ast: Attribute, context: any): any {}
+  visitText(ast: Text, context: any): any {}
+  visitComment(ast: Comment, context: any): any {}
+
+  visitExpansion(ast: Expansion, context: any): any {
+    return this.visitChildren(context, visit => { visit(ast.cases); });
+  }
+
+  visitExpansionCase(ast: ExpansionCase, context: any): any {}
+
+  private visitChildren<T extends Node>(
+      context: any, cb: (visit: (<V extends Node>(children: V[]|undefined) => void)) => void) {
+    const visitor = this.visitor || this;
+    let results: any[][] = [];
+    function visit<T extends Node>(children: T[] | undefined) {
+      if (children) results.push(visitAll(visitor, children, context));
+    }
+    cb(visit);
+    return [].concat.apply([], results);
+  }
+}
+
+class HtmlAstPathBuilder extends ChildVisitor {
+  private path: Node[] = [];
+
+  constructor(private position: number) { super(); }
+
+  visit(ast: Node, context: any): any {
+    let span = spanOf(ast);
+    if (inSpan(this.position, span)) {
+      this.path.push(ast);
+    } else {
+      // Returning a value here will result in the children being skipped.
+      return true;
+    }
+  }
+
+  getPath(): Node[] { return this.path; }
+}