refactor(compiler-cli): move the expression expression type checker (#16562)

The expression type checker moved from the language service
to the compiler-cli in preparation to using it to check
template expressions.

packages/compiler/src/ml_parser/ast.ts

@@ -6,6 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import {AstPath} from '../ast_path';
 import {ParseSourceSpan} from '../parse_util';
 
 export interface Node {
@@ -80,3 +81,70 @@ export function visitAll(visitor: Visitor, nodes: Node[], context: any = null):
   });
   return result;
 }
+
+export class RecursiveVisitor implements Visitor {
+  constructor() {}
+
+  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) {
+    let results: any[][] = [];
+    let t = this;
+    function visit<T extends Node>(children: T[] | undefined) {
+      if (children) results.push(visitAll(t, children, context));
+    }
+    cb(visit);
+    return [].concat.apply([], results);
+  }
+}
+
+export type HtmlAstPath = AstPath<Node>;
+
+function spanOf(ast: Node) {
+  const start = ast.sourceSpan.start.offset;
+  let end = ast.sourceSpan.end.offset;
+  if (ast instanceof Element) {
+    if (ast.endSourceSpan) {
+      end = ast.endSourceSpan.end.offset;
+    } else if (ast.children && ast.children.length) {
+      end = spanOf(ast.children[ast.children.length - 1]).end;
+    }
+  }
+  return {start, end};
+}
+
+export function findNode(nodes: Node[], position: number): HtmlAstPath {
+  const path: Node[] = [];
+
+  const visitor = new class extends RecursiveVisitor {
+    visit(ast: Node, context: any): any {
+      const span = spanOf(ast);
+      if (span.start <= position && position < span.end) {
+        path.push(ast);
+      } else {
+        // Returning a value here will result in the children being skipped.
+        return true;
+      }
+    }
+  }
+
+  visitAll(visitor, nodes);
+
+  return new AstPath<Node>(path, position);
+}