From beaab27a49ac6b26d9431251999b90091d267b84 Mon Sep 17 00:00:00 2001
From: Ayaz Hafiz <ayaz.hafiz.1@gmail.com>
Date: Mon, 10 Jun 2019 09:19:35 -0700
Subject: [PATCH] feat(ivy): index identifiers discovered in templates (#30963)

Add support for indexing of property reads, method calls in a template.
Visit AST of template syntax expressions to extract identifiers.

Child of #30959

PR Close #30963
---
 .../compiler-cli/src/ngtsc/indexer/src/api.ts |  25 ++-
 .../src/ngtsc/indexer/src/template.ts         | 209 ++++++++++++++++++
 .../src/ngtsc/indexer/test/BUILD.bazel        |  25 +++
 .../src/ngtsc/indexer/test/template_spec.ts   |  98 ++++++++
 4 files changed, 355 insertions(+), 2 deletions(-)
 create mode 100644 packages/compiler-cli/src/ngtsc/indexer/src/template.ts
 create mode 100644 packages/compiler-cli/src/ngtsc/indexer/test/BUILD.bazel
 create mode 100644 packages/compiler-cli/src/ngtsc/indexer/test/template_spec.ts

diff --git a/packages/compiler-cli/src/ngtsc/indexer/src/api.ts b/packages/compiler-cli/src/ngtsc/indexer/src/api.ts
index 75d51e6e65..0a9f98d4cd 100644
--- a/packages/compiler-cli/src/ngtsc/indexer/src/api.ts
+++ b/packages/compiler-cli/src/ngtsc/indexer/src/api.ts
@@ -6,13 +6,23 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {ParseSourceFile, ParseSpan} from '@angular/compiler';
+import {InterpolationConfig, ParseSourceFile} from '@angular/compiler';
+import {ParseTemplateOptions} from '@angular/compiler/src/render3/view/template';
 import * as ts from 'typescript';
 
 /**
  * Describes the kind of identifier found in a template.
  */
 export enum IdentifierKind {
+  Property,
+  Method,
+}
+
+/**
+ * Describes the absolute byte offsets of a text anchor in a source code.
+ */
+export class AbsoluteSourceSpan {
+  constructor(public start: number, public end: number) {}
 }
 
 /**
@@ -21,7 +31,7 @@ export enum IdentifierKind {
  */
 export interface TemplateIdentifier {
   name: string;
-  span: ParseSpan;
+  span: AbsoluteSourceSpan;
   kind: IdentifierKind;
   file: ParseSourceFile;
 }
@@ -39,3 +49,14 @@ export interface IndexedComponent {
     usedComponents: Set<ts.ClassDeclaration>,
   };
 }
+
+/**
+ * Options for restoring a parsed template. See `template.ts#restoreTemplate`.
+ */
+export interface RestoreTemplateOptions extends ParseTemplateOptions {
+  /**
+   * The interpolation configuration of the template is lost after it already
+   * parsed, so it must be respecified.
+   */
+  interpolationConfig: InterpolationConfig;
+}
diff --git a/packages/compiler-cli/src/ngtsc/indexer/src/template.ts b/packages/compiler-cli/src/ngtsc/indexer/src/template.ts
new file mode 100644
index 0000000000..63bfd991c3
--- /dev/null
+++ b/packages/compiler-cli/src/ngtsc/indexer/src/template.ts
@@ -0,0 +1,209 @@
+/**
+ * @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 {AST, HtmlParser, Lexer, MethodCall, ParseSourceFile, PropertyRead, RecursiveAstVisitor, TmplAstNode, TokenType, visitAll} from '@angular/compiler';
+import {BoundText, Element, Node, RecursiveVisitor as RecursiveTemplateVisitor, Template} from '@angular/compiler/src/render3/r3_ast';
+import {htmlAstToRender3Ast} from '@angular/compiler/src/render3/r3_template_transform';
+import {I18nMetaVisitor} from '@angular/compiler/src/render3/view/i18n/meta';
+import {makeBindingParser} from '@angular/compiler/src/render3/view/template';
+import {AbsoluteSourceSpan, IdentifierKind, RestoreTemplateOptions, TemplateIdentifier} from './api';
+
+/**
+ * A parsed node in a template, which may have a name (if it is a selector) or
+ * be anonymous (like a text span).
+ */
+interface HTMLNode extends Node {
+  tagName?: string;
+  name?: string;
+}
+
+/**
+ * Updates the location of an identifier to its real anchor in a source code.
+ *
+ * The compiler's expression parser records the location of some expressions in a manner not
+ * useful to the indexer. For example, a `MethodCall` `foo(a, b)` will record the span of the
+ * entire method call, but the indexer is interested only in the method identifier.
+ *
+ * To remedy all this, the visitor tokenizes the template node the expression was discovered in,
+ * and updates the locations of entities found during expression traversal with those of the
+ * tokens.
+ *
+ * TODO(ayazhafiz): Think about how to handle `PropertyRead`s in `BoundAttribute`s. The Lexer
+ * tokenizes the attribute as a string and ignores quotes.
+ *
+ * @param entities entities to update
+ * @param currentNode node expression was in
+ */
+function updateIdentifierSpans(identifiers: TemplateIdentifier[], currentNode: Node) {
+  const localSpan = currentNode.sourceSpan;
+  const localExpression = localSpan.toString();
+
+  const lexedIdentifiers =
+      new Lexer().tokenize(localExpression).filter(token => token.type === TokenType.Identifier);
+
+  // Join the relative position of the expression within a node with the absolute position of the
+  // node to get the absolute position of the expression in the source code.
+  const absoluteOffset = currentNode.sourceSpan.start.offset;
+  identifiers.forEach((id, index) => {
+    const lexedId = lexedIdentifiers[index];
+    if (id.name !== lexedId.strValue) {
+      throw new Error(
+          'Impossible state: lexed and parsed expression should contain the same tokens.');
+    }
+
+    const start = absoluteOffset + lexedId.index;
+    const absoluteSpan = new AbsoluteSourceSpan(start, start + lexedId.strValue.length);
+    id.span = absoluteSpan;
+  });
+}
+
+/**
+ * Visits the AST of an Angular template syntax expression, finding interesting
+ * entities (variable references, etc.). Creates an array of Entities found in
+ * the expression, with the location of the Entities being relative to the
+ * expression.
+ *
+ * Visiting `text {{prop}}` will return `[TemplateIdentifier {name: 'prop', span: {start: 7, end:
+ * 11}}]`.
+ */
+class ExpressionVisitor extends RecursiveAstVisitor {
+  private readonly file: ParseSourceFile;
+
+  private constructor(context: Node, readonly identifiers: TemplateIdentifier[] = []) {
+    super();
+
+    this.file = context.sourceSpan.start.file;
+  }
+
+  static getIdentifiers(ast: AST, context: Node): TemplateIdentifier[] {
+    const visitor = new ExpressionVisitor(context);
+    visitor.visit(ast);
+    const identifiers = visitor.identifiers;
+
+    updateIdentifierSpans(identifiers, context);
+
+    return identifiers;
+  }
+
+  visit(ast: AST) { ast.visit(this); }
+
+  visitMethodCall(ast: MethodCall, context: {}) {
+    this.addIdentifier(ast, IdentifierKind.Method);
+    super.visitMethodCall(ast, context);
+  }
+
+  visitPropertyRead(ast: PropertyRead, context: {}) {
+    this.addIdentifier(ast, IdentifierKind.Property);
+    super.visitPropertyRead(ast, context);
+  }
+
+  private addIdentifier(ast: AST&{name: string}, kind: IdentifierKind) {
+    this.identifiers.push({
+      name: ast.name,
+      span: ast.span, kind,
+      file: this.file,
+    });
+  }
+}
+
+/**
+ * Visits the AST of a parsed Angular template. Discovers and stores
+ * identifiers of interest, deferring to an `ExpressionVisitor` as needed.
+ */
+class TemplateVisitor extends RecursiveTemplateVisitor {
+  // identifiers of interest found in the template
+  readonly identifiers = new Set<TemplateIdentifier>();
+
+  /**
+   * Visits a node in the template.
+   * @param node node to visit
+   */
+  visit(node: HTMLNode) { node.visit(this); }
+
+  visitAll(nodes: Node[]) { nodes.forEach(node => this.visit(node)); }
+
+  visitElement(element: Element) {
+    this.visitAll(element.attributes);
+    this.visitAll(element.children);
+    this.visitAll(element.references);
+  }
+  visitTemplate(template: Template) {
+    this.visitAll(template.attributes);
+    this.visitAll(template.children);
+    this.visitAll(template.references);
+    this.visitAll(template.variables);
+  }
+  visitBoundText(text: BoundText) { this.addIdentifiers(text); }
+
+  /**
+   * Adds identifiers to the visitor's state.
+   * @param visitedEntities interesting entities to add as identifiers
+   * @param curretNode node entities were discovered in
+   */
+  private addIdentifiers(node: Node&{value: AST}) {
+    const identifiers = ExpressionVisitor.getIdentifiers(node.value, node);
+    identifiers.forEach(id => this.identifiers.add(id));
+  }
+}
+
+/**
+ * Unwraps and reparses a template, preserving whitespace and with no leading trivial characters.
+ *
+ * A template may previously have been parsed without preserving whitespace, and was definitely
+ * parsed with leading trivial characters (see `parseTemplate` from the compiler package API).
+ * Both of these are detrimental for indexing as they result in a manipulated AST not representing
+ * the template source code.
+ *
+ * TODO(ayazhafiz): Remove once issues with `leadingTriviaChars` and `parseTemplate` are resolved.
+ */
+function restoreTemplate(template: TmplAstNode[], options: RestoreTemplateOptions): TmplAstNode[] {
+  // try to recapture the template content and URL
+  // if there was nothing in the template to begin with, this is just a no-op
+  if (template.length === 0) {
+    return [];
+  }
+  const {content: templateStr, url: templateUrl} = template[0].sourceSpan.start.file;
+
+  options.preserveWhitespaces = true;
+  const {interpolationConfig, preserveWhitespaces} = options;
+
+  const bindingParser = makeBindingParser(interpolationConfig);
+  const htmlParser = new HtmlParser();
+  const parseResult = htmlParser.parse(templateStr, templateUrl, {
+    ...options,
+    tokenizeExpansionForms: true,
+  });
+
+  if (parseResult.errors && parseResult.errors.length > 0) {
+    throw new Error('Impossible state: template must have been successfully parsed previously.');
+  }
+
+  const rootNodes = visitAll(
+      new I18nMetaVisitor(interpolationConfig, !preserveWhitespaces), parseResult.rootNodes);
+
+  const {nodes, errors} = htmlAstToRender3Ast(rootNodes, bindingParser);
+  if (errors && errors.length > 0) {
+    throw new Error('Impossible state: template must have been successfully parsed previously.');
+  }
+
+  return nodes;
+}
+
+/**
+ * Traverses a template AST and builds identifiers discovered in it.
+ * @param template template to extract indentifiers from
+ * @param options options for restoring the parsed template to a indexable state
+ * @return identifiers in template
+ */
+export function getTemplateIdentifiers(
+    template: TmplAstNode[], options: RestoreTemplateOptions): Set<TemplateIdentifier> {
+  const restoredTemplate = restoreTemplate(template, options);
+  const visitor = new TemplateVisitor();
+  visitor.visitAll(restoredTemplate);
+  return visitor.identifiers;
+}
diff --git a/packages/compiler-cli/src/ngtsc/indexer/test/BUILD.bazel b/packages/compiler-cli/src/ngtsc/indexer/test/BUILD.bazel
new file mode 100644
index 0000000000..98a9bc2401
--- /dev/null
+++ b/packages/compiler-cli/src/ngtsc/indexer/test/BUILD.bazel
@@ -0,0 +1,25 @@
+load("//tools:defaults.bzl", "jasmine_node_test", "ts_library")
+
+package(default_visibility = ["//visibility:public"])
+
+ts_library(
+    name = "test_lib",
+    testonly = True,
+    srcs = glob([
+        "**/*.ts",
+    ]),
+    deps = [
+        "//packages/compiler",
+        "//packages/compiler-cli/src/ngtsc/indexer",
+        "@npm//typescript",
+    ],
+)
+
+jasmine_node_test(
+    name = "test",
+    bootstrap = ["angular/tools/testing/init_node_no_angular_spec.js"],
+    deps = [
+        ":test_lib",
+        "//tools/testing:node_no_angular",
+    ],
+)
diff --git a/packages/compiler-cli/src/ngtsc/indexer/test/template_spec.ts b/packages/compiler-cli/src/ngtsc/indexer/test/template_spec.ts
new file mode 100644
index 0000000000..488235a8a9
--- /dev/null
+++ b/packages/compiler-cli/src/ngtsc/indexer/test/template_spec.ts
@@ -0,0 +1,98 @@
+/**
+ * @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 {InterpolationConfig, ParseSourceFile, TmplAstNode, parseTemplate} from '@angular/compiler';
+import {AbsoluteSourceSpan, IdentifierKind, RestoreTemplateOptions} from '..';
+import {getTemplateIdentifiers} from '../src/template';
+
+const TEST_FILE = 'TEST';
+
+function parse(template: string): TmplAstNode[] {
+  return parseTemplate(template, TEST_FILE).nodes;
+}
+
+describe('getTemplateIdentifiers', () => {
+  const DEFAULT_RESTORE_OPTIONS:
+      RestoreTemplateOptions = {interpolationConfig: new InterpolationConfig('{{', '}}')};
+
+  it('should generate nothing in HTML-only template', () => {
+    const refs = getTemplateIdentifiers(parse('<div></div>'), DEFAULT_RESTORE_OPTIONS);
+
+    expect(refs.size).toBe(0);
+  });
+
+  it('should ignore comments', () => {
+    const refs = getTemplateIdentifiers(
+        parse(`
+    <!-- {{my_module}} -->
+    <div><!-- {{goodbye}} --></div>
+    `),
+        DEFAULT_RESTORE_OPTIONS);
+
+    expect(refs.size).toBe(0);
+  });
+
+  it('should use any interpolation config', () => {
+    const template = '<div>((foo))</div>';
+    const refs = getTemplateIdentifiers(
+        parse(template), {interpolationConfig: new InterpolationConfig('((', '))')});
+
+    const [ref] = Array.from(refs);
+    expect(ref.name).toBe('foo');
+    expect(ref.kind).toBe(IdentifierKind.Property);
+    expect(ref.span).toEqual(new AbsoluteSourceSpan(7, 10));
+    expect(ref.file).toEqual(new ParseSourceFile(template, TEST_FILE));
+  });
+
+  describe('generates identifiers for PropertyReads', () => {
+    it('should discover component properties', () => {
+      const template = '<div>{{foo}}</div>';
+      const refs = getTemplateIdentifiers(parse(template), DEFAULT_RESTORE_OPTIONS);
+      expect(refs.size).toBe(1);
+
+      const [ref] = Array.from(refs);
+      expect(ref.name).toBe('foo');
+      expect(ref.kind).toBe(IdentifierKind.Property);
+      expect(ref.span).toEqual(new AbsoluteSourceSpan(7, 10));
+      expect(ref.file).toEqual(new ParseSourceFile(template, TEST_FILE));
+    });
+
+    it('should discover component method calls', () => {
+      const template = '<div>{{foo()}}</div>';
+      const refs = getTemplateIdentifiers(parse(template), DEFAULT_RESTORE_OPTIONS);
+
+      const [ref] = Array.from(refs);
+      expect(ref.name).toBe('foo');
+      expect(ref.kind).toBe(IdentifierKind.Method);
+      expect(ref.span).toEqual(new AbsoluteSourceSpan(7, 10));
+      expect(ref.file).toEqual(new ParseSourceFile(template, TEST_FILE));
+    });
+
+    it('should handle arbitrary whitespace', () => {
+      const template = '<div>\n\n   {{foo}}</div>';
+      const refs = getTemplateIdentifiers(parse(template), DEFAULT_RESTORE_OPTIONS);
+
+      const [ref] = Array.from(refs);
+      expect(ref.name).toBe('foo');
+      expect(ref.kind).toBe(IdentifierKind.Property);
+      expect(ref.span).toEqual(new AbsoluteSourceSpan(12, 15));
+      expect(ref.file).toEqual(new ParseSourceFile(template, TEST_FILE));
+    });
+
+    it('should handle nested scopes', () => {
+      const template = '<div><span>{{foo}}</span></div>';
+      const refs = getTemplateIdentifiers(parse(template), DEFAULT_RESTORE_OPTIONS);
+
+      const [ref] = Array.from(refs);
+      expect(ref.name).toBe('foo');
+      expect(ref.kind).toBe(IdentifierKind.Property);
+      expect(ref.span).toEqual(new AbsoluteSourceSpan(13, 16));
+      expect(ref.file).toEqual(new ParseSourceFile(template, TEST_FILE));
+    });
+  });
+});