Start implementing search support in AnalysisDriver.

pkg/analyzer/lib/src/dart/analysis/search.dart

+// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+
+import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/ast/visitor.dart';
+import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/visitor.dart';
+import 'package:analyzer/src/dart/analysis/driver.dart';
+import 'package:analyzer/src/dart/ast/utilities.dart';
+import 'package:analyzer/src/dart/element/element.dart';
+
+/**
+ * Search support for an [AnalysisDriver].
+ */
+class Search {
+  final AnalysisDriver _driver;
+
+  Search(this._driver);
+
+  /**
+   * Returns references to the element at the given [offset] in the file with
+   * the given [path].
+   */
+  Future<List<SearchResult>> references(String path, int offset) async {
+    // Search only in added files.
+    if (!_driver.addedFiles.contains(path)) {
+      return const <SearchResult>[];
+    }
+
+    AnalysisResult analysisResult = await _driver.getResult(path);
+    CompilationUnit unit = analysisResult.unit;
+
+    // Prepare the node.
+    AstNode node = new NodeLocator(offset).searchWithin(unit);
+    if (node == null) {
+      return const <SearchResult>[];
+    }
+
+    // Prepare the element.
+    Element element = ElementLocator.locate(node);
+    if (element == null) {
+      return const <SearchResult>[];
+    }
+
+    ElementKind kind = element.kind;
+    if (kind == ElementKind.LABEL || kind == ElementKind.LOCAL_VARIABLE) {
+      Block block = node.getAncestor((n) => n is Block);
+      return _searchReferences_Local(element, unit.element, block);
+    }
+    // TODO(scheglov) support other kinds
+    return [];
+  }
+
+  Future<List<SearchResult>> _searchReferences_Local(
+      Element element,
+      CompilationUnitElement enclosingUnitElement,
+      AstNode enclosingNode) async {
+    _LocalReferencesVisitor visitor =
+        new _LocalReferencesVisitor(element, enclosingUnitElement);
+    enclosingNode?.accept(visitor);
+    return visitor.matches;
+  }
+}
+
+/**
+ * A single search result.
+ */
+class SearchResult {
+  /**
+   * The element that is used at this result.
+   */
+  final Element element;
+
+  /**
+   * The deep most element that contains this result.
+   */
+  final Element enclosingElement;
+
+  /**
+   * The kind of the [element] usage.
+   */
+  final SearchResultKind kind;
+
+  /**
+   * The offset relative to the beginning of the containing file.
+   */
+  final int offset;
+
+  /**
+   * The length of the usage in the containing file context.
+   */
+  final int length;
+
+  /**
+   * Is `true` if a field or a method is using with a qualifier.
+   */
+  final bool isResolved;
+
+  /**
+   * Is `true` if the result is a resolved reference to [element].
+   */
+  final bool isQualified;
+
+  SearchResult._(this.element, this.enclosingElement, this.kind, this.offset,
+      this.length, this.isResolved, this.isQualified);
+
+  @override
+  String toString() {
+    StringBuffer buffer = new StringBuffer();
+    buffer.write("SearchResult(kind=");
+    buffer.write(kind);
+    buffer.write(", offset=");
+    buffer.write(offset);
+    buffer.write(", length=");
+    buffer.write(length);
+    buffer.write(", isResolved=");
+    buffer.write(isResolved);
+    buffer.write(", isQualified=");
+    buffer.write(isQualified);
+    buffer.write(", enclosingElement=");
+    buffer.write(enclosingElement);
+    buffer.write(")");
+    return buffer.toString();
+  }
+}
+
+/**
+ * The kind of reference in a [SearchResult].
+ */
+enum SearchResultKind { READ, READ_WRITE, WRITE, INVOCATION, REFERENCE }
+
+/**
+ * A visitor that finds the deep-most [Element] that contains the [offset].
+ */
+class _ContainingElementFinder extends GeneralizingElementVisitor {
+  final int offset;
+  Element containingElement;
+
+  _ContainingElementFinder(this.offset);
+
+  visitElement(Element element) {
+    if (element is ElementImpl) {
+      if (element.codeOffset != null &&
+          element.codeOffset <= offset &&
+          offset <= element.codeOffset + element.codeLength) {
+        containingElement = element;
+        super.visitElement(element);
+      }
+    }
+  }
+}
+
+/**
+ * Visitor that adds [SearchResult]s for local elements of a block, method,
+ * class or a library - labels, local functions, local variables and parameters,
+ * type parameters, import prefixes.
+ */
+class _LocalReferencesVisitor extends RecursiveAstVisitor {
+  final List<SearchResult> matches = <SearchResult>[];
+
+  final Element element;
+  final CompilationUnitElement enclosingUnitElement;
+
+  _LocalReferencesVisitor(this.element, this.enclosingUnitElement);
+
+  @override
+  visitSimpleIdentifier(SimpleIdentifier node) {
+    if (node.inDeclarationContext()) {
+      return;
+    }
+    if (node.staticElement == element) {
+      AstNode parent = node.parent;
+      SearchResultKind kind = SearchResultKind.REFERENCE;
+      if (element is FunctionElement) {
+        if (parent is MethodInvocation && parent.methodName == node) {
+          kind = SearchResultKind.INVOCATION;
+        }
+      } else if (element is VariableElement) {
+        bool isGet = node.inGetterContext();
+        bool isSet = node.inSetterContext();
+        if (isGet && isSet) {
+          kind = SearchResultKind.READ_WRITE;
+        } else if (isGet) {
+          if (parent is MethodInvocation && parent.methodName == node) {
+            kind = SearchResultKind.INVOCATION;
+          } else {
+            kind = SearchResultKind.READ;
+          }
+        } else if (isSet) {
+          kind = SearchResultKind.WRITE;
+        }
+      }
+      _addMatch(node, kind);
+    }
+  }
+
+  void _addMatch(AstNode node, SearchResultKind kind) {
+    bool isQualified = node.parent is Label;
+    var finder = new _ContainingElementFinder(node.offset);
+    enclosingUnitElement.accept(finder);
+    matches.add(new SearchResult._(element, finder.containingElement, kind,
+        node.offset, node.length, true, isQualified));
+  }
+}