Issue 22833. Quick Assist to convert for-each into for-index.

pkg/analysis_server/lib/src/services/correction/util.dart

 // Copyright (c) 2014, 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.
 
 library services.src.correction.util;
 
 import 'dart:math';
 
 import 'package:analysis_server/src/protocol.dart'
     show SourceChange, SourceEdit;
 import 'package:analysis_server/src/protocol_server.dart'
     show doSourceChange_addElementEdit;
 import 'package:analysis_server/src/services/correction/source_range.dart';
 import 'package:analysis_server/src/services/correction/strings.dart';
+import 'package:analysis_server/src/services/search/element_visitors.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/resolver.dart';
 import 'package:analyzer/src/generated/scanner.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:path/path.dart';
 
 /**
  * Adds edits to the given [change] that ensure that all the [libraries] are
@@ skipping 564 matching lines @@
     return new SourceEdit(range.offset, range.length, newSource);
   }
 
   /**
    * Returns the [AstNode] that encloses the given offset.
    */
   AstNode findNode(int offset) =>
       new NodeLocator.con1(offset).searchWithin(unit);
 
   /**
+   * Returns names of elements that might conflict with a new local variable
+   * declared at [offset].
+   */
+  Set<String> findPossibleLocalVariableConflicts(int offset) {
+    Set<String> conflicts = new Set<String>();
+    AstNode enclosingNode = findNode(offset);
+    Block enclosingBlock = enclosingNode.getAncestor((node) => node is Block);
+    if (enclosingBlock != null) {
+      SourceRange newRange = rangeStartEnd(offset, enclosingBlock.end);
+      ExecutableElement enclosingExecutable =
+          getEnclosingExecutableElement(enclosingNode);
+      if (enclosingExecutable != null) {
+        visitChildren(enclosingExecutable, (Element element) {
+          if (element is LocalElement) {
+            SourceRange elementRange = element.visibleRange;
+            if (elementRange != null && elementRange.intersects(newRange)) {
+              conflicts.add(element.displayName);
+            }
+          }
+          return true;
+        });
+      }
+    }
+    return conflicts;
+  }
+
+  /**
    * Returns the actual type source of the given [Expression], may be `null`
    * if can not be resolved, should be treated as the `dynamic` type.
    */
   String getExpressionTypeSource(
       Expression expression, Set<LibraryElement> librariesToImport) {
     if (expression == null) {
       return null;
     }
     DartType type = expression.bestType;
     if (type.isDynamic) {
@@ skipping 864 matching lines @@
 
   @override
   Object visitExpression(Expression node) {
     if (node is BinaryExpression && node.operator.type == groupOperatorType) {
       return super.visitNode(node);
     }
     operands.add(node);
     return null;
   }
 }