Fix for map and list literal indentation (dartbug.com/15453).

pkg/analyzer/lib/src/services/formatter_impl.dart

 // Copyright (c) 2013, 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 formatter_impl;
 
 import 'dart:math';
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/src/generated/java_core.dart' show CharSequence;
@@ skipping 337 matching lines @@
 
   /// Cached previous token for calculating preceding whitespace.
   Token previousToken;
 
   /// A flag to indicate that a newline should be emitted before the next token.
   bool needsNewline = false;
 
   /// A counter for spaces that should be emitted preceding the next token.
   int leadingSpaces = 0;
 
+  /// A flag to specify whether line-leading spaces should be preserved (and
+  /// addded to the indent level).
+  bool allowLineLeadingSpaces;
+
   /// Used for matching EOL comments
   final twoSlashes = new RegExp(r'//[^/]');
 
   /// Original pre-format selection information (may be null).
   final Selection preSelection;
 
   final bool codeTransforms;
 
   /// Post format selection information.
   Selection selection;
@@ skipping 223 matching lines @@
   visitConstructorInitializers(ConstructorDeclaration node) {
     newlines();
     indent(2);
     token(node.separator /* : */);
     space();
     for (var i = 0; i < node.initializers.length; i++) {
       if (i > 0) {
         // preceding comma
         token(node.initializers[i].beginToken.previous);
         newlines();
-        space(2);
+        space(n: 2, allowLineLeading: true);
       }
       node.initializers[i].accept(this);
     }
     unindent(2);
   }
 
   visitConstructorRedirects(ConstructorDeclaration node) {
     token(node.separator /* = */, precededBy: space, followedBy: space);
     visitCommaSeparatedNodes(node.initializers);
     visit(node.redirectedConstructor);
@@ skipping 317 matching lines @@
   }
 
   visitLibraryIdentifier(LibraryIdentifier node) {
     append(node.name);
   }
 
   visitListLiteral(ListLiteral node) {
     modifier(node.constKeyword);
     visit(node.typeArguments);
     token(node.leftBracket);
+    indent();
     visitCommaSeparatedNodes(node.elements);
     optionalTrailingComma(node.rightBracket);
+    unindent();
     token(node.rightBracket);
   }
 
   visitMapLiteral(MapLiteral node) {
     modifier(node.constKeyword);
     visitNode(node.typeArguments, followedBy: space);
     token(node.leftBracket);
+    indent();
     visitCommaSeparatedNodes(node.entries);
     optionalTrailingComma(node.rightBracket);
+    unindent();
     token(node.rightBracket);
   }
 
   visitMapLiteralEntry(MapLiteralEntry node) {
     visit(node.key);
     token(node.separator);
     space();
     visit(node.value);
   }
 
@@ skipping 384 matching lines @@
       append(token.lexeme);
       if (followedBy != null) {
         followedBy();
       }
       previousToken = token;
     }
   }
 
   emitSpaces() {
     while (leadingSpaces > 0) {
-      writer.print(' ');
+      if (!writer.currentLine.isWhitespace() || allowLineLeadingSpaces) {
+        writer.print(' ');
+      }
+      allowLineLeadingSpaces = false;
       leadingSpaces--;
     }
   }
 
   checkForSelectionUpdate(Token token) {
     // Cache the first token on or AFTER the selection offset
     if (preSelection != null && selection == null) {
       // Check for overshots
       var overshot = token.offset - preSelection.offset;
       if (overshot >= 0) {
         //TODO(pquitslund): update length (may need truncating)
         selection = new Selection(
             writer.toString().length + leadingSpaces - overshot,
             preSelection.length);
       }
     }
   }
 
-  /// Emit a non-breakable space.
-  space([n = 1]) {
+  /// Emit a non-breakable space. If [allowLineLeading] is specified, spaces
+  /// will be preserved at the start of a line (in addition to the
+  /// indent-level), otherwise line-leading spaces will be ignored.
+  space({n: 1, allowLineLeading: false}) {
     //TODO(pquitslund): replace with a proper space token
     leadingSpaces+=n;
+    allowLineLeadingSpaces = allowLineLeading;
   }
 
   /// Emit a breakable space
   breakableSpace() {
     //Implement
   }
 
   /// Append the given [string] to the source writer if it's non-null.
   append(String string) {
     if (string != null && !string.isEmpty) {
@@ skipping 164 matching lines @@
     var lastLine =
         lineInfo.getLocation(lastOffset).lineNumber;
     var currentLine =
         lineInfo.getLocation(currentOffset).lineNumber;
     return currentLine - lastLine;
   }
 
   String toString() => writer.toString();
 
 }