Move diff.dart to dart2js_incremental.

dart/site/try/poi/diff.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 trydart.poi.diff;
-
-import 'package:compiler/implementation/elements/elements.dart' show
-    AbstractFieldElement,
-    ClassElement,
-    CompilationUnitElement,
-    Element,
-    ElementCategory,
-    FunctionElement,
-    LibraryElement,
-    ScopeContainerElement;
-
-import 'package:compiler/implementation/elements/modelx.dart' as modelx;
-
-import 'package:compiler/implementation/elements/modelx.dart' show
-    DeclarationSite;
-
-import 'package:compiler/implementation/scanner/scannerlib.dart' show
-    EOF_TOKEN,
-    ErrorToken,
-    IDENTIFIER_TOKEN,
-    KEYWORD_TOKEN,
-    PartialClassElement,
-    PartialElement,
-    Token;
-
-class Difference {
-  final DeclarationSite before;
-  final DeclarationSite after;
-  Token token;
-
-  Difference(this.before, this.after);
-
-  String toString() {
-    if (before == null) return 'Added($after)';
-    if (after == null) return 'Removed($before)';
-    return 'Modified($after -> $before)';
-  }
-}
-
-List<Difference> computeDifference(
-    ScopeContainerElement before,
-    ScopeContainerElement after) {
-  Map<String, DeclarationSite> beforeMap = <String, DeclarationSite>{};
-  before.forEachLocalMember((modelx.ElementX element) {
-    DeclarationSite site = element.declarationSite;
-    assert(site != null);
-    beforeMap[element.name] = site;
-  });
-  List<Difference> modifications = <Difference>[];
-  List<Difference> potentiallyChanged = <Difference>[];
-  after.forEachLocalMember((modelx.ElementX element) {
-    DeclarationSite existing = beforeMap.remove(element.name);
-    if (existing == null) {
-      modifications.add(new Difference(null, element.declarationSite));
-    } else {
-      potentiallyChanged.add(new Difference(existing, element.declarationSite));
-    }
-  });
-
-  modifications.addAll(
-      beforeMap.values.map(
-          (DeclarationSite site) => new Difference(site, null)));
-
-  modifications.addAll(
-      potentiallyChanged.where(areDifferentElements));
-
-  return modifications;
-}
-
-bool areDifferentElements(Difference diff) {
-  DeclarationSite before = diff.before;
-  DeclarationSite after = diff.after;
-  if (before is PartialElement && after is PartialElement) {
-    Token beforeToken = before.beginToken;
-    Token afterToken = after.beginToken;
-    Token stop = before.endToken;
-    int beforeKind = beforeToken.kind;
-    int afterKind = afterToken.kind;
-    while (beforeKind != EOF_TOKEN && afterKind != EOF_TOKEN) {
-
-      if (beforeKind != afterKind) {
-        diff.token = afterToken;
-        return true;
-      }
-
-      if (beforeToken is! ErrorToken && afterToken is! ErrorToken) {
-        if (beforeToken.value != afterToken.value) {
-          diff.token = afterToken;
-          return true;
-        }
-      }
-
-      if (beforeToken == stop) return false;
-
-      beforeToken = beforeToken.next;
-      afterToken = afterToken.next;
-      beforeKind = beforeToken.kind;
-      afterKind = afterToken.kind;
-    }
-    return beforeKind != afterKind;
-  }
-  print("$before isn't a PartialElement");
-  return true;
-}