Move dart2js from sdk/lib/_internal/compiler to pkg/compiler

sdk/lib/_internal/compiler/implementation/dart_backend/renamer.dart

-// Copyright (c) 2012, 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.
-
-part of dart_backend;
-
-Comparator get _compareNodes =>
-    compareBy((n) => n.getBeginToken().charOffset);
-
-abstract class Renamable implements Comparable {
-  final int RENAMABLE_TYPE_ELEMENT = 1;
-  final int RENAMABLE_TYPE_MEMBER = 2;
-  final int RENAMABLE_TYPE_LOCAL = 3;
-
-  final Set<Node> nodes;
-
-  Renamable(this.nodes);
-  int compareTo(Renamable other) {
-    int nodesDiff = other.nodes.length.compareTo(this.nodes.length);
-    if (nodesDiff != 0) return nodesDiff;
-    int typeDiff = this.kind.compareTo(other.kind);
-    return typeDiff != 0 ? typeDiff : compareInternals(other);
-  }
-
-  int compareInternals(Renamable other);
-  int get kind;
-
-  String createNewName(PlaceholderRenamer placeholderRenamer);
-}
-
-class GlobalRenamable extends Renamable {
-  final Entity entity;
-
-  GlobalRenamable(this.entity, Set<Node> nodes)
-      : super(nodes);
-
-  int compareInternals(GlobalRenamable other) =>
-      compareElements(this.entity, other.entity);
-  int get kind => RENAMABLE_TYPE_ELEMENT;
-  String createNewName(PlaceholderRenamer placeholderRenamer) {
-    return placeholderRenamer._renameGlobal(entity);
-  }
-}
-
-class MemberRenamable extends Renamable {
-  final String identifier;
-  MemberRenamable(this.identifier, Set<Node> nodes)
-      : super(nodes);
-  int compareInternals(MemberRenamable other) =>
-      this.identifier.compareTo(other.identifier);
-  int get kind => RENAMABLE_TYPE_MEMBER;
-  String createNewName(PlaceholderRenamer placeholderRenamer) {
-    return placeholderRenamer._generateMemberName(identifier);
-  }
-}
-
-class LocalRenamable extends Renamable {
-  LocalRenamable(Set<Node> nodes)
-      : super(nodes);
-  int compareInternals(LocalRenamable other) =>
-      _compareNodes(sorted(this.nodes, _compareNodes)[0],
-          sorted(other.nodes, _compareNodes)[0]);
-  int get kind => RENAMABLE_TYPE_LOCAL;
-  String createNewName(PlaceholderRenamer placeholderRenamer) {
-    return placeholderRenamer._generateUniqueTopLevelName("");
-  }
-}
-
-/**
- * Renames only top-level elements that would lead to ambiguity if not renamed.
- */
-class PlaceholderRenamer {
-  /// After running [computeRenames] this will contain the computed renames.
-  final Map<Node, String> renames = new Map<Node, String>();
-  /// After running [computeRenames] this will contain the used platform
-  /// libraries.
-  final Set<LibraryElement> platformImports = new Set<LibraryElement>();
-
-  final bool enableMinification;
-  final Set<String> fixedMemberNames;
-  final Map<Element, LibraryElement> reexportingLibraries;
-  final bool cutDeclarationTypes;
-
-  final Map<Entity, String> _renamedCache = new Map<Entity, String>();
-  final Map<Entity, Map<String, String>> _privateCache =
-      new Map<Entity, Map<String, String>>();
-
-  // Identifiers that has already been used, or are reserved by the
-  // language/platform.
-  Set<String> _forbiddenIdentifiers;
-  Set<String> _allNamedParameterIdentifiers;
-
-  Generator _generator;
-
-  PlaceholderRenamer(this.fixedMemberNames,
-                     this.reexportingLibraries,
-                     {this.enableMinification, this.cutDeclarationTypes});
-
-  void _renameNodes(Iterable<Node> nodes, String renamer(Node node)) {
-    for (Node node in sorted(nodes, _compareNodes)) {
-      renames[node] = renamer(node);
-    }
-  }
-
-  String _generateUniqueTopLevelName(originalName) {
-    String newName = _generator.generate(originalName, (name) {
-      return _forbiddenIdentifiers.contains(name) ||
-             _allNamedParameterIdentifiers.contains(name);
-    });
-    _forbiddenIdentifiers.add(newName);
-    return newName;
-  }
-
-  String _generateMemberName(String original) {
-    return _generator.generate(original, _forbiddenIdentifiers.contains);
-  }
-
-  /// Looks up [originalName] in the [_privateCache] cache of [library].
-  /// If [originalName] was not renamed before, generate a new name.
-  String _getPrivateName(LibraryElement library, String originalName) {
-    return _privateCache.putIfAbsent(library, () => new Map<String, String>())
-        .putIfAbsent(originalName,
-                     () => _generateUniqueTopLevelName(originalName));
-  }
-
-  String _renameConstructor(ConstructorPlaceholder placeholder) {
-    String name = placeholder.element.name;
-    if (name == '') return "";
-    String result = _renameGlobal(placeholder.element);
-    return result;
-  }
-
-  String _renameGlobal(Entity entity) {
-    assert(entity is! Element ||
-           Elements.isErroneousElement(entity) ||
-           Elements.isStaticOrTopLevel(entity) ||
-           entity is TypeVariableElement);
-    // TODO(smok): We may want to reuse class static field and method names.
-    if (entity is Element) {
-      LibraryElement library = entity.library;
-      if (reexportingLibraries.containsKey(entity)) {
-        library = reexportingLibraries[entity];
-      }
-      if (library.isPlatformLibrary) {
-        if (library.canonicalUri != Compiler.DART_CORE) {
-          platformImports.add(library);
-        }
-        if (library.isInternalLibrary) {
-          throw new SpannableAssertionFailure(entity,
-              "Internal library $library should never have been imported from "
-              "the code compiled by dart2dart.");
-        }
-        return entity.name;
-      }
-    }
-    String name = _renamedCache.putIfAbsent(entity,
-            () => _generateUniqueTopLevelName(entity.name));
-    // Look up in [_renamedCache] for a name for [entity] .
-    // If it was not renamed before, generate a new name.
-    return name;
-  }
-
-  void _computeMinifiedRenames(PlaceholderCollector placeholderCollector) {
-    _generator = new MinifyingGenerator();
-
-    // Build a list sorted by usage of local nodes that will be renamed to
-    // the same identifier. So the top-used local variables in all functions
-    // will be renamed first and will all share the same new identifier.
-    int maxLength = placeholderCollector.functionScopes.values.fold(0,
-        (a, b) => max(a, b.localPlaceholders.length));
-
-    List<Set<Node>> allLocals = new List<Set<Node>>
-        .generate(maxLength, (_) => new Set<Node>());
-
-    for (FunctionScope functionScope
-        in placeholderCollector.functionScopes.values) {
-      // Add current sorted local identifiers to the whole sorted list
-      // of all local identifiers for all functions.
-      List<LocalPlaceholder> currentSortedPlaceholders =
-          sorted(functionScope.localPlaceholders,
-              compareBy((LocalPlaceholder ph) => -ph.nodes.length));
-
-      List<Set<Node>> currentSortedNodes = currentSortedPlaceholders
-          .map((LocalPlaceholder ph) => ph.nodes).toList();
-
-      for (int i = 0; i < currentSortedNodes.length; i++) {
-        allLocals[i].addAll(currentSortedNodes[i]);
-      }
-    }
-
-    // Rename elements, members and locals together based on their usage
-    // count, otherwise when we rename elements first there will be no good
-    // identifiers left for members even if they are used often.
-    List<Renamable> renamables = new List<Renamable>();
-    placeholderCollector.elementNodes.forEach(
-        (Element element, Set<Node> nodes) {
-      renamables.add(new GlobalRenamable(element, nodes));
-    });
-    placeholderCollector.memberPlaceholders.forEach(
-        (String memberName, Set<Identifier> identifiers) {
-      renamables.add(new MemberRenamable(memberName, identifiers));
-    });
-    for (Set<Node> localIdentifiers in allLocals) {
-      renamables.add(new LocalRenamable(localIdentifiers));
-    }
-    renamables.sort();
-    for (Renamable renamable in renamables) {
-      String newName = renamable.createNewName(this);
-      _renameNodes(renamable.nodes, (_) => newName);
-    }
-  }
-
-  void _computeNonMinifiedRenames(PlaceholderCollector placeholderCollector) {
-    _generator = new ConservativeGenerator();
-    // Rename elements.
-    placeholderCollector.elementNodes.forEach(
-        (Element element, Set<Node> nodes) {
-      _renameNodes(nodes, (_) => _renameGlobal(element));
-    });
-
-    // Rename locals.
-    placeholderCollector.functionScopes.forEach(
-        (functionElement, functionScope) {
-
-      Set<String> memberIdentifiers = new Set<String>();
-      Set<LocalPlaceholder> placeholders = functionScope.localPlaceholders;
-      if (functionElement.enclosingClass != null) {
-        functionElement.enclosingClass.forEachMember(
-            (enclosingClass, member) {
-              memberIdentifiers.add(member.name);
-            });
-      }
-      Set<String> usedLocalIdentifiers = new Set<String>();
-      for (LocalPlaceholder placeholder in placeholders) {
-        String nextId = _generator.generate(placeholder.identifier, (name) {
-          return functionScope.parameterIdentifiers.contains(name)
-              || _forbiddenIdentifiers.contains(name)
-              || usedLocalIdentifiers.contains(name)
-              || memberIdentifiers.contains(name);
-        });
-        usedLocalIdentifiers.add(nextId);
-        _renameNodes(placeholder.nodes, (_) => nextId);
-      }
-    });
-
-    // Do not rename members to top-levels, that allows to avoid renaming
-    // members to constructors.
-    placeholderCollector.memberPlaceholders.forEach((identifier, nodes) {
-      String newIdentifier = _generateMemberName(identifier);
-      _renameNodes(nodes, (_) => newIdentifier);
-    });
-  }
-
-  /// Finds renamings for all the placeholders in [placeholderCollector] and
-  /// stores them in [renames].
-  /// Also adds to [platformImports] all the platform-libraries that are used.
-  void computeRenames(PlaceholderCollector placeholderCollector) {
-    _allNamedParameterIdentifiers = new Set<String>();
-    for (FunctionScope functionScope in
-        placeholderCollector.functionScopes.values) {
-      _allNamedParameterIdentifiers.addAll(functionScope.parameterIdentifiers);
-    }
-
-    _forbiddenIdentifiers = new Set<String>.from(fixedMemberNames);
-    _forbiddenIdentifiers.addAll(Keyword.keywords.keys);
-    _forbiddenIdentifiers.add('main');
-
-    if (enableMinification) {
-      _computeMinifiedRenames(placeholderCollector);
-    } else {
-      _computeNonMinifiedRenames(placeholderCollector);
-    }
-
-    // Rename constructors.
-    for (ConstructorPlaceholder placeholder in
-        placeholderCollector.constructorPlaceholders) {
-      renames[placeholder.node] =
-          _renameConstructor(placeholder);
-    };
-
-    // Rename private identifiers uniquely for each library.
-    placeholderCollector.privateNodes.forEach(
-        (LibraryElement library, Set<Identifier> identifiers) {
-      for (Identifier identifier in identifiers) {
-        renames[identifier] = _getPrivateName(library, identifier.source);
-      }
-    });
-
-    // Rename unresolved nodes, to make sure they still do not resolve.
-    for (Node node in placeholderCollector.unresolvedNodes) {
-      renames[node] = _generateUniqueTopLevelName('Unresolved');
-    }
-
-    // Erase prefixes that are now not needed.
-    for (Node node in placeholderCollector.prefixNodesToErase) {
-      renames[node] = '';
-    }
-
-    if (cutDeclarationTypes) {
-      for (DeclarationTypePlaceholder placeholder in
-           placeholderCollector.declarationTypePlaceholders) {
-        renames[placeholder.typeNode] = placeholder.requiresVar ? 'var' : '';
-      }
-    }
-  }
-}
-
-/**
- * Generates mini ID based on index.
- * In other words, it converts index to visual representation
- * as if digits are given characters.
- */
-String generateMiniId(int index) {
-  const String firstCharAlphabet =
-      r'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
-  const String otherCharsAlphabet =
-      r'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_$';
-  // It's like converting index in decimal to [chars] radix.
-  if (index < firstCharAlphabet.length) return firstCharAlphabet[index];
-  StringBuffer resultBuilder = new StringBuffer();
-  resultBuilder.writeCharCode(
-     firstCharAlphabet.codeUnitAt(index % firstCharAlphabet.length));
-  index ~/= firstCharAlphabet.length;
-  int length = otherCharsAlphabet.length;
-  while (index >= length) {
-    resultBuilder.writeCharCode(otherCharsAlphabet.codeUnitAt(index % length));
-    index ~/= length;
-  }
-  resultBuilder.write(otherCharsAlphabet[index]);
-  return resultBuilder.toString();
-}
-
-abstract class Generator {
-  String generate(String originalName, bool isForbidden(String name));
-}
-
-/// Always tries to return original identifier name unless it is forbidden.
-class ConservativeGenerator implements Generator {
-  String generate(String originalName, bool isForbidden(String name)) {
-    String result = originalName;
-    int index = 0;
-    while (isForbidden(result) ){ //|| result == originalName) {
-      result = '${originalName}_${generateMiniId(index++)}';
-    }
-    return result;
-  }
-}
-
-/// Always tries to generate the most compact identifier.
-class MinifyingGenerator implements Generator {
-  int index = 0;
-
-  MinifyingGenerator();
-
-  String generate(String originalName, bool isForbidden(String name)) {
-    String result;
-    do {
-      result = generateMiniId(index++);
-    } while (isForbidden(result));
-    return result;
-  }
-}