'Inline Method' refactoring.

pkg/analysis_server/lib/src/services/refactoring/inline_method.dart

Index: pkg/analysis_server/lib/src/services/refactoring/inline_method.dart
diff --git a/pkg/analysis_server/lib/src/services/refactoring/inline_method.dart b/pkg/analysis_server/lib/src/services/refactoring/inline_method.dart
new file mode 100644
index 0000000000000000000000000000000000000000..034ee04bc4c01cf712aaced7ca61050c2c96edd4
--- /dev/null
+++ b/pkg/analysis_server/lib/src/services/refactoring/inline_method.dart
@@ -0,0 +1,810 @@
+// 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.refactoring.inline_method;
+
+import 'dart:async';
+
+import 'package:analysis_server/src/protocol.dart' hide Element;
+import 'package:analysis_server/src/services/correction/source_range.dart';
+import 'package:analysis_server/src/services/correction/status.dart';
+import 'package:analysis_server/src/services/correction/util.dart';
+import 'package:analysis_server/src/services/refactoring/refactoring.dart';
+import 'package:analysis_server/src/services/refactoring/refactoring_internal.dart';
+import 'package:analysis_server/src/services/search/element_visitors.dart';
+import 'package:analysis_server/src/services/search/hierarchy.dart';
+import 'package:analysis_server/src/services/search/search_engine.dart';
+import 'package:analyzer/src/generated/ast.dart';
+import 'package:analyzer/src/generated/element.dart';
+import 'package:analyzer/src/generated/scanner.dart';
+import 'package:analyzer/src/generated/source.dart';
+
+
+/**
+ * Resolver sets [ParameterElement] for the most cases, but not for setter invocation.

[Brian Wilkerson, 2014/08/31 15:59:56]

First, the resolver never sets the parameter elements, they are computed when
requested. That implies that either the computation is wrong or that the
resolver isn't setting the element for the assignment to the setter. Shouldn't
this be fixed by either fixing the computation of the parameter element or by
fixing the resolver so that the right element is associated with the assignment
expression?

[scheglov, 2014/08/31 16:43:23]

The underlaying problem is that for "f = 0" the AssignmentExpression doesn't
have a static element.
I will investigate this.

+ *
+ * Returns the best available [ParameterElement] for which the given [Expression] is used.
+ */
+ParameterElement _getBestParameterElement(Expression expr) {
+  // setter invocation
+  if (expr.parent is AssignmentExpression) {

[Brian Wilkerson, 2014/08/31 15:59:56]

Alternatively, assign "expr.parent" to a local variable before the test and
avoid the need for the cast altogether.

+    AssignmentExpression assignment = expr.parent as AssignmentExpression;
+    if (identical(assignment.rightHandSide, expr) &&
+        assignment.operator.type == TokenType.EQ) {
+      Expression lhs = assignment.leftHandSide;
+      Element lhsElement = null;
+      if (lhs is Identifier) {
+        lhsElement = lhs.bestElement;
+      }
+      if (lhs is PropertyAccess) {
+        lhsElement = lhs.propertyName.bestElement;
+      }
+      if (lhsElement is PropertyAccessorElement) {
+        List<ParameterElement> parameters = lhsElement.parameters;
+        if (parameters.length != 0) {
+          return parameters[0];
+        }
+      }
+    }
+  }
+  // use resolver
+  return expr.bestParameterElement;
+}
+
+
+/**
+ * Returns the [SourceRange] to find conflicting locals in.
+ */
+SourceRange _getLocalsConflictingRange(AstNode node) {
+  // maybe Block
+  Block block = node.getAncestor((node) => node is Block);
+  if (block != null) {
+    int offset = node.offset;
+    int endOffset = block.end;
+    return rangeStartEnd(offset, endOffset);
+  }
+  // maybe whole executable
+  AstNode executableNode = getEnclosingExecutableNode(node);
+  if (executableNode != null) {
+    return rangeNode(executableNode);
+  }
+  // not a part of a declaration with locals
+  return SourceRange.EMPTY;
+}
+
+
+/**
+ * Returns the source which should replace given invocation with given
+ * arguments.
+ */
+String _getMethodSourceForInvocation(_SourcePart part, CorrectionUtils utils,
+    AstNode contextNode, Expression targetExpression, List<Expression> arguments) {
+  // prepare edits to replace parameters with arguments
+  List<SourceEdit> edits = <SourceEdit>[];
+  part._parameters.forEach((ParameterElement parameter, occurrences) {

[Brian Wilkerson, 2014/08/31 15:59:56]

Missing type annotation on "occurrences".

[scheglov, 2014/08/31 16:43:23]

Fixed.

+    // prepare argument
+    Expression argument = null;
+    for (Expression arg in arguments) {
+      if (_getBestParameterElement(arg) == parameter) {
+        argument = arg;
+        break;
+      }
+    }
+    if (argument is NamedExpression) {
+      argument = (argument as NamedExpression).expression;
+    }
+    int argumentPrecedence = getExpressionPrecedence(argument);
+    String argumentSource = utils.getNodeText(argument);
+    // replace all occurrences of this parameter
+    for (_ParameterOccurrence occurrence in occurrences) {
+      SourceRange range = occurrence.range;
+      // prepare argument source to apply at this occurrence
+      String occurrenceArgumentSource;
+      if (argumentPrecedence < occurrence.parentPrecedence) {
+        occurrenceArgumentSource = "(${argumentSource})";
+      } else {
+        occurrenceArgumentSource = argumentSource;
+      }
+      // do replace
+      edits.add(new SourceEdit.range(range, occurrenceArgumentSource));
+    }
+  });
+  // replace static field "qualifier" with invocation target
+  part._staticFieldQualifiers.forEach((className, List<SourceRange> ranges) {
+    for (SourceRange range in ranges) {
+      edits.add(new SourceEdit.range(range, className + '.'));
+    }
+  });
+  // replace instance field "qualifier" with invocation target
+  if (targetExpression != null) {
+    String targetSource = utils.getNodeText(targetExpression) + '.';
+    for (SourceRange qualifierRange in part._instanceFieldQualifiers) {
+      edits.add(new SourceEdit.range(qualifierRange, targetSource));
+    }
+  }
+  // prepare edits to replace conflicting variables
+  Set<String> conflictingNames = _getNamesConflictingAt(contextNode);
+  part._variables.forEach((VariableElement variable, ranges) {
+    String originalName = variable.displayName;
+    // prepare unique name
+    String uniqueName;
+    {
+      uniqueName = originalName;
+      int uniqueIndex = 2;
+      while (conflictingNames.contains(uniqueName)) {
+        uniqueName = originalName + uniqueIndex.toString();
+        uniqueIndex++;
+      }
+    }
+    // update references, if name was change
+    if (uniqueName != originalName) {
+      for (SourceRange range in ranges) {
+        edits.add(new SourceEdit.range(range, uniqueName));
+      }
+    }
+  });
+  // prepare source with applied arguments
+  edits.sort((a, b) => b.offset - a.offset);
+  return SourceEdit.applySequence(part._source, edits);
+}
+
+
+/**
+ * Returns the names which will shadow or will be shadowed by any declaration
+ * at [node].
+ */
+Set<String> _getNamesConflictingAt(AstNode node) {
+  Set<String> result = new Set<String>();
+  // local variables and functions
+  {
+    SourceRange localsRange = _getLocalsConflictingRange(node);
+    ExecutableElement enclosingExecutable = getEnclosingExecutableElement(node);
+    if (enclosingExecutable != null) {
+      visitChildren(enclosingExecutable, (element) {
+        if (element is LocalElement) {
+          SourceRange elementRange = element.visibleRange;
+          if (elementRange != null && elementRange.intersects(localsRange)) {
+            result.add(element.displayName);
+          }
+        }
+        return true;
+      });
+    }
+  }
+  // fields
+  {
+    ClassElement enclosingClassElement = getEnclosingClassElement(node);
+    if (enclosingClassElement != null) {
+      Set<ClassElement> elements = new Set<ClassElement>();
+      elements.add(enclosingClassElement);
+      elements.addAll(getSuperClasses(enclosingClassElement));
+      for (ClassElement classElement in elements) {
+        List<Element> classMembers = getChildren(classElement);
+        for (Element classMemberElement in classMembers) {
+          result.add(classMemberElement.displayName);
+        }
+      }
+    }
+  }
+  // done
+  return result;
+}
+
+
+/**
+ * [InlineMethodRefactoring] implementation.
+ */
+class InlineMethodRefactoringImpl extends RefactoringImpl implements
+    InlineMethodRefactoring {
+  final SearchEngine searchEngine;
+  final CompilationUnit unit;
+  final int offset;
+  String file;
+  CorrectionUtils utils;
+  SourceChange change;
+
+  bool deleteSource = false;
+  bool inlineAll = true;
+
+  ExecutableElement _methodElement;
+  String _methodFile;
+  CompilationUnit _methodUnit;
+  CorrectionUtils _methodUtils;
+  AstNode _methodNode;
+  FormalParameterList _methodParameters;
+  FunctionBody _methodBody;
+  Expression _methodExpression;
+  _SourcePart _methodExpressionPart;
+  _SourcePart _methodStatementsPart;
+  List<_ReferenceProcessor> _referenceProcessors = [];
+
+  InlineMethodRefactoringImpl(this.searchEngine, this.unit, this.offset) {
+    file = unit.element.source.fullName;
+    utils = new CorrectionUtils(unit);
+  }
+
+  @override
+  String get refactoringName {
+    if (_methodElement is MethodElement) {
+      return "Inline Method";
+    } else {
+      return "Inline Function";
+    }
+  }
+
+  @override
+  Future<RefactoringStatus> checkFinalConditions() {
+    change = new SourceChange(refactoringName);
+    RefactoringStatus result = new RefactoringStatus();
+    // check for compatibility of "deleteSource" and "inlineAll"
+    if (deleteSource && !inlineAll) {
+      result.addError('All references must be inlined to remove the source.');
+    }
+    // prepare changes
+    for (_ReferenceProcessor processor in _referenceProcessors) {
+      processor._process(result);
+    }
+    // delete method
+    if (deleteSource && inlineAll) {
+      SourceRange methodRange = rangeNode(_methodNode);
+      SourceRange linesRange = _methodUtils.getLinesRange(methodRange);
+      change.addEdit(_methodFile, new SourceEdit.range(linesRange, ""));
+    }
+    // done
+    return new Future.value(result);
+  }
+
+  @override
+  Future<RefactoringStatus> checkInitialConditions() {
+    RefactoringStatus result = new RefactoringStatus();
+    // prepare method information
+    result.addStatus(_prepareMethod());
+    if (result.hasFatalError) {
+      return new Future.value(result);
+    }
+    // maybe operator
+    if (_methodElement.isOperator) {
+      result = new RefactoringStatus.fatal('Cannot inline operator.');
+      return new Future.value(result);
+    }
+    // analyze method body
+    result.addStatus(_prepareMethodParts());
+    // process references
+    return searchEngine.searchReferences(_methodElement).then((references) {
+      _referenceProcessors.clear();
+      for (SearchMatch reference in references) {
+        _ReferenceProcessor processor =
+            new _ReferenceProcessor(this, reference);
+        _referenceProcessors.add(processor);
+      }
+    }).then((_) {
+      return result;
+    });
+  }
+
+  @override
+  Future<SourceChange> createChange() {
+    return new Future.value(change);
+  }
+
+  @override
+  bool requiresPreview() => false;
+
+  _SourcePart _createSourcePart(SourceRange range) {
+    String source = _methodUtils.getRangeText(range);
+    String prefix = getLinesPrefix(source);
+    _SourcePart result = new _SourcePart(range.offset, source, prefix);
+    // remember parameters and variables occurrences
+    _methodUnit.accept(new _VariablesVisitor(_methodElement, range, result));
+    // done
+    return result;
+  }
+
+  /**
+   * Initializes [_methodElement] and related fields.
+   */
+  RefactoringStatus _prepareMethod() {
+    _methodElement = null;
+    _methodParameters = null;
+    _methodBody = null;
+    deleteSource = false;
+    inlineAll = false;
+    // prepare selected SimpleIdentifier
+    AstNode selectedNode = new NodeLocator.con1(offset).searchWithin(unit);
+    if (selectedNode is! SimpleIdentifier) {
+      return new RefactoringStatus.fatal(
+          'Method declaration or reference must be selected to activate this refactoring.');
+    }
+    SimpleIdentifier selectedIdentifier = selectedNode as SimpleIdentifier;
+    // prepare selected ExecutableElement
+    Element selectedElement = selectedIdentifier.bestElement;
+    if (selectedElement is! ExecutableElement) {
+      return new RefactoringStatus.fatal(
+          'Method declaration or reference must be selected to activate this refactoring.');
+    }
+    _methodElement = selectedElement as ExecutableElement;
+    _methodFile = _methodElement.source.fullName;
+    _methodUnit = selectedElement.unit;
+    _methodUtils = new CorrectionUtils(_methodUnit);
+    if (selectedElement is MethodElement ||
+        selectedElement is PropertyAccessorElement) {
+      MethodDeclaration methodDeclaration =
+          _methodElement.node as MethodDeclaration;
+      _methodNode = methodDeclaration;
+      _methodParameters = methodDeclaration.parameters;
+      _methodBody = methodDeclaration.body;
+      // prepare mode
+      deleteSource = selectedNode == methodDeclaration.name;
+      inlineAll = deleteSource;
+    }
+    if (selectedElement is FunctionElement) {
+      FunctionDeclaration functionDeclaration =
+          _methodElement.node as FunctionDeclaration;
+      _methodNode = functionDeclaration;
+      _methodParameters = functionDeclaration.functionExpression.parameters;
+      _methodBody = functionDeclaration.functionExpression.body;
+      // prepare mode
+      deleteSource = selectedNode == functionDeclaration.name;
+      inlineAll = deleteSource;
+    }
+    // OK
+    return new RefactoringStatus();
+  }
+
+  /**
+   * Analyze [_methodBody] to fill [_methodExpressionPart] and
+   * [_methodStatementsPart].
+   */
+  RefactoringStatus _prepareMethodParts() {
+    RefactoringStatus result = new RefactoringStatus();
+    if (_methodBody is ExpressionFunctionBody) {
+      ExpressionFunctionBody body = _methodBody as ExpressionFunctionBody;
+      _methodExpression = body.expression;
+      SourceRange methodExpressionRange = rangeNode(_methodExpression);
+      _methodExpressionPart = _createSourcePart(methodExpressionRange);
+    } else if (_methodBody is BlockFunctionBody) {
+      Block body = (_methodBody as BlockFunctionBody).block;
+      List<Statement> statements = body.statements;
+      if (statements.length >= 1) {
+        Statement lastStatement = statements[statements.length - 1];
+        // "return" statement requires special handling
+        if (lastStatement is ReturnStatement) {
+          _methodExpression = lastStatement.expression;
+          SourceRange methodExpressionRange = rangeNode(_methodExpression);
+          _methodExpressionPart = _createSourcePart(methodExpressionRange);
+          // exclude "return" statement from statements
+          statements = statements.sublist(0, statements.length - 1);
+        }
+        // if there are statements, process them
+        if (!statements.isEmpty) {
+          SourceRange statementsRange =
+              _methodUtils.getLinesRangeStatements(statements);
+          _methodStatementsPart = _createSourcePart(statementsRange);
+        }
+      }
+      // check if more than one return
+      body.accept(new _ReturnsValidatorVisitor(result));
+    } else {
+      return new RefactoringStatus.fatal('Cannot inline method without body.');
+    }
+    return result;
+  }
+}
+
+
+class _ParameterOccurrence {
+  final int parentPrecedence;
+  final SourceRange range;
+  _ParameterOccurrence(this.parentPrecedence, this.range);
+}
+
+
+/**
+ * Processor for single [SearchMatch] reference to [methodElement].
+ */
+class _ReferenceProcessor {
+  final InlineMethodRefactoringImpl ref;
+
+  String _refFile;
+  CorrectionUtils _refUtils;
+  AstNode _node;
+  SourceRange _refLineRange;
+  String _refPrefix;
+
+  _ReferenceProcessor(this.ref, SearchMatch reference) {
+    // prepare SourceChange to update
+    Element refElement = reference.element;
+    _refFile = refElement.source.fullName;
+    // prepare CorrectionUtils
+    CompilationUnit refUnit = refElement.unit;
+    _refUtils = new CorrectionUtils(refUnit);
+    // prepare node and environment
+    _node = _refUtils.findNode(reference.sourceRange.offset);
+    Statement refStatement = _node.getAncestor((node) => node is Statement);
+    if (refStatement != null) {
+      _refLineRange = _refUtils.getLinesRangeStatements([refStatement]);
+      _refPrefix = _refUtils.getNodePrefix(refStatement);
+    } else {
+      _refLineRange = null;
+      _refPrefix = _refUtils.getLinePrefix(_node.offset);
+    }
+  }
+
+  bool _canInlineBody(AstNode usage) {
+    // no statements, usually just expression
+    if (ref._methodStatementsPart == null) {
+      // empty method, inline as closure
+      if (ref._methodExpressionPart == null) {
+        return false;
+      }
+      // OK, just expression
+      return true;
+    }
+    // analyze point of invocation
+    AstNode parent = usage.parent;
+    AstNode parent2 = parent.parent;
+    // OK, if statement in block
+    if (parent is Statement) {
+      return parent2 is Block;
+    }
+    // maybe assignment, in block
+    if (parent is AssignmentExpression) {
+      AssignmentExpression assignment = parent;
+      // inlining setter
+      if (identical(assignment.leftHandSide, usage)) {
+        return parent2 is Statement && parent2.parent is Block;
+      }
+      // inlining initializer
+      return ref._methodExpressionPart != null;
+    }
+    // maybe value for variable initializer, in block
+    if (ref._methodExpressionPart != null) {
+      if (parent is VariableDeclaration) {
+        if (parent2 is VariableDeclarationList) {
+          AstNode parent3 = parent2.parent;
+          return parent3 is VariableDeclarationStatement &&
+              parent3.parent is Block;
+        }
+      }
+    }
+    // not in block, cannot inline body
+    return false;
+  }
+
+  void _inlineMethodInvocation(RefactoringStatus status, Expression methodUsage,
+      bool cascaded, Expression target, List<Expression> arguments) {
+    // we don't support cascade
+    if (cascaded) {
+      status.addError(
+          'Cannot inline cascade invocation.',
+          new Location.fromNode(methodUsage));
+    }
+    // can we inline method body into "methodUsage" block?
+    if (_canInlineBody(methodUsage)) {
+      // insert non-return statements
+      if (ref._methodStatementsPart != null) {
+        // prepare statements source for invocation
+        String source = _getMethodSourceForInvocation(
+            ref._methodStatementsPart,
+            _refUtils,
+            methodUsage,
+            target,
+            arguments);
+        source = _refUtils.replaceSourceIndent(
+            source,
+            ref._methodStatementsPart._prefix,
+            _refPrefix);
+        // do insert
+        SourceRange range = rangeStartLength(_refLineRange, 0);
+        SourceEdit edit = new SourceEdit.range(range, source);
+        ref.change.addEdit(_refFile, edit);
+      }
+      // replace invocation with return expression
+      if (ref._methodExpressionPart != null) {
+        // prepare expression source for invocation
+        String source = _getMethodSourceForInvocation(
+            ref._methodExpressionPart,
+            _refUtils,
+            methodUsage,
+            target,
+            arguments);
+        if (getExpressionPrecedence(ref._methodExpression) <
+            getExpressionParentPrecedence(methodUsage)) {
+          source = "(${source})";
+        }
+        // do replace
+        SourceRange methodUsageRange = rangeNode(methodUsage);
+        SourceEdit edit = new SourceEdit.range(methodUsageRange, source);
+        ref.change.addEdit(_refFile, edit);
+      } else {
+        SourceEdit edit = new SourceEdit.range(_refLineRange, "");
+        ref.change.addEdit(_refFile, edit);
+      }
+      return;
+    }
+    // inline as closure invocation
+    String source;
+    {
+      source = ref._methodUtils.getRangeText(
+          rangeStartEnd(ref._methodParameters.leftParenthesis, ref._methodNode));
+      String methodPrefix =
+          ref._methodUtils.getLinePrefix(ref._methodNode.offset);
+      source = _refUtils.replaceSourceIndent(source, methodPrefix, _refPrefix);
+      source = source.trim();
+    }
+    // do insert
+    SourceRange range = rangeNode(_node);
+    SourceEdit edit = new SourceEdit.range(range, source);
+    ref.change.addEdit(_refFile, edit);
+  }
+
+  void _process(RefactoringStatus status) {
+    AstNode nodeParent = _node.parent;
+    // may be only single place should be inlined
+    if (!_shouldProcess()) {
+      return;
+    }
+    // may be invocation of inline method
+    if (nodeParent is MethodInvocation) {
+      MethodInvocation invocation = nodeParent;
+      Expression target = invocation.target;
+      List<Expression> arguments = invocation.argumentList.arguments;
+      _inlineMethodInvocation(
+          status,
+          invocation,
+          invocation.isCascaded,
+          target,
+          arguments);
+    } else {
+      // cannot inline reference to method: var v = new A().method;
+      if (ref._methodElement is MethodElement) {
+        status.addFatalError(
+            'Cannot inline class method reference.',
+            new Location.fromNode(_node));
+        return;
+      }
+      // PropertyAccessorElement
+      if (ref._methodElement is PropertyAccessorElement) {
+        Expression target = null;
+        bool cascade = false;
+        if (nodeParent is PrefixedIdentifier) {
+          PrefixedIdentifier propertyAccess = nodeParent;
+          target = propertyAccess.prefix;
+          cascade = false;
+        }
+        if (nodeParent is PropertyAccess) {
+          PropertyAccess propertyAccess = nodeParent;
+          target = propertyAccess.realTarget;
+          cascade = propertyAccess.isCascaded;
+        }
+        // prepare arguments
+        List<Expression> arguments = [];
+        if ((_node as SimpleIdentifier).inSetterContext()) {
+          arguments.add(
+              (nodeParent.parent as AssignmentExpression).rightHandSide);
+        }
+        // inline body
+        _inlineMethodInvocation(
+            status,
+            nodeParent as Expression,
+            cascade,
+            target,
+            arguments);
+        return;
+      }
+      // not invocation, just reference to function
+      String source;
+      {
+        source = ref._methodUtils.getRangeText(
+            rangeStartEnd(ref._methodParameters.leftParenthesis, ref._methodNode));
+        String methodPrefix =
+            ref._methodUtils.getLinePrefix(ref._methodNode.offset);
+        source =
+            _refUtils.replaceSourceIndent(source, methodPrefix, _refPrefix);
+        source = source.trim();
+      }
+      // do insert
+      SourceRange range = rangeNode(_node);
+      SourceEdit edit = new SourceEdit.range(range, source);
+      ref.change.addEdit(_refFile, edit);
+    }
+  }
+
+  bool _shouldProcess() {
+    if (!ref.inlineAll) {
+      SourceRange parentRange = rangeNode(_node);
+      return parentRange.contains(ref.offset);
+    }
+    return true;
+  }
+}
+
+class _ReturnsValidatorVisitor extends RecursiveAstVisitor {
+  final RefactoringStatus result;
+  int _numReturns = 0;
+
+  _ReturnsValidatorVisitor(this.result);
+
+  @override
+  visitReturnStatement(ReturnStatement node) {
+    _numReturns++;
+    if (_numReturns == 2) {
+      result.addError('Ambiguous return value.', new Location.fromNode(node));
+    }
+  }
+}
+
+/**
+ * Information about the source of a method being inlined.
+ */
+class _SourcePart {
+  /**
+   * The base for all [SourceRange]s.
+   */
+  final int _base;
+
+  /**
+   * The source of the method.
+   */
+  final String _source;
+
+  /**
+   * The original prefix of the method.
+   */
+  final String _prefix;
+
+  /**
+   * The occurrences of the method parameters.
+   */
+  Map<ParameterElement, List<_ParameterOccurrence>> _parameters = {};
+
+  /**
+   * The occurrences of the method local variables.
+   */
+  Map<VariableElement, List<SourceRange>> _variables = {};
+
+  /**
+   * The source ranges of the qualifiers in instance field references.
+   * Some of them have length `0`.
+   */
+  List<SourceRange> _instanceFieldQualifiers = [];
+
+  /**
+   * The source ranges of the qualifiers in instance field references.
+   * Some of them have length `0`.
+   */
+  Map<String, List<SourceRange>> _staticFieldQualifiers = {};
+
+  _SourcePart(this._base, this._source, this._prefix);
+
+  void addInstanceFieldQualifier(SourceRange range) {
+    range = rangeFromBase(range, _base);
+    _instanceFieldQualifiers.add(range);
+  }
+
+  void addParameterOccurrence(ParameterElement parameter, SourceRange range,
+      int precedence) {
+    if (parameter != null) {
+      List<_ParameterOccurrence> occurrences = _parameters[parameter];
+      if (occurrences == null) {
+        occurrences = [];
+        _parameters[parameter] = occurrences;
+      }
+      range = rangeFromBase(range, _base);
+      occurrences.add(new _ParameterOccurrence(precedence, range));
+    }
+  }
+
+  void addStaticFieldQualifier(String className, SourceRange range) {
+    List<SourceRange> ranges = _staticFieldQualifiers[className];
+    if (ranges == null) {
+      ranges = [];
+      _staticFieldQualifiers[className] = ranges;
+    }
+    range = rangeFromBase(range, _base);
+    ranges.add(range);
+  }
+
+  void addVariable(VariableElement element, SourceRange range) {
+    List<SourceRange> ranges = _variables[element];
+    if (ranges == null) {
+      ranges = [];
+      _variables[element] = ranges;
+    }
+    range = rangeFromBase(range, _base);
+    ranges.add(range);
+  }
+}
+
+/**
+ * A visitor that fills [_SourcePart] with fields, parameters and variables.
+ */
+class _VariablesVisitor extends GeneralizingAstVisitor {
+  /**
+   * The [ExecutableElement] being inlined.
+   */
+  final ExecutableElement methodElement;
+
+  /**
+   * The [SourceRange] of the element body.
+   */
+  SourceRange bodyRange;
+
+  /**
+   * The [_SourcePart] to record reference into.
+   */
+  _SourcePart result;
+
+  _VariablesVisitor(this.methodElement, this.bodyRange, this.result);
+
+  @override
+  visitNode(AstNode node) {
+    SourceRange nodeRange = rangeNode(node);
+    if (!bodyRange.intersects(nodeRange)) {
+      return null;
+    }
+    super.visitNode(node);
+  }
+
+  @override
+  visitSimpleIdentifier(SimpleIdentifier node) {
+    SourceRange nodeRange = rangeNode(node);
+    if (bodyRange.covers(nodeRange)) {
+      _addInstanceFieldQualifier(node);
+      _addParameter(node);
+      _addVariable(node);
+    }
+  }
+
+  void _addInstanceFieldQualifier(SimpleIdentifier node) {
+    PropertyAccessorElement accessor = getPropertyAccessorElement(node);
+    if (isFieldAccessorElement(accessor)) {
+      AstNode qualifier = getNodeQualifier(node);
+      if (qualifier == null || qualifier is ThisExpression) {
+        if (accessor.isStatic) {
+          String className = accessor.enclosingElement.displayName;
+          if (qualifier == null) {
+            SourceRange qualifierRange = rangeStartLength(node, 0);
+            result.addStaticFieldQualifier(className, qualifierRange);
+          }
+        } else {
+          SourceRange qualifierRange;
+          if (qualifier != null) {
+            qualifierRange = rangeStartStart(qualifier, node);
+          } else {
+            qualifierRange = rangeStartLength(node, 0);
+          }
+          result.addInstanceFieldQualifier(qualifierRange);
+        }
+      }
+    }
+  }
+
+  void _addParameter(SimpleIdentifier node) {
+    ParameterElement parameterElement = getParameterElement(node);
+    // not a parameter
+    if (parameterElement == null) {
+      return;
+    }
+    // not a parameter of the function being inlined
+    if (!methodElement.parameters.contains(parameterElement)) {
+      return;
+    }
+    // OK, add occurrence
+    SourceRange nodeRange = rangeNode(node);
+    int parentPrecedence = getExpressionParentPrecedence(node);
+    result.addParameterOccurrence(
+        parameterElement,
+        nodeRange,
+        parentPrecedence);
+  }
+
+  void _addVariable(SimpleIdentifier node) {
+    VariableElement variableElement = getLocalVariableElement(node);
+    if (variableElement != null) {
+      SourceRange nodeRange = rangeNode(node);
+      result.addVariable(variableElement, nodeRange);
+    }
+  }
+}