source: stable/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.CSharp-5.5.0/Refactoring/VariableReferenceGraph.cs @ 17120

// 
// VariableReferenceGraph.cs
// 
// Author:
//      Mansheng Yang <lightyang0@gmail.com>
// 
// Copyright (c) 2012 Mansheng Yang <lightyang0@gmail.com>
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

using System.Collections.Generic;
using System.Linq;
using ICSharpCode.NRefactory.CSharp.Analysis;
using ICSharpCode.NRefactory.CSharp.Resolver;
using System.Threading;

namespace ICSharpCode.NRefactory.CSharp.Refactoring
{
  class VariableReferenceNode
  {
    public IList<AstNode> References {
      get;
      private set;
    }

    public IList<VariableReferenceNode> NextNodes {
      get;
      private set;
    }

    public IList<VariableReferenceNode> PreviousNodes {
      get;
      private set;
    }

    public VariableReferenceNode ()
    {
      References = new List<AstNode> ();
      NextNodes = new List<VariableReferenceNode> ();
      PreviousNodes = new List<VariableReferenceNode> ();
    }

    public void AddNextNode (VariableReferenceNode node)
    {
      if (node == null)
        return;
      NextNodes.Add (node);
      node.PreviousNodes.Add (this);
    }
  }

  class VariableReferenceGraphBuilder
  {
    ControlFlowGraphBuilder cfgBuilder = new ControlFlowGraphBuilder ();
    CfgVariableReferenceNodeBuilder cfgVrNodeBuilder;
    BaseRefactoringContext ctx;

    public VariableReferenceGraphBuilder(BaseRefactoringContext ctx)
    {
      this.ctx = ctx;
      cfgVrNodeBuilder = new CfgVariableReferenceNodeBuilder (this);
    }

    public VariableReferenceNode Build (ISet<AstNode> references, CSharpAstResolver resolver,
      Expression expression)
    {
      return ExpressionNodeCreationVisitor.CreateNode (references, resolver, new [] { expression });
    }

    public VariableReferenceNode Build (Statement statement, ISet<AstNode> references,
      ISet<Statement> refStatements, BaseRefactoringContext context)
    {
      var cfg = cfgBuilder.BuildControlFlowGraph (statement, context.Resolver, context.CancellationToken);
      if (cfg.Count == 0)
        return new VariableReferenceNode ();
      return cfgVrNodeBuilder.Build (cfg [0], references, refStatements, context.Resolver);
    }

    public VariableReferenceNode Build (Statement statement, ISet<AstNode> references,
                                               ISet<Statement> refStatements, CSharpAstResolver resolver, CancellationToken cancellationToken = default(CancellationToken))
    {
      var cfg = cfgBuilder.BuildControlFlowGraph (statement, resolver, cancellationToken);
      if (cfg.Count == 0)
        return new VariableReferenceNode();
      return cfgVrNodeBuilder.Build (cfg [0], references, refStatements, resolver);
    }

    class GetExpressionsVisitor : DepthFirstAstVisitor<IEnumerable<Expression>>
    {

      public override IEnumerable<Expression> VisitIfElseStatement (IfElseStatement ifElseStatement)
      {
        yield return ifElseStatement.Condition;
      }

      public override IEnumerable<Expression> VisitSwitchStatement (SwitchStatement switchStatement)
      {
        yield return switchStatement.Expression;
      }

      public override IEnumerable<Expression> VisitForStatement (ForStatement forStatement)
      {
        yield return forStatement.Condition;
      }

      public override IEnumerable<Expression> VisitDoWhileStatement (DoWhileStatement doWhileStatement)
      {
        yield return doWhileStatement.Condition;
      }

      public override IEnumerable<Expression> VisitWhileStatement (WhileStatement whileStatement)
      {
        yield return whileStatement.Condition;
      }

      public override IEnumerable<Expression> VisitForeachStatement (ForeachStatement foreachStatement)
      {
        yield return foreachStatement.InExpression;
      }

      public override IEnumerable<Expression> VisitExpressionStatement (ExpressionStatement expressionStatement)
      {
        yield return expressionStatement.Expression;
      }

      public override IEnumerable<Expression> VisitLockStatement (LockStatement lockStatement)
      {
        yield return lockStatement.Expression;
      }

      public override IEnumerable<Expression> VisitReturnStatement (ReturnStatement returnStatement)
      {
        yield return returnStatement.Expression;
      }

      public override IEnumerable<Expression> VisitThrowStatement (ThrowStatement throwStatement)
      {
        yield return throwStatement.Expression;
      }

      public override IEnumerable<Expression> VisitUsingStatement (UsingStatement usingStatement)
      {
        var expr = usingStatement.ResourceAcquisition as Expression;
        if (expr != null)
          return new [] { expr };

        return usingStatement.ResourceAcquisition.AcceptVisitor (this);
      }

      public override IEnumerable<Expression> VisitVariableDeclarationStatement (
        VariableDeclarationStatement variableDeclarationStatement)
      {
        return variableDeclarationStatement.Variables.Select (v => v.Initializer);
      }

      public override IEnumerable<Expression> VisitYieldReturnStatement (YieldReturnStatement yieldReturnStatement)
      {
        yield return yieldReturnStatement.Expression;
      }

      public override IEnumerable<Expression> VisitBlockStatement(BlockStatement blockStatement)
      {
        yield break;
      }
    }

    class CfgVariableReferenceNodeBuilder
    {
      readonly VariableReferenceGraphBuilder variableReferenceGraphBuilder;
      GetExpressionsVisitor getExpr = new GetExpressionsVisitor ();

      ISet<AstNode> references;
      ISet<Statement> refStatements;
      CSharpAstResolver resolver;
      Dictionary<ControlFlowNode, VariableReferenceNode> nodeDict;

      public CfgVariableReferenceNodeBuilder(VariableReferenceGraphBuilder variableReferenceGraphBuilder)
      {
        this.variableReferenceGraphBuilder = variableReferenceGraphBuilder;
      }

      public VariableReferenceNode Build (ControlFlowNode startNode, ISet<AstNode> references,
        ISet<Statement> refStatements, CSharpAstResolver resolver)
      {
        this.references = references;
        this.refStatements = refStatements;
        this.resolver = resolver;
        nodeDict = new Dictionary<ControlFlowNode, VariableReferenceNode> ();
        return AddNode (startNode);
      }

      static bool IsValidControlFlowNode (ControlFlowNode node)
      {
        if (node.NextStatement == null)
          return false;
        if (node.Type == ControlFlowNodeType.LoopCondition) {
          if (node.NextStatement is ForeachStatement)
            return false;
        } else {
          if (node.NextStatement is WhileStatement || node.NextStatement is DoWhileStatement ||
            node.NextStatement is ForStatement)
            return false;
        }
        return true;
      }

      VariableReferenceNode GetStatementEndNode (VariableReferenceNode currentNode, Statement statement)
      {
        var expressions = statement.AcceptVisitor (getExpr);
        VariableReferenceNode endNode;
        ExpressionNodeCreationVisitor.CreateNode (references, resolver, expressions, currentNode, out endNode);
        return endNode;
      }

      VariableReferenceNode AddNode (ControlFlowNode startNode)
      {
        var node = new VariableReferenceNode ();
        var cfNode = startNode;
        while (true) {
          if (variableReferenceGraphBuilder.ctx.CancellationToken.IsCancellationRequested)
            return null;
          if (nodeDict.ContainsKey (cfNode)) {
            node.AddNextNode (nodeDict [cfNode]);
            break;
          }
          // create a new node for fork point
          if (cfNode.Incoming.Count > 1 || cfNode.Outgoing.Count > 1) {
            nodeDict [cfNode] = node;

            var forkNode = new VariableReferenceNode ();
            node.AddNextNode (forkNode);
            node = forkNode;
          }
          nodeDict [cfNode] = node;

          if (IsValidControlFlowNode (cfNode) && refStatements.Contains (cfNode.NextStatement)) {
            node = GetStatementEndNode (node, cfNode.NextStatement);
          }

          if (cfNode.Outgoing.Count == 1) {
            cfNode = cfNode.Outgoing [0].To;
          } else {
            foreach (var e in cfNode.Outgoing) {
              node.AddNextNode (AddNode (e.To));
            }
            break;
          }
        }
        VariableReferenceNode result;
        if (!nodeDict.TryGetValue (startNode, out result))
          return new VariableReferenceNode ();
        return result;
      }
    }

    class ExpressionNodeCreationVisitor : DepthFirstAstVisitor
    {
      VariableReferenceNode startNode;
      VariableReferenceNode endNode;
      ISet<AstNode> references;
      CSharpAstResolver resolver;

      ExpressionNodeCreationVisitor (ISet<AstNode> references, CSharpAstResolver resolver,
        VariableReferenceNode startNode)
      {
        this.references = references;
        this.resolver = resolver;
        this.startNode = this.endNode = startNode ?? new VariableReferenceNode ();
      }

      public static VariableReferenceNode CreateNode (ISet<AstNode> references, CSharpAstResolver resolver,
        params Expression [] expressions)
      {
        VariableReferenceNode endNode;
        return CreateNode (references, resolver, expressions, null, out endNode);
      }

      public static VariableReferenceNode CreateNode (ISet<AstNode> references, CSharpAstResolver resolver,
        IEnumerable<Expression> expressions, VariableReferenceNode startNode, out VariableReferenceNode endNode)
      {
        startNode = startNode ?? new VariableReferenceNode ();
        endNode = startNode;
        if (expressions != null) {
          foreach (var expr in expressions) {
            var visitor = CreateVisitor(references, resolver, expr, endNode);
            endNode = visitor.endNode;
          }
        }
        return startNode;
      }

      static ExpressionNodeCreationVisitor CreateVisitor (ISet<AstNode> references, CSharpAstResolver resolver,
        Expression rootExpr, VariableReferenceNode startNode = null, VariableReferenceNode nextNode = null)
      {
        var visitor = new ExpressionNodeCreationVisitor (references, resolver, startNode);
        rootExpr.AcceptVisitor (visitor);
        if (nextNode != null)
          visitor.endNode.AddNextNode (nextNode);
        return visitor;
      }

      static VariableReferenceNode CreateNode (ISet<AstNode> references, CSharpAstResolver resolver, 
        Expression rootExpr, VariableReferenceNode startNode = null, VariableReferenceNode nextNode = null)
      {
        return CreateVisitor (references, resolver, rootExpr, startNode, nextNode).startNode;
      }

      #region Skipped Expressions
      public override void VisitAnonymousMethodExpression (AnonymousMethodExpression anonymousMethodExpression)
      {
      }

      public override void VisitLambdaExpression (LambdaExpression lambdaExpression)
      {
      }

      public override void VisitBaseReferenceExpression (BaseReferenceExpression baseReferenceExpression)
      {
      }

      public override void VisitNullReferenceExpression (NullReferenceExpression nullReferenceExpression)
      {
      }

      public override void VisitPrimitiveExpression (PrimitiveExpression primitiveExpression)
      {
      }

      public override void VisitSizeOfExpression (SizeOfExpression sizeOfExpression)
      {
      }

      public override void VisitThisReferenceExpression (ThisReferenceExpression thisReferenceExpression)
      {
      }

      public override void VisitTypeOfExpression (TypeOfExpression typeOfExpression)
      {
      }

      public override void VisitTypeReferenceExpression (TypeReferenceExpression typeReferenceExpression)
      {
      }

      public override void VisitUndocumentedExpression (UndocumentedExpression undocumentedExpression)
      {
      }

      public override void VisitDefaultValueExpression (DefaultValueExpression defaultValueExpression)
      {
      }

      #endregion

      public override void VisitAssignmentExpression (AssignmentExpression assignmentExpression)
      {
        assignmentExpression.Right.AcceptVisitor (this);
        assignmentExpression.Left.AcceptVisitor (this);
      }

      public override void VisitBinaryOperatorExpression (BinaryOperatorExpression binaryOperatorExpression)
      {
        binaryOperatorExpression.Left.AcceptVisitor (this);
        binaryOperatorExpression.Right.AcceptVisitor (this);
      }

      public override void VisitCastExpression (CastExpression castExpression)
      {
        castExpression.Expression.AcceptVisitor (this);
      }

      public override void VisitCheckedExpression (CheckedExpression checkedExpression)
      {
        checkedExpression.Expression.AcceptVisitor (this);
      }

      public override void VisitConditionalExpression (ConditionalExpression conditionalExpression)
      {
        conditionalExpression.Condition.AcceptVisitor (this);
        var resolveResult = resolver.Resolve (conditionalExpression.Condition);
        if (resolveResult.ConstantValue is bool) {
          if ((bool) resolveResult.ConstantValue)
            conditionalExpression.TrueExpression.AcceptVisitor (this);
          else
            conditionalExpression.FalseExpression.AcceptVisitor (this);
          return;
        }
        var nextEndNode = new VariableReferenceNode ();
        var trueNode = CreateNode (references, resolver, conditionalExpression.TrueExpression, null, 
          nextEndNode);
        var falseNode = CreateNode (references, resolver, conditionalExpression.FalseExpression, null, 
          nextEndNode);
        endNode.AddNextNode (trueNode);
        endNode.AddNextNode (falseNode);
        endNode = nextEndNode;
      }

      public override void VisitIdentifierExpression (IdentifierExpression identifierExpression)
      {
        if (references.Contains (identifierExpression))
          endNode.References.Add (identifierExpression);
      }

      public override void VisitIndexerExpression (IndexerExpression indexerExpression)
      {
        indexerExpression.Target.AcceptVisitor (this);
        foreach (var arg in indexerExpression.Arguments)
          arg.AcceptVisitor (this);
      }

      public override void VisitInvocationExpression (InvocationExpression invocationExpression)
      {
        invocationExpression.Target.AcceptVisitor (this);
        var outArguments = new List<Expression> ();
        foreach (var arg in invocationExpression.Arguments) {
          var directionExpr = arg as DirectionExpression;
          if (directionExpr != null && directionExpr.FieldDirection == FieldDirection.Out) {
            outArguments.Add (directionExpr);
            continue;
          }
          arg.AcceptVisitor (this);
        }
        foreach (var arg in outArguments)
          arg.AcceptVisitor (this);
      }

      public override void VisitDirectionExpression (DirectionExpression directionExpression)
      {
        directionExpression.Expression.AcceptVisitor (this);
      }

      public override void VisitMemberReferenceExpression (MemberReferenceExpression memberReferenceExpression)
      {
        memberReferenceExpression.Target.AcceptVisitor (this);
      }

      public override void VisitObjectCreateExpression (ObjectCreateExpression objectCreateExpression)
      {
        foreach (var arg in objectCreateExpression.Arguments)
          arg.AcceptVisitor (this);
        objectCreateExpression.Initializer.AcceptVisitor (this);
      }

      public override void VisitAnonymousTypeCreateExpression (
        AnonymousTypeCreateExpression anonymousTypeCreateExpression)
      {
        foreach (var init in anonymousTypeCreateExpression.Initializers)
          init.AcceptVisitor (this);
      }

      public override void VisitArrayCreateExpression (ArrayCreateExpression arrayCreateExpression)
      {
        foreach (var arg in arrayCreateExpression.Arguments)
          arg.AcceptVisitor (this);
        arrayCreateExpression.Initializer.AcceptVisitor (this);
      }

      public override void VisitParenthesizedExpression (ParenthesizedExpression parenthesizedExpression)
      {
        parenthesizedExpression.Expression.AcceptVisitor (this);
      }

      public override void VisitPointerReferenceExpression (PointerReferenceExpression pointerReferenceExpression)
      {
        pointerReferenceExpression.Target.AcceptVisitor (this);
      }

      public override void VisitStackAllocExpression (StackAllocExpression stackAllocExpression)
      {
        stackAllocExpression.CountExpression.AcceptVisitor (this);
      }

      public override void VisitUnaryOperatorExpression (UnaryOperatorExpression unaryOperatorExpression)
      {
        unaryOperatorExpression.Expression.AcceptVisitor (this);
      }

      public override void VisitUncheckedExpression (UncheckedExpression uncheckedExpression)
      {
        uncheckedExpression.Expression.AcceptVisitor (this);
      }

      public override void VisitAsExpression (AsExpression asExpression)
      {
        asExpression.Expression.AcceptVisitor (this);
      }

      public override void VisitIsExpression (IsExpression isExpression)
      {
        isExpression.Expression.AcceptVisitor (this);
      }

      public override void VisitArrayInitializerExpression (ArrayInitializerExpression arrayInitializerExpression)
      {
        foreach (var element in arrayInitializerExpression.Elements)
          element.AcceptVisitor (this);
      }

      public override void VisitNamedArgumentExpression (NamedArgumentExpression namedArgumentExpression)
      {
        namedArgumentExpression.Expression.AcceptVisitor (this);
      }

      public override void VisitNamedExpression (NamedExpression namedExpression)
      {
        namedExpression.Expression.AcceptVisitor (this);
      }

      public override void VisitQueryExpression (QueryExpression queryExpression)
      {
        foreach (var clause in queryExpression.Clauses)
          clause.AcceptVisitor (this);
      }

      #region Query Clauses

      public override void VisitQueryContinuationClause (QueryContinuationClause queryContinuationClause)
      {
        queryContinuationClause.PrecedingQuery.AcceptVisitor (this);
      }

      public override void VisitQueryFromClause (QueryFromClause queryFromClause)
      {
        queryFromClause.Expression.AcceptVisitor (this);
      }

      public override void VisitQueryJoinClause (QueryJoinClause queryJoinClause)
      {
        queryJoinClause.InExpression.AcceptVisitor (this);
      }

      public override void VisitQueryLetClause (QueryLetClause queryLetClause)
      {
      }

      public override void VisitQueryWhereClause (QueryWhereClause queryWhereClause)
      {
      }

      public override void VisitQueryOrderClause (QueryOrderClause queryOrderClause)
      {
      }

      public override void VisitQueryOrdering (QueryOrdering queryOrdering)
      {
      }

      public override void VisitQuerySelectClause (QuerySelectClause querySelectClause)
      {
      }

      public override void VisitQueryGroupClause (QueryGroupClause queryGroupClause)
      {
      }

      #endregion
    }
  }
}