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//
// UnreachableCodeIssue.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;
using System.Collections.Generic;
using ICSharpCode.NRefactory.CSharp.Analysis;
using System.Linq;
using ICSharpCode.NRefactory.Refactoring;
namespace ICSharpCode.NRefactory.CSharp.Refactoring
{
[IssueDescription ("Code is unreachable",
Description = "Code is unreachable.",
Category = IssueCategories.Redundancies,
Severity = Severity.Warning,
IssueMarker = IssueMarker.GrayOut)]
public class UnreachableCodeIssue : ICodeIssueProvider
{
public IEnumerable<CodeIssue> GetIssues (BaseRefactoringContext context)
{
return new GatherVisitor (context).GetIssues ();
}
class GatherVisitor : GatherVisitorBase<UnreachableCodeIssue>
{
HashSet<AstNode> unreachableNodes;
public GatherVisitor (BaseRefactoringContext ctx)
: base (ctx)
{
unreachableNodes = new HashSet<AstNode> ();
}
public override void VisitMethodDeclaration (MethodDeclaration methodDeclaration)
{
StatementIssueCollector.Collect (this, methodDeclaration.Body);
base.VisitMethodDeclaration (methodDeclaration);
}
public override void VisitLambdaExpression (LambdaExpression lambdaExpression)
{
var blockStatement = lambdaExpression.Body as BlockStatement;
if (blockStatement != null)
StatementIssueCollector.Collect (this, blockStatement);
base.VisitLambdaExpression (lambdaExpression);
}
public override void VisitAnonymousMethodExpression (AnonymousMethodExpression anonymousMethodExpression)
{
StatementIssueCollector.Collect (this, anonymousMethodExpression.Body);
base.VisitAnonymousMethodExpression (anonymousMethodExpression);
}
public override void VisitConditionalExpression (ConditionalExpression conditionalExpression)
{
var resolveResult = ctx.Resolve (conditionalExpression.Condition);
if (resolveResult.ConstantValue is bool) {
var condition = (bool)resolveResult.ConstantValue;
Expression resultExpr, unreachableExpr;
if (condition) {
resultExpr = conditionalExpression.TrueExpression;
unreachableExpr = conditionalExpression.FalseExpression;
} else {
resultExpr = conditionalExpression.FalseExpression;
unreachableExpr = conditionalExpression.TrueExpression;
}
unreachableNodes.Add (unreachableExpr);
AddIssue (unreachableExpr, ctx.TranslateString ("Remove unreachable code"),
script => script.Replace (conditionalExpression, resultExpr.Clone ()));
}
base.VisitConditionalExpression (conditionalExpression);
}
protected override void VisitChildren (AstNode node)
{
// skip unreachable nodes
if (!unreachableNodes.Contains (node))
base.VisitChildren (node);
}
class StatementIssueCollector : DepthFirstAstVisitor
{
GatherVisitor visitor;
ReachabilityAnalysis reachability;
HashSet<Statement> collectedStatements;
private StatementIssueCollector (GatherVisitor visitor, ReachabilityAnalysis reachability)
{
collectedStatements = new HashSet<Statement> ();
this.visitor = visitor;
this.reachability = reachability;
}
public static void Collect (GatherVisitor visitor, BlockStatement body)
{
if (body.IsNull)
return;
var reachability = visitor.ctx.CreateReachabilityAnalysis (body);
var collector = new StatementIssueCollector (visitor, reachability);
collector.VisitBlockStatement (body);
}
protected override void VisitChildren (AstNode node)
{
var statement = node as Statement;
if (statement == null || !AddStatement (statement))
base.VisitChildren (node);
}
bool AddStatement(Statement statement)
{
if (reachability.IsReachable (statement))
return false;
if (collectedStatements.Contains (statement))
return true;
var prevEnd = statement.GetPrevNode (n => !(n is NewLineNode)).EndLocation;
// group multiple continuous statements into one issue
var start = statement.StartLocation;
collectedStatements.Add (statement);
visitor.unreachableNodes.Add (statement);
while (statement.GetNextSibling (s => s is Statement) != null) {
statement = (Statement)statement.GetNextSibling (s => s is Statement);
collectedStatements.Add (statement);
visitor.unreachableNodes.Add (statement);
}
var end = statement.EndLocation;
var removeAction = new CodeAction (visitor.ctx.TranslateString ("Remove unreachable code"),
script =>
{
var startOffset = script.GetCurrentOffset (prevEnd);
var endOffset = script.GetCurrentOffset (end);
script.RemoveText (startOffset, endOffset - startOffset);
}, collectedStatements.First().StartLocation, collectedStatements.Last().EndLocation);
var commentAction = new CodeAction(visitor.ctx.TranslateString("Comment unreachable code"),
script =>
{
var startOffset = script.GetCurrentOffset(prevEnd);
script.InsertText(startOffset, Environment.NewLine + "/*");
var endOffset = script.GetCurrentOffset(end);
script.InsertText(endOffset, Environment.NewLine + "*/");
}, collectedStatements.First().StartLocation, collectedStatements.Last().EndLocation);
var actions = new [] { removeAction, commentAction };
visitor.AddIssue (start, end, visitor.ctx.TranslateString ("Code is unreachable"), actions);
return true;
}
// skip lambda and anonymous method
public override void VisitLambdaExpression (LambdaExpression lambdaExpression)
{
}
public override void VisitAnonymousMethodExpression (
AnonymousMethodExpression anonymousMethodExpression)
{
}
}
}
}
}
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