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//
// OptionalParameterCouldBeSkippedIssue.cs
//
// Author:
// Simon Lindgren <simon.n.lindgren@gmail.com>
//
// Copyright (c) 2012 Simon Lindgren
//
// 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 ICSharpCode.NRefactory.CSharp.Resolver;
using System.Linq;
using ICSharpCode.NRefactory.Semantics;
using ICSharpCode.NRefactory.TypeSystem;
using System;
using ICSharpCode.NRefactory.Refactoring;
namespace ICSharpCode.NRefactory.CSharp.Refactoring
{
[IssueDescription("Optional argument has default value and can be skipped",
Description = "Finds calls to functions where optional parameters are used and the passed argument is the same as the default.",
Category = IssueCategories.Redundancies,
Severity = Severity.Hint,
IssueMarker = IssueMarker.GrayOut)]
public class OptionalParameterCouldBeSkippedIssue : ICodeIssueProvider
{
public IEnumerable<CodeIssue> GetIssues(BaseRefactoringContext context)
{
return new GatherVisitor(context).GetIssues();
}
class GatherVisitor : GatherVisitorBase<OptionalParameterCouldBeSkippedIssue>
{
public GatherVisitor(BaseRefactoringContext context) : base (context)
{
}
public override void VisitObjectCreateExpression(ObjectCreateExpression objectCreateExpression)
{
base.VisitObjectCreateExpression(objectCreateExpression);
CheckMethodCall(objectCreateExpression, objectCreateExpression.Arguments,
(objectCreation, args) => new ObjectCreateExpression(objectCreation.Type.Clone(), args));
}
public override void VisitInvocationExpression(InvocationExpression invocationExpression)
{
base.VisitInvocationExpression(invocationExpression);
CheckMethodCall(invocationExpression, invocationExpression.Arguments,
(invocation, args) => new InvocationExpression(invocation.Target.Clone(), args));
}
void CheckMethodCall<T> (T node, IEnumerable<Expression> args, Func<T, IEnumerable<Expression>, T> generateReplacement) where T: AstNode
{
// The first two checks are unnecessary, but eliminates the majority of calls early,
// improving performance.
var arguments = args.ToArray();
if (arguments.Length == 0)
return;
var lastArg = arguments[arguments.Length - 1];
if (!(lastArg is PrimitiveExpression || lastArg is NamedArgumentExpression))
return;
var invocationResolveResult = ctx.Resolve(node) as CSharpInvocationResolveResult;
if (invocationResolveResult == null)
return;
string actionMessage = ctx.TranslateString("Remove redundant arguments");
var redundantArguments = GetRedundantArguments(arguments, invocationResolveResult);
var action = new CodeAction(actionMessage, script => {
var newArgumentList = arguments
.Where(arg => !redundantArguments.Contains(arg))
.Select(arg => arg.Clone());
var newInvocation = generateReplacement(node, newArgumentList);
script.Replace(node, newInvocation);
}, node);
var issueMessage = ctx.TranslateString("Argument is identical to the default value");
var lastPositionalArgument = redundantArguments.FirstOrDefault(expression => !(expression is NamedArgumentExpression));
foreach (var argument in redundantArguments) {
var localArgument = argument;
var actions = new List<CodeAction>();
actions.Add(action);
if (localArgument is NamedArgumentExpression || localArgument == lastPositionalArgument) {
var title = ctx.TranslateString("Remove this argument");
actions.Add(new CodeAction(title, script => {
var newArgumentList = arguments
.Where(arg => arg != localArgument)
.Select(arg => arg.Clone());
var newInvocation = generateReplacement(node, newArgumentList);
script.Replace(node, newInvocation);
}, node));
} else {
var title = ctx.TranslateString("Remove this and the following positional arguments");
actions.Add(new CodeAction(title, script => {
var newArgumentList = arguments
.Where(arg => arg.StartLocation < localArgument.StartLocation && !(arg is NamedArgumentExpression))
.Select(arg => arg.Clone());
var newInvocation = generateReplacement(node, newArgumentList);
script.Replace(node, newInvocation);
}, node));
}
AddIssue(localArgument, issueMessage, actions);
}
}
IList<Expression> GetRedundantArguments(Expression[] arguments, CSharpInvocationResolveResult invocationResolveResult)
{
var argumentToParameterMap = invocationResolveResult.GetArgumentToParameterMap();
var resolvedParameters = invocationResolveResult.Member.Parameters;
IList<Expression> redundantArguments = new List<Expression>();
for (int i = arguments.Length - 1; i >= 0; i--) {
var parameterIndex = argumentToParameterMap[i];
if (parameterIndex == -1)
// This particular parameter is an error, but keep trying the other ones
continue;
var parameter = resolvedParameters[parameterIndex];
var argument = arguments[i];
if (argument is PrimitiveExpression) {
if (parameter.IsParams)
// before positional params arguments all optional arguments are needed, otherwise some of the
// param arguments will be shifted out of the params into the fixed parameters
break;
if (!parameter.IsOptional)
// There can be no optional parameters preceding a required one
break;
var argumentResolveResult = ctx.Resolve(argument) as ConstantResolveResult;
if (argumentResolveResult == null || parameter.ConstantValue != argumentResolveResult.ConstantValue)
// Stop here since any arguments before this one has to be there
// to enable the passing of this argument
break;
redundantArguments.Add(argument);
} else if (argument is NamedArgumentExpression) {
var expression = ((NamedArgumentExpression)argument).Expression as PrimitiveExpression;
if (expression == null)
continue;
var expressionResolveResult = ctx.Resolve(expression) as ConstantResolveResult;
if (expressionResolveResult == null || parameter.ConstantValue != expressionResolveResult.ConstantValue)
// continue, since there can still be more arguments that are redundant
continue;
redundantArguments.Add(argument);
} else {
// This is a non-constant positional argument => no more redundancies are possible
break;
}
}
return redundantArguments;
}
}
}
}
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