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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
namespace Microsoft.CodeAnalysis.CSharp
{
/// <summary>
/// Represents a <see cref="CSharpSyntaxVisitor"/> that descends an entire <see cref="CSharpSyntaxNode"/> graph
/// visiting each CSharpSyntaxNode and its child SyntaxNodes and <see cref="SyntaxToken"/>s in depth-first order.
/// </summary>
public abstract class CSharpSyntaxWalker : CSharpSyntaxVisitor
{
protected SyntaxWalkerDepth Depth { get; }
protected CSharpSyntaxWalker(SyntaxWalkerDepth depth = SyntaxWalkerDepth.Node)
{
this.Depth = depth;
}
private int _recursionDepth;
public override void Visit(SyntaxNode? node)
{
if (node != null)
{
_recursionDepth++;
StackGuard.EnsureSufficientExecutionStack(_recursionDepth);
((CSharpSyntaxNode)node).Accept(this);
_recursionDepth--;
}
}
public override void DefaultVisit(SyntaxNode node)
{
var childCnt = node.ChildNodesAndTokens().Count;
int i = 0;
var slotData = new ChildSyntaxList.SlotData(node);
do
{
var child = ChildSyntaxList.ItemInternal((CSharpSyntaxNode)node, i, ref slotData);
i++;
var asNode = child.AsNode();
if (asNode != null)
{
if (this.Depth >= SyntaxWalkerDepth.Node)
{
this.Visit(asNode);
}
}
else
{
if (this.Depth >= SyntaxWalkerDepth.Token)
{
this.VisitToken(child.AsToken());
}
}
} while (i < childCnt);
}
public virtual void VisitToken(SyntaxToken token)
{
if (this.Depth >= SyntaxWalkerDepth.Trivia)
{
this.VisitLeadingTrivia(token);
this.VisitTrailingTrivia(token);
}
}
public virtual void VisitLeadingTrivia(SyntaxToken token)
{
if (token.HasLeadingTrivia)
{
foreach (var tr in token.LeadingTrivia)
{
this.VisitTrivia(tr);
}
}
}
public virtual void VisitTrailingTrivia(SyntaxToken token)
{
if (token.HasTrailingTrivia)
{
foreach (var tr in token.TrailingTrivia)
{
this.VisitTrivia(tr);
}
}
}
public virtual void VisitTrivia(SyntaxTrivia trivia)
{
if (this.Depth >= SyntaxWalkerDepth.StructuredTrivia && trivia.HasStructure)
{
this.Visit((CSharpSyntaxNode)trivia.GetStructure()!);
}
}
}
}
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