How can I automatically remove regions from code using Roslyn?

Question

I am parsing C # code from text using Roslyn. Some of the code has areas surrounding several classes. Example:

#region Classes
public class MyClass
{
}

public class MyClass2
{
    #region Methods
    #endregion
}
#endregion

I would like to remove the area surrounding the classes (“Classes” in the above example), but leave the remaining inner areas the same as those called “Methods” in the above example. How can i do this?

Answer 1

The regions are quite peculiar, since they do not correspond to the usual tree structure. For example, you can create a construct like this:

public class TestClass{
    public void TestMethod(){
        #region TestRegion
    }
}
#endregion

- . , : . , , SyntaxRewriter ( "true", ), - node.DescendantNodes(descendIntoTrivia: true).

, , , / .

, VisitRegionDirectiveTrivia, VisitEndRegionDirectiveTrivia. RegionTrivia , . , , #endregion, .

, : , , Node ClassDeclaration.

, . , - , - .

private class RegionSyntaxRewriter : CSharpSyntaxRewriter
{
    int currentPosition = 0;
    private List<int> EndRegionsForDeletion = new List<int>();
    private string deletedRegion;
    private bool useRegionNameForAnalysis = false;

    public RegionSyntaxRewriter(string deletedRegion) : base(true)
    {
        this.deletedRegion = deletedRegion;
    }

    public override SyntaxNode VisitRegionDirectiveTrivia(
            RegionDirectiveTriviaSyntax node)
    {
        currentPosition++;
        var regionText = node.ToFullString().Substring(8).Trim();
        if (!useRegionNameForAnalysis &&
            node.ParentTrivia.Token.Parent is ClassDeclarationSyntax)
        {
            EndRegionsForDeletion.Add(currentPosition);
            return SyntaxFactory.SkippedTokensTrivia();
        }
        if (useRegionNameForAnalysis && 
            regionText == deletedRegion)
        {
            EndRegionsForDeletion.Add(currentPosition);
            return SyntaxFactory.SkippedTokensTrivia();
        }

        return base.VisitRegionDirectiveTrivia(node);
    }

    public override SyntaxNode VisitEndRegionDirectiveTrivia(
            EndRegionDirectiveTriviaSyntax node)
    {
        var oldPosition = currentPosition;
        currentPosition--;
        if (EndRegionsForDeletion.Contains(oldPosition))
        {
            EndRegionsForDeletion.Remove(currentPosition);
            return SyntaxFactory.SkippedTokensTrivia();
        }

        return base.VisitEndRegionDirectiveTrivia(node);
    }
}

Answer 2

Sievajet CSharpSyntaxRewriter Region, node ( : ClassDeclarationSyntax).

:

 public class RegionRemoval : CSharpSyntaxRewriter
    {
        public override SyntaxNode VisitClassDeclaration(ClassDeclarationSyntax node)
        {

            if(node.HasLeadingTrivia)
            {
                var enumerator = node.GetLeadingTrivia().GetEnumerator();

                while(enumerator.MoveNext())
                {
                    var syntaxTrivia = enumerator.Current;
                    if(syntaxTrivia.Kind().Equals(SyntaxKind.RegionDirectiveTrivia))
                    {
                        node = node.ReplaceTrivia(syntaxTrivia, SyntaxFactory.Whitespace("\n"));
                    }
                }

            }
            return node;
        }
    }

    class RoslynTry
    {
        public static void RegionRemover()
        {
            //A syntax tree with an unnecessary semicolon on its own line
            var tree = CSharpSyntaxTree.ParseText(@"
                  #region Classes
        public class MyClass
        {
        }

        public class MyClass2
        {
            #region Methods
            #endregion
        }
        #endregion
        ");

            var rewriter = new RegionRemoval();
            var result = rewriter.Visit(tree.GetRoot());
            Console.WriteLine(result.ToFullString());
        }
    }

:

        public class MyClass
        {
        }

        public class MyClass2
        {
            #region Methods
            #endregion
        }
        #endregion

P.S.: . mjwills, .

P.S.: JoshVarty EmptyStatementRemoval