More efficiently generate SourceTexts

canton7 · Mar 10, 2023 · 8bbaba7 · 8bbaba7
1 parent f7ef434
commit 8bbaba7
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Showing 4 changed files with 43 additions and 6 deletions.
diff --git a/src/PropertyChanged.SourceGenerator/BetterIndentedTextWriter.cs b/src/PropertyChanged.SourceGenerator/BetterIndentedTextWriter.cs
@@ -1,10 +1,9 @@
 using System;
 using System.CodeDom.Compiler;
-using System.Collections.Generic;
-using System.Diagnostics;
 using System.IO;
 using System.Runtime.CompilerServices;
 using System.Text;
+using Microsoft.CodeAnalysis.Text;
 
 namespace PropertyChanged.SourceGenerator;
 
@@ -16,6 +15,42 @@ public BetterIndentedTextWriter() : base(new StringWriter())
 
     public void Write([InterpolatedStringHandlerArgument("")] ref AppendInterpolatedStringHandler handler) { }
     public void WriteLine([InterpolatedStringHandlerArgument("")] ref AppendInterpolatedStringHandler handler) => this.WriteLine();
+
+    public SourceText ToSourceText()
+    {
+        var stringWriter = (StringWriter)this.InnerWriter;
+        var stringBuilder = stringWriter.GetStringBuilder();
+        stringWriter.Close(); // Attempts to interact with it after this point will fail
+        return new StringBuilderText(stringBuilder);
+    }
+
+    private class StringBuilderText : SourceText
+    {
+        private readonly StringBuilder stringBuilder;
+
+        public StringBuilderText(StringBuilder stringBuilder)
+        {
+            this.stringBuilder = stringBuilder;
+        }
+        public override Encoding? Encoding => Encoding.UTF8;
+
+        public override char this[int position] => this.stringBuilder[position];
+
+        public override int Length => this.stringBuilder.Length;
+
+        public override void CopyTo(int sourceIndex, char[] destination, int destinationIndex, int count) =>
+            this.stringBuilder.CopyTo(sourceIndex, destination, destinationIndex, count);
+
+        public override string ToString(TextSpan span)
+        {
+            if (span.End > this.stringBuilder.Length)
+            {
+                throw new ArgumentOutOfRangeException(nameof(span));
+            }
+
+            return this.stringBuilder.ToString(span.Start, span.Length);
+        }
+    }
 }
 
 [InterpolatedStringHandler]

diff --git a/src/PropertyChanged.SourceGenerator/EventArgsCacheGenerator.cs b/src/PropertyChanged.SourceGenerator/EventArgsCacheGenerator.cs
@@ -3,6 +3,7 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Text;
+using Microsoft.CodeAnalysis.Text;
 using PropertyChanged.SourceGenerator;
 using PropertyChanged.SourceGenerator.EventArgs;
 
@@ -55,5 +56,5 @@ private static string EscapeString(string? str)
             : "@\"" + str.Replace("\"", "\"\"") + "\"";
     }
 
-    public override string ToString() => this.writer.InnerWriter.ToString();
+    public SourceText ToSourceText() => this.writer.ToSourceText();
 }
diff --git a/src/PropertyChanged.SourceGenerator/Generator.cs b/src/PropertyChanged.SourceGenerator/Generator.cs
@@ -7,6 +7,7 @@
 using System.Linq;
 using System.Text;
 using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Text;
 using PropertyChanged.SourceGenerator.Analysis;
 using PropertyChanged.SourceGenerator.EventArgs;
 
@@ -567,5 +568,5 @@ private static string EscapeString(string? str)
             : "@\"" + str.Replace("\"", "\"\"") + "\"";
     }
 
-    public override string ToString() => this.writer.InnerWriter.ToString();
+    public SourceText ToSourceText() => this.writer.ToSourceText();
 }
diff --git a/src/PropertyChanged.SourceGenerator/PropertyChangedSourceGenerator.cs b/src/PropertyChanged.SourceGenerator/PropertyChangedSourceGenerator.cs
@@ -118,7 +118,7 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
             var (typeAnalysis, eventArgsCacheLookup) = pair;
             var generator = new Generator(eventArgsCacheLookup);
             generator.Generate(typeAnalysis);
-            ctx.AddSource(typeAnalysis.TypeNameForGeneratedFileName + ".g", generator.ToString());
+            ctx.AddSource(typeAnalysis.TypeNameForGeneratedFileName + ".g", generator.ToSourceText());
         });
 
         context.RegisterSourceOutput(eventArgsCacheSource, (ctx, eventArgsCache) =>
@@ -127,7 +127,7 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
             {
                 var generator = new EventArgsCacheGenerator(eventArgsCache);
                 generator.GenerateNameCache();
-                ctx.AddSource("PropertyChanged.SourceGenerator.Internal.EventArgsCache.g", generator.ToString());
+                ctx.AddSource("PropertyChanged.SourceGenerator.Internal.EventArgsCache.g", generator.ToSourceText());
             }
         });
     }