From 0ff40a6777f393685213b59f69d25ed29fb22378 Mon Sep 17 00:00:00 2001
From: Loretta <jozsef.b@aycode.com>
Date: Sun, 1 Mar 2026 07:22:13 +0100
Subject: [PATCH] Refactor string read logic; remove UseGeneratedCode option

Refactored EmitReadString to use a switch for O(1) dispatch of string wire formats, improving performance and clarity. Updated comments to document the new approach and its benefits. Removed the UseGeneratedCode property from AcBinarySerializerOptions.
---
 .../AcBinarySourceGenerator.cs                | 49 +++++++++++++------
 .../Binaries/AcBinarySerializerOptions.cs     |  1 -
 2 files changed, 33 insertions(+), 17 deletions(-)

diff --git a/AyCode.Core.Serializers.SourceGenerator/AcBinarySourceGenerator.cs b/AyCode.Core.Serializers.SourceGenerator/AcBinarySourceGenerator.cs
index f07a866..1cadf4e 100644
--- a/AyCode.Core.Serializers.SourceGenerator/AcBinarySourceGenerator.cs
+++ b/AyCode.Core.Serializers.SourceGenerator/AcBinarySourceGenerator.cs
@@ -2020,6 +2020,11 @@ public class AcBinarySourceGenerator : IIncrementalGenerator
 
     /// <summary>
     /// Emits inline string read from type code. Handles all string wire formats.
+    /// FixStr (range 34-65) is checked first as hot path for short strings.
+    /// Remaining codes use switch for O(1) JIT jump-table dispatch:
+    ///   String=16, StringInterned=17, StringEmpty=18, StringInternFirst=19, Null=0.
+    /// This eliminates the sequential if-else chain that penalized StringInterned
+    /// (the hot path for repeated interned strings) with 4 comparisons.
     /// </summary>
     private static void EmitReadString(StringBuilder sb, string a, string tc, string i)
     {
@@ -2029,24 +2034,36 @@ public class AcBinarySourceGenerator : IIncrementalGenerator
         sb.AppendLine($"{i}    var flen = BinaryTypeCode.DecodeFixStrLength({tc});");
         sb.AppendLine($"{i}    {a} = flen == 0 ? string.Empty : context.ReadStringUtf8(flen);");
         sb.AppendLine($"{i}}}");
-        sb.AppendLine($"{i}else if ({tc} == BinaryTypeCode.String)");
+        // Switch gives O(1) dispatch via JIT jump table for codes 0, 16-19.
+        // StringInterned (17) is the hot path for repeated interned strings — no longer buried at 4th else-if.
+        sb.AppendLine($"{i}else switch ({tc})");
         sb.AppendLine($"{i}{{");
-        sb.AppendLine($"{i}    var slen = (int)context.ReadVarUInt();");
-        sb.AppendLine($"{i}    {a} = slen == 0 ? string.Empty : context.ReadStringUtf8(slen);");
+        sb.AppendLine($"{i}    case BinaryTypeCode.StringInterned:");
+        sb.AppendLine($"{i}        {a} = context.GetInternedString((int)context.ReadVarUInt());");
+        sb.AppendLine($"{i}        break;");
+        sb.AppendLine($"{i}    case BinaryTypeCode.String:");
+        sb.AppendLine($"{i}    {{");
+        sb.AppendLine($"{i}        var slen = (int)context.ReadVarUInt();");
+        sb.AppendLine($"{i}        {a} = slen == 0 ? string.Empty : context.ReadStringUtf8(slen);");
+        sb.AppendLine($"{i}        break;");
+        sb.AppendLine($"{i}    }}");
+        sb.AppendLine($"{i}    case BinaryTypeCode.StringInternFirst:");
+        sb.AppendLine($"{i}    {{");
+        sb.AppendLine($"{i}        context.DisableStringCaching();");
+        sb.AppendLine($"{i}        var sci = (int)context.ReadVarUInt();");
+        sb.AppendLine($"{i}        var slen2 = (int)context.ReadVarUInt();");
+        sb.AppendLine($"{i}        var sv = slen2 == 0 ? string.Empty : context.ReadStringUtf8(slen2);");
+        sb.AppendLine($"{i}        context.RegisterInternedValueAt(sci, sv);");
+        sb.AppendLine($"{i}        {a} = sv;");
+        sb.AppendLine($"{i}        break;");
+        sb.AppendLine($"{i}    }}");
+        sb.AppendLine($"{i}    case BinaryTypeCode.Null:");
+        sb.AppendLine($"{i}        {a} = null;");
+        sb.AppendLine($"{i}        break;");
+        sb.AppendLine($"{i}    case BinaryTypeCode.StringEmpty:");
+        sb.AppendLine($"{i}        {a} = string.Empty;");
+        sb.AppendLine($"{i}        break;");
         sb.AppendLine($"{i}}}");
-        sb.AppendLine($"{i}else if ({tc} == BinaryTypeCode.StringInternFirst)");
-        sb.AppendLine($"{i}{{");
-        sb.AppendLine($"{i}    context.DisableStringCaching();");
-        sb.AppendLine($"{i}    var sci = (int)context.ReadVarUInt();");
-        sb.AppendLine($"{i}    var slen2 = (int)context.ReadVarUInt();");
-        sb.AppendLine($"{i}    var sv = slen2 == 0 ? string.Empty : context.ReadStringUtf8(slen2);");
-        sb.AppendLine($"{i}    context.RegisterInternedValueAt(sci, sv);");
-        sb.AppendLine($"{i}    {a} = sv;");
-        sb.AppendLine($"{i}}}");
-        sb.AppendLine($"{i}else if ({tc} == BinaryTypeCode.StringInterned)");
-        sb.AppendLine($"{i}    {a} = context.GetInternedString((int)context.ReadVarUInt());");
-        sb.AppendLine($"{i}else if ({tc} == BinaryTypeCode.Null) {a} = null;");
-        sb.AppendLine($"{i}else if ({tc} == BinaryTypeCode.StringEmpty) {a} = string.Empty;");
     }
 
     /// <summary>
diff --git a/AyCode.Core/Serializers/Binaries/AcBinarySerializerOptions.cs b/AyCode.Core/Serializers/Binaries/AcBinarySerializerOptions.cs
index 6b01f75..681e792 100644
--- a/AyCode.Core/Serializers/Binaries/AcBinarySerializerOptions.cs
+++ b/AyCode.Core/Serializers/Binaries/AcBinarySerializerOptions.cs
@@ -83,7 +83,6 @@ public sealed class AcBinarySerializerOptions : AcSerializerOptions
     /// Default: false (no overhead)
     /// </summary>
     public bool UseMetadata { get; set; } = false;
-
     public bool UseGeneratedCode { get; set; } = true;
 
     /// <summary>