Replace string.StartsWith with a custom version

Saves about 3% on startup since we're not checking CultureInfo.
sorear · Nov 17, 2010 · bdf7346 · bdf7346
1 parent c861224
commit bdf7346
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Showing 2 changed files with 18 additions and 2 deletions.
diff --git a/Niecza.proj b/Niecza.proj
@@ -39,7 +39,8 @@
     <Target Name="Kernel.dll" Inputs="lib\Kernel.cs;lib\Cursor.cs;lib/JSYNC.cs"
         Outputs="obj\Kernel.dll">
         <Csc Sources="lib\Kernel.cs;lib\Cursor.cs;lib\JSYNC.cs" TargetType="library"
-            OutputAssembly="obj\Kernel.dll" EmitDebugInformation="true"/>
+            OutputAssembly="obj\Kernel.dll" EmitDebugInformation="true"
+            AllowUnsafeBlocks="true"/>
     </Target>
 
     <Target Name="CORE.cs" Inputs="@(CompilerPerl);obj\SAFE.store;lib\CORE.setting" Outputs="obj\CORE.cs;obj\CORE.store" DependsOnTargets="SAFE.cs;Grammar;PerlTask">

diff --git a/lib/Cursor.cs b/lib/Cursor.cs
@@ -1439,6 +1439,21 @@ public class Lexer {
         return ret;
     }
 
+    // s1 must not have embedded nuls
+    private static unsafe bool StartsWithInvariant(string s1, string s2) {
+        fixed (char* st1 = s1) {
+            char* p1 = st1;
+            fixed (char* st2 = s2) {
+                char* p2 = st2;
+                while (*p1 != '\0' && *p1 == *p2) {
+                    p1++;
+                    p2++;
+                }
+                return (*p1 == '\0');
+            }
+        }
+    }
+
     public static DynObject[] ResolveProtoregex(LexerCache lc,
             string name) {
         DynObject[] ret;
@@ -1467,7 +1482,7 @@ public class Lexer {
             if (proto != k.Can(name))
                 continue;
             foreach (KeyValuePair<string,IP6> o in k.ord_methods) {
-                if (!o.Key.StartsWith(filter))
+                if (!StartsWithInvariant(filter, o.Key))
                     continue;
                 if (cursor_class.Can(o.Key) == o.Value) {
                     raword.Add((DynObject) o.Value);