Specialize Symbol.hashCode

Patch internal.Symbol.hashCode and specialize JS version to avoid recomputing String.hashCode R=sigmund@google.com Review URL: https://codereview.chromium.org/2038853003 .
dart-lang · Jun 3, 2016 · b377479 · b377479
1 parent 5e9f7a8
commit b377479
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Showing 3 changed files with 17 additions and 4 deletions.
diff --git a/runtime/lib/symbol_patch.dart b/runtime/lib/symbol_patch.dart
@@ -51,4 +51,9 @@ patch class Symbol {
     }
     return result.toString();
   }
+
+  /* patch */ int get hashCode {
+    const arbitraryPrime = 664597;
+    return 0x1fffffff & (arbitraryPrime * _name.hashCode);
+  }
 }
diff --git a/sdk/lib/_internal/js_runtime/lib/internal_patch.dart b/sdk/lib/_internal/js_runtime/lib/internal_patch.dart
@@ -5,12 +5,23 @@
 import 'dart:_js_primitives' show printString;
 import 'dart:_js_helper' show patch;
 import 'dart:_interceptors' show JSArray;
+import 'dart:_foreign_helper' show JS;
 
 @patch
 class Symbol implements core.Symbol {
   @patch
   const Symbol(String name)
       : this._name = name;
+
+  @patch
+  int get hashCode {
+    int hash = JS('int|Null', '#._hashCode', this);
+    if (hash != null) return hash;
+    const arbitraryPrime = 664597;
+    hash = 0x1fffffff & (arbitraryPrime * _name.hashCode);
+    JS('', '#._hashCode = #', this, hash);
+    return hash;
+  }
 }
 
 @patch

diff --git a/sdk/lib/internal/symbol.dart b/sdk/lib/internal/symbol.dart
@@ -112,10 +112,7 @@ class Symbol implements core.Symbol {
 
   bool operator ==(other) => other is Symbol && _name == other._name;
 
-  int get hashCode {
-    const arbitraryPrime = 664597;
-    return 0x1fffffff & (arbitraryPrime * _name.hashCode);
-  }
+  external int get hashCode;
 
   toString() => 'Symbol("$_name")';