1 files changed, 82 insertions, 56 deletions
diff --git a/Source/JavaScriptCore/runtime/StringObject.h b/Source/JavaScriptCore/runtime/StringObject.h
index df6361474..60cb61fea 100644
--- a/Source/JavaScriptCore/runtime/StringObject.h
+++ b/Source/JavaScriptCore/runtime/StringObject.h
@@ -1,6 +1,6 @@
 /*
  *  Copyright (C) 1999-2000 Harri Porten (porten@kde.org)
- *  Copyright (C) 2007, 2008 Apple Inc. All rights reserved.
+ *  Copyright (C) 2007-2008, 2016 Apple Inc. All rights reserved.
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
@@ -18,69 +18,95 @@
  *
  */
 
-#ifndef StringObject_h
-#define StringObject_h
+#pragma once
 
 #include "JSWrapperObject.h"
 #include "JSString.h"
 
 namespace JSC {
 
-    class StringObject : public JSWrapperObject {
-    public:
-        typedef JSWrapperObject Base;
-
-        static StringObject* create(VM& vm, Structure* structure)
-        {
-            JSString* string = jsEmptyString(&vm);
-            StringObject* object = new (NotNull, allocateCell<StringObject>(vm.heap)) StringObject(vm, structure);
-            object->finishCreation(vm, string);
-            return object;
-        }
-        static StringObject* create(VM& vm, Structure* structure, JSString* string)
-        {
-            StringObject* object = new (NotNull, allocateCell<StringObject>(vm.heap)) StringObject(vm, structure);
-            object->finishCreation(vm, string);
-            return object;
-        }
-        static StringObject* create(VM&, JSGlobalObject*, JSString*);
-
-        static bool getOwnPropertySlot(JSObject*, ExecState*, PropertyName, PropertySlot&);
-        static bool getOwnPropertySlotByIndex(JSObject*, ExecState*, unsigned propertyName, PropertySlot&);
-
-        static void put(JSCell*, ExecState*, PropertyName, JSValue, PutPropertySlot&);
-        static void putByIndex(JSCell*, ExecState*, unsigned propertyName, JSValue, bool shouldThrow);
-
-        static bool deleteProperty(JSCell*, ExecState*, PropertyName);
-        static bool deletePropertyByIndex(JSCell*, ExecState*, unsigned propertyName);
-        static void getOwnPropertyNames(JSObject*, ExecState*, PropertyNameArray&, EnumerationMode);
-        static bool defineOwnProperty(JSObject*, ExecState*, PropertyName, const PropertyDescriptor&, bool shouldThrow);
-
-        DECLARE_EXPORT_INFO;
-
-        JSString* internalValue() const { return asString(JSWrapperObject::internalValue());}
-
-        static Structure* createStructure(VM& vm, JSGlobalObject* globalObject, JSValue prototype)
-        {
-            return Structure::create(vm, globalObject, prototype, TypeInfo(ObjectType, StructureFlags), info());
-        }
-
-    protected:
-        JS_EXPORT_PRIVATE void finishCreation(VM&, JSString*);
-        static const unsigned StructureFlags = OverridesGetOwnPropertySlot | InterceptsGetOwnPropertySlotByIndexEvenWhenLengthIsNotZero | OverridesGetPropertyNames | JSWrapperObject::StructureFlags;
-        JS_EXPORT_PRIVATE StringObject(VM&, Structure*);
-    };
-
-    StringObject* asStringObject(JSValue);
-
-    inline StringObject* asStringObject(JSValue value)
+class StringObject : public JSWrapperObject {
+public:
+    typedef JSWrapperObject Base;
+    static const unsigned StructureFlags = Base::StructureFlags | OverridesGetOwnPropertySlot | InterceptsGetOwnPropertySlotByIndexEvenWhenLengthIsNotZero | OverridesGetPropertyNames;
+
+    static StringObject* create(VM& vm, Structure* structure)
+    {
+        JSString* string = jsEmptyString(&vm);
+        StringObject* object = new (NotNull, allocateCell<StringObject>(vm.heap)) StringObject(vm, structure);
+        object->finishCreation(vm, string);
+        return object;
+    }
+    static StringObject* create(VM& vm, Structure* structure, JSString* string)
     {
-        ASSERT(asObject(value)->inherits(StringObject::info()));
-        return static_cast<StringObject*>(asObject(value));
+        StringObject* object = new (NotNull, allocateCell<StringObject>(vm.heap)) StringObject(vm, structure);
+        object->finishCreation(vm, string);
+        return object;
     }
+    static StringObject* create(VM&, JSGlobalObject*, JSString*);
 
-    JS_EXPORT_PRIVATE StringObject* constructString(VM&, JSGlobalObject*, JSValue);
+    JS_EXPORT_PRIVATE static bool getOwnPropertySlot(JSObject*, ExecState*, PropertyName, PropertySlot&);
+    JS_EXPORT_PRIVATE static bool getOwnPropertySlotByIndex(JSObject*, ExecState*, unsigned propertyName, PropertySlot&);
 
-} // namespace JSC
+    JS_EXPORT_PRIVATE static bool put(JSCell*, ExecState*, PropertyName, JSValue, PutPropertySlot&);
+    JS_EXPORT_PRIVATE static bool putByIndex(JSCell*, ExecState*, unsigned propertyName, JSValue, bool shouldThrow);
+
+    JS_EXPORT_PRIVATE static bool deleteProperty(JSCell*, ExecState*, PropertyName);
+    JS_EXPORT_PRIVATE static bool deletePropertyByIndex(JSCell*, ExecState*, unsigned propertyName);
+    JS_EXPORT_PRIVATE static void getOwnPropertyNames(JSObject*, ExecState*, PropertyNameArray&, EnumerationMode);
+    JS_EXPORT_PRIVATE static bool defineOwnProperty(JSObject*, ExecState*, PropertyName, const PropertyDescriptor&, bool shouldThrow);
+
+    DECLARE_EXPORT_INFO;
+
+    JSString* internalValue() const { return asString(JSWrapperObject::internalValue());}
 
-#endif // StringObject_h
+    static Structure* createStructure(VM& vm, JSGlobalObject* globalObject, JSValue prototype)
+    {
+        return Structure::create(vm, globalObject, prototype, TypeInfo(ObjectType, StructureFlags), info());
+    }
+
+protected:
+    JS_EXPORT_PRIVATE void finishCreation(VM&, JSString*);
+    JS_EXPORT_PRIVATE StringObject(VM&, Structure*);
+};
+
+StringObject* asStringObject(JSValue);
+
+inline StringObject* asStringObject(JSValue value)
+{
+    ASSERT(asObject(value)->inherits(*value.getObject()->vm(), StringObject::info()));
+    return static_cast<StringObject*>(asObject(value));
+}
+
+JS_EXPORT_PRIVATE StringObject* constructString(VM&, JSGlobalObject*, JSValue);
+
+// Helper for producing a JSString for 'string', where 'string' was been produced by
+// calling ToString on 'originalValue'. In cases where 'originalValue' already was a
+// string primitive we can just use this, otherwise we need to allocate a new JSString.
+// FIXME: Basically any use of this is bad. toString() returns a JSString* so we don't need to
+// pass around the originalValue; we could just pass around the JSString*. Then you don't need
+// this function. You just use the JSString* that toString() returned.
+static inline JSString* jsStringWithReuse(ExecState* exec, JSValue originalValue, const String& string)
+{
+    if (originalValue.isString()) {
+        ASSERT(asString(originalValue)->value(exec) == string);
+        return asString(originalValue);
+    }
+    return jsString(exec, string);
+}
+
+// Helper that tries to use the JSString substring sharing mechanism if 'originalValue' is a JSString.
+// FIXME: Basically any use of this is bad. toString() returns a JSString* so we don't need to
+// pass around the originalValue; we could just pass around the JSString*. And since we've
+// resolved it, we know that we can just allocate the substring cell directly.
+// https://bugs.webkit.org/show_bug.cgi?id=158140
+static inline JSString* jsSubstring(ExecState* exec, JSValue originalValue, const String& string, unsigned offset, unsigned length)
+{
+    if (originalValue.isString()) {
+        ASSERT(asString(originalValue)->value(exec) == string);
+        return jsSubstring(exec, asString(originalValue), offset, length);
+    }
+    return jsSubstring(exec, string, offset, length);
+}
+
+} // namespace JSC