Changeset 184575 in webkit for trunk/Source/JavaScriptCore/runtime/JSString.h

Timestamp:

May 19, 2015, 10:06:23 AM (10 years ago)

Author:

[email protected]

Message:

Give JSString a StringView getter and start using it.
<​https://webkit.org/b/145131>

Reviewed by Anders Carlsson.

When JSString is a substring internally, calling value(ExecState*) on it
will reify the baseString/start/length tuple into a new StringImpl.

For clients that only want to look at the characters of a JSString, but
don't actually need a reffable StringImpl, adding a light-weight StringView
getter lets them avoid constructing anything.

This patch adds JSString::view(ExecState*) and uses it in a few places.
There are many more opportunities to use this API, but let's do a few things
at a time.

• runtime/FunctionConstructor.cpp:

(JSC::constructFunctionSkippingEvalEnabledCheck):

• runtime/JSGlobalObjectFunctions.cpp:

(JSC::decode):
(JSC::parseInt):
(JSC::jsToNumber):
(JSC::parseFloat):
(JSC::globalFuncParseInt):
(JSC::globalFuncParseFloat):
(JSC::globalFuncEscape):
(JSC::globalFuncUnescape):

• runtime/JSGlobalObjectFunctions.h:
• runtime/JSONObject.cpp:

(JSC::JSONProtoFuncParse):

• runtime/JSString.cpp:

(JSC::JSString::getPrimitiveNumber):
(JSC::JSString::toNumber):

• runtime/JSString.h:

(JSC::JSRopeString::view):
(JSC::JSString::view):

File:

• trunk/Source/JavaScriptCore/runtime/JSString.h (modified) (4 diffs)

trunk/Source/JavaScriptCore/runtime/JSString.h

@@ -31 +31 @@
 #include "Structure.h"
 #include <array>
+#include <wtf/text/StringView.h>
 
 namespace JSC {
@@ -144 +145 @@
     AtomicString toAtomicString(ExecState*) const;
     AtomicStringImpl* toExistingAtomicString(ExecState*) const;
+    StringView view(ExecState*) const;
     const String& value(ExecState*) const;
     const String& tryGetValue() const;
@@ -370 +372 @@
     void resolveRopeInternal16NoSubstring(UChar*) const;
     void clearFibers() const;
+    StringView view(ExecState*) const;
 
     JS_EXPORT_PRIVATE JSString* getIndexSlowCase(ExecState*, unsigned);
@@ -699 +702 @@
 }
 
+ALWAYS_INLINE StringView JSRopeString::view(ExecState* exec) const
+{
+    if (isSubstring()) {
+        if (is8Bit())
+            return StringView(substringBase()->m_value.characters8() + substringOffset(), m_length);
+        return StringView(substringBase()->m_value.characters16() + substringOffset(), m_length);
+    }
+    resolveRope(exec);
+    return StringView(m_value);
+}
+
+ALWAYS_INLINE StringView JSString::view(ExecState* exec) const
+{
+    if (isRope())
+        return static_cast<const JSRopeString*>(this)->view(exec);
+    return StringView(m_value);
+}
+
 } // namespace JSC