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* modification, are permitted provided that the following conditions are
* met:
*
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* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
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*
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "V8Binding.h"
#include "AtomicString.h"
#include "CString.h"
#include "MathExtras.h"
#include "PlatformString.h"
#include "StdLibExtras.h"
#include "StringBuffer.h"
#include "StringHash.h"
#include "Threading.h"
#include "V8Proxy.h"
#include <v8.h>
namespace WebCore {
// WebCoreStringResource is a helper class for v8ExternalString. It is used
// to manage the life-cycle of the underlying buffer of the external string.
class WebCoreStringResource : public v8::String::ExternalStringResource {
public:
explicit WebCoreStringResource(const String& string)
: m_plainString(string)
{
#ifndef NDEBUG
m_threadId = WTF::currentThread();
#endif
v8::V8::AdjustAmountOfExternalAllocatedMemory(2 * length());
}
explicit WebCoreStringResource(const AtomicString& string)
: m_plainString(string)
, m_atomicString(string)
{
#ifndef NDEBUG
m_threadId = WTF::currentThread();
#endif
v8::V8::AdjustAmountOfExternalAllocatedMemory(2 * length());
}
virtual ~WebCoreStringResource()
{
#ifndef NDEBUG
ASSERT(m_threadId == WTF::currentThread());
#endif
int reducedExternalMemory = -2 * length();
if (!m_plainString.impl()->inTable())
reducedExternalMemory *= 2;
v8::V8::AdjustAmountOfExternalAllocatedMemory(reducedExternalMemory);
}
const uint16_t* data() const
{
return reinterpret_cast<const uint16_t*>(m_plainString.characters());
}
size_t length() const { return m_plainString.length(); }
String webcoreString() { return m_plainString; }
AtomicString atomicString()
{
#ifndef NDEBUG
ASSERT(m_threadId == WTF::currentThread());
#endif
if (m_atomicString.isNull()) {
m_atomicString = AtomicString(m_plainString);
if (!m_plainString.impl()->inTable())
v8::V8::AdjustAmountOfExternalAllocatedMemory(2 * length());
}
return m_atomicString;
}
static WebCoreStringResource* toStringResource(v8::Handle<v8::String> v8String)
{
return static_cast<WebCoreStringResource*>(v8String->GetExternalStringResource());
}
private:
// A shallow copy of the string. Keeps the string buffer alive until the V8 engine garbage collects it.
String m_plainString;
// If this string is atomic or has been made atomic earlier the
// atomic string is held here. In the case where the string starts
// off non-atomic and becomes atomic later it is necessary to keep
// the original string alive because v8 may keep derived pointers
// into that string.
AtomicString m_atomicString;
#ifndef NDEBUG
WTF::ThreadIdentifier m_threadId;
#endif
};
String v8StringToWebCoreString(v8::Handle<v8::String> v8String, ExternalMode external,
StringType type)
{
WebCoreStringResource* stringResource = WebCoreStringResource::toStringResource(v8String);
if (stringResource)
return stringResource->webcoreString();
int length = v8String->Length();
if (!length) {
// Avoid trying to morph empty strings, as they do not have enough room to contain the external reference.
return StringImpl::empty();
}
UChar* buffer;
String result = String::createUninitialized(length, buffer);
v8String->Write(reinterpret_cast<uint16_t*>(buffer), 0, length);
if (type == AtomicStringType)
result = AtomicString(result);
if (external == Externalize) {
WebCoreStringResource* resource = new WebCoreStringResource(result);
if (!v8String->MakeExternal(resource)) {
// In case of a failure delete the external resource as it was not used.
delete resource;
}
}
return result;
}
AtomicString v8StringToAtomicWebCoreString(v8::Handle<v8::String> v8String)
{
WebCoreStringResource* stringResource = WebCoreStringResource::toStringResource(v8String);
if (!stringResource) {
// If this string hasn't been externalized, we force it now.
String plain = v8StringToWebCoreString(v8String, Externalize, AtomicStringType);
// If the string is empty there's no room to cache an atomic
// string so we bail out.
if (plain.isEmpty())
return plain;
stringResource = WebCoreStringResource::toStringResource(v8String);
ASSERT(stringResource != NULL);
}
return stringResource->atomicString();
}
String v8ValueToWebCoreString(v8::Handle<v8::Value> object)
{
if (object->IsString())
return v8StringToWebCoreString(v8::Handle<v8::String>::Cast(object), Externalize, PlainStringType);
if (object->IsInt32()) {
int value = object->Int32Value();
// Most numbers used are <= 100. Even if they aren't used there's very little in using the space.
const int kLowNumbers = 100;
static AtomicString lowNumbers[kLowNumbers + 1];
String webCoreString;
if (0 <= value && value <= kLowNumbers) {
webCoreString = lowNumbers[value];
if (!webCoreString) {
AtomicString valueString = AtomicString(String::number(value));
lowNumbers[value] = valueString;
webCoreString = valueString;
}
} else
webCoreString = String::number(value);
return webCoreString;
}
v8::TryCatch block;
v8::Handle<v8::String> v8String = object->ToString();
// Handle the case where an exception is thrown as part of invoking toString on the object.
if (block.HasCaught()) {
throwError(block.Exception());
return StringImpl::empty();
}
return v8StringToWebCoreString(v8String, DoNotExternalize, PlainStringType);
}
AtomicString v8ValueToAtomicWebCoreString(v8::Handle<v8::Value> v8Value)
{
if (v8Value->IsString())
return v8StringToAtomicWebCoreString(v8::Handle<v8::String>::Cast(v8Value));
String string = v8ValueToWebCoreString(v8Value);
return AtomicString(string);
}
v8::Handle<v8::String> v8String(const String& string)
{
return v8ExternalString(string);
}
static bool stringImplCacheEnabled = false;
void enableStringImplCache()
{
stringImplCacheEnabled = true;
}
static v8::Local<v8::String> makeExternalString(const String& string)
{
WebCoreStringResource* stringResource = new WebCoreStringResource(string);
v8::Local<v8::String> newString = v8::String::NewExternal(stringResource);
if (newString.IsEmpty())
delete stringResource;
return newString;
}
typedef HashMap<StringImpl*, v8::String*> StringCache;
static StringCache& getStringCache()
{
ASSERT(WTF::isMainThread());
DEFINE_STATIC_LOCAL(StringCache, mainThreadStringCache, ());
return mainThreadStringCache;
}
static void cachedStringCallback(v8::Persistent<v8::Value> wrapper, void* parameter)
{
ASSERT(WTF::isMainThread());
StringImpl* stringImpl = static_cast<StringImpl*>(parameter);
ASSERT(getStringCache().contains(stringImpl));
getStringCache().remove(stringImpl);
wrapper.Dispose();
stringImpl->deref();
}
v8::Local<v8::String> v8ExternalString(const String& string)
{
if (!string.length())
return v8::String::Empty();
if (!stringImplCacheEnabled)
return makeExternalString(string);
StringImpl* stringImpl = string.impl();
StringCache& stringCache = getStringCache();
v8::String* cachedV8String = stringCache.get(stringImpl);
if (cachedV8String)
return v8::Local<v8::String>(cachedV8String);
v8::Local<v8::String> newString = makeExternalString(string);
if (newString.IsEmpty())
return newString;
v8::Persistent<v8::String> wrapper = v8::Persistent<v8::String>::New(newString);
if (wrapper.IsEmpty())
return newString;
stringImpl->ref();
wrapper.MakeWeak(stringImpl, cachedStringCallback);
stringCache.set(stringImpl, *wrapper);
return newString;
}
} // namespace WebCore