--- /dev/null
+/*
+ * Copyright (C) 2009 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. 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 distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef UStringImpl_h
+#define UStringImpl_h
+
+#include <limits>
+#include <wtf/CrossThreadRefCounted.h>
+#include <wtf/OwnFastMallocPtr.h>
+#include <wtf/PossiblyNull.h>
+#include <wtf/StringHashFunctions.h>
+#include <wtf/Vector.h>
+#include <wtf/unicode/Unicode.h>
+
+namespace JSC {
+
+class IdentifierTable;
+
+typedef CrossThreadRefCounted<OwnFastMallocPtr<UChar> > SharedUChar;
+
+class UntypedPtrAndBitfield {
+public:
+ UntypedPtrAndBitfield() {}
+
+ UntypedPtrAndBitfield(void* ptrValue, uintptr_t bitValue)
+ : m_value(reinterpret_cast<uintptr_t>(ptrValue) | bitValue)
+#ifndef NDEBUG
+ , m_leaksPtr(ptrValue)
+#endif
+ {
+ ASSERT(ptrValue == asPtr<void*>());
+ ASSERT((*this & ~s_alignmentMask) == bitValue);
+ }
+
+ template<typename T>
+ T asPtr() const { return reinterpret_cast<T>(m_value & s_alignmentMask); }
+
+ UntypedPtrAndBitfield& operator&=(uintptr_t bits)
+ {
+ m_value &= bits | s_alignmentMask;
+ return *this;
+ }
+
+ UntypedPtrAndBitfield& operator|=(uintptr_t bits)
+ {
+ m_value |= bits & ~s_alignmentMask;
+ return *this;
+ }
+
+ uintptr_t operator&(uintptr_t mask) const
+ {
+ return m_value & mask & ~s_alignmentMask;
+ }
+
+private:
+ static const uintptr_t s_alignmentMask = ~static_cast<uintptr_t>(0x7);
+ uintptr_t m_value;
+#ifndef NDEBUG
+ void* m_leaksPtr; // Only used to allow tools like leaks on OSX to detect that the memory is referenced.
+#endif
+};
+
+class UStringImpl : Noncopyable {
+public:
+ template<size_t inlineCapacity>
+ static PassRefPtr<UStringImpl> adopt(Vector<UChar, inlineCapacity>& vector)
+ {
+ if (unsigned length = vector.size())
+ return adoptRef(new UStringImpl(vector.releaseBuffer(), length, BufferOwned));
+ return &empty();
+ }
+
+ static PassRefPtr<UStringImpl> create(const UChar* buffer, int length)
+ {
+ UChar* newBuffer;
+ if (PassRefPtr<UStringImpl> impl = tryCreateUninitialized(length, newBuffer)) {
+ copyChars(newBuffer, buffer, length);
+ return impl;
+ }
+ return &null();
+ }
+
+ static PassRefPtr<UStringImpl> create(PassRefPtr<UStringImpl> rep, int offset, int length)
+ {
+ ASSERT(rep);
+ rep->checkConsistency();
+ return adoptRef(new UStringImpl(rep->m_data + offset, length, rep->bufferOwnerString()));
+ }
+
+ static PassRefPtr<UStringImpl> create(PassRefPtr<SharedUChar> sharedBuffer, UChar* buffer, int length)
+ {
+ return adoptRef(new UStringImpl(buffer, length, sharedBuffer));
+ }
+
+ static PassRefPtr<UStringImpl> createUninitialized(unsigned length, UChar*& output)
+ {
+ if (!length) {
+ output = 0;
+ return &empty();
+ }
+
+ if (length > ((std::numeric_limits<size_t>::max() - sizeof(UStringImpl)) / sizeof(UChar)))
+ CRASH();
+ UStringImpl* resultImpl = static_cast<UStringImpl*>(fastMalloc(sizeof(UChar) * length + sizeof(UStringImpl)));
+ output = reinterpret_cast<UChar*>(resultImpl + 1);
+ return adoptRef(new(resultImpl) UStringImpl(output, length, BufferInternal));
+ }
+
+ static PassRefPtr<UStringImpl> tryCreateUninitialized(unsigned length, UChar*& output)
+ {
+ if (!length) {
+ output = 0;
+ return &empty();
+ }
+
+ if (length > ((std::numeric_limits<size_t>::max() - sizeof(UStringImpl)) / sizeof(UChar)))
+ return 0;
+ UStringImpl* resultImpl;
+ if (!tryFastMalloc(sizeof(UChar) * length + sizeof(UStringImpl)).getValue(resultImpl))
+ return 0;
+ output = reinterpret_cast<UChar*>(resultImpl + 1);
+ return adoptRef(new(resultImpl) UStringImpl(output, length, BufferInternal));
+ }
+
+ SharedUChar* sharedBuffer();
+ UChar* data() const { return m_data; }
+ int size() const { return m_length; }
+ size_t cost()
+ {
+ // For substrings, return the cost of the base string.
+ if (bufferOwnership() == BufferSubstring)
+ return m_dataBuffer.asPtr<UStringImpl*>()->cost();
+
+ if (m_dataBuffer & s_reportedCostBit)
+ return 0;
+ m_dataBuffer |= s_reportedCostBit;
+ return m_length;
+ }
+ unsigned hash() const { if (!m_hash) m_hash = computeHash(data(), m_length); return m_hash; }
+ unsigned existingHash() const { ASSERT(m_hash); return m_hash; } // fast path for Identifiers
+ void setHash(unsigned hash) { ASSERT(hash == computeHash(data(), m_length)); m_hash = hash; } // fast path for Identifiers
+ bool isIdentifier() const { return m_isIdentifier; }
+ void setIsIdentifier(bool isIdentifier) { m_isIdentifier = isIdentifier; }
+
+ UStringImpl* ref() { m_refCount += s_refCountIncrement; return this; }
+ ALWAYS_INLINE void deref() { if (!(m_refCount -= s_refCountIncrement)) delete this; }
+
+ static void copyChars(UChar* destination, const UChar* source, unsigned numCharacters)
+ {
+ if (numCharacters <= s_copyCharsInlineCutOff) {
+ for (unsigned i = 0; i < numCharacters; ++i)
+ destination[i] = source[i];
+ } else
+ memcpy(destination, source, numCharacters * sizeof(UChar));
+ }
+
+ static unsigned computeHash(const UChar* s, int length) { ASSERT(length >= 0); return WTF::stringHash(s, length); }
+ static unsigned computeHash(const char* s, int length) { ASSERT(length >= 0); return WTF::stringHash(s, length); }
+ static unsigned computeHash(const char* s) { return WTF::stringHash(s); }
+
+ static UStringImpl& null() { return *s_null; }
+ static UStringImpl& empty() { return *s_empty; }
+
+ ALWAYS_INLINE void checkConsistency() const
+ {
+ // There is no recursion of substrings.
+ ASSERT(bufferOwnerString()->bufferOwnership() != BufferSubstring);
+ // Static strings cannot be put in identifier tables, because they are globally shared.
+ ASSERT(!isStatic() || !isIdentifier());
+ }
+
+private:
+ enum BufferOwnership {
+ BufferInternal,
+ BufferOwned,
+ BufferSubstring,
+ BufferShared,
+ };
+
+ // For SmallStringStorage, which allocates an array and uses an in-place new.
+ UStringImpl() { }
+
+ // Used to construct normal strings with an internal or external buffer.
+ UStringImpl(UChar* data, int length, BufferOwnership ownership)
+ : m_data(data)
+ , m_length(length)
+ , m_refCount(s_refCountIncrement)
+ , m_hash(0)
+ , m_isIdentifier(false)
+ , m_dataBuffer(0, ownership)
+ {
+ ASSERT((ownership == BufferInternal) || (ownership == BufferOwned));
+ checkConsistency();
+ }
+
+ // Used to construct static strings, which have an special refCount that can never hit zero.
+ // This means that the static string will never be destroyed, which is important because
+ // static strings will be shared across threads & ref-counted in a non-threadsafe manner.
+ enum StaticStringConstructType { ConstructStaticString };
+ UStringImpl(UChar* data, int length, StaticStringConstructType)
+ : m_data(data)
+ , m_length(length)
+ , m_refCount(s_staticRefCountInitialValue)
+ , m_hash(0)
+ , m_isIdentifier(false)
+ , m_dataBuffer(0, BufferOwned)
+ {
+ checkConsistency();
+ }
+
+ // Used to create new strings that are a substring of an existing string.
+ UStringImpl(UChar* data, int length, PassRefPtr<UStringImpl> base)
+ : m_data(data)
+ , m_length(length)
+ , m_refCount(s_refCountIncrement)
+ , m_hash(0)
+ , m_isIdentifier(false)
+ , m_dataBuffer(base.releaseRef(), BufferSubstring)
+ {
+ // Do use static strings as a base for substrings; UntypedPtrAndBitfield assumes
+ // that all pointers will be at least 8-byte aligned, we cannot guarantee that of
+ // UStringImpls that are not heap allocated.
+ ASSERT(m_dataBuffer.asPtr<UStringImpl*>()->size());
+ ASSERT(!m_dataBuffer.asPtr<UStringImpl*>()->isStatic());
+ checkConsistency();
+ }
+
+ // Used to construct new strings sharing an existing shared buffer.
+ UStringImpl(UChar* data, int length, PassRefPtr<SharedUChar> sharedBuffer)
+ : m_data(data)
+ , m_length(length)
+ , m_refCount(s_refCountIncrement)
+ , m_hash(0)
+ , m_isIdentifier(false)
+ , m_dataBuffer(sharedBuffer.releaseRef(), BufferShared)
+ {
+ checkConsistency();
+ }
+
+ using Noncopyable::operator new;
+ void* operator new(size_t, void* inPlace) { return inPlace; }
+
+ ~UStringImpl();
+
+ // This number must be at least 2 to avoid sharing empty, null as well as 1 character strings from SmallStrings.
+ static const int s_minLengthToShare = 10;
+ static const unsigned s_copyCharsInlineCutOff = 20;
+ static const uintptr_t s_bufferOwnershipMask = 3;
+ static const uintptr_t s_reportedCostBit = 4;
+ // We initialize and increment/decrement the refCount for all normal (non-static) strings by the value 2.
+ // We initialize static strings with an odd number (specifically, 1), such that the refCount cannot reach zero.
+ static const int s_refCountIncrement = 2;
+ static const int s_staticRefCountInitialValue = 1;
+
+ UStringImpl* bufferOwnerString() { return (bufferOwnership() == BufferSubstring) ? m_dataBuffer.asPtr<UStringImpl*>() : this; }
+ const UStringImpl* bufferOwnerString() const { return (bufferOwnership() == BufferSubstring) ? m_dataBuffer.asPtr<UStringImpl*>() : this; }
+ SharedUChar* baseSharedBuffer();
+ unsigned bufferOwnership() const { return m_dataBuffer & s_bufferOwnershipMask; }
+ bool isStatic() const { return m_refCount & 1; }
+
+ // unshared data
+ UChar* m_data;
+ int m_length;
+ unsigned m_refCount;
+ mutable unsigned m_hash : 31;
+ mutable unsigned m_isIdentifier : 1;
+ UntypedPtrAndBitfield m_dataBuffer;
+
+ JS_EXPORTDATA static UStringImpl* s_null;
+ JS_EXPORTDATA static UStringImpl* s_empty;
+
+ friend class JIT;
+ friend class SmallStringsStorage;
+ friend void initializeUString();
+};
+
+bool equal(const UStringImpl*, const UStringImpl*);
+
+}
+
+#endif
projects / apple / javascriptcore.git / blobdiff