X-Git-Url: https://git.saurik.com/apple/javascriptcore.git/blobdiff_plain/f9bf01c6616d5ddcf65b13b33cedf9e387ff7a63..b80e619319b1def83d1e8b4f84042b661be1be7f:/runtime/JSString.cpp diff --git a/runtime/JSString.cpp b/runtime/JSString.cpp index 1e23a15..6128790 100644 --- a/runtime/JSString.cpp +++ b/runtime/JSString.cpp @@ -30,41 +30,8 @@ #include "StringPrototype.h" namespace JSC { - -void JSString::Rope::destructNonRecursive() -{ - Vector workQueue; - Rope* rope = this; - - while (true) { - unsigned length = rope->ropeLength(); - for (unsigned i = 0; i < length; ++i) { - Fiber& fiber = rope->fibers(i); - if (fiber.isString()) - fiber.string()->deref(); - else { - Rope* nextRope = fiber.rope(); - if (nextRope->hasOneRef()) - workQueue.append(nextRope); - else - nextRope->deref(); - } - } - if (rope != this) - fastFree(rope); - - if (workQueue.isEmpty()) - return; - - rope = workQueue.last(); - workQueue.removeLast(); - } -} - -JSString::Rope::~Rope() -{ - destructNonRecursive(); -} + +static const unsigned resolveRopeForSubstringCutoff = 4; // Overview: this methods converts a JSString from holding a string in rope form // down to a simple UString representation. It does so by building up the string @@ -72,7 +39,7 @@ JSString::Rope::~Rope() // representing the rope is likely imbalanced with more nodes down the left side // (since appending to the string is likely more common) - and as such resolving // in this fashion should minimize work queue size. (If we built the queue forwards -// we would likely have to place all of the constituent UString::Reps into the +// we would likely have to place all of the constituent UStringImpls into the // Vector before performing any concatenation, but by working backwards we likely // only fill the queue with the number of substrings at any given level in a // rope-of-ropes.) @@ -82,51 +49,52 @@ void JSString::resolveRope(ExecState* exec) const // Allocate the buffer to hold the final string, position initially points to the end. UChar* buffer; - if (PassRefPtr newImpl = UStringImpl::tryCreateUninitialized(m_stringLength, buffer)) + if (PassRefPtr newImpl = UStringImpl::tryCreateUninitialized(m_length, buffer)) m_value = newImpl; else { - for (unsigned i = 0; i < m_ropeLength; ++i) { - m_fibers[i].deref(); - m_fibers[i] = static_cast(0); + for (unsigned i = 0; i < m_fiberCount; ++i) { + RopeImpl::deref(m_other.m_fibers[i]); + m_other.m_fibers[i] = 0; } - m_ropeLength = 0; + m_fiberCount = 0; ASSERT(!isRope()); ASSERT(m_value == UString()); - throwOutOfMemoryError(exec); + if (exec) + throwOutOfMemoryError(exec); return; } - UChar* position = buffer + m_stringLength; - - // Start with the current Rope. - Vector workQueue; - Rope::Fiber currentFiber; - for (unsigned i = 0; i < (m_ropeLength - 1); ++i) - workQueue.append(m_fibers[i]); - currentFiber = m_fibers[m_ropeLength - 1]; + UChar* position = buffer + m_length; + + // Start with the current RopeImpl. + Vector workQueue; + RopeImpl::Fiber currentFiber; + for (unsigned i = 0; i < (m_fiberCount - 1); ++i) + workQueue.append(m_other.m_fibers[i]); + currentFiber = m_other.m_fibers[m_fiberCount - 1]; while (true) { - if (currentFiber.isRope()) { - Rope* rope = currentFiber.rope(); + if (RopeImpl::isRope(currentFiber)) { + RopeImpl* rope = static_cast(currentFiber); // Copy the contents of the current rope into the workQueue, with the last item in 'currentFiber' // (we will be working backwards over the rope). - unsigned ropeLengthMinusOne = rope->ropeLength() - 1; - for (unsigned i = 0; i < ropeLengthMinusOne; ++i) - workQueue.append(rope->fibers(i)); - currentFiber = rope->fibers(ropeLengthMinusOne); + unsigned fiberCountMinusOne = rope->fiberCount() - 1; + for (unsigned i = 0; i < fiberCountMinusOne; ++i) + workQueue.append(rope->fibers()[i]); + currentFiber = rope->fibers()[fiberCountMinusOne]; } else { - UString::Rep* string = currentFiber.string(); - unsigned length = string->size(); + UStringImpl* string = static_cast(currentFiber); + unsigned length = string->length(); position -= length; - UStringImpl::copyChars(position, string->data(), length); + UStringImpl::copyChars(position, string->characters(), length); // Was this the last item in the work queue? if (workQueue.isEmpty()) { // Create a string from the UChar buffer, clear the rope RefPtr. ASSERT(buffer == position); - for (unsigned i = 0; i < m_ropeLength; ++i) { - m_fibers[i].deref(); - m_fibers[i] = static_cast(0); + for (unsigned i = 0; i < m_fiberCount; ++i) { + RopeImpl::deref(m_other.m_fibers[i]); + m_other.m_fibers[i] = 0; } - m_ropeLength = 0; + m_fiberCount = 0; ASSERT(!isRope()); return; @@ -138,6 +106,123 @@ void JSString::resolveRope(ExecState* exec) const } } } + +// This function construsts a substring out of a rope without flattening by reusing the existing fibers. +// This can reduce memory usage substantially. Since traversing ropes is slow the function will revert +// back to flattening if the rope turns out to be long. +JSString* JSString::substringFromRope(ExecState* exec, unsigned substringStart, unsigned substringLength) +{ + ASSERT(isRope()); + + JSGlobalData* globalData = &exec->globalData(); + + UString substringFibers[3]; + + unsigned fiberCount = 0; + unsigned substringFiberCount = 0; + unsigned substringEnd = substringStart + substringLength; + unsigned fiberEnd = 0; + + RopeIterator end; + for (RopeIterator it(m_other.m_fibers, m_fiberCount); it != end; ++it) { + ++fiberCount; + UStringImpl* fiberString = *it; + unsigned fiberStart = fiberEnd; + fiberEnd = fiberStart + fiberString->length(); + if (fiberEnd <= substringStart) + continue; + unsigned copyStart = std::max(substringStart, fiberStart); + unsigned copyEnd = std::min(substringEnd, fiberEnd); + if (copyStart == fiberStart && copyEnd == fiberEnd) + substringFibers[substringFiberCount++] = UString(fiberString); + else + substringFibers[substringFiberCount++] = UString(UStringImpl::create(fiberString, copyStart - fiberStart, copyEnd - copyStart)); + if (fiberEnd >= substringEnd) + break; + if (fiberCount > resolveRopeForSubstringCutoff || substringFiberCount >= 3) { + // This turned out to be a really inefficient rope. Just flatten it. + resolveRope(exec); + return jsSubstring(&exec->globalData(), m_value, substringStart, substringLength); + } + } + ASSERT(substringFiberCount && substringFiberCount <= 3); + + if (substringLength == 1) { + ASSERT(substringFiberCount == 1); + UChar c = substringFibers[0].data()[0]; + if (c <= 0xFF) + return globalData->smallStrings.singleCharacterString(globalData, c); + } + if (substringFiberCount == 1) + return new (globalData) JSString(globalData, substringFibers[0]); + if (substringFiberCount == 2) + return new (globalData) JSString(globalData, substringFibers[0], substringFibers[1]); + return new (globalData) JSString(globalData, substringFibers[0], substringFibers[1], substringFibers[2]); +} + +JSValue JSString::replaceCharacter(ExecState* exec, UChar character, const UString& replacement) +{ + if (!isRope()) { + unsigned matchPosition = m_value.find(character); + if (matchPosition == UString::NotFound) + return JSValue(this); + return jsString(exec, m_value.substr(0, matchPosition), replacement, m_value.substr(matchPosition + 1)); + } + + RopeIterator end; + + // Count total fibers and find matching string. + size_t fiberCount = 0; + UStringImpl* matchString = 0; + int matchPosition = -1; + for (RopeIterator it(m_other.m_fibers, m_fiberCount); it != end; ++it) { + ++fiberCount; + if (matchString) + continue; + + UStringImpl* string = *it; + matchPosition = string->find(character); + if (matchPosition == -1) + continue; + matchString = string; + } + + if (!matchString) + return this; + + RopeBuilder builder(replacement.size() ? fiberCount + 2 : fiberCount + 1); + if (UNLIKELY(builder.isOutOfMemory())) + return throwOutOfMemoryError(exec); + + for (RopeIterator it(m_other.m_fibers, m_fiberCount); it != end; ++it) { + UStringImpl* string = *it; + if (string != matchString) { + builder.append(UString(string)); + continue; + } + + builder.append(UString(string).substr(0, matchPosition)); + if (replacement.size()) + builder.append(replacement); + builder.append(UString(string).substr(matchPosition + 1)); + matchString = 0; + } + + JSGlobalData* globalData = &exec->globalData(); + return JSValue(new (globalData) JSString(globalData, builder.release())); +} + +JSString* JSString::getIndexSlowCase(ExecState* exec, unsigned i) +{ + ASSERT(isRope()); + resolveRope(exec); + // Return a safe no-value result, this should never be used, since the excetion will be thrown. + if (exec->exception()) + return jsString(exec, ""); + ASSERT(!isRope()); + ASSERT(i < m_value.size()); + return jsSingleCharacterSubstring(exec, m_value, i); +} JSValue JSString::toPrimitive(ExecState*, PreferredPrimitiveType) const { @@ -153,7 +238,7 @@ bool JSString::getPrimitiveNumber(ExecState* exec, double& number, JSValue& resu bool JSString::toBoolean(ExecState*) const { - return m_stringLength; + return m_length; } double JSString::toNumber(ExecState* exec) const @@ -166,16 +251,6 @@ UString JSString::toString(ExecState* exec) const return value(exec); } -UString JSString::toThisString(ExecState* exec) const -{ - return value(exec); -} - -JSString* JSString::toThisJSString(ExecState*) -{ - return this; -} - inline StringObject* StringObject::create(ExecState* exec, JSString* string) { return new (exec) StringObject(exec->lexicalGlobalObject()->stringObjectStructure(), string); @@ -215,14 +290,14 @@ bool JSString::getOwnPropertySlot(ExecState* exec, const Identifier& propertyNam bool JSString::getStringPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor) { if (propertyName == exec->propertyNames().length) { - descriptor.setDescriptor(jsNumber(exec, m_stringLength), DontEnum | DontDelete | ReadOnly); + descriptor.setDescriptor(jsNumber(exec, m_length), DontEnum | DontDelete | ReadOnly); return true; } bool isStrictUInt32; unsigned i = propertyName.toStrictUInt32(&isStrictUInt32); - if (isStrictUInt32 && i < m_stringLength) { - descriptor.setDescriptor(jsSingleCharacterSubstring(exec, value(exec), i), DontDelete | ReadOnly); + if (isStrictUInt32 && i < m_length) { + descriptor.setDescriptor(getIndex(exec, i), DontDelete | ReadOnly); return true; }