JavaScriptCore-903.tar.gz

[apple/javascriptcore.git] / runtime / JSString.cpp

diff --git a/runtime/JSString.cpp b/runtime/JSString.cpp
index 1d5e639714f5f47811390be4d7bdeb8030936b8e..da15997d32db78aed7b57f07f0cc4b529331f010 100644 (file)
--- a/runtime/JSString.cpp
+++ b/runtime/JSString.cpp
@@ -24,12 +24,61 @@
 #include "JSString.h"
 
 #include "JSGlobalObject.h"
 #include "JSString.h"
 
 #include "JSGlobalObject.h"

+#include "JSGlobalObjectFunctions.h"

 #include "JSObject.h"
 #include "Operations.h"
 #include "StringObject.h"
 #include "StringPrototype.h"
 
 namespace JSC {
 #include "JSObject.h"
 #include "Operations.h"
 #include "StringObject.h"
 #include "StringPrototype.h"
 
 namespace JSC {

+    
+static const unsigned substringFromRopeCutoff = 4;
+
+const ClassInfo JSString::s_info = { "string", 0, 0, 0 };
+
+void JSString::resolveRope(ExecState* exec) const
+{
+    ASSERT(isRope());
+
+    UChar* buffer;
+    if (PassRefPtr<StringImpl> newImpl = StringImpl::tryCreateUninitialized(m_length, buffer))
+        m_value = newImpl;
+    else {
+        outOfMemory(exec);
+        return;
+    }
+
+    RopeImpl::Fiber currentFiber = m_fibers[0];
+
+    if ((m_fiberCount > 2) || (RopeImpl::isRope(currentFiber)) 
+        || ((m_fiberCount == 2) && (RopeImpl::isRope(m_fibers[1])))) {
+        resolveRopeSlowCase(exec, buffer);
+        return;
+    }
+
+    UChar* position = buffer;
+    StringImpl* string = static_cast<StringImpl*>(currentFiber);
+    unsigned length = string->length();
+    StringImpl::copyChars(position, string->characters(), length);
+
+    if (m_fiberCount > 1) {
+        position += length;
+        currentFiber = m_fibers[1];
+        string = static_cast<StringImpl*>(currentFiber);
+        length = string->length();
+        StringImpl::copyChars(position, string->characters(), length);
+        position += length;
+    }
+
+    ASSERT((buffer + m_length) == position);
+    for (unsigned i = 0; i < m_fiberCount; ++i) {
+        RopeImpl::deref(m_fibers[i]);
+        m_fibers[i] = 0;
+    }
+    m_fiberCount = 0;
+
+    ASSERT(!isRope());
+}

 
 // 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
 
 // 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


@@ -37,38 +86,22 @@ namespace JSC {
 // 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
 // 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 UStringImpls into the
+// we would likely have to place all of the constituent StringImpls 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
 // 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.)
-void JSString::resolveRope(ExecState* exec) const
+// rope-of-ropes.)    
+void JSString::resolveRopeSlowCase(ExecState* exec, UChar* buffer) const

 {
 {

-    ASSERT(isRope());
+    UNUSED_PARAM(exec);

 
 

-    // Allocate the buffer to hold the final string, position initially points to the end.
-    UChar* buffer;
-    if (PassRefPtr<UStringImpl> newImpl = UStringImpl::tryCreateUninitialized(m_length, buffer))
-        m_value = newImpl;
-    else {
-        for (unsigned i = 0; i < m_fiberCount; ++i) {
-            RopeImpl::deref(m_other.m_fibers[i]);
-            m_other.m_fibers[i] = 0;
-        }
-        m_fiberCount = 0;
-        ASSERT(!isRope());
-        ASSERT(m_value == UString());
-        if (exec)
-            throwOutOfMemoryError(exec);
-        return;
-    }

     UChar* position = buffer + m_length;
 
     // Start with the current RopeImpl.
     Vector<RopeImpl::Fiber, 32> workQueue;
     RopeImpl::Fiber currentFiber;
     for (unsigned i = 0; i < (m_fiberCount - 1); ++i)
     UChar* position = buffer + m_length;
 
     // Start with the current RopeImpl.
     Vector<RopeImpl::Fiber, 32> 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];
+        workQueue.append(m_fibers[i]);
+    currentFiber = m_fibers[m_fiberCount - 1];

     while (true) {
         if (RopeImpl::isRope(currentFiber)) {
             RopeImpl* rope = static_cast<RopeImpl*>(currentFiber);
     while (true) {
         if (RopeImpl::isRope(currentFiber)) {
             RopeImpl* rope = static_cast<RopeImpl*>(currentFiber);


@@ -79,21 +112,21 @@ void JSString::resolveRope(ExecState* exec) const
                 workQueue.append(rope->fibers()[i]);
             currentFiber = rope->fibers()[fiberCountMinusOne];
         } else {
                 workQueue.append(rope->fibers()[i]);
             currentFiber = rope->fibers()[fiberCountMinusOne];
         } else {

-            UStringImpl* string = static_cast<UStringImpl*>(currentFiber);
+            StringImpl* string = static_cast<StringImpl*>(currentFiber);

             unsigned length = string->length();
             position -= length;
             unsigned length = string->length();
             position -= length;

-            UStringImpl::copyChars(position, string->characters(), length);
+            StringImpl::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_fiberCount; ++i) {
 
             // 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_fiberCount; ++i) {

-                    RopeImpl::deref(m_other.m_fibers[i]);
-                    m_other.m_fibers[i] = 0;
+                    RopeImpl::deref(m_fibers[i]);
+                    m_fibers[i] = 0;

                 }
                 m_fiberCount = 0;
                 }
                 m_fiberCount = 0;

-
+                

                 ASSERT(!isRope());
                 return;
             }
                 ASSERT(!isRope());
                 return;
             }


@@ -105,29 +138,96 @@ void JSString::resolveRope(ExecState* exec) const
     }
 }
 
     }
 }
 

+void JSString::outOfMemory(ExecState* exec) const
+{
+    for (unsigned i = 0; i < m_fiberCount; ++i) {
+        RopeImpl::deref(m_fibers[i]);
+        m_fibers[i] = 0;
+    }
+    m_fiberCount = 0;
+    ASSERT(!isRope());
+    ASSERT(m_value == UString());
+    if (exec)
+        throwOutOfMemoryError(exec);
+}
+
+// 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());
+    ASSERT(substringLength);
+    
+    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_fibers.data(), m_fiberCount); it != end; ++it) {
+        ++fiberCount;
+        StringImpl* 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(StringImpl::create(fiberString, copyStart - fiberStart, copyEnd - copyStart));
+        if (fiberEnd >= substringEnd)
+            break;
+        if (fiberCount > substringFromRopeCutoff || 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].characters()[0];
+        if (c <= maxSingleCharacterString)
+            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()) {
 JSValue JSString::replaceCharacter(ExecState* exec, UChar character, const UString& replacement)
 {
     if (!isRope()) {

-        unsigned matchPosition = m_value.find(character);
-        if (matchPosition == UString::NotFound)
+        size_t matchPosition = m_value.find(character);
+        if (matchPosition == notFound)

             return JSValue(this);
             return JSValue(this);

-        return jsString(exec, m_value.substr(0, matchPosition), replacement, m_value.substr(matchPosition + 1));
+        return jsString(exec, m_value.substringSharingImpl(0, matchPosition), replacement, m_value.substringSharingImpl(matchPosition + 1));

     }
 
     RopeIterator end;
     
     // Count total fibers and find matching string.
     size_t fiberCount = 0;
     }
 
     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) {
+    StringImpl* matchString = 0;
+    size_t matchPosition = notFound;
+    for (RopeIterator it(m_fibers.data(), m_fiberCount); it != end; ++it) {

         ++fiberCount;
         if (matchString)
             continue;
 
         ++fiberCount;
         if (matchString)
             continue;
 

-        UStringImpl* string = *it;
+        StringImpl* string = *it;

         matchPosition = string->find(character);
         matchPosition = string->find(character);

-        if (matchPosition == -1)
+        if (matchPosition == notFound)

             continue;
         matchString = string;
     }
             continue;
         matchString = string;
     }


@@ -135,21 +235,21 @@ JSValue JSString::replaceCharacter(ExecState* exec, UChar character, const UStri
     if (!matchString)
         return this;
 
     if (!matchString)
         return this;
 

-    RopeBuilder builder(replacement.size() ? fiberCount + 2 : fiberCount + 1);
+    RopeBuilder builder(replacement.length() ? fiberCount + 2 : fiberCount + 1);

     if (UNLIKELY(builder.isOutOfMemory()))
         return throwOutOfMemoryError(exec);
 
     if (UNLIKELY(builder.isOutOfMemory()))
         return throwOutOfMemoryError(exec);
 

-    for (RopeIterator it(m_other.m_fibers, m_fiberCount); it != end; ++it) {
-        UStringImpl* string = *it;
+    for (RopeIterator it(m_fibers.data(), m_fiberCount); it != end; ++it) {
+        StringImpl* string = *it;

         if (string != matchString) {
             builder.append(UString(string));
             continue;
         }
 
         if (string != matchString) {
             builder.append(UString(string));
             continue;
         }
 

-        builder.append(UString(string).substr(0, matchPosition));
-        if (replacement.size())
+        builder.append(UString(string).substringSharingImpl(0, matchPosition));
+        if (replacement.length())

             builder.append(replacement);
             builder.append(replacement);

-        builder.append(UString(string).substr(matchPosition + 1));
+        builder.append(UString(string).substringSharingImpl(matchPosition + 1));

         matchString = 0;
     }
 
         matchString = 0;
     }
 


@@ -165,7 +265,7 @@ JSString* JSString::getIndexSlowCase(ExecState* exec, unsigned i)
     if (exec->exception())
         return jsString(exec, "");
     ASSERT(!isRope());
     if (exec->exception())
         return jsString(exec, "");
     ASSERT(!isRope());

-    ASSERT(i < m_value.size());
+    ASSERT(i < m_value.length());

     return jsSingleCharacterSubstring(exec, m_value, i);
 }
 
     return jsSingleCharacterSubstring(exec, m_value, i);
 }
 


@@ -177,7 +277,7 @@ JSValue JSString::toPrimitive(ExecState*, PreferredPrimitiveType) const
 bool JSString::getPrimitiveNumber(ExecState* exec, double& number, JSValue& result)
 {
     result = this;
 bool JSString::getPrimitiveNumber(ExecState* exec, double& number, JSValue& result)
 {
     result = this;

-    number = value(exec).toDouble();
+    number = jsToNumber(value(exec));

     return false;
 }
 
     return false;
 }
 


@@ -188,7 +288,7 @@ bool JSString::toBoolean(ExecState*) const
 
 double JSString::toNumber(ExecState* exec) const
 {
 
 double JSString::toNumber(ExecState* exec) const
 {

-    return value(exec).toDouble();
+    return jsToNumber(value(exec));

 }
 
 UString JSString::toString(ExecState* exec) const
 }
 
 UString JSString::toString(ExecState* exec) const


@@ -196,19 +296,19 @@ UString JSString::toString(ExecState* exec) const
     return value(exec);
 }
 
     return value(exec);
 }
 

-inline StringObject* StringObject::create(ExecState* exec, JSString* string)
+inline StringObject* StringObject::create(ExecState* exec, JSGlobalObject* globalObject, JSString* string)

 {
 {

-    return new (exec) StringObject(exec->lexicalGlobalObject()->stringObjectStructure(), string);
+    return new (exec) StringObject(exec->globalData(), globalObject->stringObjectStructure(), string);

 }
 
 }
 

-JSObject* JSString::toObject(ExecState* exec) const
+JSObject* JSString::toObject(ExecState* exec, JSGlobalObject* globalObject) const

 {
 {

-    return StringObject::create(exec, const_cast<JSString*>(this));
+    return StringObject::create(exec, globalObject, const_cast<JSString*>(this));

 }
 
 JSObject* JSString::toThisObject(ExecState* exec) const
 {
 }
 
 JSObject* JSString::toThisObject(ExecState* exec) const
 {

-    return StringObject::create(exec, const_cast<JSString*>(this));
+    return StringObject::create(exec, exec->lexicalGlobalObject(), const_cast<JSString*>(this));

 }
 
 bool JSString::getOwnPropertySlot(ExecState* exec, const Identifier& propertyName, PropertySlot& slot)
 }
 
 bool JSString::getOwnPropertySlot(ExecState* exec, const Identifier& propertyName, PropertySlot& slot)


@@ -235,12 +335,12 @@ bool JSString::getOwnPropertySlot(ExecState* exec, const Identifier& propertyNam
 bool JSString::getStringPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)
 {
     if (propertyName == exec->propertyNames().length) {
 bool JSString::getStringPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)
 {
     if (propertyName == exec->propertyNames().length) {

-        descriptor.setDescriptor(jsNumber(exec, m_length), DontEnum | DontDelete | ReadOnly);
+        descriptor.setDescriptor(jsNumber(m_length), DontEnum | DontDelete | ReadOnly);

         return true;
     }
     
     bool isStrictUInt32;
         return true;
     }
     
     bool isStrictUInt32;

-    unsigned i = propertyName.toStrictUInt32(&isStrictUInt32);
+    unsigned i = propertyName.toUInt32(isStrictUInt32);

     if (isStrictUInt32 && i < m_length) {
         descriptor.setDescriptor(getIndex(exec, i), DontDelete | ReadOnly);
         return true;
     if (isStrictUInt32 && i < m_length) {
         descriptor.setDescriptor(getIndex(exec, i), DontDelete | ReadOnly);
         return true;