Changeset 54464 in webkit for trunk/JavaScriptCore/runtime/UString.cpp

Timestamp:

Feb 6, 2010, 12:55:31 AM (15 years ago)

Author:

[email protected]

Message:

Change UStringImpl::create to CRASH if the string cannot be allocated,
rather than returning a null string (which will behave like a zero-length
string if used).

Reviewed by Geoff Garen.

Also move createRep function from UString to become new overloaded
UStringImpl::create methods. In doing so, bring their behaviour closer to
being in line with WebCore::StringImpl, in removing the behaviour that they
can be used to produce null UStrings (ASSERT the char* provided is non-null).
This behaviour of converting null C-strings to null UStrings is inefficient
(cmompared to just using UString::null()), incompatible with WebCore::StringImpl's
behaviour, and may generate unexpected behaviour, since in many cases a null
UString can be used like an empty string.

With these changes UStringImpl need not have a concept of null impls, we can
start transitioning this to become an implementation detail of UString, that
internally it chooses to use a null-object rather than an actually zero impl
pointer.

• JavaScriptCore.exp:
• debugger/Debugger.cpp:

(JSC::Debugger::recompileAllJSFunctions):

• debugger/DebuggerCallFrame.cpp:

(JSC::DebuggerCallFrame::calculatedFunctionName):

• parser/Parser.cpp:

(JSC::Parser::parse):

• profiler/Profile.cpp:

(JSC::Profile::Profile):

• profiler/ProfileGenerator.cpp:

(JSC::ProfileGenerator::stopProfiling):

• runtime/Error.cpp:

(JSC::Error::create):
(JSC::throwError):

• runtime/ExceptionHelpers.cpp:

(JSC::createError):

• runtime/Identifier.cpp:

(JSC::Identifier::add):

• runtime/PropertyNameArray.cpp:

(JSC::PropertyNameArray::add):

• runtime/UString.cpp:

(JSC::initializeUString):
(JSC::UString::UString):
(JSC::UString::operator=):

• runtime/UString.h:

(JSC::UString::isNull):
(JSC::UString::null):
(JSC::UString::rep):
(JSC::UString::UString):

• runtime/UStringImpl.cpp:

(JSC::UStringImpl::create):

• runtime/UStringImpl.h:

File:

• trunk/JavaScriptCore/runtime/UString.cpp (modified) (4 diffs)

trunk/JavaScriptCore/runtime/UString.cpp

@@ -150 +150 @@
 // reduce the possibility of it becoming zero due to ref/deref not being thread-safe.
 static UChar sharedEmptyChar;
-UStringImpl* UStringImpl::s_null;
 UStringImpl* UStringImpl::s_empty;
-UString* UString::nullUString;
+
+UString::Rep* UString::s_nullRep;
+UString* UString::s_nullUString;
 
 void initializeUString()
 {
-    UStringImpl::s_null = new UStringImpl(0, 0, UStringImpl::ConstructStaticString);
     UStringImpl::s_empty = new UStringImpl(&sharedEmptyChar, 0, UStringImpl::ConstructStaticString);
-    UString::nullUString = new UString;
-}
-
-static PassRefPtr<UString::Rep> createRep(const char* c)
-{
-    if (!c)
-        return &UString::Rep::null();
-
-    if (!c[0])
-        return &UString::Rep::empty();
-
-    size_t length = strlen(c);
-    UChar* d;
-    PassRefPtr<UStringImpl> result = UStringImpl::tryCreateUninitialized(length, d);
-    if (!result)
-        return &UString::Rep::null();
-
-    for (size_t i = 0; i < length; i++)
-        d[i] = static_cast<unsigned char>(c[i]); // use unsigned char to zero-extend instead of sign-extend
-    return result;
-}
-
-static inline PassRefPtr<UString::Rep> createRep(const char* c, int length)
-{
-    if (!c)
-        return &UString::Rep::null();
-
-    if (!length)
-        return &UString::Rep::empty();
-
-    UChar* d;
-    PassRefPtr<UStringImpl> result = UStringImpl::tryCreateUninitialized(length, d);
-    if (!result)
-        return &UString::Rep::null();
-
-    for (int i = 0; i < length; i++)
-        d[i] = static_cast<unsigned char>(c[i]); // use unsigned char to zero-extend instead of sign-extend
-    return result;
+
+    UString::s_nullRep = new UStringImpl(0, 0, UStringImpl::ConstructStaticString);
+    UString::s_nullUString = new UString;
 }
 
 UString::UString(const char* c)
-    : m_rep(createRep(c))
+    : m_rep(Rep::create(c))
 {
 }
 
 UString::UString(const char* c, int length)
-    : m_rep(createRep(c, length))
+    : m_rep(Rep::create(c, length))
 {
 }
@@ -460 +425 @@
 {
     if (!c) {
-        m_rep = &Rep::null();
+        m_rep = s_nullRep;
         return *this;
     }
@@ -476 +441 @@
             d[i] = static_cast<unsigned char>(c[i]); // use unsigned char to zero-extend instead of sign-extend
     } else
-        makeNull();
+        m_rep = s_nullRep;;
 
     return *this;
@@ -889 +854 @@
 }
 
-// For use in error handling code paths -- having this not be inlined helps avoid PIC branches to fetch the global on Mac OS X.
-NEVER_INLINE void UString::makeNull()
-{
-    m_rep = &Rep::null();
-}
-
-// For use in error handling code paths -- having this not be inlined helps avoid PIC branches to fetch the global on Mac OS X.
-NEVER_INLINE UString::Rep* UString::nullRep()
-{
-    return &Rep::null();
-}
-
 } // namespace JSC