Revision: 4011
Author: [email protected]
Date: Wed Mar 3 08:40:29 2010
Log: Fast case conversion for ascii strings.
Review URL: http://codereview.chromium.org/660455
http://code.google.com/p/v8/source/detail?r=4011
Modified:
/branches/bleeding_edge/src/runtime.cc
=======================================
--- /branches/bleeding_edge/src/runtime.cc Wed Mar 3 06:19:04 2010
+++ /branches/bleeding_edge/src/runtime.cc Wed Mar 3 08:40:29 2010
@@ -4084,18 +4084,83 @@
}
-template <class Converter>
-static Object* ConvertCase(Arguments args,
- unibrow::Mapping<Converter, 128>* mapping) {
- NoHandleAllocation ha;
-
+static inline SeqAsciiString* TryGetSeqAsciiString(String* s) {
+ if (!s->IsFlat() || !s->IsAsciiRepresentation()) return NULL;
+ if (s->IsConsString()) {
+ ASSERT(ConsString::cast(s)->second()->length() == 0);
+ return SeqAsciiString::cast(ConsString::cast(s)->first());
+ }
+ return SeqAsciiString::cast(s);
+}
+
+
+namespace {
+
+struct ToLowerTraits {
+ typedef unibrow::ToLowercase UnibrowConverter;
+
+ static bool ConvertAscii(char* dst, char* src, int length) {
+ bool changed = false;
+ for (int i = 0; i < length; ++i) {
+ char c = src[i];
+ if ('A' <= c && c <= 'Z') {
+ c += ('a' - 'A');
+ changed = true;
+ }
+ dst[i] = c;
+ }
+ return changed;
+ }
+};
+
+
+struct ToUpperTraits {
+ typedef unibrow::ToUppercase UnibrowConverter;
+
+ static bool ConvertAscii(char* dst, char* src, int length) {
+ bool changed = false;
+ for (int i = 0; i < length; ++i) {
+ char c = src[i];
+ if ('a' <= c && c <= 'z') {
+ c -= ('a' - 'A');
+ changed = true;
+ }
+ dst[i] = c;
+ }
+ return changed;
+ }
+};
+
+} // namespace
+
+
+template <typename ConvertTraits>
+static Object* ConvertCase(
+ Arguments args,
+ unibrow::Mapping<typename ConvertTraits::UnibrowConverter, 128>*
mapping) {
+ NoHandleAllocation ha;
CONVERT_CHECKED(String, s, args[0]);
s->TryFlatten();
- int input_string_length = s->length();
+ const int length = s->length();
// Assume that the string is not empty; we need this assumption later
- if (input_string_length == 0) return s;
- int length = input_string_length;
+ if (length == 0) return s;
+
+ // Simpler handling of ascii strings.
+ //
+ // NOTE: This assumes that the upper/lower case of an ascii
+ // character is also ascii. This is currently the case, but it
+ // might break in the future if we implement more context and locale
+ // dependent upper/lower conversions.
+ SeqAsciiString* seq_ascii = TryGetSeqAsciiString(s);
+ if (seq_ascii != NULL) {
+ Object* o = Heap::AllocateRawAsciiString(length);
+ if (o->IsFailure()) return o;
+ SeqAsciiString* result = SeqAsciiString::cast(o);
+ bool has_changed_character = ConvertTraits::ConvertAscii(
+ result->GetChars(), seq_ascii->GetChars(), length);
+ return has_changed_character ? result : s;
+ }
Object* answer = ConvertCaseHelper(s, length, length, mapping);
if (answer->IsSmi()) {
@@ -4107,17 +4172,19 @@
static Object* Runtime_StringToLowerCase(Arguments args) {
- return ConvertCase<unibrow::ToLowercase>(args, &to_lower_mapping);
+ return ConvertCase<ToLowerTraits>(args, &to_lower_mapping);
}
static Object* Runtime_StringToUpperCase(Arguments args) {
- return ConvertCase<unibrow::ToUppercase>(args, &to_upper_mapping);
-}
+ return ConvertCase<ToUpperTraits>(args, &to_upper_mapping);
+}
+
static inline bool IsTrimWhiteSpace(unibrow::uchar c) {
return unibrow::WhiteSpace::Is(c) || c == 0x200b;
}
+
static Object* Runtime_StringTrim(Arguments args) {
NoHandleAllocation ha;
--
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