Use ICU case conversion/transliterator for case conversion behind a flag

src/runtime/runtime-i18n.cc

Index: src/runtime/runtime-i18n.cc
diff --git a/src/runtime/runtime-i18n.cc b/src/runtime/runtime-i18n.cc
index 27f970bdb4b17392cee21a375e7a04a49c4985aa..38cc832181e26224b9418e02e0e96243da07d93f 100644
--- a/src/runtime/runtime-i18n.cc
+++ b/src/runtime/runtime-i18n.cc
@@ -29,10 +29,12 @@
 #include "unicode/rbbi.h"
 #include "unicode/smpdtfmt.h"
 #include "unicode/timezone.h"
+#include "unicode/translit.h"
 #include "unicode/uchar.h"
 #include "unicode/ucol.h"
 #include "unicode/ucurr.h"
 #include "unicode/uloc.h"
+#include "unicode/unistr.h"
 #include "unicode/unum.h"
 #include "unicode/uversion.h"
 
@@ -749,6 +751,316 @@ RUNTIME_FUNCTION(Runtime_BreakIteratorBreakType) {
     return *isolate->factory()->NewStringFromStaticChars("unknown");
   }
 }
+
+namespace {
+void ConvertCaseWithTransliterator(icu::UnicodeString* input,
+                                   const char* transliterator_id) {
+  UErrorCode status = U_ZERO_ERROR;
+  base::SmartPointer<icu::Transliterator> translit(
+      icu::Transliterator::createInstance(
+          icu::UnicodeString(transliterator_id, -1, US_INV), UTRANS_FORWARD,
+          status));
+  if (U_FAILURE(status)) return;
+  translit->transliterate(*input);
+}
+
+MUST_USE_RESULT Object* LocaleConvertCase(Handle<String> s, Isolate* isolate,
+                                          bool is_to_upper, const char* lang) {
+  int32_t src_length = s->length();
+  const UChar* src = nullptr;
+
+  base::SmartArrayPointer<uc16> sap;
+  if (s->IsOneByteRepresentationUnderneath()) {
+    sap = s->ToWideCString();
+    src = reinterpret_cast<const UChar*>(sap.get());
+  }
+
+  // Greek uppercasing has to be done via transliteration.
+  // TODO(jshin): Drop this special-casing once ICU's regular case conversion
+  // API supports Greek uppercasing. See
+  // http://bugs.icu-project.org/trac/ticket/10582 .
+  // ICU's C API for transliteration is nasty and we just use C++ API.
+  if (V8_UNLIKELY(!strncmp(lang, "el", 2) && is_to_upper)) {
+    icu::UnicodeString converted;
+    {
+      DisallowHeapAllocation no_gc;
+      String::FlatContent flat = s->GetFlatContent();
+      if (src == nullptr) {
+        DCHECK(flat.IsTwoByte());
+        src = reinterpret_cast<const UChar*>(flat.ToUC16Vector().start());
+      }
+      // Starts with the source string and will be replaced by the converted
+      // result.
+      converted.fastCopyFrom(icu::UnicodeString(false, src, src_length));
+      ConvertCaseWithTransliterator(&converted, "el-Upper");
+    }
+    Handle<String> result;
+    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+        isolate, result,
+        isolate->factory()->NewStringFromTwoByte(Vector<const uint16_t>(
+            reinterpret_cast<const uint16_t*>(converted.getBuffer()),
+            converted.length())));
+    return *result;
+  }
+
+  auto case_converter = is_to_upper ? u_strToUpper : u_strToLower;
+
+  int32_t dest_length = src_length;
+  UErrorCode error;
+  Handle<SeqTwoByteString> result;
+
+  // This is not a real loop. It'll be executed only once (no overflow) or
+  // twice (overflow).
+  for (int i = 0; i < 2; ++i) {
+    result =
+        isolate->factory()->NewRawTwoByteString(dest_length).ToHandleChecked();
+    base::SmartArrayPointer<uc16> sap;
+    DisallowHeapAllocation no_gc;
+    String::FlatContent flat = s->GetFlatContent();
+    // For OneByteString, |src| is already obtained with |sap| outside the loop.
+    if (flat.IsTwoByte())
+      src = reinterpret_cast<const UChar*>(flat.ToUC16Vector().start());
+    error = U_ZERO_ERROR;
+    dest_length = case_converter(reinterpret_cast<UChar*>(result->GetChars()),
+                                 dest_length, src, src_length, lang, &error);
+    if (error != U_BUFFER_OVERFLOW_ERROR) break;
+  }
+
+  // In most cases, the output will fill the destination buffer completely
+  // leading to an unterminated string (U_STRING_NOT_TERMINATED_WARNING).
+  // Only in rare cases, it'll be shorter than the destination buffer and
+  // |result| has to be truncated.
+  DCHECK(U_SUCCESS(error));
+  // dest_length == result->length()
+  if (V8_LIKELY(error == U_STRING_NOT_TERMINATED_WARNING)) return *result;
+  if (U_SUCCESS(error)) {
+    // dest_length < result->length()
+    return *Handle<SeqTwoByteString>::cast(
+        SeqString::Truncate(result, dest_length));
+  }
+  return *s;
+}
+
+inline bool IsASCIIUpper(uint16_t ch) { return ch >= 'A' && ch <= 'Z'; }
+
+inline uint16_t ToLatin1Lower(uint16_t ch) {
+  return ch |
+         (((ch >= 'A' && ch <= 'Z') || (ch >= 0xC0 && ch <= 0xDE && ch != 0xD7))
+          << 5);
+}
+
+inline uint16_t ToASCIIUpper(uint16_t ch) {
+  return ch & ~((ch >= 'a' && ch <= 'z') << 5);
+}
+
+// Does not work for U+00DF (sharp-s), U+00B5 (micron), U+00FF.
+inline uint16_t ToLatin1Upper(uint16_t ch) {
+  DCHECK(ch != 0xDF && ch != 0xB5 && ch != 0xFF);
+  return ch &
+         ~(((ch >= 'a' && ch <= 'z') || (((ch & 0xE0) == 0xE0) && ch != 0xE7))
+           << 5);
+}
+
+template <typename Char>
+bool ToUpperFastASCII(const Vector<const Char>& src,
+                      Handle<SeqOneByteString> result) {
+  // Do a faster loop for the case where all the characters are ASCII.
+  uint16_t ored = 0;
+  int32_t index = 0;
+  for (auto it = src.begin(); it != src.end(); ++it) {
+    uint16_t ch = static_cast<uint16_t>(*it);
+    ored |= ch;
+    result->SeqOneByteStringSet(index++, ToASCIIUpper(ch));
+  }
+  return !(ored & ~0x7F);
+}
+
+const uint16_t sharp_s = 0xDF;
+
+template <typename Char>
+bool ToUpperOneByte(const Vector<const Char>& src,
+                    Handle<SeqOneByteString> result, int* sharp_s_count) {
+  // Still pretty-fast path for the input with non-ASCII Latin-1 characters.
+
+  // There are two special cases.
+  //  1. U+00B5 and U+00FF are mapped to a character beyond U+00FF.
+  //  2. Lower case sharp-S converts to "SS" (two characters)
+  *sharp_s_count = 0;
+  int32_t index = 0;
+  for (auto it = src.begin(); it != src.end(); ++it) {
+    uint16_t ch = static_cast<uint16_t>(*it);
+    if (V8_UNLIKELY(ch == sharp_s)) {
+      ++(*sharp_s_count);
+      continue;
+    }
+    if (V8_UNLIKELY(ch == 0xB5 || ch == 0xFF)) {
+      // Since this upper-cased character does not fit in an 8-bit string, we
+      // need to take the 16-bit path.
+      return false;
+    }
+    result->SeqOneByteStringSet(index++, ToLatin1Upper(ch));
+  }
+
+  return true;
+}
+
+template <typename Char>
+void ToUpperWithSharpS(const Vector<const Char>& src,
+                       Handle<SeqOneByteString> result) {
+  int32_t dest_index = 0;
+  for (auto it = src.begin(); it != src.end(); ++it) {
+    uint16_t ch = static_cast<uint16_t>(*it);
+    if (ch == sharp_s) {
+      result->SeqOneByteStringSet(dest_index++, 'S');
+      result->SeqOneByteStringSet(dest_index++, 'S');
+    } else {
+      result->SeqOneByteStringSet(dest_index++, ToLatin1Upper(ch));
+    }
+  }
+}
+
+}  // namespace
+
+RUNTIME_FUNCTION(Runtime_StringToLowerCaseI18N) {
+  HandleScope scope(isolate);
+  DCHECK_EQ(args.length(), 1);
+  CONVERT_ARG_HANDLE_CHECKED(String, s, 0);
+
+  int length = s->length();
+  s = String::Flatten(s);
+  // First scan the string for uppercase and non-ASCII characters:
+  if (s->HasOnlyOneByteChars()) {
+    unsigned first_index_to_lower = length;
+    for (int index = 0; index < length; ++index) {
+      // Blink specializes this path for one-byte strings, so it
+      // does not need to do a generic get, but can do the equivalent
+      // of SeqOneByteStringGet.
+      uint16_t ch = s->Get(index);
+      if (V8_UNLIKELY(IsASCIIUpper(ch) || ch & ~0x7F)) {
+        first_index_to_lower = index;
+        break;
+      }
+    }
+
+    // Nothing to do if the string is all ASCII with no uppercase.
+    if (first_index_to_lower == length) return *s;
+
+    // We depend here on the invariant that the length of a Latin1
+    // string is invariant under ToLowerCase, and the result always
+    // fits in the Latin1 range in the *root locale*. It does not hold
+    // for ToUpperCase even in the root locale.
+    Handle<SeqOneByteString> result;
+    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+        isolate, result, isolate->factory()->NewRawOneByteString(length));
+
+    DisallowHeapAllocation no_gc;
+    String::FlatContent flat = s->GetFlatContent();
+    if (flat.IsOneByte()) {
+      const uint8_t* src = flat.ToOneByteVector().start();
+      CopyChars(result->GetChars(), src, first_index_to_lower);
+      for (int index = first_index_to_lower; index < length; ++index) {
+        uint16_t ch = static_cast<uint16_t>(src[index]);
+        result->SeqOneByteStringSet(index, ToLatin1Lower(ch));
+      }
+    } else {
+      const uint16_t* src = flat.ToUC16Vector().start();
+      CopyChars(result->GetChars(), src, first_index_to_lower);
+      for (int index = first_index_to_lower; index < length; ++index) {
+        uint16_t ch = src[index];
+        result->SeqOneByteStringSet(index, ToLatin1Lower(ch));
+      }
+    }
+
+    return *result;
+  }
+
+  // Blink had an additional case here for ASCII 2-byte strings, but
+  // that is subsumed by the above code (assuming there isn't a false
+  // negative for HasOnlyOneByteChars).
+
+  // Do a slower implementation for cases that include non-ASCII characters.
+  return LocaleConvertCase(s, isolate, false, "");
+}
+
+RUNTIME_FUNCTION(Runtime_StringToUpperCaseI18N) {
+  HandleScope scope(isolate);
+  DCHECK_EQ(args.length(), 1);
+  CONVERT_ARG_HANDLE_CHECKED(String, s, 0);
+
+  // This function could be optimized for no-op cases the way lowercase
+  // counterpart is, but in empirical testing, few actual calls to upper()
+  // are no-ops. So, it wouldn't be worth the extra time for pre-scanning.
+
+  int32_t length = s->length();
+  s = String::Flatten(s);
+
+  if (s->HasOnlyOneByteChars()) {
+    Handle<SeqOneByteString> result;
+    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+        isolate, result, isolate->factory()->NewRawOneByteString(length));
+
+    int sharp_s_count;
+    bool is_result_single_byte;
+    {
+      DisallowHeapAllocation no_gc;
+      String::FlatContent flat = s->GetFlatContent();
+      // If it was ok to slow down ASCII-only input slightly, ToUpperFastASCII
+      // could be removed  because ToUpperOneByte is pretty fast now (it
+      // does not call ICU API any more.).
+      if (flat.IsOneByte()) {
+        Vector<const uint8_t> src = flat.ToOneByteVector();
+        if (ToUpperFastASCII(src, result)) return *result;
+        is_result_single_byte = ToUpperOneByte(src, result, &sharp_s_count);
+      } else {
+        DCHECK(flat.IsTwoByte());
+        Vector<const uint16_t> src = flat.ToUC16Vector();
+        if (ToUpperFastASCII(src, result)) return *result;
+        is_result_single_byte = ToUpperOneByte(src, result, &sharp_s_count);
+      }
+    }
+
+    // Go to the full Unicode path if there are characters whose uppercase
+    // is beyond the Latin-1 range (cannot be represented in OneByteString).
+    if (V8_UNLIKELY(!is_result_single_byte))
+      return LocaleConvertCase(s, isolate, true, "");
+
+    if (sharp_s_count == 0) return *result;
+
+    // We have sharp_s_count sharp-s characters, but the result is still
+    // in the Latin-1 range.
+    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+        isolate, result,
+        isolate->factory()->NewRawOneByteString(length + sharp_s_count));
+    DisallowHeapAllocation no_gc;
+    String::FlatContent flat = s->GetFlatContent();
+    if (flat.IsOneByte())
+      ToUpperWithSharpS(flat.ToOneByteVector(), result);
+    else
+      ToUpperWithSharpS(flat.ToUC16Vector(), result);
+
+    return *result;
+  }
+
+  return LocaleConvertCase(s, isolate, true, "");
+}
+
+RUNTIME_FUNCTION(Runtime_StringLocaleConvertCase) {
+  HandleScope scope(isolate);
+  DCHECK_EQ(args.length(), 3);
+  CONVERT_ARG_HANDLE_CHECKED(String, s, 0);
+  CONVERT_BOOLEAN_ARG_CHECKED(is_upper, 1);
+  CONVERT_ARG_HANDLE_CHECKED(SeqOneByteString, lang, 2);
+
+  // All the languages requiring special handling ("az", "el", "lt", "tr")
+  // have a 2-letter language code.
+  DCHECK(lang->length() == 2);
+  uint8_t lang_str[3];
+  memcpy(lang_str, lang->GetChars(), 2);
+  lang_str[2] = 0;
+  return LocaleConvertCase(s, isolate, is_upper,
+                           reinterpret_cast<const char*>(lang_str));
+}
+
 }  // namespace internal
 }  // namespace v8