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..ea834b0fbbaf28e8144c8f093e57a4012cced583 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 +751,358 @@ 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);
+}
+
+const UChar* GetUCharBufferFromFlat(const String::FlatContent& flat,
+                                    base::SmartArrayPointer<uc16>* dest,
+                                    int32_t length) {
+  DCHECK(flat.IsFlat());
+  if (flat.IsOneByte()) {
+    if (dest->is_empty()) {
+      dest->Reset(NewArray<uc16>(length));
+      CopyChars(dest->get(), flat.ToOneByteVector().start(), length);
+    }
+    return reinterpret_cast<const UChar*>(dest->get());
+  } else {
+    return reinterpret_cast<const UChar*>(flat.ToUC16Vector().start());
+  }
+}
+
+MUST_USE_RESULT Object* LocaleConvertCase(Handle<String> s, Isolate* isolate,
+                                          bool is_to_upper, const char* lang) {
+  int32_t src_length = s->length();
+
+  // 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 .
+  // In the meantime, if there's no Greek character in |s|, call this
+  // function again with the root locale (lang="").
+  // ICU's C API for transliteration is nasty and we just use C++ API.
+  if (V8_UNLIKELY(is_to_upper && lang[0] == 'e' && lang[1] == 'l')) {
+    icu::UnicodeString converted;
+    base::SmartArrayPointer<uc16> sap;
+    {
+      DisallowHeapAllocation no_gc;
+      String::FlatContent flat = s->GetFlatContent();
+      const UChar* src = GetUCharBufferFromFlat(flat, &sap, src_length);
+      // Starts with the source string (read-only alias with copy-on-write
+      // semantics) and will be modified to contain the converted result.
+      // Using read-only alias at first saves one copy operation if
+      // transliteration does not change the input, which is rather rare.
+      // Moreover, transliteration takes rather long so that saving one copy
+      // helps only a little bit.
+      converted.setTo(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 status;
+  Handle<SeqTwoByteString> result;
+  base::SmartArrayPointer<uc16> sap;
+
+  // 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();
+    DisallowHeapAllocation no_gc;
+    String::FlatContent flat = s->GetFlatContent();
+    const UChar* src = GetUCharBufferFromFlat(flat, &sap, src_length);
+    status = U_ZERO_ERROR;
+    dest_length = case_converter(reinterpret_cast<UChar*>(result->GetChars()),
+                                 dest_length, src, src_length, lang, &status);
+    if (status != 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(status));
+  if (V8_LIKELY(status == U_STRING_NOT_TERMINATED_WARNING)) {
+    DCHECK(dest_length == result->length());
+    return *result;
+  }
+  if (U_SUCCESS(status)) {
+    DCHECK(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'; }
+
+const uint8_t kToLower[256] = {
+    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B,
+    0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+    0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, 0x23,
+    0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F,
+    0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B,
+    0x3C, 0x3D, 0x3E, 0x3F, 0x40, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
+    0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F, 0x70, 0x71, 0x72, 0x73,
+    0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x5B, 0x5C, 0x5D, 0x5E, 0x5F,
+    0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6A, 0x6B,
+    0x6C, 0x6D, 0x6E, 0x6F, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
+    0x78, 0x79, 0x7A, 0x7B, 0x7C, 0x7D, 0x7E, 0x7F, 0x80, 0x81, 0x82, 0x83,
+    0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8A, 0x8B, 0x8C, 0x8D, 0x8E, 0x8F,
+    0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, 0x9B,
+    0x9C, 0x9D, 0x9E, 0x9F, 0xA0, 0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7,
+    0xA8, 0xA9, 0xAA, 0xAB, 0xAC, 0xAD, 0xAE, 0xAF, 0xB0, 0xB1, 0xB2, 0xB3,
+    0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xBB, 0xBC, 0xBD, 0xBE, 0xBF,
+    0xE0, 0xE1, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA, 0xEB,
+    0xEC, 0xED, 0xEE, 0xEF, 0xF0, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xD7,
+    0xF8, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFE, 0xDF, 0xE0, 0xE1, 0xE2, 0xE3,
+    0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA, 0xEB, 0xEC, 0xED, 0xEE, 0xEF,
+    0xF0, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8, 0xF9, 0xFA, 0xFB,
+    0xFC, 0xFD, 0xFE, 0xFF,
+};
+
+inline uint16_t ToLatin1Lower(uint16_t ch) {
+  return static_cast<uint16_t>(kToLower[ch]);
+}
+
+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;
+  s = String::Flatten(s);
+  // TODO(jshin): Consider adding a fast path for ASCII or Latin-1. The fastpath
+  // in the root locale needs to be adjusted for az, lt and tr because even case
+  // mapping of ASCII range characters are different in those locales.
+  // Greek (el) does not require any adjustment, though.
+  return LocaleConvertCase(s, isolate, is_upper,
+                           reinterpret_cast<const char*>(lang_str));
+}
+
 }  // namespace internal
 }  // namespace v8