Update //base to chromium 9659b08ea5a34f889dc4166217f438095ddc10d2

base/i18n/case_conversion.cc

Index: base/i18n/case_conversion.cc
diff --git a/base/i18n/case_conversion.cc b/base/i18n/case_conversion.cc
index 5debc2ec8d662aec1cf347c293686bb1f7a59fbd..d0eceb90920572397ca8d7af0c61005ea8cdfa10 100644
--- a/base/i18n/case_conversion.cc
+++ b/base/i18n/case_conversion.cc
@@ -4,22 +4,91 @@
 
 #include "base/i18n/case_conversion.h"
 
+#include "base/numerics/safe_conversions.h"
 #include "base/strings/string16.h"
+#include "base/strings/string_util.h"
+#include "third_party/icu/source/common/unicode/uchar.h"
 #include "third_party/icu/source/common/unicode/unistr.h"
+#include "third_party/icu/source/common/unicode/ustring.h"
 
 namespace base {
 namespace i18n {
 
-string16 ToLower(const StringPiece16& string) {
-  icu::UnicodeString unicode_string(string.data(), string.size());
-  unicode_string.toLower();
-  return string16(unicode_string.getBuffer(), unicode_string.length());
+namespace {
+
+// Provides a uniform interface for upper/lower/folding which take take
+// slightly varying parameters.
+typedef int32_t (*CaseMapperFunction)(UChar* dest,
+                                      int32_t dest_capacity,
+                                      const UChar* src,
+                                      int32_t src_length,
+                                      UErrorCode* error);
+
+int32_t ToUpperMapper(UChar* dest,
+                      int32_t dest_capacity,
+                      const UChar* src,
+                      int32_t src_length,
+                      UErrorCode* error) {
+  // Use default locale.
+  return u_strToUpper(dest, dest_capacity, src, src_length, NULL, error);
+}
+
+int32_t ToLowerMapper(UChar* dest,
+                      int32_t dest_capacity,
+                      const UChar* src,
+                      int32_t src_length,
+                      UErrorCode* error) {
+  // Use default locale.
+  return u_strToLower(dest, dest_capacity, src, src_length, NULL, error);
+}
+
+int32_t FoldCaseMapper(UChar* dest,
+                       int32_t dest_capacity,
+                       const UChar* src,
+                       int32_t src_length,
+                       UErrorCode* error) {
+  return u_strFoldCase(dest, dest_capacity, src, src_length,
+                       U_FOLD_CASE_DEFAULT, error);
+}
+
+// Provides similar functionality as UnicodeString::caseMap but on string16.
+string16 CaseMap(StringPiece16 string, CaseMapperFunction case_mapper) {
+  string16 dest;
+  if (string.empty())
+    return dest;
+
+  // Provide an initial guess that the string length won't change. The typical
+  // strings we use will very rarely change length in this process, so don't
+  // optimize for that case.
+  dest.resize(string.size());
+
+  UErrorCode error;
+  do {
+    error = U_ZERO_ERROR;
+
+    // ICU won't terminate the string if there's not enough room for the null
+    // terminator, but will otherwise. So we don't need to save room for that.
+    // Don't use WriteInto, which assumes null terminators.
+    int32_t new_length = case_mapper(
+        &dest[0], saturated_cast<int32_t>(dest.size()), string.data(),
+        saturated_cast<int32_t>(string.size()), &error);
+    dest.resize(new_length);
+  } while (error == U_BUFFER_OVERFLOW_ERROR);
+  return dest;
+}
+
+}  // namespace
+
+string16 ToLower(StringPiece16 string) {
+  return CaseMap(string, &ToLowerMapper);
+}
+
+string16 ToUpper(StringPiece16 string) {
+  return CaseMap(string, &ToUpperMapper);
 }
 
-string16 ToUpper(const StringPiece16& string) {
-  icu::UnicodeString unicode_string(string.data(), string.size());
-  unicode_string.toUpper();
-  return string16(unicode_string.getBuffer(), unicode_string.length());
+string16 FoldCase(StringPiece16 string) {
+  return CaseMap(string, &FoldCaseMapper);
 }
 
 }  // namespace i18n