import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

security/sandbox/chromium/base/strings/utf_string_conversion_utils.cc

@@ -0,0 +1,148 @@
+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/strings/utf_string_conversion_utils.h"
+
+#include "base/third_party/icu/icu_utf.h"
+
+namespace base {
+
+// ReadUnicodeCharacter --------------------------------------------------------
+
+bool ReadUnicodeCharacter(const char* src,
+                          int32_t src_len,
+                          int32_t* char_index,
+                          uint32_t* code_point_out) {
+  // U8_NEXT expects to be able to use -1 to signal an error, so we must
+  // use a signed type for code_point.  But this function returns false
+  // on error anyway, so code_point_out is unsigned.
+  int32_t code_point;
+  CBU8_NEXT(src, *char_index, src_len, code_point);
+  *code_point_out = static_cast<uint32_t>(code_point);
+
+  // The ICU macro above moves to the next char, we want to point to the last
+  // char consumed.
+  (*char_index)--;
+
+  // Validate the decoded value.
+  return IsValidCodepoint(code_point);
+}
+
+bool ReadUnicodeCharacter(const char16* src,
+                          int32_t src_len,
+                          int32_t* char_index,
+                          uint32_t* code_point) {
+  if (CBU16_IS_SURROGATE(src[*char_index])) {
+    if (!CBU16_IS_SURROGATE_LEAD(src[*char_index]) ||
+        *char_index + 1 >= src_len ||
+        !CBU16_IS_TRAIL(src[*char_index + 1])) {
+      // Invalid surrogate pair.
+      return false;
+    }
+
+    // Valid surrogate pair.
+    *code_point = CBU16_GET_SUPPLEMENTARY(src[*char_index],
+                                          src[*char_index + 1]);
+    (*char_index)++;
+  } else {
+    // Not a surrogate, just one 16-bit word.
+    *code_point = src[*char_index];
+  }
+
+  return IsValidCodepoint(*code_point);
+}
+
+#if defined(WCHAR_T_IS_UTF32)
+bool ReadUnicodeCharacter(const wchar_t* src,
+                          int32_t src_len,
+                          int32_t* char_index,
+                          uint32_t* code_point) {
+  // Conversion is easy since the source is 32-bit.
+  *code_point = src[*char_index];
+
+  // Validate the value.
+  return IsValidCodepoint(*code_point);
+}
+#endif  // defined(WCHAR_T_IS_UTF32)
+
+// WriteUnicodeCharacter -------------------------------------------------------
+
+size_t WriteUnicodeCharacter(uint32_t code_point, std::string* output) {
+  if (code_point <= 0x7f) {
+    // Fast path the common case of one byte.
+    output->push_back(static_cast<char>(code_point));
+    return 1;
+  }
+
+
+  // CBU8_APPEND_UNSAFE can append up to 4 bytes.
+  size_t char_offset = output->length();
+  size_t original_char_offset = char_offset;
+  output->resize(char_offset + CBU8_MAX_LENGTH);
+
+  CBU8_APPEND_UNSAFE(&(*output)[0], char_offset, code_point);
+
+  // CBU8_APPEND_UNSAFE will advance our pointer past the inserted character, so
+  // it will represent the new length of the string.
+  output->resize(char_offset);
+  return char_offset - original_char_offset;
+}
+
+size_t WriteUnicodeCharacter(uint32_t code_point, string16* output) {
+  if (CBU16_LENGTH(code_point) == 1) {
+    // Thie code point is in the Basic Multilingual Plane (BMP).
+    output->push_back(static_cast<char16>(code_point));
+    return 1;
+  }
+  // Non-BMP characters use a double-character encoding.
+  size_t char_offset = output->length();
+  output->resize(char_offset + CBU16_MAX_LENGTH);
+  CBU16_APPEND_UNSAFE(&(*output)[0], char_offset, code_point);
+  return CBU16_MAX_LENGTH;
+}
+
+// Generalized Unicode converter -----------------------------------------------
+
+template<typename CHAR>
+void PrepareForUTF8Output(const CHAR* src,
+                          size_t src_len,
+                          std::string* output) {
+  output->clear();
+  if (src_len == 0)
+    return;
+  if (src[0] < 0x80) {
+    // Assume that the entire input will be ASCII.
+    output->reserve(src_len);
+  } else {
+    // Assume that the entire input is non-ASCII and will have 3 bytes per char.
+    output->reserve(src_len * 3);
+  }
+}
+
+// Instantiate versions we know callers will need.
+template void PrepareForUTF8Output(const wchar_t*, size_t, std::string*);
+template void PrepareForUTF8Output(const char16*, size_t, std::string*);
+
+template<typename STRING>
+void PrepareForUTF16Or32Output(const char* src,
+                               size_t src_len,
+                               STRING* output) {
+  output->clear();
+  if (src_len == 0)
+    return;
+  if (static_cast<unsigned char>(src[0]) < 0x80) {
+    // Assume the input is all ASCII, which means 1:1 correspondence.
+    output->reserve(src_len);
+  } else {
+    // Otherwise assume that the UTF-8 sequences will have 2 bytes for each
+    // character.
+    output->reserve(src_len / 2);
+  }
+}
+
+// Instantiate versions we know callers will need.
+template void PrepareForUTF16Or32Output(const char*, size_t, std::wstring*);
+template void PrepareForUTF16Or32Output(const char*, size_t, string16*);
+
+}  // namespace base