Copy the relevant parts of ICU to a new file base/third_party/icu/icu_utf.*

so we can do basic UTF8/16/32 conversions without linking all of ICU.

Change callers who used to call SysUTF8ToWide/SysWideToUTF8 in base to using
these new functions. I will remove the Sys versions of these functions in a
later patch.

TEST=none
BUG=none
Review URL: http://codereview.chromium.org/243102

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@28219 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 361 insertions, 0 deletions

diff --git a/base/utf_string_conversions.cc b/base/utf_string_conversions.cc
new file mode 100644
index 0000000..6b25cd8
--- /dev/null
+++ b/base/utf_string_conversions.cc
@@ -0,0 +1,361 @@
+// 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/utf_string_conversions.h"
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/logging.h"
+#include "base/string_util.h"
+#include "base/third_party/icu/icu_utf.h"
+
+namespace {
+
+inline bool IsValidCodepoint(uint32 code_point) {
+  // Excludes the surrogate code points ([0xD800, 0xDFFF]) and
+  // codepoints larger than 0x10FFFF (the highest codepoint allowed).
+  // Non-characters and unassigned codepoints are allowed.
+  return code_point < 0xD800u ||
+         (code_point >= 0xE000u && code_point <= 0x10FFFFu);
+}
+
+// ReadUnicodeCharacter --------------------------------------------------------
+
+// Reads a UTF-8 stream, placing the next code point into the given output
+// |*code_point|. |src| represents the entire string to read, and |*char_index|
+// is the character offset within the string to start reading at. |*char_index|
+// will be updated to index the last character read, such that incrementing it
+// (as in a for loop) will take the reader to the next character.
+//
+// Returns true on success. On false, |*code_point| will be invalid.
+bool ReadUnicodeCharacter(const char* src, int32 src_len,
+                          int32* char_index, uint32* 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 code_point;
+  CBU8_NEXT(src, *char_index, src_len, code_point);
+  *code_point_out = static_cast<uint32>(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);
+}
+
+// Reads a UTF-16 character. The usage is the same as the 8-bit version above.
+bool ReadUnicodeCharacter(const char16* src, int32 src_len,
+                          int32* char_index, uint32* 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)
+// Reads UTF-32 character. The usage is the same as the 8-bit version above.
+bool ReadUnicodeCharacter(const wchar_t* src, int32 src_len,
+                          int32* char_index, uint32* 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 -------------------------------------------------------
+
+// Appends a UTF-8 character to the given 8-bit string.
+void WriteUnicodeCharacter(uint32 code_point, std::string* output) {
+  if (code_point <= 0x7f) {
+    // Fast path the common case of one byte.
+    output->push_back(code_point);
+    return;
+  }
+
+  // U8_APPEND_UNSAFE can append up to 4 bytes.
+  int32 char_offset = static_cast<int32>(output->length());
+  output->resize(char_offset + CBU8_MAX_LENGTH);
+
+  CBU8_APPEND_UNSAFE(&(*output)[0], char_offset, code_point);
+
+  // U8_APPEND_UNSAFE will advance our pointer past the inserted character, so
+  // it will represent the new length of the string.
+  output->resize(char_offset);
+}
+
+// Appends the given code point as a UTF-16 character to the STL string.
+void WriteUnicodeCharacter(uint32 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));
+  } else {
+    // Non-BMP characters use a double-character encoding.
+    int32 char_offset = static_cast<int32>(output->length());
+    output->resize(char_offset + CBU16_MAX_LENGTH);
+    CBU16_APPEND_UNSAFE(&(*output)[0], char_offset, code_point);
+  }
+}
+
+#if defined(WCHAR_T_IS_UTF32)
+// Appends the given UTF-32 character to the given 32-bit string.
+inline void WriteUnicodeCharacter(uint32 code_point, std::wstring* output) {
+  // This is the easy case, just append the character.
+  output->push_back(code_point);
+}
+#endif  // defined(WCHAR_T_IS_UTF32)
+
+// Generalized Unicode converter -----------------------------------------------
+
+// Converts the given source Unicode character type to the given destination
+// Unicode character type as a STL string. The given input buffer and size
+// determine the source, and the given output STL string will be replaced by
+// the result.
+template<typename SRC_CHAR, typename DEST_STRING>
+bool ConvertUnicode(const SRC_CHAR* src, size_t src_len, DEST_STRING* output) {
+  output->clear();
+
+  // ICU requires 32-bit numbers.
+  bool success = true;
+  int32 src_len32 = static_cast<int32>(src_len);
+  for (int32 i = 0; i < src_len32; i++) {
+    uint32 code_point;
+    if (ReadUnicodeCharacter(src, src_len32, &i, &code_point)) {
+      WriteUnicodeCharacter(code_point, output);
+    } else {
+      // TODO(jungshik): consider adding 'Replacement character' (U+FFFD)
+      // in place of an invalid codepoint.
+      success = false;
+    }
+  }
+  return success;
+}
+
+// Guesses the length of the output in UTF-8 in bytes, and reserves that amount
+// of space in the given string. We also assume that the input character types
+// are unsigned, which will be true for UTF-16 and -32 on our systems. We assume
+// the string length is greater than zero.
+template<typename CHAR>
+void ReserveUTF8Output(const CHAR* src, size_t src_len, std::string* output) {
+  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);
+  }
+}
+
+// Guesses the size of the output buffer (containing either UTF-16 or -32 data)
+// given some UTF-8 input that will be converted to it. See ReserveUTF8Output.
+// We assume the source length is > 0.
+template<typename STRING>
+void ReserveUTF16Or32Output(const char* src, size_t src_len, STRING* output) {
+  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);
+  }
+}
+
+}  // namespace
+
+// UTF-8 <-> Wide --------------------------------------------------------------
+
+std::string WideToUTF8(const std::wstring& wide) {
+  std::string ret;
+  if (wide.empty())
+    return ret;
+
+  // Ignore the success flag of this call, it will do the best it can for
+  // invalid input, which is what we want here.
+  WideToUTF8(wide.data(), wide.length(), &ret);
+  return ret;
+}
+
+bool WideToUTF8(const wchar_t* src, size_t src_len, std::string* output) {
+  if (src_len == 0) {
+    output->clear();
+    return true;
+  }
+
+  ReserveUTF8Output(src, src_len, output);
+  return ConvertUnicode<wchar_t, std::string>(src, src_len, output);
+}
+
+std::wstring UTF8ToWide(const base::StringPiece& utf8) {
+  std::wstring ret;
+  if (utf8.empty())
+    return ret;
+
+  UTF8ToWide(utf8.data(), utf8.length(), &ret);
+  return ret;
+}
+
+bool UTF8ToWide(const char* src, size_t src_len, std::wstring* output) {
+  if (src_len == 0) {
+    output->clear();
+    return true;
+  }
+
+  ReserveUTF16Or32Output(src, src_len, output);
+  return ConvertUnicode<char, std::wstring>(src, src_len, output);
+}
+
+// UTF-16 <-> Wide -------------------------------------------------------------
+
+#if defined(WCHAR_T_IS_UTF16)
+
+// When wide == UTF-16, then conversions are a NOP.
+string16 WideToUTF16(const std::wstring& wide) {
+  return wide;
+}
+
+bool WideToUTF16(const wchar_t* src, size_t src_len, string16* output) {
+  output->assign(src, src_len);
+  return true;
+}
+
+std::wstring UTF16ToWide(const string16& utf16) {
+  return utf16;
+}
+
+bool UTF16ToWide(const char16* src, size_t src_len, std::wstring* output) {
+  output->assign(src, src_len);
+  return true;
+}
+
+#elif defined(WCHAR_T_IS_UTF32)
+
+string16 WideToUTF16(const std::wstring& wide) {
+  string16 ret;
+  if (wide.empty())
+    return ret;
+
+  WideToUTF16(wide.data(), wide.length(), &ret);
+  return ret;
+}
+
+bool WideToUTF16(const wchar_t* src, size_t src_len, string16* output) {
+  if (src_len == 0) {
+    output->clear();
+    return true;
+  }
+
+  // Assume that normally we won't have any non-BMP characters so the counts
+  // will be the same.
+  output->reserve(src_len);
+  return ConvertUnicode<wchar_t, string16>(src, src_len, output);
+}
+
+std::wstring UTF16ToWide(const string16& utf16) {
+  std::wstring ret;
+  if (utf16.empty())
+    return ret;
+
+  UTF16ToWide(utf16.data(), utf16.length(), &ret);
+  return ret;
+}
+
+bool UTF16ToWide(const char16* src, size_t src_len, std::wstring* output) {
+  if (src_len == 0) {
+    output->clear();
+    return true;
+  }
+
+  // Assume that normally we won't have any non-BMP characters so the counts
+  // will be the same.
+  output->reserve(src_len);
+  return ConvertUnicode<char16, std::wstring>(src, src_len, output);
+}
+
+#endif  // defined(WCHAR_T_IS_UTF32)
+
+// UTF16 <-> UTF8 --------------------------------------------------------------
+
+#if defined(WCHAR_T_IS_UTF32)
+
+bool UTF8ToUTF16(const char* src, size_t src_len, string16* output) {
+  if (src_len == 0) {
+    output->clear();
+    return true;
+  }
+
+  ReserveUTF16Or32Output(src, src_len, output);
+  return ConvertUnicode<char, string16>(src, src_len, output);
+}
+
+string16 UTF8ToUTF16(const std::string& utf8) {
+  string16 ret;
+  if (utf8.empty())
+    return ret;
+
+  // Ignore the success flag of this call, it will do the best it can for
+  // invalid input, which is what we want here.
+  UTF8ToUTF16(utf8.data(), utf8.length(), &ret);
+  return ret;
+}
+
+bool UTF16ToUTF8(const char16* src, size_t src_len, std::string* output) {
+  if (src_len == 0) {
+    output->clear();
+    return true;
+  }
+
+  ReserveUTF8Output(src, src_len, output);
+  return ConvertUnicode<char16, std::string>(src, src_len, output);
+}
+
+std::string UTF16ToUTF8(const string16& utf16) {
+  std::string ret;
+  if (utf16.empty())
+    return ret;
+
+  // Ignore the success flag of this call, it will do the best it can for
+  // invalid input, which is what we want here.
+  UTF16ToUTF8(utf16.data(), utf16.length(), &ret);
+  return ret;
+}
+
+#elif defined(WCHAR_T_IS_UTF16)
+// Easy case since we can use the "wide" versions we already wrote above.
+
+bool UTF8ToUTF16(const char* src, size_t src_len, string16* output) {
+  return UTF8ToWide(src, src_len, output);
+}
+
+string16 UTF8ToUTF16(const std::string& utf8) {
+  return UTF8ToWide(utf8);
+}
+
+bool UTF16ToUTF8(const char16* src, size_t src_len, std::string* output) {
+  return WideToUTF8(src, src_len, output);
+}
+
+std::string UTF16ToUTF8(const string16& utf16) {
+  return WideToUTF8(utf16);
+}
+
+#endif