Split *AndAdjustOffset() functions into their own header, to restore utf_string_conversions.h to a simple, readable state.

BUG=4010
TEST=none
Review URL: http://codereview.chromium.org/387012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@31928 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 22 insertions, 218 deletions

diff --git a/base/utf_string_conversions.cc b/base/utf_string_conversions.cc
index ee52f47..7376933 100644
--- a/base/utf_string_conversions.cc
+++ b/base/utf_string_conversions.cc
@@ -4,133 +4,16 @@
 
 #include "base/utf_string_conversions.h"
 
-#include <vector>
+#include "base/string_piece.h"
+#include "base/utf_string_conversion_utils.h"
 
-#include "base/basictypes.h"
-#include "base/logging.h"
-#include "base/string_util.h"
-#include "base/third_party/icu/icu_utf.h"
+using base::PrepareForUTF8Output;
+using base::PrepareForUTF16Or32Output;
+using base::ReadUnicodeCharacter;
+using base::WriteUnicodeCharacter;
 
 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.  Returns the number of
-// bytes written.
-size_t 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 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;
-}
-
-// Appends the given code point as a UTF-16 character to the given 16-bit
-// string.  Returns the number of 16-bit values written.
-size_t 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));
-    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;
-}
-
-#if defined(WCHAR_T_IS_UTF32)
-// Appends the given UTF-32 character to the given 32-bit string.  Returns the
-// number of 32-bit values written.
-inline size_t WriteUnicodeCharacter(uint32 code_point, std::wstring* output) {
-  // This is the easy case, just append the character.
-  output->push_back(code_point);
-  return 1;
-}
-#endif  // defined(WCHAR_T_IS_UTF32)
-
 // Generalized Unicode converter -----------------------------------------------
 
 // Converts the given source Unicode character type to the given destination
@@ -140,90 +23,31 @@ inline size_t WriteUnicodeCharacter(uint32 code_point, std::wstring* output) {
 template<typename SRC_CHAR, typename DEST_STRING>
 bool ConvertUnicode(const SRC_CHAR* src,
                     size_t src_len,
-                    DEST_STRING* output,
-                    size_t* offset_for_adjustment) {
-  size_t output_offset =
-      (offset_for_adjustment && *offset_for_adjustment < src_len) ?
-          *offset_for_adjustment : DEST_STRING::npos;
-
+                    DEST_STRING* output) {
   // 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;
-    size_t original_i = i;
-    size_t chars_written = 0;
     if (ReadUnicodeCharacter(src, src_len32, &i, &code_point)) {
-      chars_written = WriteUnicodeCharacter(code_point, output);
+      WriteUnicodeCharacter(code_point, output);
     } else {
       // TODO(jungshik): consider adding 'Replacement character' (U+FFFD)
       // in place of an invalid codepoint.
       success = false;
     }
-    if ((output_offset != DEST_STRING::npos) &&
-        (*offset_for_adjustment > original_i)) {
-      // NOTE: ReadUnicodeCharacter() adjusts |i| to point _at_ the last
-      // character read, not after it (so that incrementing it in the loop
-      // increment will place it at the right location), so we need to account
-      // for that in determining the amount that was read.
-      if (*offset_for_adjustment <= static_cast<size_t>(i))
-        output_offset = DEST_STRING::npos;
-      else
-        output_offset += chars_written - (i - original_i + 1);
-    }
   }
 
-  if (offset_for_adjustment)
-    *offset_for_adjustment = output_offset;
   return success;
 }
 
-// Guesses the length of the output in UTF-8 in bytes, clears that output
-// string, and reserves that amount of space.  We assume that the input
-// character types are unsigned, which will be true for UTF-16 and -32 on our
-// systems.
-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);
-  }
-}
-
-// Prepares an output buffer (containing either UTF-16 or -32 data) given some
-// UTF-8 input that will be converted to it.  See PrepareForUTF8Output().
-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);
-  }
-}
-
 }  // namespace
 
 // UTF-8 <-> Wide --------------------------------------------------------------
 
 bool WideToUTF8(const wchar_t* src, size_t src_len, std::string* output) {
   PrepareForUTF8Output(src, src_len, output);
-  return ConvertUnicode<wchar_t, std::string>(src, src_len, output, NULL);
+  return ConvertUnicode(src, src_len, output);
 }
 
 std::string WideToUTF8(const std::wstring& wide) {
@@ -234,20 +58,14 @@ std::string WideToUTF8(const std::wstring& wide) {
   return ret;
 }
 
-bool UTF8ToWideAndAdjustOffset(const char* src,
-                               size_t src_len,
-                               std::wstring* output,
-                               size_t* offset_for_adjustment) {
+bool UTF8ToWide(const char* src, size_t src_len, std::wstring* output) {
   PrepareForUTF16Or32Output(src, src_len, output);
-  return ConvertUnicode<char, std::wstring>(src, src_len, output,
-                                            offset_for_adjustment);
+  return ConvertUnicode(src, src_len, output);
 }
 
-std::wstring UTF8ToWideAndAdjustOffset(const base::StringPiece& utf8,
-                                       size_t* offset_for_adjustment) {
+std::wstring UTF8ToWide(const base::StringPiece& utf8) {
   std::wstring ret;
-  UTF8ToWideAndAdjustOffset(utf8.data(), utf8.length(), &ret,
-                            offset_for_adjustment);
+  UTF8ToWide(utf8.data(), utf8.length(), &ret);
   return ret;
 }
 
@@ -265,20 +83,12 @@ string16 WideToUTF16(const std::wstring& wide) {
   return wide;
 }
 
-bool UTF16ToWideAndAdjustOffset(const char16* src,
-                                size_t src_len,
-                                std::wstring* output,
-                                size_t* offset_for_adjustment) {
+bool UTF16ToWide(const char16* src, size_t src_len, std::wstring* output) {
   output->assign(src, src_len);
-  if (offset_for_adjustment && (*offset_for_adjustment >= src_len))
-    *offset_for_adjustment = std::wstring::npos;
   return true;
 }
 
-std::wstring UTF16ToWideAndAdjustOffset(const string16& utf16,
-                                        size_t* offset_for_adjustment) {
-  if (offset_for_adjustment && (*offset_for_adjustment >= utf16.length()))
-    *offset_for_adjustment = std::wstring::npos;
+std::wstring UTF16ToWide(const string16& utf16) {
   return utf16;
 }
 
@@ -289,7 +99,7 @@ bool WideToUTF16(const wchar_t* src, size_t src_len, string16* output) {
   // 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, NULL);
+  return ConvertUnicode(src, src_len, output);
 }
 
 string16 WideToUTF16(const std::wstring& wide) {
@@ -298,23 +108,17 @@ string16 WideToUTF16(const std::wstring& wide) {
   return ret;
 }
 
-bool UTF16ToWideAndAdjustOffset(const char16* src,
-                                size_t src_len,
-                                std::wstring* output,
-                                size_t* offset_for_adjustment) {
+bool UTF16ToWide(const char16* src, size_t src_len, std::wstring* output) {
   output->clear();
   // 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,
-                                              offset_for_adjustment);
+  return ConvertUnicode(src, src_len, output);
 }
 
-std::wstring UTF16ToWideAndAdjustOffset(const string16& utf16,
-                                        size_t* offset_for_adjustment) {
+std::wstring UTF16ToWide(const string16& utf16) {
   std::wstring ret;
-  UTF16ToWideAndAdjustOffset(utf16.data(), utf16.length(), &ret,
-                             offset_for_adjustment);
+  UTF16ToWide(utf16.data(), utf16.length(), &ret);
   return ret;
 }
 
@@ -326,7 +130,7 @@ std::wstring UTF16ToWideAndAdjustOffset(const string16& utf16,
 
 bool UTF8ToUTF16(const char* src, size_t src_len, string16* output) {
   PrepareForUTF16Or32Output(src, src_len, output);
-  return ConvertUnicode<char, string16>(src, src_len, output, NULL);
+  return ConvertUnicode(src, src_len, output);
 }
 
 string16 UTF8ToUTF16(const std::string& utf8) {
@@ -339,7 +143,7 @@ string16 UTF8ToUTF16(const std::string& utf8) {
 
 bool UTF16ToUTF8(const char16* src, size_t src_len, std::string* output) {
   PrepareForUTF8Output(src, src_len, output);
-  return ConvertUnicode<char16, std::string>(src, src_len, output, NULL);
+  return ConvertUnicode(src, src_len, output);
 }
 
 std::string UTF16ToUTF8(const string16& utf16) {