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, 122 insertions, 0 deletions

diff --git a/base/utf_offset_string_conversions.cc b/base/utf_offset_string_conversions.cc
new file mode 100644
index 0000000..69b572e
--- /dev/null
+++ b/base/utf_offset_string_conversions.cc
@@ -0,0 +1,122 @@
+// 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_offset_string_conversions.h"
+
+#include "base/string_piece.h"
+#include "base/utf_string_conversion_utils.h"
+
+using base::PrepareForUTF16Or32Output;
+using base::ReadUnicodeCharacter;
+using base::WriteUnicodeCharacter;
+
+// 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>
+bool ConvertUnicode(const SRC_CHAR* src,
+                    size_t src_len,
+                    std::wstring* output,
+                    size_t* offset_for_adjustment) {
+  size_t output_offset =
+      (offset_for_adjustment && *offset_for_adjustment < src_len) ?
+          *offset_for_adjustment : std::wstring::npos;
+
+  // 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);
+    } else {
+      // TODO(jungshik): consider adding 'Replacement character' (U+FFFD)
+      // in place of an invalid codepoint.
+      success = false;
+    }
+    if ((output_offset != std::wstring::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 = std::wstring::npos;
+      else
+        output_offset += chars_written - (i - original_i + 1);
+    }
+  }
+
+  if (offset_for_adjustment)
+    *offset_for_adjustment = output_offset;
+  return success;
+}
+
+// UTF-8 <-> Wide --------------------------------------------------------------
+
+bool UTF8ToWideAndAdjustOffset(const char* src,
+                               size_t src_len,
+                               std::wstring* output,
+                               size_t* offset_for_adjustment) {
+  PrepareForUTF16Or32Output(src, src_len, output);
+  return ConvertUnicode(src, src_len, output, offset_for_adjustment);
+}
+
+std::wstring UTF8ToWideAndAdjustOffset(const base::StringPiece& utf8,
+                                       size_t* offset_for_adjustment) {
+  std::wstring ret;
+  UTF8ToWideAndAdjustOffset(utf8.data(), utf8.length(), &ret,
+                            offset_for_adjustment);
+  return ret;
+}
+
+// UTF-16 <-> Wide -------------------------------------------------------------
+
+#if defined(WCHAR_T_IS_UTF16)
+
+// When wide == UTF-16, then conversions are a NOP.
+bool UTF16ToWideAndAdjustOffset(const char16* src,
+                                size_t src_len,
+                                std::wstring* output,
+                                size_t* offset_for_adjustment) {
+  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;
+  return utf16;
+}
+
+#elif defined(WCHAR_T_IS_UTF32)
+
+bool UTF16ToWideAndAdjustOffset(const char16* src,
+                                size_t src_len,
+                                std::wstring* output,
+                                size_t* offset_for_adjustment) {
+  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(src, src_len, output, offset_for_adjustment);
+}
+
+std::wstring UTF16ToWideAndAdjustOffset(const string16& utf16,
+                                        size_t* offset_for_adjustment) {
+  std::wstring ret;
+  UTF16ToWideAndAdjustOffset(utf16.data(), utf16.length(), &ret,
+                             offset_for_adjustment);
+  return ret;
+}
+
+#endif  // defined(WCHAR_T_IS_UTF32)