Add functions to get the length or compute a substring of UTF8 and UTF16...

base/i18n/char_iterator.h

+// Copyright (c) 2010 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.
+
+#ifndef BASE_I18N_CHAR_ITERATOR_H_
+#define BASE_I18N_CHAR_ITERATOR_H_
+#pragma once
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/string16.h"
+
+// The CharIterator classes iterate through the characters in UTF8 and
+// UTF16 strings.  Example usage:
+//
+//   UTF8CharIterator iter(&str);
+//   while (!iter.End()) {
+//     LOG(INFO) << iter.get();
+//     iter.Advance();
+//   }
+
+namespace base {
+
+class UTF8CharIterator {
+ public:
+  // Requires |str| to live as long as the UTF8CharIterator does.
+  UTF8CharIterator(const std::string* str);
+  ~UTF8CharIterator() {}
+
+  // Return the starting array index of the current character within the
+  // string.
+  int32 array_pos() const { return array_pos_; }
+
+  // Return the logical index of the current character, independent of the
+  // number of bytes each character takes.
+  int32 char_pos() const { return char_pos_; }
+
+  // Return the current char.
+  int32 get() const { return char_; }
+
+  // Returns true if we're at the end of the string.
+  bool end() const { return array_pos_ == len_; }
+
+  // Advance to the next actual character.  Returns false if we're at the
+  // end of the string.
+  bool Advance();
+
+ private:
+  // The string we're iterating over.
+  const uint8_t* str_;
+
+  // The length of the encoded string.
+  int32 len_;
+
+  // Array index.
+  int32 array_pos_;
+
+  // The next array index.
+  int32 next_pos_;
+
+  // Character index.
+  int32 char_pos_;
+
+  // The current character.
+  int32 char_;
+
+  DISALLOW_COPY_AND_ASSIGN(UTF8CharIterator);
+};
+
+class UTF16CharIterator {
+ public:
+  // Requires |str| to live as long as the UTF16CharIterator does.
+  UTF16CharIterator(const string16* str);
+  ~UTF16CharIterator() {}
+
+  // Return the starting array index of the current character within the
+  // string.
+  int32 array_pos() const { return array_pos_; }
+
+  // Return the logical index of the current character, independent of the
+  // number of codewords each character takes.
+  int32 char_pos() const { return char_pos_; }
+
+  // Return the current char.
+  int32 get() const { return char_; }
+
+  // Returns true if we're at the end of the string.
+  bool end() const { return array_pos_ == len_; }
+
+  // Advance to the next actual character.  Returns false if we're at the
+  // end of the string.
+  bool Advance();
+
+ private:
+  // The string we're iterating over.
+  const char16* str_;
+
+  // The length of the encoded string.
+  int32 len_;
+
+  // Array index.
+  int32 array_pos_;
+
+  // The next array index.
+  int32 next_pos_;
+
+  // Character index.
+  int32 char_pos_;
+
+  // The current character.
+  int32 char_;
+
+  DISALLOW_COPY_AND_ASSIGN(UTF16CharIterator);
+};
+
+}  // namespace base
+
+#endif  // BASE_I18N_CHAR_ITERATOR_H_