text: // Copyright 2010-2014, Google Inc.
  // All rights reserved.
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  // notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //     * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  #ifndef MOZC_UNIX_IBUS_SURROUNDING_TEXT_URIL_H_
  #define MOZC_UNIX_IBUS_SURROUNDING_TEXT_URIL_H_
  
  #include <string>
  
  #include "base/port.h"
  #include "unix/ibus/ibus_header.h"
  
  namespace mozc {
  namespace ibus {
  
  class SurroundingTextUtil {
   public:
    // Calculates |from| - |to| and stores the result into |delta| with
    // checking integer overflow.
    // Returns true when neither |abs(delta)| nor |-delta| does not cause
    // integer overflow, that is, |delta| is in a safe range.
    // Returns false otherwise.
    static bool GetSafeDelta(guint from, guint to, int32 *delta);
  
    // Returns true if
    // 1. |surrounding_text| contains |selected_text|
    //    from |cursor_pos| to |*anchor_pos|.
    // or,
    // 2. |surrounding_text| contains |selected_text|
    //    from |*anchor_pos| to |cursor_pos|.
    // with calculating |*anchor_pos|,
    // where |cursor_pos| and |*anchor_pos| are counts of Unicode characters.
    // When both 1) and 2) are satisfied, this function calculates
    // |*anchor_pos| for case 1).
    // Otherwise returns false.
    static bool GetAnchorPosFromSelection(
        const string &surrounding_text,
        const string &selected_text,
        guint cursor_pos,
        guint *anchor_pos);
  
   private:
    DISALLOW_IMPLICIT_CONSTRUCTORS(SurroundingTextUtil);
  };
  
  }  // namespace ibus
  }  // namespace mozc
  
  #endif  // MOZC_UNIX_IBUS_SURROUNDING_TEXT_URIL_H_
  