//=========================================================================
//
//  Part of PEG parser generator Mouse.
//
//  Copyright (C) 2009, 2010 by Roman R. Redziejowski (www.romanredz.se).
//
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at
//
//       http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.
//
//-------------------------------------------------------------------------
//
//  Change log
//    090701 License changed by the author to Apache v.2.
//    090810 Package name changed.
//
//=========================================================================

package source;

import util.apache.UnicodeUnescaper;


//HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
//
//  Interface to source text wrapper.
//  The generated parser accesses its input through a wrapper that
//  presents the input as a sequence of characters. These characters
//  can be individually accessed by specifying their position in the
//  sequence. The positions are numbered starting with 0.
//  For diagnostic purposes, the wrapper has the method 'where' that
//  describes a given position in terms compatible with the input
//  medium, for example, as line and column number for a file.
//
//HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH

public interface Source
{
  UnicodeUnescaper unescaper = new UnicodeUnescaper();

  //-------------------------------------------------------------------
  //  Returns position of the last character plus 1
  //  (= length of the sequence).
  //-------------------------------------------------------------------
  int end();

  //-------------------------------------------------------------------
  //  Returns character at position p.
  //-------------------------------------------------------------------
  char at(int p);

  //-------------------------------------------------------------------
  //  Returns characters at positions p through q-1.
  //-------------------------------------------------------------------
  String at(int p, int q);

  //-------------------------------------------------------------------
  //  Describes position p in user's terms.
  //-------------------------------------------------------------------
  String where(int p);
}