export class LexerEvent
{
  static readonly LENGTH_ERROR_ID = -1;
  static readonly LENGTH_DONE_ID = -2;

  private _type:string;
  get type(){ return this._type; }
  private _offset:number;
  get offset(){ return this._offset; }
  private _length:number;
  get length(){ return this._length; }
  private _match:string = null;
  get match(){ return this._match;}

  get exclusiveEnd()
  {
    return this.offset + this.length;
  }

  get lastSourceIndex()
  {
    return this.exclusiveEnd - 1;
  } 

  extendLength( num:number )
  {
    this._length += num;
  }

  constructor( type:string, offset:number, length:number )
  {
    this.set( type, offset, length );  
  }

  set( type:string, offset:number, length:number )
  {
    this._type = type;
    this._offset = offset;
    this._length = length;      
  }

  isType( type:string )
  {
    return this._type == type;
  }

  get isError(){ return this._length === LexerEvent.LENGTH_ERROR_ID; }
  get isDone(){ return this._length === LexerEvent.LENGTH_DONE_ID; }
  get isDoneOrError(){ return this.isDone || this.isError }

  get end() { return this._offset + this._length; }

  toString()
  {
    return "Token{ '" + this._type + "' (" + this._offset + "-" + this.end + ") }"; 
  }

  clone()
  {
    return new LexerEvent( this._type, this._offset, this._length );
  }

  
  getMatch( source:string )
  {
    if ( this._match )
    {
      return this._match;
    }
    
    this.setMatch( source.substring( this._offset, this.end ) );
    return this._match;
  }

  setMatch( source:string )
  {
    this._match = source;
  }

}