private int unregisterSourceFile(String file){
  if (!sourceFiles.contains(file))   return -1;
  sourceFiles.remove(file);
  this.size--;
  return sourceFiles.size() - 1;
}

private int unregisterSourceFile ( String file ) { if ( ! sourceFiles . contains ( file ) ) return - 1 ; sourceFiles . remove ( file ) ; this . size -- ; return sourceFiles . size ( ) - 1 ; }
unregister the source file . this method is used to implement file inclusion . each included file gets a uniq identifier ( which is the index in the array of source files ) .
