public ProgramRewriter(HopRewriteRule rewrite){
  _dagRuleSet=new ArrayList<HopRewriteRule>();
  _dagRuleSet.add(rewrite);
  _sbRuleSet=new ArrayList<StatementBlockRewriteRule>();
}

public ProgramRewriter ( HopRewriteRule rewrite ) { _dagRuleSet = new ArrayList < HopRewriteRule > ( ) ; _dagRuleSet . add ( rewrite ) ; _sbRuleSet = new ArrayList < StatementBlockRewriteRule > ( ) ; }
construct a program rewriter for a given rewrite which is passed from outside .
