sexprvisitor.java

一种将c高级语言转化给VHDL的编译器

/*
 *
 LA-CC 05-135 Trident 0.7.1

Copyright Notice
Copyright 2006 (c) the Regents of the University of California.

This Software was produced under a U.S. Government contract
(W-7405-ENG-36) by Los Alamos National Laboratory, which is operated
by the University of California for the U.S. Department of Energy. The
U.S. Government is licensed to use, reproduce, and distribute this
Software. Permission is granted to the public to copy and use this
Software without charge, provided that this Notice and any statement
of authorship are reproduced on all copies. Neither the Government nor
the University makes any warranty, express or implied, or assumes any
liability or responsibility for the user of this Software.


 */


package fp.util.sexpr;

import java.util.*;

public class SExprVisitor {
  public void forSymbol(Symbol that) {}
  public void forVector(Vector that) {}
  public void forString(String that) {}
  public void forNumber(Number that) {}
  public void forUnknown(Object that) {}

  protected String getLabel(Vector v) {
    if (v.size() > 0) {
      Object o = v.elementAt(0);
      // is this really necessary?
      if (o instanceof Symbol || o instanceof String) {
	return v.elementAt(0).toString();
      }
    }
    return null;
  }

  public void visit(Object expr) {
    if (expr == null)
      return;
    else if (expr instanceof Number) {
      forNumber((Number)expr);
    } else if (expr instanceof Vector) {
      forVector((Vector)expr);
      for(int i=0; i < ((Vector)expr).size(); i++) {
	visit(((Vector)expr).elementAt(i));
      }
    } else if (expr instanceof String) {
      forString((String)expr);
    } else if (expr instanceof SExpr) {
      if (expr instanceof Enumeration) {
	for(Enumeration e = (Enumeration)expr; e.hasMoreElements(); ) {
	  Object element = e.nextElement();
	  visit(e);
	}
      } else if (expr instanceof Cons) {
	Cons c = (Cons) expr;
	System.out.println("Cons ");

	for(Enumeration e = c.elements(); e.hasMoreElements(); ) {
	  Object element = e.nextElement();
	  visit(e);
	}
      } else if (expr instanceof Symbol) {
	forSymbol((Symbol)expr);
      } else {
	System.out.println("SExpr ");
	forUnknown(expr);
      }
    } else {
      forUnknown(expr);
    }
  }
}