PARSER_BEGIN(SimpleExp) 
    package org.virbo.dsutil.dd;
    import java.io.*;
    import java.util.*;
    import java.nio.ByteBuffer;
    import org.das2.util.ByteBufferInputStream;

    class SimpleExp {
    	public static void main(String[] arg) 
	throws ParseException, TokenMgrError, NumberFormatException, IOException {
	    if (arg.length != 1) { 
	        System.out.println("Usage: Java SimpleExp file");
            }

InputStream is;
if ( arg.length==0 ) {
            is = new ByteBufferInputStream( ByteBuffer.wrap( "3+4".getBytes() ) );
} else {
            is = new FileInputStream(arg[0]);
}

	    SimpleExp parser = new SimpleExp(is);
            List<Node> program = parser.Start();
            boolean flag = Semantic.checkProgram(program);
	    if (flag) System.out.println("Check succeeded");
	    if (!flag) System.out.println("Check failed");
        }
    }

PARSER_END(SimpleExp)


SKIP : { " " | "\n" | "\r" }

TOKEN : {<PLUS  : "+">}
TOKEN : {<EQUAL : "=">}
TOKEN : {<SEMI  : ";">}

TOKEN : {<OPEN_PAR  : "(">}
TOKEN : {<CLOSE_PAR : ")">}

TOKEN : {<NUMBER : ((["0" - "9"])+)("." (["0"-"9"])+)? >}
TOKEN : {<IDENTIFIER : (["a" - "z"](["a" - "z"] | ["0" - "9"])*)>}

List<Node> Start () :
{
    List<Node> l = new ArrayList<Node>();
    Node n;
}
{   
  ( 
    n = Statement()
    { l.add(n); }
  )*
  { return l; }
}


Node Statement() :
{ 
    Node ident, expr;
}
{
    ident = Identifier()
    <EQUAL>
    expr = Expression()
    <SEMI>
    {
 	Node n = new Node(Id.ASSIGN);
	n.add(ident);
	n.add(expr);
	return n;
    }
}		

Node Identifier () :
{
    Token t;
}
{
    t = <IDENTIFIER>
    {
	return new IdentifierNode(t.image);
    }
}

Node Expression()  :
{
    Node expr, term, temp;
}
{
    expr = Term()
    (
 	<PLUS>
	term = Term()
  	{ 
	   temp = new Node(Id.PLUS);
	   temp.add(expr);
	   temp.add(term);
	   expr = temp;
	}		
    )*
    { return expr; }
}

Node Term () throws NumberFormatException :
{ 
    Node expr;
    Token t;
}
{
    t = <NUMBER>
    { 
        return new DoubleNode(Double.parseDouble(t.image));
    }  
|
    <OPEN_PAR>
    expr = Expression()
    <CLOSE_PAR>
    {
        return expr;
    }

|    
    expr = Identifier() 
    {	
	return expr;
    }

}