/*
 * Function.java
 * Copyright (C) 2004-2008, Bjorn Bringert (bringert@cs.chalmers.se)
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package se.chalmers.cs.pgf;

import se.chalmers.cs.pgf.raw.*;

import java.util.*;

/**
 *  Represents a PGF abstract syntax function.
 */
public class Function {
        
    private String name;

    private FunType funType;

    public Function(String name, Term type) {
	this.name = name;
	this.funType = termToFunType(type);
    }

    /**
     *  Get the name of this function.
     */
    public String getName() {
	return name;
    }

    /**
     *  Get the argument types of this function.
     */
    public List<String> getArgCats() {
	return funType.argCats;
    }

    /**
     *  Get one of the argument types of this function.
     */
    public String getArgCat(int i) {
	return funType.argCats.get(i);
    }

    /**
     *  Get the result type of this function
     */
    public String getResultCat() {
	return funType.resultCat;
    }

    /**
     *  Get the number of arguments that this function takes.
     */
    public int getArity() {
	return funType.argCats.size();
    }

    public boolean equals(Object o) {
	return o instanceof Function && equals((Function)o);
    }

    public boolean equals(Function f) {
	return name.equals(f.name) 
	    && funType.argCats.equals(f.funType.argCats) 
	    && funType.resultCat.equals(f.funType.resultCat);
    }

    public int hashCode() {
	return name.hashCode() + funType.argCats.hashCode() + funType.resultCat.hashCode();
    }

    public String toString() {
	StringBuilder sb = new StringBuilder();
	sb.append("fun ");
	sb.append(name);
	sb.append(" : ");
	for (String c : funType.argCats) 
	    sb.append(c).append(" -> ");
	sb.append(funType.resultCat);
	return sb.toString();
    }

    /*
      GF:
      That : Kind -> Item ;
      PGF:
      (That (Item (H (_ (Kind H X))) X) Eq)
    */

    private static FunType termToFunType(Term term) {
	Fun f = (Fun)term;
	Fun t = (Fun)f.listterm_[0];
	List<String> args = new LinkedList<String>();
	for (Term h : t.listterm_) {
	    FunType argFunType = termToFunType(((Fun)h).listterm_[0]);
	    args.add(argFunType.resultCat);
	}
	return new FunType(args, f.id_);
    }

    private static class FunType {
	public List<String> argCats;
	public String resultCat;
	public FunType(List<String> argCats, String resultCat) {
	    this.argCats = argCats;
	    this.resultCat = resultCat;
	}
    }

}