/* Soot - a J*va Optimization Framework
 * Copyright (C) 1997 Clark Verbrugge
 *
 * 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.
 */

/*
 * Modified by the Sable Research Group and others 1997-1999.  
 * See the 'credits' file distributed with Soot for the complete list of
 * contributors.  (Soot is distributed at http://www.sable.mcgill.ca/soot)
 */







package soot.coffi;

import java.io.*;

import soot.*;

/*
 * A less resource hungry implementation of the TypeStack would just have pointers to
 * 'sub-stacks' instead of copying the entire array around.
 */

class TypeStack
{
    private Type[] types;

    private TypeStack()
    {
        // no constructor
    }

    public Object clone()
    {
        TypeStack newTypeStack = new TypeStack();

        newTypeStack.types = types.clone();

        return newTypeStack;
    }

    /**
     * Returns an empty stack.
     */

    public static TypeStack v()
    {
        TypeStack typeStack = new TypeStack();

        typeStack.types = new Type[0];

        return typeStack;
    }

    public TypeStack pop()
    {
        TypeStack newStack = new TypeStack();

        newStack.types = new Type[types.length - 1];
        System.arraycopy(types, 0, newStack.types, 0, types.length - 1);

        return newStack;
    }

    public TypeStack push(Type type)
    {
        TypeStack newStack = new TypeStack();

        newStack.types = new Type[types.length + 1];
        System.arraycopy(types, 0, newStack.types, 0, types.length);

        newStack.types[types.length] = type;

        return newStack;
    }

    public Type get(int index)
    {
        return types[index];
    }

    public int topIndex()
    {
        return types.length - 1;
    }

    public Type top()
    {
        if(types.length == 0)
            throw new RuntimeException("TypeStack is empty");
        else
            return types[types.length - 1];
    }

    public boolean equals(Object object)
    {
        if(object instanceof TypeStack)
        {
            TypeStack otherStack = (TypeStack) object;

            if(otherStack.types.length != types.length)
                return false;

            for (Type element : types)
				if(!element.equals(element))
                    return false;

            return true;
        }
        else
            return false;
    }

    public TypeStack merge(TypeStack other)
    {

        if(types.length != other.types.length)
            throw new RuntimeException("TypeStack merging failed; unequal " +
            "stack lengths: " + types.length + " and " + other.types.length);

        TypeStack newStack = new TypeStack();

        newStack.types = new Type[other.types.length];

        for(int i = 0; i < types.length; i++)
            if(types[i].equals(other.types[i]))
                newStack.types[i] = types[i];
            else {
                if((!(types[i] instanceof ArrayType) && !(types[i] instanceof RefType)) || 
                    (!(other.types[i] instanceof RefType) && !(other.types[i] instanceof ArrayType)))
                {
                    throw new RuntimeException("TypeStack merging failed; incompatible types " + types[i] + " and " + other.types[i]);
                }

                // G.v().out.println("Merging: " + types[i] + " with " + other.types[i]);

                newStack.types[i] = RefType.v("java.lang.Object");
            }

        return newStack;
    }

    public void print(PrintStream out)
    {
        for(int i = types.length - 1; i >= 0; i--)
            out.println(i + ": " + types[i].toString());

        if(types.length == 0)
            out.println("<empty>");
    }
}