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/*
 * Bytecode Analysis Framework
 * Copyright (C) 2003,2004 University of Maryland
 *
 * 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 edu.umd.cs.findbugs.ba.bcp;

/**
 * A set of Bindings, which are definitions of variables occurring in a
 * ByteCodePattern. BindingSets are immutable; to add a binding, a new cell is
 * allocated. (Are we CONSING yet?)
 *
 * @author David Hovemeyer
 * @see Binding
 */
public class BindingSet {
    private final Binding binding;

    private final BindingSet parent;

    /**
     * Constructor; creates a new BindingSet as an extension of an existing one.
     *
     * @param binding
     *            a variable binding
     * @param parent
     *            the parent BindingSet, containing other bindings
     */
    public BindingSet(Binding binding, BindingSet parent) {
        this.binding = binding;
        this.parent = parent;
    }

    /**
     * Look for a Binding for given variable.
     *
     * @param varName
     *            name of the variable
     * @return the Binding, or null if no such Binding is present in the set
     */
    public Binding lookup(String varName) {
        if (varName.equals(binding.getVarName())) {
            return binding;
        }
        return parent != null ? parent.lookup(varName) : null;
    }

    @Override
    public String toString() {
        StringBuilder buf = new StringBuilder();
        BindingSet cur = this;
        buf.append('[');
        while (cur != null) {
            if (cur != this) {
                buf.append(", ");
            }
            buf.append(cur.binding.toString());
            cur = cur.parent;
        }
        buf.append(']');
        return buf.toString();
    }
}