HashEnv.java

/*
 * Vitry, copyright (C) Hans Hoglund 2011
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * at your option) any later version.
 * 
 * This program 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * See COPYING.txt for details.
 */
package vitry.runtime;

import java.util.HashMap;

import vitry.runtime.error.BindingError;
import vitry.runtime.struct.Seq;
import vitry.runtime.struct.Seqs;


/**
 * Basic non-persistent environment.
 *
 * @author Hans Hoglund
 */
public class HashEnv<K, V> extends AbstractEnv<K, V>
{
    protected final HashMap<K, V> bindings = new HashMap<K, V>();

    public HashEnv() {
        super();
    }

    public HashEnv(Env<K, V> env) {
        super(env);
    }

    public Env<K, V> define(K key, V val) throws BindingError
    {
        if (this.hasBinding(key))
            throw new BindingError(key, this);
        bindings.put(key, val);
        return this;
    }

    public Env<K, V> extend(K key, V val)
    {
        return extend().define(key, val);
    }

    public Env<K, V> extend()
    {
        return new HashEnv<K, V>(this);
    }

    public V getBinding(K key)
    {
        return bindings.get(key);
    }

    public boolean hasBinding(K key)
    {
        return bindings.containsKey(key);
    }

    public boolean isPersistent()
    {
        return false;
    }

    public Env<K, V> assoc(K key, V val)
    {
        bindings.put(key, val);
        return this;
    }
}