FunctionUtils.java

/**
 *  Copyright (C) 2010 dennis zhuang (killme2008@gmail.com)
 *
 *  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 program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 **/
package com.googlecode.aviator.runtime.function;

import java.util.Map;

import com.googlecode.aviator.AviatorEvaluator;
import com.googlecode.aviator.exception.ExpressionRuntimeException;
import com.googlecode.aviator.runtime.type.AviatorFunction;
import com.googlecode.aviator.runtime.type.AviatorJavaType;
import com.googlecode.aviator.runtime.type.AviatorObject;
import com.googlecode.aviator.runtime.type.AviatorRuntimeJavaType;
import com.googlecode.aviator.runtime.type.AviatorType;


/**
 * Function helper
 * 
 * @author dennis
 * 
 */
public class FunctionUtils {

    public static final String getStringValue(AviatorObject arg, Map<String, Object> env) {
        String result = null;

        final Object value = arg.getValue(env);
        if (value == null && arg.getAviatorType() == AviatorType.JavaType) {
            throw new NullPointerException("There is no string named" + ((AviatorJavaType) arg).getName());
        }
        if (value instanceof Character) {
            result = value.toString();
        }
        else {
            result = (String) value;
        }
        return result;
    }


    public static Object getJavaObject(AviatorObject arg, Map<String, Object> env) {
        if (arg.getAviatorType() != AviatorType.JavaType) {
            throw new ExpressionRuntimeException(arg.desc(env) + " is not a javaType");
        }
        return env.get(((AviatorJavaType) arg).getName());
    }


    public static AviatorFunction getFunction(AviatorObject arg, Map<String, Object> env, int arity) {
        if (arg.getAviatorType() != AviatorType.JavaType) {
            throw new ExpressionRuntimeException(arg.desc(env) + " is not a function");
        }
        // Runtime type.
        if (arg instanceof AviatorRuntimeJavaType && arg.getValue(env) instanceof AviatorFunction) {
            return (AviatorFunction) arg.getValue(env);
        }
        // resolve by name.
        // special processing for "-" operator
        String name = ((AviatorJavaType) arg).getName();
        if (name.equals("-")) {
            if (arity == 2) {
                name = "-sub";
            }
            else {
                name = "-neg";
            }
        }
        AviatorFunction rt = null;
        if (env != null) {
            rt = (AviatorFunction) env.get(name);
        }
        if (rt == null) {
            rt = AviatorEvaluator.getFunction(name);
        }
        return rt;
    }


    public static final Number getNumberValue(AviatorObject arg1, Map<String, Object> env) {
        return (Number) arg1.getValue(env);
    }

}