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package com.sun.el;

import java.util.Map;
import java.util.HashMap;
import java.lang.reflect.Method;

import javax.el.ELContext;
import javax.el.ELException;
import javax.el.ExpressionFactory;
import javax.el.MethodExpression;
import javax.el.ValueExpression;
import javax.el.ELResolver;

import com.sun.el.lang.ExpressionBuilder;
import com.sun.el.lang.ELSupport;
import com.sun.el.util.MessageFactory;
import com.sun.el.stream.StreamELResolver;

/**
 * @see javax.el.ExpressionFactory
 * 
 * @author Jacob Hookom [jacob@hookom.net]
 * @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: kchung $
 */
public class ExpressionFactoryImpl extends ExpressionFactory {

    /**
     * 
     */
    public ExpressionFactoryImpl() {
        super();
    }

    public Object coerceToType(Object obj, Class type) {
        Object ret;
        try {
            ret = ELSupport.coerceToType(obj, type);
        } catch (IllegalArgumentException ex) {
            throw new ELException(ex);
        }
        return ret;
    }

    public MethodExpression createMethodExpression(ELContext context,
            String expression, Class expectedReturnType,
            Class[] expectedParamTypes) {
        ExpressionBuilder builder = new ExpressionBuilder(expression, context);
        MethodExpression me = builder.createMethodExpression(expectedReturnType,
                expectedParamTypes);
        if (expectedParamTypes == null && !me.isParametersProvided()) {
            throw new NullPointerException(MessageFactory
                    .get("error.method.nullParms"));
        }
        return me;
    }

    public ValueExpression createValueExpression(ELContext context,
            String expression, Class expectedType) {
        if (expectedType == null) {
            throw new NullPointerException(MessageFactory
                    .get("error.value.expectedType"));
        }
        ExpressionBuilder builder = new ExpressionBuilder(expression, context);
        return builder.createValueExpression(expectedType);
    }

    public ValueExpression createValueExpression(Object instance,
            Class expectedType) {
        if (expectedType == null) {
            throw new NullPointerException(MessageFactory
                    .get("error.value.expectedType"));
        }
        return new ValueExpressionLiteral(instance, expectedType);
    }

    @Override
    public ELResolver getStreamELResolver() {
        return new StreamELResolver();
    }

    @Override
    public Map<String, Method> getInitFunctionMap() {
        Map<String, Method> funcs = new HashMap<String, Method>();
/*
        Class<Generation> genClass = Generation.class;
        try {
            funcs.put("collections:range", genClass.getMethod("range",
                    new Class<?>[] {Integer.TYPE, Integer.TYPE}));
            funcs.put("collections:repeat", genClass.getMethod("repeat",
                    new Class<?>[] {Object.class, Integer.TYPE}));
        } catch (NoSuchMethodException ex) {
            // Should not happen
        }
*/
        return funcs;
    }
}
