JXTExpression.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.cocoon.template.expression;

import java.util.Iterator;

import org.apache.cocoon.components.expression.Expression;
import org.apache.cocoon.components.expression.ExpressionContext;
import org.apache.cocoon.components.expression.jxpath.JXPathExpression;

/**
 * @version $Id$
 */
public class JXTExpression extends Subst {

    private String raw;
    private Object compiledExpression;

    public JXTExpression(String raw, Object expr) {
        this.raw = raw;
        this.compiledExpression = expr;
    }

    public Object getCompiledExpression() {
        return compiledExpression;
    }

    public void setCompiledExpression(Object compiledExpression) {
        this.compiledExpression = compiledExpression;
    }

    public String getRaw() {
        return raw;
    }

    // Geting the value of the expression in various forms

    // Hack: try to prevent JXPath from converting result to a String
    public Object getNode(ExpressionContext expressionContext)
        throws Exception {
        Object compiled = this.getCompiledExpression();
        if (compiled instanceof Expression)
            return ((Expression)compiled).getNode(expressionContext);
        return this.getRaw();
    }

    public Iterator getIterator(ExpressionContext expressionContext)
        throws Exception {
        Iterator iter = null;
        if (this.getCompiledExpression() != null || this.getRaw() != null) {
            if (this.getCompiledExpression() instanceof Expression) {
                iter =
                    ((Expression)this.getCompiledExpression()).iterate(expressionContext);
            } else {
                // literal value
                iter = new Iterator() {
                        Object val = this;
                        
                        public boolean hasNext() {
                            return val != null;
                        }
                        
                        public Object next() {
                            Object res = val;
                            val = null;
                            return res;
                        }
                        
                        public void remove() {
                            // EMPTY
                        }
                    };
            }
        } else {
            iter = NULL_ITER;
        }
        return iter;
    }

    public Boolean getBooleanValue(ExpressionContext expressionContext)
        throws Exception {
        Object res = getValue(expressionContext);
        return res instanceof Boolean ? (Boolean)res : null;
    }

    public String getStringValue(ExpressionContext expressionContext)
        throws Exception {
        Object res = getValue(expressionContext);
        if (res != null) {
            return res.toString();
        }
        if (this.getCompiledExpression() == null) {
            return this.getRaw();
        }
        return null;
    }

    public Number getNumberValue(ExpressionContext expressionContext)
        throws Exception {
        Object res = getValue(expressionContext);
        if (res instanceof Number) {
            return (Number)res;
        }
        if (res != null) {
            return Double.valueOf(res.toString());
        }
        return null;
    }

    public int getIntValue(ExpressionContext expressionContext)
        throws Exception {
        Object res = getValue(expressionContext);
        return res instanceof Number ? ((Number)res).intValue() : 0;
    }

    public Object getValue(ExpressionContext expressionContext)
        throws Exception {
        if (this.getCompiledExpression() != null) {
            Object compiled = this.getCompiledExpression();
            if (compiled instanceof Expression)
                return ((Expression)compiled).evaluate(expressionContext);
            else
                return compiled;
        } else
            return this.getRaw();
    }

    public void setLenient(Boolean lenient) {
        if (this.compiledExpression instanceof Expression)
            //TODO: hack! bases on particular expression implementation.
            ((Expression)this.compiledExpression).setProperty(JXPathExpression.LENIENT, lenient);
    }

    public static final Iterator EMPTY_ITER = new Iterator() {
        public boolean hasNext() {
            return false;
        }

        public Object next() {
            return null;
        }

        public void remove() {
            // EMPTY
        }
    };

    static public final Iterator NULL_ITER = new Iterator() {
        public boolean hasNext() {
            return true;
        }

        public Object next() {
            return null;
        }

        public void remove() {
            // EMPTY
        }
    };
}