constant.java

来自「JXPath」· Java 代码 · 共 78 行

/*
 * Copyright 1999-2004 The Apache Software Foundation
 *
 * Licensed 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.commons.jxpath.ri.compiler;

import org.apache.commons.jxpath.ri.EvalContext;

/**
 * A compile tree element containing a constant number or string.
 *
 * @author Dmitri Plotnikov
 * @version $Revision: 1.8 $ $Date: 2004/02/29 14:17:39 $
 */
public class Constant extends Expression {

    private Object value;

    public Constant(Number number) {
        this.value = number;
    }

    public Constant(String string) {
        this.value = string;
    }

    public Object compute(EvalContext context) {
        return value;
    }

    /**
     * Returns the value of the constant.
     */
    public Object computeValue(EvalContext context) {
        return value;
    }

    /**
     * Returns false
     */
    public boolean isContextDependent() {
        return false;
    }

    /**
     * Returns false
     */
    public boolean computeContextDependent() {
        return false;
    }

    public String toString() {
        if (value instanceof Number) {
            double doubleValue = ((Number) value).doubleValue();
            long longValue = ((Number) value).longValue();
            if (doubleValue == longValue) {
                return String.valueOf(longValue);
            }
            else {
                return String.valueOf(doubleValue);
            }
        }
        else {
            return "'" + value + "'";
        }
    }
}