gstringexpression.java

大名鼎鼎的java动态脚本语言。已经通过了sun的认证

/*
 $Id: GStringExpression.java,v 1.15 2006/01/19 00:06:51 blackdrag Exp $

 Copyright 2003 (C) James Strachan and Bob Mcwhirter. All Rights Reserved.

 Redistribution and use of this software and associated documentation
 ("Software"), with or without modification, are permitted provided
 that the following conditions are met:

 1. Redistributions of source code must retain copyright
    statements and notices.  Redistributions must also contain a
    copy of this document.

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    above copyright notice, this list of conditions and the
    following disclaimer in the documentation and/or other
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 3. The name "groovy" must not be used to endorse or promote
    products derived from this Software without prior written
    permission of The Codehaus.  For written permission,
    please contact [e-mail].

 4. Products derived from this Software may not be called "groovy"
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    permission of The Codehaus. "groovy" is a registered
    trademark of The Codehaus.

 5. Due credit should be given to The Codehaus -
    http://groovy.codehaus.org/

 THIS SOFTWARE IS PROVIDED BY THE CODEHAUS AND CONTRIBUTORS
 ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
 NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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package org.codehaus.groovy.ast.expr;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.codehaus.groovy.ast.ClassHelper;
import org.codehaus.groovy.ast.GroovyCodeVisitor;

/**
 * Represents a String expression which contains embedded values inside
 * it such as "hello there ${user} how are you" which is expanded lazily
 * 
 * @author <a href="mailto:[e-mail]">James Strachan</a>
 * @version $Revision: 1.15 $
 */
public class GStringExpression extends Expression {

    private String verbatimText;
    private List strings = new ArrayList();
    private List values = new ArrayList();
    
    public GStringExpression(String verbatimText) {
        this.verbatimText = verbatimText;
        super.setType(ClassHelper.GSTRING_TYPE);
    }

    public GStringExpression(String verbatimText, List strings, List values) {
        this.verbatimText = verbatimText;
        this.strings = strings;
        this.values = values;
        super.setType(ClassHelper.GSTRING_TYPE);
    }

    public void visit(GroovyCodeVisitor visitor) {
        visitor.visitGStringExpression(this);
    }

    public Expression transformExpression(ExpressionTransformer transformer) {
        Expression ret = new GStringExpression(
                verbatimText,
                transformExpressions(strings, transformer),
                transformExpressions(values, transformer));
        ret.setSourcePosition(this);
        return ret;        
    }

    public String toString() {
        return super.toString() + "[strings: " + strings + " values: " + values + "]";
    }

    public String getText() {
        return verbatimText;
    }

    public List getStrings() {
        return strings;
    }

    public List getValues() {
        return values;
    }

    public void addString(ConstantExpression text) {
        if (text == null) {
            throw new NullPointerException("Cannot add a null text expression");
        }
        strings.add(text);
    }

    public void addValue(Expression value) {
        // If the first thing is an value, then we need a dummy empty string in front of it so that when we
        // toString it they come out in the correct order.
        if (strings.size() == 0)
            strings.add(ConstantExpression.EMPTY_STRING);
        values.add(value);
    }

    public Expression getValue(int idx) {
        return (Expression) values.get(idx);
    }

    public boolean isConstantString() {
        return values.isEmpty();
    }

    public Expression asConstantString() {
        StringBuffer buffer = new StringBuffer();
        for (Iterator iter = strings.iterator(); iter.hasNext();) {
            ConstantExpression expression = (ConstantExpression) iter.next();
            Object value = expression.getValue();
            if (value != null) {
                buffer.append(value);
            }
        }
        return new ConstantExpression(buffer.toString());
    }
}