/*
 * Copyright (c) 2003 The Visigoth Software Society. All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Visigoth Software Society (http://www.visigoths.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
 * 4. Neither the name "FreeMarker", "Visigoth", nor any of the names of the 
 *    project contributors may be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact visigoths@visigoths.org.
 *
 * 5. Products derived from this software may not be called "FreeMarker" or "Visigoth"
 *    nor may "FreeMarker" or "Visigoth" appear in their names
 *    without prior written permission of the Visigoth Software Society.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE VISIGOTH SOFTWARE SOCIETY OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Visigoth Software Society. For more
 * information on the Visigoth Software Society, please see
 * http://www.visigoths.org/
 */

package freemarker.core;

import freemarker.template.TemplateException;
import freemarker.template.TemplateModel;

/**
 * A reference to a top-level variable
 */
final class Identifier extends Expression {

    private final String name;

    Identifier(String name) {
        this.name = name;
    }

    TemplateModel _eval(Environment env) throws TemplateException {
        try {
            return env.getVariable(name);
        } catch (NullPointerException e) {
            if (env == null) {
                throw new _MiscTemplateException(new Object[] {
                        "Variables are not available (certainly you are in a parse-time executed directive). "
                        + "The name of the variable you tried to read: ", name });
            } else {
                throw e;
            }
        }
    }

    public String toString() {
        return name;
    }

    public String getCanonicalForm() {
        return name;
    }
    
    String getNodeTypeSymbol() {
        return getCanonicalForm();
    }

    boolean isLiteral() {
        return false;
    }
    
    int getParameterCount() {
        return 0;
    }

    Object getParameterValue(int idx) {
        throw new IndexOutOfBoundsException();
    }

    ParameterRole getParameterRole(int idx) {
        throw new IndexOutOfBoundsException();
    }

    protected Expression deepCloneWithIdentifierReplaced_inner(
            String replacedIdentifier, Expression replacement, ReplacemenetState replacementState) {
        if(this.name.equals(replacedIdentifier)) {
            if (replacementState.replacementAlreadyInUse) {
                Expression clone = replacement.deepCloneWithIdentifierReplaced(null, null, replacementState);
                clone.copyLocationFrom(replacement);
                return clone;
            } else {
                replacementState.replacementAlreadyInUse = true;
                return replacement;
            }
        } else {
            return new Identifier(this.name);
        }
    }

}