/*
 * Copyright 2014 Attila Szegedi, Daniel Dekany, Jonathan Revusky
 * 
 * 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 freemarker.core;

import freemarker.template.TemplateException;

/**
 * Represents a <stop> instruction to abort template processing.
 */
final class StopInstruction extends TemplateElement {

    private Expression exp;

    StopInstruction(Expression exp) {
        this.exp = exp;
    }

    @Override
    void accept(Environment env) throws TemplateException {
        if (exp == null) {
            throw new StopException(env);
        }
        throw new StopException(env, exp.evalAndCoerceToString(env));
    }

    @Override
    protected String dump(boolean canonical) {
        StringBuilder sb = new StringBuilder();
        if (canonical) sb.append('<');
        sb.append(getNodeTypeSymbol());
        if (exp != null) {
            sb.append(' ');
            sb.append(exp.getCanonicalForm());
        }
        if (canonical) sb.append("/>");
        return sb.toString();
    }
    
    @Override
    String getNodeTypeSymbol() {
        return "#stop";
    }
    
    @Override
    int getParameterCount() {
        return 1;
    }

    @Override
    Object getParameterValue(int idx) {
        if (idx != 0) throw new IndexOutOfBoundsException();
        return exp;
    }

    @Override
    ParameterRole getParameterRole(int idx) {
        if (idx != 0) throw new IndexOutOfBoundsException();
        return ParameterRole.MESSAGE;
    }

    @Override
    boolean isNestedBlockRepeater() {
        return false;
    }
    
}