utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ModuleListener.java

/*
 * Copyright 2016 Open Networking Laboratory
 *
 * 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.onosproject.yangutils.parser.impl.listeners;

import org.onosproject.yangutils.datamodel.YangModule;
import org.onosproject.yangutils.parser.ParsableDataType;
import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
import org.onosproject.yangutils.parser.exceptions.ParserException;
import org.onosproject.yangutils.parser.impl.TreeWalkListener;
import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;

/*
 * Reference: RFC6020 and YANG ANTLR Grammar
 *
 * ABNF grammar as per RFC6020
 * module-stmt         = optsep module-keyword sep identifier-arg-str
 *                       optsep
 *                       "{" stmtsep
 *                           module-header-stmts
 *                           linkage-stmts
 *                           meta-stmts
 *                           revision-stmts
 *                           body-stmts
 *                       "}" optsep
 *
 * ANTLR grammar rule
 * module_stmt : MODULE_KEYWORD IDENTIFIER LEFT_CURLY_BRACE module_body* RIGHT_CURLY_BRACE;
 */

/**
 * Implements listener based call back function corresponding to the "module"
 * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
 */
public final class ModuleListener {

    /**
     * Creates a new module listener.
     */
    private ModuleListener() {
    }

    /**
     * It is called when parser receives an input matching the grammar
     * rule (module), perform validations and update the data model
     * tree.
     *
     * @param listener Listener's object.
     * @param ctx context object of the grammar rule.
     */
    public static void processModuleEntry(TreeWalkListener listener, GeneratedYangParser.ModuleStatementContext ctx) {

        // Check if stack is empty.
        ListenerValidation
                .checkStackIsEmpty(listener, ListenerErrorType.INVALID_HOLDER, ParsableDataType.MODULE_DATA,
                                   String.valueOf(ctx.IDENTIFIER().getText()), ListenerErrorLocation.ENTRY);

        YangModule yangModule = new YangModule();
        yangModule.setName(ctx.IDENTIFIER().getText());

        listener.getParsedDataStack().push(yangModule);
    }

    /**
     * It is called when parser exits from grammar rule (module), it perform
     * validations and update the data model tree.
     *
     * @param listener Listener's object.
     * @param ctx context object of the grammar rule.
     */
    public static void processModuleExit(TreeWalkListener listener, GeneratedYangParser.ModuleStatementContext ctx) {

        // Check for stack to be non empty.
        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
                                                ParsableDataType.MODULE_DATA,
                                                String.valueOf(ctx.IDENTIFIER().getText()),
                                                ListenerErrorLocation.EXIT);

        if (!(listener.getParsedDataStack().peek() instanceof YangModule)) {
            throw new ParserException(
                                      ListenerErrorMessageConstruction
                                              .constructListenerErrorMessage(ListenerErrorType.MISSING_CURRENT_HOLDER,
                                                                             ParsableDataType.MODULE_DATA, String
                                                                                     .valueOf(ctx.IDENTIFIER()
                                                                                             .getText()),
                                                                             ListenerErrorLocation.EXIT));
        }
    }
}