de.topicmapslab.jexc.eXql.grammar.expression.FromExpression.java Source code

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Here is the source code for de.topicmapslab.jexc.eXql.grammar.expression.FromExpression.java

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/*******************************************************************************
 * Copyright 2010, Topic Map Lab ( http://www.topicmapslab.de )
 * 
 * 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 de.topicmapslab.jexc.eXql.grammar.expression;

import java.util.Collection;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;

import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;

import de.topicmapslab.jexc.eXql.grammar.tokens.Comma;
import de.topicmapslab.jexc.eXql.grammar.tokens.ExqlToken;
import de.topicmapslab.jexc.eXql.grammar.tokens.ExqlTokens;
import de.topicmapslab.jexc.eXql.grammar.tokens.Last;
import de.topicmapslab.jexc.eXql.grammar.tokens.RoundBracketClose;
import de.topicmapslab.jexc.eXql.grammar.tokens.RoundBracketOpen;
import de.topicmapslab.jexc.eXql.grammar.tokens.To;
import de.topicmapslab.jexc.eXql.parser.ExqlParser;
import de.topicmapslab.jexc.eXql.parser.IeXqlParserCallback;
import de.topicmapslab.jexc.exception.JeXcException;

/**
 * @author Sven Krosse
 * 
 */
public class FromExpression extends ExqlExpression {

    /**
     * constructor
     * 
     * @param tokens
     *            the tokens
     */
    @SuppressWarnings("unchecked")
    public FromExpression(List<ExqlToken> tokens) throws JeXcException {
        super(tokens);

        IeXqlParserCallback callback = new IeXqlParserCallback() {

            int numberOfExpression = 0;

            public void newToken(List<ExqlToken> tokens, ExqlToken foundDelimer) throws JeXcException {
                /*
                 * ignore sheet name
                 */
                if (numberOfExpression > 0) {
                    addExpression(new ValueExpression(tokens));
                }
                numberOfExpression++;
            }
        };
        ExqlParser.parse(callback, tokens, true, RoundBracketClose.class, RoundBracketOpen.class, To.class,
                Comma.class);
    }

    /**
     * {@inheritDoc}
     */
    public Collection<Row> interpret(Workbook workBook, Object... input) throws JeXcException {
        /*
         * get sheet by name
         */
        String sheetName = getTokens().get(1).token();
        if (sheetName.startsWith("\"")) {
            sheetName = sheetName.substring(1, sheetName.length() - 1);
        }
        Sheet sheet = workBook.getSheet(sheetName);
        if (sheet == null) {
            return Collections.emptyList();
        }
        Collection<Row> rows = new LinkedList<Row>();
        /*
         * is a TO b syntax
         */
        if (containsToken(ExqlTokens.tokenInstance(To.TOKEN))) {
            if (getNumberOfExpressions() != 2) {
                throw new JeXcException(
                        "Invalid number of numeric indexes by using the keyword 'TO'! Expected 2 but was "
                                + getNumberOfExpressions() + ".");
            }
            int from = Integer.parseInt(getExpressions().get(0).getTokens().get(0).token());
            int to;
            ExqlToken token = getExpressions().get(1).getTokens().get(0);
            if (token instanceof Last) {
                to = sheet.getLastRowNum();
            } else {
                to = Integer.parseInt(token.token());
            }
            for (int i = from; i <= to; i++) {
                Row row = sheet.getRow(i);
                /*
                 * ignore non existing cells
                 */
                if (row == null) {
                    continue;
                }
                rows.add(row);
            }
        }
        /*
         * is index syntax
         */
        else {
            for (ExqlExpression e : getExpressions()) {
                int index = Integer.parseInt(e.getTokens().get(0).token());
                Row row = sheet.getRow(index);
                /*
                 * ignore non existing cells
                 */
                if (row == null) {
                    continue;
                }
                rows.add(row);
            }
        }
        return rows;
    }

}