Rule.java

/*
 * Copyright 2005 Red Hat, Inc. and/or its affiliates.
 *
 * 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.drools.template.model;

import java.util.LinkedList;
import java.util.List;

/**
 * Represents a rule.
 */
public class Rule extends AttributedDRLElement
        implements DRLJavaEmitter {

    public static final int MAX_ROWS = 65535;

    private String _name;
    private String _description;

    private List<String>      _metadata;
    private List<Condition>   _lhs;
    private List<Consequence> _rhs;
    private int               _spreadsheetRow;

    /**
     * Create a new rule. Note that the rule name should be post-fixed with the row number,
     * as one way of providing tracability for errors back to the originating spreadsheet.
     *
     * @param name           The name of the rule. This may be used to calculate DRL row error
     *                       to Spreadsheet row error (just need to keep track of output lines, and map spreadsheetRow to a start
     *                       and end range in the rendered output).
     * @param salience
     * @param spreadsheetRow The phyical row number from the spreadsheet.
     */
    public Rule(final String name,
                final Integer salience,
                final int spreadsheetRow) {
        super(salience);
        this._name = asStringLiteral(name);
        this._description = null;
        this._metadata = new LinkedList<String>();
        this._lhs = new LinkedList<Condition>();
        this._rhs = new LinkedList<Consequence>();
        this._spreadsheetRow = spreadsheetRow;
    }

    public void addMetadata(final String meta) {
        this._metadata.add(meta);
    }

    public void addCondition(final Condition con) {
        this._lhs.add(con);
    }

    public void addConsequence(final Consequence con) {
        this._rhs.add(con);
    }

    public void renderDRL(final DRLOutput out) {
        if (isCommented()) {
            out.writeLine("//" + getComment());
        }
        out.writeLine("rule " + this._name);
        if (this._description != null) {
            out.writeLine("\t// " + this._description);
        }

        // metadata
        for (String ms : this._metadata) {
            out.writeLine("\t@" + ms);
        }

        // attributes
        super.renderDRL(out);

        out.writeLine("\twhen");
        renderDRL(this._lhs, out);
        out.writeLine("\tthen");
        renderDRL(this._rhs, out);
        out.writeLine("end\n");
    }

    private void renderDRL(final List<? extends DRLJavaEmitter> list,
                           final DRLOutput out) {
        for (DRLJavaEmitter item : list) {
            item.renderDRL(out);
        }
    }

    public List<String> getMetadata() {
        return this._metadata;
    }

    public List<Condition> getConditions() {
        return this._lhs;
    }

    public List<Consequence> getConsequences() {
        return this._rhs;
    }

    public void setName(final String value) {
        this._name = asStringLiteral(value);
    }

    public String getName() {
        return this._name;
    }


    public void setDescription(final String value) {
        this._description = value;
    }

    public void appendDescription(final String value) {
        this._description += value;
    }


    /**
     * @return The row in the spreadsheet this represents.
     *         This can be handy when mapping a line error from Parser back to the rule row.
     *         Will need to have a map of ranges of line numbers that each rule covers.
     *         Then can find out the rule that cause it, and this will give the row number to report.
     */
    public int getSpreadsheetRowNumber() {
        return this._spreadsheetRow;
    }

}