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Ant example source code file (LineContainsRegExp.java)

This example Ant source code file (LineContainsRegExp.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Ant tags/keywords

baseparamfilterreader, chainablereader, io, linecontainsregexp, linecontainsregexp, negate_key, parameter, reader, regexp, regularexpression, regularexpression, string, string, util, vector, vector

The LineContainsRegExp.java source code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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.apache.tools.ant.filters;

import java.io.IOException;
import java.io.Reader;
import java.util.Vector;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.types.Parameter;
import org.apache.tools.ant.types.RegularExpression;
import org.apache.tools.ant.util.regexp.Regexp;

/**
 * Filter which includes only those lines that contain the user-specified
 * regular expression matching strings.
 *
 * Example:
 * <pre><linecontainsregexp>
 *   <regexp pattern="foo*">
 * </linecontainsregexp></pre>
 *
 * Or:
 *
 * <pre><filterreader classname="org.apache.tools.ant.filters.LineContainsRegExp">
 *    <param type="regexp" value="foo*"/>
 * </filterreader></pre>
 *
 * This will fetch all those lines that contain the pattern <code>foo
 *
 */
public final class LineContainsRegExp
    extends BaseParamFilterReader
    implements ChainableReader {
    /** Parameter name for the regular expression to filter on. */
    private static final String REGEXP_KEY = "regexp";

    /** Parameter name for the words to filter on. */
    private static final String NEGATE_KEY = "negate";

    /** Vector that holds the expressions that input lines must contain. */
    private Vector regexps = new Vector();

    /**
     * Remaining line to be read from this filter, or <code>null if
     * the next call to <code>read() should read the original stream
     * to find the next matching line.
     */
    private String line = null;

    private boolean negate = false;

    /**
     * Constructor for "dummy" instances.
     *
     * @see BaseFilterReader#BaseFilterReader()
     */
    public LineContainsRegExp() {
        super();
    }

    /**
     * Creates a new filtered reader.
     *
     * @param in A Reader object providing the underlying stream.
     *           Must not be <code>null.
     */
    public LineContainsRegExp(final Reader in) {
        super(in);
    }

    /**
     * Returns the next character in the filtered stream, only including
     * lines from the original stream which match all of the specified
     * regular expressions.
     *
     * @return the next character in the resulting stream, or -1
     * if the end of the resulting stream has been reached
     *
     * @exception IOException if the underlying stream throws an IOException
     * during reading
     */
    public int read() throws IOException {
        if (!getInitialized()) {
            initialize();
            setInitialized(true);
        }

        int ch = -1;

        if (line != null) {
            ch = line.charAt(0);
            if (line.length() == 1) {
                line = null;
            } else {
                line = line.substring(1);
            }
        } else {
            final int regexpsSize = regexps.size();

            for (line = readLine(); line != null; line = readLine()) {
                boolean matches = true;
                for (int i = 0; matches && i < regexpsSize; i++) {
                    RegularExpression regexp
                        = (RegularExpression) regexps.elementAt(i);
                    Regexp re = regexp.getRegexp(getProject());
                    matches = re.matches(line);
                }
                if (matches ^ isNegated()) {
                    break;
                }
            }
            if (line != null) {
                return read();
            }
        }
        return ch;
    }

    /**
     * Adds a <code>regexp element.
     *
     * @param regExp The <code>regexp element to add.
     *               Must not be <code>null.
     */
    public void addConfiguredRegexp(final RegularExpression regExp) {
        this.regexps.addElement(regExp);
    }

    /**
     * Sets the vector of regular expressions which must be contained within
     * a line read from the original stream in order for it to match this
     * filter.
     *
     * @param regexps A vector of regular expressions which must be contained
     * within a line in order for it to match in this filter. Must not be
     * <code>null.
     */
    private void setRegexps(final Vector regexps) {
        this.regexps = regexps;
    }

    /**
     * Returns the vector of regular expressions which must be contained within
     * a line read from the original stream in order for it to match this
     * filter.
     *
     * @return the vector of regular expressions which must be contained within
     * a line read from the original stream in order for it to match this
     * filter. The returned object is "live" - in other words, changes made to
     * the returned object are mirrored in the filter.
     */
    private Vector getRegexps() {
        return regexps;
    }

    /**
     * Creates a new LineContainsRegExp using the passed in
     * Reader for instantiation.
     *
     * @param rdr A Reader object providing the underlying stream.
     *            Must not be <code>null.
     *
     * @return a new filter based on this configuration, but filtering
     *         the specified reader
     */
    public Reader chain(final Reader rdr) {
        LineContainsRegExp newFilter = new LineContainsRegExp(rdr);
        newFilter.setRegexps(getRegexps());
        newFilter.setNegate(isNegated());
        return newFilter;
    }

    /**
     * Set the negation mode.  Default false (no negation).
     * @param b the boolean negation mode to set.
     */
    public void setNegate(boolean b) {
        negate = b;
    }

    /**
     * Find out whether we have been negated.
     * @return boolean negation flag.
     */
    public boolean isNegated() {
        return negate;
    }

    /**
     * Parses parameters to add user defined regular expressions.
     */
    private void initialize() {
        Parameter[] params = getParameters();
        if (params != null) {
            for (int i = 0; i < params.length; i++) {
                if (REGEXP_KEY.equals(params[i].getType())) {
                    String pattern = params[i].getValue();
                    RegularExpression regexp = new RegularExpression();
                    regexp.setPattern(pattern);
                    regexps.addElement(regexp);
                } else if (NEGATE_KEY.equals(params[i].getType())) {
                    setNegate(Project.toBoolean(params[i].getValue()));
                }
            }
        }
    }
}

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