proposal/sandbox/filterreaders/src/main/org/apache/tools/ant/filters/LineContainsRegExp.java

/*
 *  The Apache Software License, Version 1.1
 *
 *  Copyright (c) 2002 The Apache Software Foundation.  All rights
 *  reserved.
 *
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 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *  notice, this list of conditions and the following disclaimer.
 *
 *  2. Redistributions in binary form must reproduce the above copyright
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 *  the documentation and/or other materials provided with the
 *  distribution.
 *
 *  3. The end-user documentation included with the redistribution, if
 *  any, must include the following acknowlegement:
 *  "This product includes software developed by the
 *  Apache Software Foundation (http://www.apache.org/)."
 *  Alternately, this acknowlegement may appear in the software itself,
 *  if and wherever such third-party acknowlegements normally appear.
 *
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 *  OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 *  ====================================================================
 *
 *  This software consists of voluntary contributions made by many
 *  individuals on behalf of the Apache Software Foundation.  For more
 *  information on the Apache Software Foundation, please see
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package org.apache.tools.ant.filters;

import java.io.IOException;
import java.io.Reader;
import java.util.Vector;

import org.apache.tools.ant.types.Parameter;
import org.apache.tools.ant.types.RegularExpression;
import org.apache.tools.ant.util.regexp.Regexp;

/**
 * Filter Reader to fetch only those lines that contain user specified
 * regular expression matching strings.
 *
 * Example:
 * =======
 *
 * &lt;linecontainsregexp&gt;
 *   &lt;regexp pattern=&quot;foo*&quot;&gt;
 * &lt;/linecontainsregexp&gt;
 *
 * Or:
 *
 * &lt;filterreader classname=&quot;org.apache.tools.ant.filters.LineContainsRegExp&quot;&gt;
 *    &lt;param type=&quot;regexp&quot; value=&quot;foo*&quot;/&gt;
 * &lt;/filterreader&gt;
 *
 * This will fetch all those lines that contain the pattern foo
 *
 * @author <a href="mailto:umagesh@apache.org">Magesh Umasankar</a>
 */
public final class LineContainsRegExp
    extends BaseParamFilterReader
    implements ChainableReader
{
    /** contains key */
    private static final String REGEXP_KEY = "regexp";

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

    /** Currently read in line. */
    private String line = null;

    /**
     * This constructor is a dummy constructor and is
     * not meant to be used by any class other than Ant's
     * introspection mechanism. This will close the filter
     * that is created making it useless for further operations.
     */
    public LineContainsRegExp() {
        super();
    }

    /**
     * Create a new filtered reader.
     *
     * @param in  a Reader object providing the underlying stream.
     */
    public LineContainsRegExp(final Reader in) {
        super(in);
    }

    /**
     * Choose only those lines that contains
     * user defined values.
     */
    public final 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 {
            line = readLine();
            if (line == null) {
                ch = -1;
            } else {
                final int regexpsSize = regexps.size();
                for (int i = 0; i < regexpsSize; i++) {
                    RegularExpression regexp = (RegularExpression)
                                                        regexps.elementAt(i);
                    Regexp re = regexp.getRegexp(getProject());
                    boolean matches = re.matches(line);
                    if (!matches) {
                        line = null;
                        break;
                    }
                }

                return read();
            }
        }

        return ch;
    }

    /**
     * Add a contains element.
     */
    public final void addConfiguredRegexp(final RegularExpression regExp) {
        this.regexps.addElement(regExp);
    }

    /**
     * Set regexps vector.
     */
    private void setRegexps(final Vector regexps) {
        this.regexps = regexps;
    }

    /**
     * Get regexps vector.
     */
    private final Vector getRegexps() {
        return regexps;
    }

    /**
     * Create a new LineContainsRegExp using the passed in
     * Reader for instantiation.
     */
    public final Reader chain(final Reader rdr) {
        LineContainsRegExp newFilter = new LineContainsRegExp(rdr);
        newFilter.setRegexps(getRegexps());
        newFilter.setInitialized(true);
        return newFilter;
    }

    /**
     * Parse params to add user defined contains strings.
     */
    private final 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);
                }
            }
        }
    }
}