Grep1.java Source code

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Here is the source code for Grep1.java

Source

/*
 * Copyright (c) Ian F. Darwin, http://www.darwinsys.com/, 1996-2002.
 * All rights reserved. Software written by Ian F. Darwin and others.
 * $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
 *
 * Redistribution and use in source and binary forms, with or without
 * 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
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Java, the Duke mascot, and all variants of Sun's Java "steaming coffee
 * cup" logo are trademarks of Sun Microsystems. Sun's, and James Gosling's,
 * pioneering role in inventing and promulgating (and standardizing) the Java 
 * language and environment is gratefully acknowledged.
 * 
 * The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
 * inventing predecessor languages C and C++ is also gratefully acknowledged.
 */
import java.util.regex.*;
import java.io.*;

/** A command-line grep-like program. No options, but takes a pattern
 * and an arbitrary list of text files.
 */
public class Grep1 {
    /** The pattern we're looking for */
    protected Pattern pattern;
    /** The matcher for this pattern */
    protected Matcher matcher;

    /** Main will make a Grep object for the pattern, and run it
     * on all input files listed in argv.
     */
    public static void main(String[] argv) throws Exception {

        if (argv.length < 1) {
            System.err.println("Usage: Grep1 pattern [filename]");
            System.exit(1);
        }

        Grep1 pg = new Grep1(argv[0]);

        if (argv.length == 1)
            pg.process(new BufferedReader(new InputStreamReader(System.in)), "(standard input)", false);
        else
            for (int i = 1; i < argv.length; i++) {
                pg.process(new BufferedReader(new FileReader(argv[i])), argv[i], true);
            }
    }

    /** Construct a Grep1 program */
    public Grep1(String patt) {
        pattern = Pattern.compile(patt);
        matcher = pattern.matcher("");
    }

    /** Do the work of scanning one file
     * @param ifile BufferedReader object already open
     * @param fileName String Name of the input file
     * @param printFileName Boolean - true to print filename
     * before lines that match.
     */
    public void process(BufferedReader inputFile, String fileName, boolean printFileName) {

        String inputLine;

        try {
            while ((inputLine = inputFile.readLine()) != null) {
                matcher.reset(inputLine);
                if (matcher.lookingAt()) {
                    if (printFileName) {
                        System.out.print(fileName + ": ");
                    }
                    System.out.println(inputLine);
                }
            }
            inputFile.close();
        } catch (IOException e) {
            System.err.println(e);
        }
    }
}