Mega Code Archive
A command-line grep-like program
<![CDATA[
/*
* 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); }
}
}
]]>