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Grep2.javaAPI DocExample4222Thu Mar 25 20:49:22 GMT 2004None

Grep2

public class Grep2 extends Object
A command-line grep-like program. Accepts some command-line options, and takes a pattern and a list of text files.

Fields Summary
protected Pattern
pattern
The pattern we're looking for
protected Matcher
matcher
The matcher for this pattern
protected BufferedReader
d
The Reader for the current file
protected boolean
countOnly
Are we to only count lines, instead of printing?
protected boolean
ignoreCase
Are we to ignore case?
protected boolean
dontPrintFileName
Are we to suppress printing of filenames?
protected boolean
listOnly
Are we to only list names of files that match?
protected boolean
numbered
are we to print line numbers?
protected boolean
silent
Are we to be silent about errors?
protected boolean
inVert
are we to print only lines that DONT match?
Constructors Summary
public Grep2(String patt, BitSet args)
Construct a Grep2 object.

param
patt The pattern to look for
param
args the command-line options.

		// compile the regular expression
		if (args.get('C"))
			countOnly = true;
		if (args.get('H"))
			dontPrintFileName = true;
		if (args.get('I"))
			ignoreCase = true;
		if (args.get('L"))
			listOnly = true;
		if (args.get('N"))
			numbered = true;
		if (args.get('S"))
			silent = true;
		if (args.get('V"))
			inVert = true;
		int caseMode = ignoreCase ?
			Pattern.UNICODE_CASE | Pattern.CASE_INSENSITIVE :
			0;
		pattern = Pattern.compile(patt, caseMode);
		matcher = pattern.matcher("");
Methods Summary
public static voidmain(java.lang.String[] argv)
Construct a Grep2 object for each pattern, and run it on all input files listed in argv. Be aware that a few of the command-line options are not acted upon in this version - this is an exercise for the reader!


	                                         	 
	     

		if (argv.length < 1) {
		    System.err.println(
			"Usage: Grep2 pattern [-chilsnv][-f pattfile][filename...]");
		    System.exit(1);
		}
		String patt = null;

		GetOpt go = new GetOpt("cf:hilnsv");
		BitSet args = new BitSet();

		char c;
		while ((c = go.getopt(argv)) != 0) {
			switch(c) {
				case 'c":
					args.set('C");
					break;
				case 'f":
					try {
						BufferedReader b = new BufferedReader(new FileReader(go.optarg()));
						patt = b.readLine();
						b.close();
					} catch (IOException e) {
						System.err.println("Can't read pattern file " + go.optarg());
						System.exit(1);
					}
					break;
				case 'h":
					args.set('H");
					break;
				case 'i":
					args.set('I");
					break;
				case 'l":
					args.set('L");
					break;
				case 'n":
					args.set('N");
					break;
				case 's":
					args.set('S");
					break;
				case 'v":
					args.set('V");
					break;
			}
		}

		int ix = go.getOptInd();

		if (patt == null)
			patt = argv[ix];

		Grep2 pg = null;
		try {
			pg = new Grep2(patt, args);
		} catch (PatternSyntaxException ex) {
			System.err.println("RE Syntax error in " + patt);
			return;
		}

		if (argv.length == ix)
			pg.process(new InputStreamReader(System.in), "(standard input)");
		else
			for (int i=ix; i<argv.length; i++) {
				try {
					pg.process(new FileReader(argv[i]), argv[i]);
				} catch(Exception e) {
					System.err.println(e);
				}
			}
public voidprocess(java.io.Reader ifile, java.lang.String fileName)
Do the work of scanning one file

param
ifile Reader Reader object already open
param
fileName String Name of the input file


		String inputLine;
		int matches = 0;

		try {
			d = new BufferedReader(ifile);
		    
			while ((inputLine = d.readLine()) != null) {
				matcher.reset(inputLine);
				if (matcher.lookingAt()) {
					if (countOnly)
						matches++;
					else {
					if (!dontPrintFileName)
						System.out.print(fileName + ": ");
					System.out.println(inputLine);
					}
				} else if (inVert) {
					System.out.println(inputLine);
				}
			}
			if (countOnly)
				System.out.println(matches + " matches in " + fileName);
			d.close();
		} catch (IOException e) { System.err.println(e); }