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Grep2.javaAPI DocExample3810Tue Oct 09 15:27:12 BST 2001None

Grep2

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

Fields Summary
protected RE
pattern
The pattern we're looking for
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 print 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 bout errors?
protected boolean
inVert
are we to print only lines that DONT match?
Constructors Summary
public Grep2(String arg, BitSet args)

		// 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?RE.MATCH_CASEINDEPENDENT:RE.MATCH_NORMAL;
		pattern = new RE(arg, caseMode);
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 pattern = 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()));
						pattern = 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 (pattern == null)
			pattern = argv[ix-1];

		Grep2 pg = new Grep2(pattern, args);

		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 line;
		int matches = 0;

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