net.haefelingerit.tagmod
Class Parser

java.lang.Object
  net.haefelingerit.tagmod.Parser

public class Parser
extends Object

This class implements a parser to analyze a log file containing tag operations.

The format of the file is rather simple:

• The file must be line based.
• Lines other than those starting with 0x1 are ignored.
• 0x1 lines must match the following format:

   0x1 p=".." o=".." t=".." D=".." U=".."
   

  where .. contains any character sequence other than ". In addition, field D must match time format YYYY-MM-DD HH:MM:SS UTC.

• Leading and trailing whitespace as well as whitespace between the fields are ignored.
• Lines must be in reverse chronological order, i.e. most recent event is the first 0x1 line, the oldest event is the last 0x1 line in the file.

The following example shows such a line

 0x1 p="foo/bar" o="add" t="r-1.0" D="2008-12-20 
 13:29:43 UTC" U="alibaba"
 

The following code snippet shows a typical usage pattern of this class:

    parser.open(file);
    while (parser.advance())
      if (parser.match(last, now)) {
         // do something with parser.m 
      }
    parser.close();
 

Author:

geronimo

Field Summary

protected boolean	cont A flag to indicate whether it makes sense to read further.
protected String	line The current line - or null if no line has been read so far.
protected int	lineno The current line.
protected Matcher	m A line matcher.
protected String	pname The project name.
protected String	re_tagaction The regular expression to match tag actions.
protected String	re_tagvalue The regular expression to match tag values.
protected BufferedReader	reader The underlying text stream
protected Pattern	regex The overall regular expression a line must comply to.
protected SimpleDateFormat	sdf The standard date format.

Constructor Summary

Parser()

Method Summary

boolean	advance() Digest on further line from the log file.
void	close() Tell the parser to close the underlying reader.
protected boolean	match(Date last, Date now) Checks whether the current line matches.
protected Date	mkdate(String s) A helper method to translate a date string into a date object.
void	open(File file) Tell this parser to use this file for reading.
static String	quote(String s) A helper method similar to Pattern.quote(String) found in Java 5.
void	reset() A method to reset the parser in its initial state.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

lineno

protected int lineno

The current line.

cont

protected boolean cont

A flag to indicate whether it makes sense to read further.

reader

protected BufferedReader reader

The underlying text stream

line

protected String line

The current line - or null if no line has been read so far.

sdf

protected SimpleDateFormat sdf

The standard date format.

m

protected Matcher m

A line matcher. Use this matcher to retrieve individual fields.

re_tagaction

protected String re_tagaction

The regular expression to match tag actions.

re_tagvalue

protected String re_tagvalue

The regular expression to match tag values.

pname

protected String pname

The project name.

regex

protected Pattern regex

The overall regular expression a line must comply to.

Constructor Detail

Parser

public Parser()

Method Detail

reset

public void reset()
           throws Exception

A method to reset the parser in its initial state.

Throws:

Exception

quote

public static String quote(String s)

A helper method similar to Pattern.quote(String) found in Java 5. In fact this method exists only to be Java 1.4 compatible.

advance

public boolean advance()
                throws IOException

Digest on further line from the log file.

Returns:

true if reading on further line was successful.

Throws:

IOException - if reading underlying reader or stream is not possible.

open

public void open(File file)

Tell this parser to use this file for reading. If opening is not possible an error is written to the log stream.

Parameters:

file - not null

close

public void close()

Tell the parser to close the underlying reader.

mkdate

protected Date mkdate(String s)

A helper method to translate a date string into a date object. The format of the date string is expected to be YYYY-MM-DD HH:MM:SS UTC. If translation is not possible, null is returned.

Parameters:

s - not null

match

protected boolean match(Date last,
                        Date now)

Checks whether the current line matches.