sunlabs.brazil.util.regexp

Class Regsub

public class Regsub extends Object

The Regsub class provides an iterator-like object to extract the matched and unmatched portions of a string with respect to a given regular expression.

After each match is found, the portions of the string already checked are not searched again -- searching for the next match will begin at the character just after where the last match ended.

Here is an example of using Regsub to replace all "%XX" sequences in a string with the ASCII character represented by the hex digits "XX":

 public static void
 main(String[] args)
     throws Exception
 {
     Regexp re = new Regexp("%[a-fA-F0-9][a-fA-F0-9]");
     Regsub rs = new Regsub(re, args[0]);

     StringBuffer sb = new StringBuffer();

     while (rs.nextMatch()) {
         sb.append(rs.skipped());

         String match = rs.matched();

         int hi = Character.digit(match.charAt(1), 16);
         int lo = Character.digit(match.charAt(2), 16);
         sb.append((char) ((hi << 4) | lo));
     }
     sb.append(rs.rest());

     System.out.println(sb);
 }

Version: 2.3

Author: Colin Stevens (colin.stevens@sun.com)

See Also: Regexp

Constructor Summary
	Regsub(Regexp r, String str) Construct a new `Regsub` that can be used to step through the given string, finding each substring that matches the given regular expression.

Method Summary
Regexp	getRegexp() Return the regexp used by this regsub.
String	matched() Returns a substring consisting of the characters that matched the entire regular expression during the last call to `nextMatch`.
boolean	nextMatch() Searches for the next substring that matches the regular expression.
String	rest() Returns a substring consisting of all the characters that come after the last match.
String	skipped() Returns a substring consisting of all the characters skipped between the end of the last match (or the start of the original search string) and the start of this match.
String	submatch(int i) Returns a substring consisting of the characters that matched the given parenthesized subexpression during the last call to `nextMatch`.

Constructor Detail

Regsub

public Regsub(Regexp r, String str)

Construct a new Regsub that can be used to step through the given string, finding each substring that matches the given regular expression.

Regexp contains two substitution methods, sub and subAll, that can be used instead of Regsub if just simple substitutions are being done.

Parameters: r The compiled regular expression. str The string to search.

See Also: Regexp Regexp

Method Detail

getRegexp

public Regexp getRegexp()

Return the regexp used by this regsub.

matched

public String matched()

Returns a substring consisting of the characters that matched the entire regular expression during the last call to nextMatch.

Returns: The characters that did match.

See Also: Regsub

nextMatch

public boolean nextMatch()

Searches for the next substring that matches the regular expression. After calling this method, the caller would call methods like skipped, matched, etc. to query attributes of the matched region.

Calling this function again will search for the next match, beginning at the character just after where the last match ended.

Returns: true if a match was found, false if there are no more matches.

rest

public String rest()

Returns a substring consisting of all the characters that come after the last match. As the matches progress, the rest gets shorter. When nextMatch returns false, then this method will return the rest of the string that can't be matched.

Returns: The rest of the characters after the last match.

skipped

public String skipped()

Returns a substring consisting of all the characters skipped between the end of the last match (or the start of the original search string) and the start of this match.

This method can be used extract all the portions of string that didn't match the regular expression.

Returns: The characters that didn't match.

submatch

public String submatch(int i)

Returns a substring consisting of the characters that matched the given parenthesized subexpression during the last call to nextMatch.

Parameters: i The index of the parenthesized subexpression.

Returns: The characters that matched the subexpression, or null if the given subexpression did not exist or did not match.