almondtools / regexparser

A Parser for regular expressions

RegexParser

RegexParser is a handwritten parser for (deterministic) regular expressions. Deterministic means, that the regular expression language can be compiled to a deterministic finite automaton (note that the default java regular expressions are more powerful, but suffer from unpredictable runtime).

Not supported features are:

• backreferences
• lookaheads, lookbehinds
• variations of the Kleene star (greedy, reluctant, possessive)

Syntax

The syntax of the recognized regular expressions could be characterized by following table:

Syntax	Matches
Single Characters
x	The character x, unless there exist special rules for this character
\x	The character x, if there exist special rules for this character
.	any character (newlines only in DOTALL-mode)
\	backslash character
\n	newline character
\t	tab character
\r	carriage return character
\f	form feed character
\a	alert/bell character
\e	escape character
\uhhhh	unicode character, not yet supported
Character classes
[...]	any of the contained characters
[^...]	none of the contained characters
[a-z]	char range (all chars from a to z)
[a-zA-Z]	char range, union of multiple ranges
\s	white space
\S	non white space
\w	word characters
\W	non word charachters
\d	digits
\D	non digits
\p{name}	posix character class, not yet supported
Sequences, alternatives
xy	match x followed by y
x	y
(x)	match inner expression x (grouping is not supported)
Repetitions
x?	match x or nothing
x*	match a sequence of x's or nothing
x+	match a sequence of x's (minimum one)
x{2}	match a sequence of 2 x's
x{2,4}	match a 2 to 4 x's
x{,4}	match a up to 4 x's
x{2,}	match a minimum of 2 x's
Advanced Groups	not supported
Lookaheads	not supported
Lookbehinds	not supported
References	not supported
Anchors	not supported
Flags	not supported

Maven Dependency

<dependency>
    <groupId>net.amygdalum</groupId>
    <artifactId>regexparser</artifactId>
    <version>0.1.0</version>
</dependency>