MYR(REGEX)

NAME
regex myr-regex

LIBRARY
regex

SYNOPSIS
use regex const compile : (re : byte[:] -> std.error(regex#, status)) const dbgcompile : (re : byte[:] -> std.error(regex#, status)) const free : (re : regex# -> void)
const exec : (re : regex#, str : byte[:] -> bool) const search : (re : regex#, str : byte[:] -> bool)

DESCRIPTION

The regex library provides functions for compiling and evaluating regular expressions, as described later in this document, or in myr-regex(7).

regex.compile will take a string describing a regex, and will attempt to compile it, returing `std.Success regex# if the regex is valid, and there were no error conditions encountered during compilation. If the compilation failed, `std.Failure regex.status will be returned, where regex.status is a failure code.

regex.dbgcompile is identical to regex.compile, however, it will print debugging information as it compiles, and each time the regex is evaluated.

regex.exec will take the regex passed to it, and evaluate it over the text provided, returning the `std.Some matches, or `std.None if there were no matches found. The matches must span the whole string.

regex.search is similar to regex.exec, but it will attempt to find a match somewhere within the string, instead of attempting to find a match spanning the whole string.

REGEX SYNTAX

The grammar used by libregex is below:
        regex       : altexpr
        altexpr     : catexpr ('|' altexpr)+
        catexpr     : repexpr (catexpr)+
        repexpr     : baseexpr[*+?]
        baseexpr    : literal
                    | charclass
                    | charrange
                    | escaped
                    | '.'
                    | '^'
                    | '$'
                    | '(' regex ')'
        charclass   : see below
        charrange   : '[' (literal('-' literal)?)+']'
The following metacharacters have the meanings listed below:

Matches a single unicode character

^   Matches the beginning of a line. Does not consume any characters.

$   Matches the end of a line. Does not consume any characters.

*   Matches any number of repetitions of the preceding regex fragment.

*?  Reluctantly matches any number of repetitions of the preceding regex fragment.

+   Matches one or more repetitions of the preceding regex fragment.

+?  Reluctantly matches one or more repetitions of the preceding regex fragment.

?   Matches zero or one of the preceding regex fragment.

In order to match a literal metacharacter, it needs to be preceded by a '\' character. The following character classes are supported:

\d  ASCII digits

\D  Negation of ASCII digits

\x  ASCII Hex digits

\X  Negation of ASCII Hex digits

\s  ASCII spaces

\S  Negation of ASCII spaces

\w  ASCII word characters

\W  Negation of ASCII word characters

\h  ASCII whitespace characters

\H  Negation of ASCII whitespace characters

\pX, \p{X}
    Characters with unicode property 'X'

\PX, \P{X}
    Negation of characters with unicode property 'X'

Unicode properties that are supported are listed below:

L, Letter
    Unicode letter property

Lu, Uppercase_Letter
    Uppercase letter unicode property

Ll, Lowercase_Letter
    Lowercase letter unicode property

Lt, Titlecase_Letter
    Titlecase letter unicode property

N, Number
    Number unicode property

Z, Separator
    Any separator character unicode property

Zs, Space_Separator
    Space separator unicode property

EXAMPLE
            use std
            use regex
            const main = {
                var i
                match regex.compile(pat)
                | `std.Ok re:
                        match regex.exec(re, text)
                        | `std.Some matches:
                                for i = 0; i < matches.len; i++
                                    std.put("Match {}: {}, i, matches[i])
                                ;;
                        | `std.None: std.put("Text did not match)
                        ;;
                | `std.Err err:
                        std.put("failed to compile regex")
                ;;
            }

FILES
The source code for this compiler is available from git://git.eigenstate.org/git/ori/libregex.git

SEE ALSO
6m(1)

BUGS

This code is insufficiently tested.

This code does not support all of the regex features that one would expect.