MYR(REGEX)                     (1)                     MYR(REGEX)

     NAME
          regex myr-regex

     LIBRARY
          regex

     SYNOPSIS
          use regex const compile  : (re : byte[:] -> const
          dbgcompile    : (re : byte[:] -> const free : (re : regex#
          const exec     : (re : regex#, str const search   : (re :
          regex#, str

     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 to compile it,
          returing `std.Success regex# if the regex is valid, and
          there were no error conditions encountered during compila-
          tion. 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 charac-
               ters.

          *    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:

               ASCII digits

          0.br Negation of ASCII digits

          96.br  ASCII Hex digits

          0.br Negation of ASCII Hex digits

          120.br ASCII spaces

          96.br  Negation of ASCII spaces

          01200.br ASCII word characters

          W    Negation of ASCII word characters

          96.br  ASCII whitespace characters

          96.br  Negation of ASCII whitespace characters

          X, {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 {}: {}0, i, matches[i])
                                      ;;
                              | `std.None: std.put("Text did not match0)
                              ;;
                      | `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.