108 lines
3.8 KiB
OCaml
108 lines
3.8 KiB
OCaml
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(*
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RE - A regular expression library
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Copyright (C) 2001 Jerome Vouillon
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email: Jerome.Vouillon@pps.jussieu.fr
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation, with
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linking exception; either version 2.1 of the License, or (at
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your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*)
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(** References:
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- {{:http://www.opengroup.org/onlinepubs/007908799/xbd/re.html} re}
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- {{:http://www.opengroup.org/onlinepubs/007908799/xsh/regcomp.html} regcomp}
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Example of how to use this module (to parse some IRC logs):
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{[
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type msg =
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{ time : string
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; author : string
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; content : string
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}
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let re = Core.compile (Re_posix.re "([^:].*:[^:]*:[^:]{2})<.([^>]+)> (.+)$")
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(* parse a line *)
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let match_line line =
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try
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let substrings = Core.exec re line in
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let groups = Core.get_all substrings in
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(* groups can be obtained directly by index within [substrings] *)
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Some { time = groups.(1); author = groups.(2); content = groups.(3) }
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with
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| Not_found -> None (* regex didn't match *)
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;;
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]} *)
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(* XXX Character classes *)
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exception Parse_error
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(** Errors that can be raised during the parsing of the regular expression *)
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exception Not_supported
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type opt =
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[ `ICase
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| `NoSub
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| `Newline
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]
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(** Parsing of a Posix extended regular expression *)
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val re : ?opts:opt list -> string -> Core.t
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val re_result
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: ?opts:opt list
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-> string
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-> (Core.t, [ `Not_supported | `Parse_error ]) result
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(** [compile r] is defined as [Core.compile (Core.longest r)] *)
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val compile : Core.t -> Core.re
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(** [compile_pat ?opts regex] compiles the Posix extended regular expression [regexp] *)
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val compile_pat : ?opts:opt list -> string -> Core.re
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(*
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Deviation from the standard / ambiguities in the standard
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---------------------------------------------------------
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We tested the behavior of the Linux library (glibc) and the Solaris
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library.
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(1) An expression [efg] should be parsed as [(ef)g].
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All implementations parse it as [e(fg)].
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(2) When matching the pattern "((a)|b)*" against the string "ab",
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the sub-expression "((a)|b)" should match "b", and the
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sub-expression "(a)" should not match anything.
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In both implementation, the sub-expression "(a)" matches "a".
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(3) When matching the pattern "(aa?)*" against the string "aaa", it is
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not clear whether the final match of the sub-expression "(aa?)" is
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the last "a" (all matches of the sub-expression are successively
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maximized), or "aa" (the final match is maximized).
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Both implementations implements the first case.
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(4) When matching the pattern "((a?)|b)*" against the string "ab",
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the sub-expression "((a?)|b)" should match the empty string at the
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end of the string (it is better to match the empty string than to
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match nothing).
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In both implementations, this sub-expression matches "b".
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(Strangely, in the Linux implementation, the sub-expression "(a?)"
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correctly matches the empty string at the end of the string)
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This library behaves the same way as the other libraries for all
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points, except for (2) and (4) where it follows the standard.
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The behavior of this library in theses four cases may change in future
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releases.
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*)
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