include Re2_internal_intf.S
Although OCaml strings may legally have internal null bytes, it is expensive to check for them, so this library just assumes that it will never see such a string. The failure mode is the search stops early, which isn't bad considering how rare internal null bytes are in practice.
The strings are considered in UTF-8 encoding by default or in ISO 8859-1 if Options.latin1
is used.
Basic Types
include sig ... end
val compare : t -> t -> int
type id_t = [
| `Index of int
| `Name of string
]
Subpatterns are referenced by name if labelled with the /(?P<...>...)/ syntax, or else by counting open-parens, with subpattern zero referring to the whole regex.
val index_of_id_exn : t -> id_t -> int
index_of_id t id
resolves subpattern names and indices into indices. *
The sub
keyword argument means, omit location information for subpatterns with index greater than sub
.
Subpatterns are indexed by the number of opening parentheses preceding them:
~sub:(`Index 0)
: only the whole match ~sub:(`Index 1)
: the whole match and the first submatch, etc.
If you only care whether the pattern does match, you can request no location information at all by passing ~sub:(`Index -1)
.
With one exception, I quote from re2.h:443,
> Don't ask for more match information than you will use: > runs much faster with nmatch == 1 than nmatch > 1, and > runs even faster if nmatch == 0.
For sub > 1
, re2 executes in three steps: 1. run a DFA over the entire input to get the end of the whole match 2. run a DFA backward from the end position to get the start position 3. run an NFA from the match start to match end to extract submatches sub == 1
lets it stop after (2) and sub == 0
lets it stop after (1). (See re2.cc:692 or so.)
The one exception is for the functions get_matches
, replace
, and Iterator.next
: Since they must iterate correctly through the whole string, they need at least the whole match (subpattern 0). These functions will silently rewrite ~sub
to be non-negative.
val create_exn : ?options:Options.t list -> string -> t
val num_submatches : t -> int
num_submatches t
returns 1 + the number of open-parens in the pattern.
N.B. num_submatches t == 1 + RE2::NumberOfCapturingGroups()
because RE2::NumberOfCapturingGroups()
ignores the whole match ("subpattern zero").
val pattern : t -> string
pattern t
returns the pattern from which the regex was constructed. *
find_all t input
a convenience function that returns all non-overlapping matches of t
against input
, in left-to-right order.
If sub
is given, and the requested subpattern did not capture, then no match is returned at that position even if other parts of the regex did match.
val find_all_exn : ?sub:id_t -> t -> string -> string list
find_first ?sub pattern input
finds the first match of pattern
in input
, and returns the subpattern specified by sub
, or an error if the subpattern didn't capture.
val find_first_exn : ?sub:id_t -> t -> string -> string
find_submatches t input
finds the first match and returns all submatches. Element 0 is the whole match and element 1 is the first parenthesized submatch, etc.
val find_submatches_exn : t -> string -> string option array
val matches : t -> string -> bool
val split : ?max:int -> ?include_matches:bool -> t -> string -> string list
rewrite pattern ~template input
is a convenience function for replace
: Instead of requiring an arbitrary transformation as a function, it accepts a template string with zero or more substrings of the form "\\n", each of which will be replaced by submatch n
. For every match of pattern
against input
, the template will be specialized and then substituted for the matched substring.
val rewrite_exn : t -> template:string -> string -> string
val valid_rewrite_template : t -> template:string -> bool
valid_rewrite_template pattern ~template
val escape : string -> string
Infix Operators
module Infix : sig ... end
Complicated Interface
type 'a without_trailing_none
This type marks call sites affected by a bugfix that eliminated a trailing None. When you add this wrapper, check that your call site does not still work around the bug by dropping the last element.
module Match : sig ... end
get_matches pattern input
returns all non-overlapping matches of pattern
against input
val get_matches_exn : ?sub:id_t -> ?max:int -> t -> string -> Match.t list
first_match pattern input
val first_match_exn : t -> string -> Match.t
replace ?sub ?max ~f pattern input
val replace_exn :
?sub:id_t ->
?only:int ->
f:(Match.t -> string) ->
t ->
string ->
string