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Although OCaml strings and C++ strings may legally have internal null bytes, this library doesn't handle them correctly by doing conversions via C strings. 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 according to Options.encoding which is UTF-8 by default (the alternative is ISO 8859-1).
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.
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 find_all : ?sub:id_t->t->string ->string listCore.Or_error.t
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
val find_first : ?sub:id_t->t->string ->string Core.Or_error.t
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
val find_submatches : t->string ->string option arrayCore.Or_error.t
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 split : ?max:int ->?include_matches:bool ->t->string ->string list
split pattern input
returns
input broken into pieces where pattern matches. Subpatterns are ignored.
parametermax
(default: unlimited) split only at the leftmost max matches
parameterinclude_matches
(default: false) include the matched substrings in the returned list (e.g., the regex /[,()]/ on "foo(bar,baz)" gives ["foo"; "(";
"bar"; ","; "baz"; ")"] instead of ["foo"; "bar"; "baz"])
If t never matches, the returned list has input as its one element.
val rewrite : t->template:string ->string ->string Core.Or_error.t
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 returns true iff template is a valid rewrite template for pattern
val escape : string -> string
escape nonregex returns a copy of nonregex with everything escaped (i.e., if the return value were t to regex, it would match exactly the original input)
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.