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feature: case-insensitive match #15

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feature: case-insensitive match #15

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adc34fc
feature: case insensitive match via `%pcre_i`
zazedd Aug 1, 2025
35e0805
update README for case-insensitive match ext
zazedd Aug 1, 2025
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4 changes: 4 additions & 0 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,10 @@ A variable is allowed for the universal case and is bound to the matched
string. A regular alias is currently not allowed for patterns, since it is
not obvious whether is should bind the full string or group 0.

### Case-Insensitive Match

An extension, `%pcre_i`, is available for case-insensitive matching.

### Example

The following prints out times and hosts for SMTP connections to the Postfix
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16 changes: 11 additions & 5 deletions ppx_regexp/ppx_regexp.ml
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Expand Up @@ -137,7 +137,11 @@ let rec wrap_group_bindings ~loc rhs offG = function
let [%p ppat_var ~loc varG] = [%e eG] in
[%e wrap_group_bindings ~loc rhs offG bs]]

let transform_cases ~loc cases =
let rec create_opts ~loc = function
| [] -> [%expr []]
| `Caseless :: xs -> [%expr `Caseless :: [%e create_opts ~loc xs]]

let transform_cases ~loc ~opts cases =
let aux case =
if case.pc_guard <> None then
error ~loc "Guards are not implemented for match%%pcre."
Expand Down Expand Up @@ -172,8 +176,9 @@ let transform_cases ~loc cases =
in
let cases = List.rev_map aux cases in
let res = pexp_array ~loc (List.map (fun (re, _, _, _) -> re) cases) in
let opts_expr = create_opts ~loc opts in
let comp = [%expr
let a = Array.map (fun s -> Re.mark (Re.Perl.re s)) [%e res] in
let a = Array.map (fun s -> Re.mark (Re.Perl.re ~opts:[%e opts_expr] s)) [%e res] in
let marks = Array.map fst a in
let re = Re.compile (Re.alt (Array.to_list (Array.map snd a))) in
(re, marks)
Expand Down Expand Up @@ -208,14 +213,15 @@ let transformation = object
let e_ext, acc = super#expression e_ext acc in
(match e_ext.pexp_desc with
| Pexp_extension
({txt = "pcre"; _}, PStr [{pstr_desc = Pstr_eval (e, _); _}]) ->
({txt = ("pcre" | "pcre_i") as ext; _}, PStr [{pstr_desc = Pstr_eval (e, _); _}]) ->
let opts = if String.ends_with ~suffix:"_i" ext then [`Caseless] else [] in
let loc = e.pexp_loc in
(match e.pexp_desc with
| Pexp_match (e, cases) ->
let cases, binding = transform_cases ~loc cases in
let cases, binding = transform_cases ~loc ~opts cases in
([%expr let _ppx_regexp_v = [%e e] in [%e cases]], binding :: acc)
| Pexp_function (cases) ->
let cases, binding = transform_cases ~loc cases in
let cases, binding = transform_cases ~loc ~opts cases in
([%expr fun _ppx_regexp_v -> [%e cases]], binding :: acc)
| _ ->
error ~loc "[%%pcre] only applies to match an function.")
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