// regex — POSIX extended regular expressions. Port of
// ref/hare/regex/regex.ha. Fold 1 = the data model only; compile() /
// exec / find / replace are DEFERRED to later folds.
//
// Two fold-1 constructs are held back behind filed compiler/fidelity
// gaps (see the charclass_map and finish() sites below):
//   - charclass_map (regex.ha:74-87) — a module-level const slice of
//     (str, *fn(rune) bool) tuples. Blocked on the array-literal→slice
//     element-coercion checker gap (#25; type.c:402-404 #258 borrow
//     uses exact type_eq, no element decay).
//   - finish() (regex.ha:96-102) — frees; ww is a no-free runtime (#27).
package regex;

// ref/hare/regex/regex.ha:14 — an error string describing a compilation
// error.
export type error = !str;

// ref/hare/regex/regex.ha:16-30.
export type inst_lit = rune;
export type inst_charset = struct { idx: size, is_positive: bool };
export type inst_any = void;
export type inst_split = size;
export type inst_jump = size;
export type inst_skip = void;
export type inst_match = bool;
export type inst_groupstart = size;
export type inst_groupend = void;
export type inst_repeat = struct {
	id: size,
	origin: size,
	min: (void | size),
	max: (void | size),
};

// ref/hare/regex/regex.ha:32-35.
export type inst = (inst_lit | inst_any | inst_split | inst_jump |
	inst_skip | inst_match | inst_charset |
	inst_groupstart | inst_groupend |
	inst_repeat);

// The resulting match of a [[regex]] applied to a string.
//
// The first [[capture]] corresponds to the implicit zeroth capture
// group, i.e. the whole expression.
//
// The rest of the [[capture]]s correspond to the rest of the capture
// groups, i.e. the sub-expressions.
// ref/hare/regex/regex.ha:44.
export type result = []capture;

// A (sub)match corresponding to a regular expression's capture group.
// ref/hare/regex/regex.ha:47-53.
export type capture = struct {
	content: str,
	start: size,
	start_bytesize: size,
	end: size,
	end_bytesize: size,
};

// ref/hare/regex/regex.ha:68-72.
export type charset = [](charset_lit_item | charset_range_item |
	charset_class_item);
export type charset_lit_item = rune;
export type charset_range_item = (u32, u32);
export type charset_class_item = (str, *fn(c: rune) bool);

// ref/hare/regex/regex.ha:74-87 — charclass_map: the const
// [](str, *fn(rune) bool) table mapping POSIX class tokens to the
// matching ascii predicate. DEFERRED: the array-literal→slice
// assignability check (type.c:402-404, the #258 borrow) compares
// element types with exact type_eq and applies NO element coercion, so
// the literal `[(":alnum:]", &ascii.isalnum), ...]` (typed
// `[N](untyped_str, *fn(rune) bool)`) is rejected against the declared
// `[](str, *fn(rune) bool)`. Minimal repro: `let xs: [](size, size) =
// [(1, 2)];`. Reshaping to a fixed `[12](...)` array would compile but
// is an unfaithful workaround (CLAUDE.md rule-7), so the table — and
// the `import ascii;` it needs — land with the consuming fold (compile)
// once the checker gap is fixed.

// ref/hare/regex/regex.ha:89-93.
export type regex = struct {
	insts: []inst,
	charsets: []charset,
	n_reps: size,
};

// Frees resources associated with a [[regex]].
//
// ref/hare/regex/regex.ha:96-102 frees re.insts / each charset /
// re.charsets. ww is a no-free runtime (rt/alloc.s:30 — rt_free is a
// no-op; the bump allocator can't reclaim, process-exit does), so the
// faithful ww body drops the frees, matching how the port drops every
// Hare free(). Kept for API parity with the Hare surface. Temporary
// empty body: #27 makes the free() builtin compile to a documented
// no-op, after which this ports the Hare frees VERBATIM (the no-op
// builtin reclaims nothing, same end state).
export fn finish(re: *regex) void = { };