rexen

-module(rexen).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]).

-export([new/1, compute/2]).

-if(?OTP_RELEASE >= 27).
-define(MODULEDOC(Str), -moduledoc(Str)).
-define(DOC(Str), -doc(Str)).
-else.
-define(MODULEDOC(Str), -compile([])).
-define(DOC(Str), -compile([])).
-endif.

?MODULEDOC(" Compile and evaluate regular expressions using Non-deterministic Finite Automata (NFAs).\n").

-file("src/rexen.gleam", 23).
?DOC(
    " Compiles a regular expression string into a Non-deterministic Finite Automaton (NFA).\n"
    "\n"
    " Takes a regular expression `String` and returns `Ok(NFA)` on success, or `Error(String)` on failure.\n"
    " Uses a shunting-yard algorithm to convert from infix to postfix notation\n"
    " Uses Thompson's construction to construct the nfa\n"
    "\n"
    " ## Examples\n"
    "\n"
    " ```gleam\n"
    " import rexen\n"
    "\n"
    " case rexen.new(\"ab\") {\n"
    "   Ok(_) -> io.println(\"All good\")\n"
    "   Error(err) -> io.println(err)\n"
    " }\n"
    " ```\n"
).
-spec new(binary()) -> {ok, rexen@nfa@machine:nfa()} | {error, binary()}.
new(Expression) ->
    case rexen@grammar:shunt(Expression) of
        {error, Err} ->
            {error, Err};

        {ok, Toks} ->
            rexen@nfa@thompson:to_nfa(Toks)
    end.

-file("src/rexen.gleam", 47).
?DOC(
    " Evaluates whether a given input `String` is matched by the provided Non-deterministic Finite Automaton (NFA).\n"
    "\n"
    " Takes an NFA and an input string, returning `True` if the input is accepted by the NFA, and `False` otherwise.\n"
    "\n"
    " ## Examples\n"
    "\n"
    " ```gleam\n"
    " import rexen\n"
    "\n"
    " let assert Ok(nfa) = rexen.new(\"(ab)*\")\n"
    " rexen.compute(nfa, \"ab\") // -> True\n"
    " rexen.compute(nfa, \"ababab\") // -> True\n"
    " rexen.compute(nfa, \"ababa\") // -> False\n"
    " rexen.compute(nfa, \"a\") // -> False\n"
    " ```\n"
).
-spec compute(rexen@nfa@machine:nfa(), binary()) -> boolean().
compute(Engine, Input) ->
    rexen@nfa@machine:evaluate(Engine, Input).