civicaml/phases/bool_op.ml

(**
 * The phase applies the transformations shown below. These transformations are
 * required because the CiviC VM does not offer instructions that perform these
 * operations. Another reason is that conjunction and disjunction require
 * short-circuit evaluation. In the examples below, `b1` and `b2` are
 * expressions of type boolean, `i` is of type int and `f` is of type float.
 *
 * > b1 == b2   ==>   (int)b1 == (int)b2
 * > b1 != b2   ==>   (int)b1 != (int)b2
 * > b1 && b2   ==>   b1 ? b2 : false
 * > b1 || b2   ==>   b1 ? true : b2
 * > b1 + b2    ==>   (bool)((int)b1 + (int)b2)
 * > b1 * b2    ==>   (bool)((int)b1 * (int)b2)
 * > (bool)i    ==>   i != 0
 * > (bool)f    ==>   f != 0.0
 * > (int)b1    ==>   b1 ? 1 : 0
 * > (float)b1  ==>   b1 ? 1.0 : 0.0
 *)
open Ast
open Util

let rec bool_op = function
    | Binop (Eq, (Type (_, Bool) as left), (Type (_, Bool) as right), loc) ->
        let left = Type (TypeCast (Int, left, noloc), Int) in
        let right = Type (TypeCast (Int, right, noloc), Int) in
        Binop (Eq, left, right, loc)

    | node -> transform_children bool_op node

let rec phase input =
    prerr_endline "- Convert bool operations";
    match input with
    | Ast node -> Ast (bool_op node)
    | _ -> raise (InvalidInput "bool operations")