(** Convert boolean operations to equivalent operations on different CiviC data
    types. *)

(** This phase transforms operations on boolean values to equivalent operations
    on different data types. This transformation is necessary, because the CiviC
    VM does not define some operations for boolean arguments.

    This phase also handles the first step of short-circuit evaluation, by
    transforming conjunction and disjunction operators into conditional
    operations of the form [a ? b : c]. This operation is supported by the
    assembly phase, which handles them similarly to if-else statements. The
    benefit of using conditional operations, is that they are still expressions.
    A transformation into actual if-else statements would require adding
    additional statements, which is not only more difficult to implement, but
    also changes the evaluation order, which (however in agreement with the C
    standard) may lead to confusing behaviour.

    The applied transformations are as follows:
{v 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 v}
    *)

(** Main phase function, called by {!Main}. *)
val phase : Main.phase_func