typedef int PK_comparison_t;
This datatype allows the user to supply an interval and to test when given
a number (d) whether the constraint is true or false. It has the following
values:
PK_comparison_always_c true
PK_comparison_less_c d <= constraint.interval.value[0]
PK_comparison_equal_c d = constraint.interval.value[0]
PK_comparison_greater_c d >= constraint.interval.value[1]
PK_comparison_between_c d >= constraint.interval.value[0] &&
d <= constraint.interval.value[1]
PK_comparison_outside_c d <= constraint.interval.value[0] ||
d >= constraint.interval.value[1]
PK_comparison_never_c false
