func incl*[T](x: var set[T], y: T) {.magic: "Incl".} =
## Includes element `y` in the set `x`.
##
## This is the same as `x = x + {y}`, but it might be more efficient.
runnableExamples:
var a = {1, 3, 5}
a.incl(2)
assert a == {1, 2, 3, 5}
a.incl(4)
assert a == {1, 2, 3, 4, 5}
template incl*[T](x: var set[T], y: set[T]) =
## Includes the set `y` in the set `x`.
runnableExamples:
var a = {1, 3, 5, 7}
var b = {4, 5, 6}
a.incl(b)
assert a == {1, 3, 4, 5, 6, 7}
x = x + y
func excl*[T](x: var set[T], y: T) {.magic: "Excl".} =
## Excludes element `y` from the set `x`.
##
## This is the same as `x = x - {y}`, but it might be more efficient.
runnableExamples:
var b = {2, 3, 5, 6, 12, 545}
b.excl(5)
assert b == {2, 3, 6, 12, 545}
template excl*[T](x: var set[T], y: set[T]) =
## Excludes the set `y` from the set `x`.
runnableExamples:
var a = {1, 3, 5, 7}
var b = {3, 4, 5}
a.excl(b)
assert a == {1, 7}
x = x - y
func card*[T](x: set[T]): int {.magic: "Card".} =
## Returns the cardinality of the set `x`, i.e. the number of elements
## in the set.
runnableExamples:
var a = {1, 3, 5, 7}
assert card(a) == 4
var b = {1, 3, 5, 7, 5}
assert card(b) == 4 # repeated 5 doesn't count
func len*[T](x: set[T]): int {.magic: "Card".}
## An alias for `card(x)`.
func `*`*[T](x, y: set[T]): set[T] {.magic: "MulSet".} =
## This operator computes the intersection of two sets.
runnableExamples:
assert {1, 2, 3} * {2, 3, 4} == {2, 3}
func `+`*[T](x, y: set[T]): set[T] {.magic: "PlusSet".} =
## This operator computes the union of two sets.
runnableExamples:
assert {1, 2, 3} + {2, 3, 4} == {1, 2, 3, 4}
func `-`*[T](x, y: set[T]): set[T] {.magic: "MinusSet".} =
## This operator computes the difference of two sets.
runnableExamples:
assert {1, 2, 3} - {2, 3, 4} == {1}
func contains*[T](x: set[T], y: T): bool {.magic: "InSet".} =
## One should overload this proc if one wants to overload the `in` operator.
##
## The parameters are in reverse order! `a in b` is a template for
## `contains(b, a)`.
## This is because the unification algorithm that Nim uses for overload
## resolution works from left to right.
## But for the `in` operator that would be the wrong direction for this
## piece of code:
runnableExamples:
var s: set[range['a'..'z']] = {'a'..'c'}
assert s.contains('c')
assert 'b' in s
assert 'd' notin s
assert set['a'..'z'] is set[range['a'..'z']]
## If `in` had been declared as `[T](elem: T, s: set[T])` then `T` would
## have been bound to `char`. But `s` is not compatible to type
## `set[char]`! The solution is to bind `T` to `range['a'..'z']`. This
## is achieved by reversing the parameters for `contains`; `in` then
## passes its arguments in reverse order.