jashkenas--coffeescript/test/generators.coffee

# Generators
# -----------------
#
# * Generator Definition

test "generator as argument", ->
  ok -> yield 0

test "generator definition", ->
  x = do ->
    yield 0
    yield 1
    yield 2
  y = x.next()
  ok y.value is 0 and y.done is false
  y = x.next()
  ok y.value is 1 and y.done is false
  y = x.next()
  ok y.value is 2 and y.done is false
  y = x.next()
  ok y.value is undefined and y.done is true

test "bound generator", ->
  obj =
    bound: ->
      do =>
        yield this
    unbound: ->
      do ->
        yield this
    nested: ->
      do =>
        yield do =>
          yield do =>
            yield this

  eq obj, obj.bound().next().value
  ok obj isnt obj.unbound().next().value
  eq obj, obj.nested().next().value.next().value.next().value

test "error if `yield` occurs outside of a function", ->
  throws -> CoffeeScript.compile 'yield 1'

test "error if `yield from` occurs outside of a function", ->
  throws -> CoffeeScript.compile 'yield from 1'

test "`yield from` support", ->
  x = do ->
    yield from do ->
      yield i for i in [3..4]

  y = x.next()
  ok y.value is 3 and y.done is false

  y = x.next 1
  ok y.value is 4 and y.done is false

  y = x.next 2
  arrayEq y.value, [1, 2]
  ok y.done is true

test "empty generator", ->
  x = do -> yield return

  y = x.next()
  ok y.value is undefined and y.done is true 

test "`yield` by itself not at the end of a function errors", ->
  throws -> CoffeeScript.compile 'x = -> yield; return'

test "`yield from` at the end of a function errors", ->
  throws -> CoffeeScript.compile 'x = -> x = 1; yield from'

test "yield in if statements", ->
  x = do -> if 1 is yield 2 then 3 else 4

  y = x.next()
  ok y.value is 2 and y.done is false

  y = x.next 1
  ok y.value is 3 and y.done is true