object Generators

inherit list
  Harness




Counter process given start, stop, delta
  if stop > start
    set delta default 1
    if delta <= 0
      throw new ~Error "Counter: when stop>start, delta must be positive"
    while start <= stop
      yield start
      set start + delta
  else
    set delta default -1
    if delta >= 0
      throw new ~Error "Counter: when stop<start, delta must be negative"
    while start >= stop
      yield start
      set start + delta


Execute promise

  set Twice to process given a
    yield a
    yield a

  set SimpleCounter to process given a
    count a
      yielding from Twice counter

  @Match 'generators', 6, task
    set b to 0
    iterate from SimpleCounter 3
      set b + it
    return b
    
  @Match 'iterate using', 6, task
    set b to 0
    set I to task
      set b + $
    iterate from SimpleCounter 3 using I
    return b
        
  @Match 'sorted process', 2, task
    set c10 from @Counter 10,1,-2
    return number (c10 |by . |limit 1)
    
  @Match 'collect value', 1, task
    return 1 |collect
    
  @Match 'collect iterator', 'aa', task
    set a from Twice 'a'; |collect
    return a[0]+a[1]
    
  @Match 'limit iterator 0-5', '01234', task
    set a from @Counter 0,10; |limit 5
    set a to (self |collect).join('')
    return a

  @Match 'limit iterator 2-5', '234', task
    set a from @Counter 0,10; |limit 2,3
    set a to (self |collect).join('')
    return a

  @Match 'limit iterator 0-5 short', '012', task
    set a from @Counter 0,2; |limit 5
    set a to (self |collect).join('')
    return a

  @Match 'limit iterator -5', '56789', task
    set a from @Counter 0,9; |limit -5
    set a to (self |collect).join('')
    return a

  @Match 'limit iterator -5,2', '56', task
    set a from @Counter 0,9; |limit -5,2
    set a to (self |collect).join('')
    return a
    
  @Test 'iterate iterator', task
    set a: 1, 2, 3; |iterate
    set a self |iterate
    set a self |collect 
    return a.length is 3 and a.0 is 1 and a.2 is 3

  @Match 'iterate undefined', undefined, task
    return undefined |iterate

  @Match 'iterate value', 3, task
    set i to 3 |iterate
    return i.next().value

  @Match 'iterate string', 'p', task
    set i to 'pigs' |iterate
    return i.next().value

  @Match 'iterate list', 'pigs', task
    set i to list cows,pigs; |iterate
    i.next
    return i.next().value
    
  @Match 'iterate traits', 'pigs', task
    set i to traits pasture cows, pens pigs; |iterate
    i.next
    return i.next().value[1]
    
  @Match 'iterate iterable', 8, task
    set i from @Counter 10,0,-2
    i.next
    return i.next().value
    
  @Test 'chain draining iterator', task
    set b to false
    chain: 1; |iterate
      |audit
        set b true
    return b
    
  @Match 'iterate with keys', 3, task
    set b to 0
    iterate: 1, 2, 3; |iterate
      set b + key
    return b
  
  @Match 'iterate with keys using', 3, task
    set b to 0
    set countb to task given v, k
      set b + k
    iterate: 1, 2, 3; |iterate using countb
    return b
  
  resolve
  
  
Fudge task
  nop