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Text File  |  1998-09-30  |  1.6 KB  |  51 lines
  1. "
  2.    control the values produced by a generator
  3. "
  4. Class ControlGenerator :Generator
  5. | firstGenerator secondGenerator
  6.    currentFirst currentSecond
  7.    controlBlock computeBlock |
  8. [
  9.    initA: fGen b: sGen control: aBlock compute: anotherBlock
  10.       firstGenerator <- fGen.
  11.       secondGenerator <- sGen.
  12.       controlBlock <- aBlock.
  13.       computeBlock <- anotherBlock
  14.  
  15. |   first
  16.       currentFirst <- firstGenerator first.
  17.       currentSecond <- secondGenerator first.
  18.       (currentFirst isNil & currentSecond isNil) ifTrue: [^ nil].
  19.       ^ self controlGeneratorNext
  20.  
  21. |   next
  22.       ^ self controlGeneratorNext
  23.  
  24. |   controlGeneratorNext   | control returnedValue |
  25.       control <- 0.
  26.       [ control anyMask: 12] whileFalse: [
  27.          control <- controlBlock value: currentFirst
  28.                   value: currentSecond.
  29.          (control allMask: 64) ifTrue: [^nil].
  30.          (control allMask: 32) ifTrue:
  31.             [currentFirst <- firstGenerator first].
  32.          (control allMask: 16) ifTrue:
  33.             [currentSecond <- secondGenerator first].
  34.          (control allMask: 12)
  35.          ifTrue:
  36.             [returnedValue <- computeBlock
  37.             value: currentFirst value: currentSecond]
  38.          ifFalse: [
  39.           (control allMask: 8) ifTrue:
  40.             [returnedValue <- computeBlock value: currentFirst].
  41.           (control allMask: 4) ifTrue:
  42.             [returnedValue <- computeBlock value: currentSecond].
  43.           ].
  44.          (control allMask: 2) ifTrue:
  45.             [currentFirst <- firstGenerator next].
  46.          (control allMask: 1) ifTrue:
  47.             [currentSecond <- secondGenerator next].
  48.          ].
  49.       ^ returnedValue
  50. ]
  51.