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/ C/C++ Users Group Library 1996 July / C-C++ Users Group Library July 1996.iso / vol_200 / 231_01 / control.st < prev    next >
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  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.