43 lines
840 B
Rexx
43 lines
840 B
Rexx
/* REXX ***************************************************************
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* supports push, pull, and peek
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* 11.08.2013 Walter Pachl
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**********************************************************************/
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stk.=0
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Call push 123 /*pushes 123 onto the stack. */
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Say empty()
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say peek()
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say pull() /*pops last value stacked & removes it. */
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Say empty()
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say peek()
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say push(456)
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say peek()
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Exit
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push: Procedure Expose stk.
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Parse Arg v
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z=stk.0+1
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stk.z=v
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stk.0=z
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Return v
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peek: Procedure Expose stk.
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If stk.0=0 Then
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Return 'stack is empty'
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Else Do
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z=stk.0
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Return stk.z
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End
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pull: Procedure Expose stk.
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If stk.0=0 Then
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Return 'stack is empty'
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Else Do
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z=stk.0
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res=stk.z
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stk.0=stk.0-1
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Return res
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End
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empty: Procedure Expose stk.
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Return stk.0=0
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