| [613] | 1 | PXRMSTAC ; SLC/PKR - Stack routines for use by PXRM. ;11/24/2004
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| 2 | ;;2.0;CLINICAL REMINDERS;;Feb 04, 2005
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| 3 | ;
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| 4 | ;=====================================================
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| 5 | POP(STACK) ;Pop an element off of the stack.
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| 6 | I STACK(0)=0 Q ""
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| 7 | N IND,TEMP
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| 8 | S TEMP=STACK(1)
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| 9 | F IND=2:1:STACK(0) S STACK(IND-1)=STACK(IND)
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| 10 | K STACK(STACK(0))
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| 11 | S STACK(0)=STACK(0)-1
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| 12 | Q TEMP
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| 13 | ;
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| 14 | ;=====================================================
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| 15 | POSTFIX(EXPR,OPER,PFSTACK) ;Given an expression, EXPR, in infix notation
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| 16 | ;convert it to postfix and return the result in PFSTACK. PFSTACK(0)
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| 17 | ;will contain the number of elements in PFSTACK. OPER is a
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| 18 | ;string containing allowable operators.
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| 19 | N CHAR,IND,LEN,OPERP,PFP,SP,SPACE,STACK,SYM,SYMP,SYMT,TAB,TEMP
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| 20 | S SPACE=$C(32)
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| 21 | S TAB=$C(9)
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| 22 | S TEMP=""
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| 23 | S OPERP=OPER_"()"
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| 24 | S SYMP=0
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| 25 | S LEN=$L(EXPR)
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| 26 | ;Break the expression into (, ), operators, and operands.
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| 27 | ;Remove spaces and tabs and put the symbols onto the symbol
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| 28 | ;stack in left to right order. Symbol number 1 is SYM(1).
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| 29 | F IND=1:1:LEN D
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| 30 | . S CHAR=$E(EXPR,IND)
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| 31 | . I (CHAR=SPACE)!(CHAR=TAB) Q
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| 32 | . I OPERP[CHAR D
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| 33 | .. I $L(TEMP)>0 D
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| 34 | ... S SYMP=SYMP+1
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| 35 | ... S SYM(SYMP)=TEMP
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| 36 | ... S TEMP=""
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| 37 | .. S SYMP=SYMP+1
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| 38 | .. S SYM(SYMP)=CHAR
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| 39 | . E S TEMP=TEMP_CHAR
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| 40 | . I (IND=LEN)&(TEMP'="") D
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| 41 | .. S SYMP=SYMP+1
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| 42 | .. S SYM(SYMP)=TEMP
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| 43 | ;Process the symbols.
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| 44 | S (PFP,SP)=0
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| 45 | S LEN=SYMP
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| 46 | F SYMP=1:1:LEN D
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| 47 | . S SYMT=SYM(SYMP)
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| 48 | .;
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| 49 | .;Symbol is "("
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| 50 | . I SYMT="(" D Q
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| 51 | .. S SP=SP+1
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| 52 | .. S STACK(SP)=SYMT
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| 53 | .;
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| 54 | .;Symbol is an operator
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| 55 | . I OPER[SYMT D Q
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| 56 | .. S LEN=SP
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| 57 | .. F IND=LEN:-1:1 S TEMP=STACK(IND) Q:TEMP="(" D
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| 58 | ...;M has no operator precedence so we don't need to check.
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| 59 | ... S PFP=PFP+1
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| 60 | ... S PFSTACK(PFP)=TEMP
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| 61 | ... K STACK(SP)
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| 62 | ... S SP=SP-1
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| 63 | .. S SP=SP+1
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| 64 | .. S STACK(SP)=SYMT
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| 65 | .;
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| 66 | .;Symbol is ")"
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| 67 | . I SYMT=")" D Q
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| 68 | .. S LEN=SP
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| 69 | .. F IND=LEN:-1:1 S TEMP=STACK(IND) Q:TEMP="(" D
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| 70 | ... S PFP=PFP+1
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| 71 | ... S PFSTACK(PFP)=TEMP
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| 72 | ... K STACK(SP)
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| 73 | ... S SP=SP-1
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| 74 | ..;Pop the "(" at the top of the stack.
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| 75 | .. K STACK(SP)
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| 76 | .. S SP=SP-1
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| 77 | .;
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| 78 | .;If we get to here then symbol is an operand.
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| 79 | . S PFP=PFP+1
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| 80 | . S PFSTACK(PFP)=SYMT
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| 81 | ;
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| 82 | ;Pop and output anything left on the stack.
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| 83 | F IND=SP:-1:1 D
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| 84 | . S PFP=PFP+1
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| 85 | . S PFSTACK(PFP)=STACK(IND)
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| 86 | ;
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| 87 | ;Save the number of elements in PFSTACK.
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| 88 | S PFSTACK(0)=PFP
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| 89 | Q
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| 90 | ;
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| 91 | ;=====================================================
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| 92 | PUSH(STACK,ELEM) ;Push an element on the stack.
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| 93 | I '$D(STACK) S STACK(1)=ELEM,STACK(0)=1 Q
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| 94 | I STACK(0)=0 S STACK(1)=ELEM,STACK(0)=1 Q
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| 95 | N IND
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| 96 | F IND=STACK(0):-1:1 S STACK(IND+1)=STACK(IND)
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| 97 | S STACK(1)=ELEM,STACK(0)=STACK(0)+1
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| 98 | Q
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| 99 | ;
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