tasks a-s

Task/Parsing-RPN-calculator-algorithm/BBC-BASIC/parsing-rpn-calculator-algorithm.bbc

@@ -0,0 +1,38 @@
+      @% = &60B
+      RPN$ = "3 4 2 * 1 5 - 2 3 ^ ^ / +"
+
+      DIM Stack(1000)
+      SP% = 0
+
+      FOR i% = 1 TO LEN(RPN$)
+        Token$ = MID$(RPN$,i%,1)
+        IF Token$ <> " " THEN
+          PRINT Token$ " :";
+          CASE Token$ OF
+            WHEN "+": PROCpush(FNpop + FNpop)
+            WHEN "-": PROCpush(-FNpop + FNpop)
+            WHEN "*": PROCpush(FNpop * FNpop)
+            WHEN "/": n = FNpop : PROCpush(FNpop / n)
+            WHEN "^": n = FNpop : PROCpush(FNpop ^ n)
+            WHEN "0","1","2","3","4","5","6","7","8","9":
+              PROCpush(VALMID$(RPN$,i%))
+              WHILE ASCMID$(RPN$,i%)>=48 AND ASCMID$(RPN$,1)<=57
+                i% += 1
+              ENDWHILE
+          ENDCASE
+          FOR j% = SP%-1 TO 0 STEP -1 : PRINT Stack(j%); : NEXT
+          PRINT
+        ENDIF
+      NEXT i%
+      END
+
+      DEF PROCpush(n)
+      IF SP% > DIM(Stack(),1) ERROR 100, "Stack full"
+      Stack(SP%) = n
+      SP% += 1
+      ENDPROC
+
+      DEF FNpop
+      IF SP% = 0 ERROR 100, "Stack empty"
+      SP% -= 1
+      = Stack(SP%)