Data update

Task/Parsing-RPN-calculator-algorithm/Pluto/parsing-rpn-calculator-algorithm.pluto

@@ -0,0 +1,33 @@
+require "queue"
+local fmt = require "fmt"
+
+local function rpn_calculate(expr)
+    assert(#expr > 0, "expression cannot be empty")
+    print($"For expression = {expr}\n")
+    print("Token           Action             Stack")
+    local tokens = expr:split(" "):filter(|t| -> #t > 0):reorder()
+    local stk = new stack()
+    for tokens as token do
+        local d = tonumber(token)
+        if d then
+            stk:push(d)
+            fmt.print(" %d     Push num onto top of stack  %s", d, fmt.swrite(stk:toarray()))
+        elseif #token > 1 or !(token in "+-*/^") then
+            error($"{token} is not a valid token.")
+        elseif stk:size() < 2 then
+            error("Stack contains too few operands.")
+        else
+            local d1 = stk:pop()
+            local d2 = stk:pop()
+            stk:push(token == "+" ? d2 + d1 :
+                     token == "-" ? d2 - d1 :
+                     token == "*" ? d2 * d1 :
+                     token == "/" ? d2 / d1 : d2 ^ d1)
+            fmt.print(" %s     Apply op to top of stack    %s", token, fmt.swrite(stk:toarray()))
+        end
+    end
+    fmt.print("\nThe final value is %0.14g", stk:pop())
+end
+
+local expr = "3 4 2 * 1 5 - 2 3 ^ ^ / +"
+rpn_calculate(expr)