44 lines
1.2 KiB
Go
44 lines
1.2 KiB
Go
package main
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import (
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"fmt"
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"math"
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"strconv"
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"strings"
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)
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var input = "3 4 2 * 1 5 - 2 3 ^ ^ / +"
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func main() {
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fmt.Printf("For postfix %q\n", input)
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fmt.Println("\nToken Action Stack")
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var stack []float64
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for _, tok := range strings.Fields(input) {
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action := "Apply op to top of stack"
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switch tok {
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case "+":
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stack[len(stack)-2] += stack[len(stack)-1]
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stack = stack[:len(stack)-1]
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case "-":
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stack[len(stack)-2] -= stack[len(stack)-1]
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stack = stack[:len(stack)-1]
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case "*":
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stack[len(stack)-2] *= stack[len(stack)-1]
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stack = stack[:len(stack)-1]
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case "/":
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stack[len(stack)-2] /= stack[len(stack)-1]
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stack = stack[:len(stack)-1]
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case "^":
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stack[len(stack)-2] =
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math.Pow(stack[len(stack)-2], stack[len(stack)-1])
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stack = stack[:len(stack)-1]
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default:
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action = "Push num onto top of stack"
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f, _ := strconv.ParseFloat(tok, 64)
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stack = append(stack, f)
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}
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fmt.Printf("%3s %-26s %v\n", tok, action, stack)
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}
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fmt.Println("\nThe final value is", stack[0])
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}
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