23 lines
497 B
Go
23 lines
497 B
Go
package main
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import (
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"fmt"
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)
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func rpn(expr Expr) string {
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switch e := expr.(type) {
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case Binary:
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return rpn(e.left) + " " + rpn(e.right) + " " + e.operator.Lexeme
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case Grouping:
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return rpn(e.expression) // + " group" arguable if this is even wanted
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case Literal:
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if e.value == nil {
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return "nil"
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}
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return fmt.Sprintf("%v", e.value)
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case Unary:
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return rpn(e.right) + fmt.Sprintf(" %v", e.operator.Lexeme)
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}
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return "ERROR: reached impossible branch in print function"
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}
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