Data commit

Task/Parsing-RPN-to-infix-conversion/11l/parsing-rpn-to-infix-conversion.11l

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+-V ops = ‘-+/*^’
+
+F postfix_to_infix(postfix)
+   T Expression
+      String op, ex
+      prec = 3
+
+      F (String e1, e2 = ‘’, o = ‘’)
+         I o == ‘’
+            .ex = e1
+         E
+            .ex = e1‘ ’o‘ ’e2
+            .op = o
+            .prec = :ops.index(o) I/ 2
+
+      F String()
+         R .ex
+
+   [Expression] expr
+
+   L(token) postfix.split(re:‘\s+’)
+      V c = token[0]
+      V? idx = :ops.find(c)
+      I idx != N
+         V r = expr.pop()
+         V l = expr.pop()
+         V opPrec = idx I/ 2
+
+         I l.prec < opPrec | (l.prec == opPrec & c == ‘^’)
+            l.ex = ‘(’l.ex‘)’
+
+         I r.prec < opPrec | (r.prec == opPrec & c != ‘^’)
+            r.ex = ‘(’r.ex‘)’
+         expr.append(Expression(l.ex, r.ex, token))
+      E
+         expr.append(Expression(token))
+
+      print(token‘ -> ’expr)
+
+   assert(expr.len == 1)
+   R expr[0].ex
+
+L(e) [‘3 4 2 * 1 5 - 2 3 ^ ^ / +’,
+      ‘1 2 + 3 4 + ^ 5 6 + ^’]
+   print(‘Postfix : ’e)
+   print(‘Infix : ’postfix_to_infix(e))
+   print()