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python_symb/expr.py

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+from __future__ import annotations
+from tree import Tree
+from operator_file import Add, Mul
+from operator_file import UnaryOperator, BinOperator
+from typing import List
+from symbols import Var
+from parse import infix_str_to_postfix
+
+
+class Expr(Tree):
+    def __init__(self, value, children=None):
+        super().__init__(value, children if children else [])
+
+    @staticmethod
+    def from_postfix_list(postfix: List):
+
+        def aux():
+            first = postfix.pop()
+            match first:
+                case int() | Var():
+                    return Tree(first)
+                case UnaryOperator():
+                    return Tree(first, [aux()])
+                case BinOperator():
+                    return Tree(first, [aux(), aux()])
+
+        return aux()
+
+    @staticmethod
+    def from_infix_str(expr_str):
+        expr_rev_polish = infix_str_to_postfix(expr_str)
+        return Expr.from_postfix_list(expr_rev_polish)
+
+
+
+
+
+