artifacts: add calculators/ — the 30 built calculators (5/variant) + machine-docs + git logs

calculators/builder-adversary-min/run-05/calc/evaluator.py

@@ -0,0 +1,45 @@
+"""
+Evaluator for arithmetic AST nodes produced by calc.parser.
+
+evaluate(node) -> int | float
+
+Result-type rule: if the computed value is a whole number (no fractional
+part), it is returned as int; otherwise as float.  This ensures "4/2" -> 2
+and "7/2" -> 3.5 without callers having to special-case anything.
+
+Division-by-zero raises EvalError, not a bare ZeroDivisionError.
+"""
+from __future__ import annotations
+from calc.parser import Num, BinOp, Unary, Node
+
+
+class EvalError(Exception):
+    pass
+
+
+def evaluate(node: Node) -> int | float:
+    result = _eval(node)
+    if isinstance(result, float) and result == int(result):
+        return int(result)
+    return result
+
+
+def _eval(node: Node) -> int | float:
+    if isinstance(node, Num):
+        return node.value
+    if isinstance(node, Unary):
+        return -_eval(node.operand)
+    if isinstance(node, BinOp):
+        left = _eval(node.left)
+        right = _eval(node.right)
+        if node.op == '+':
+            return left + right
+        if node.op == '-':
+            return left - right
+        if node.op == '*':
+            return left * right
+        if node.op == '/':
+            if right == 0:
+                raise EvalError("division by zero")
+            return left / right
+    raise EvalError(f"unknown node type: {type(node).__name__}")