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

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

@@ -0,0 +1,33 @@
+from calc.parser import Num, BinOp, Unary
+
+
+class EvalError(Exception):
+    pass
+
+
+def evaluate(node) -> "int | float":
+    """Walk the AST and return a numeric result.
+
+    Type rule: integer arithmetic stays int; division returns float, except when
+    the quotient is whole-valued — then it is normalised to int so the CLI can
+    print it without a trailing '.0'.
+    """
+    if isinstance(node, Num):
+        return node.value
+    if isinstance(node, Unary):
+        return -evaluate(node.operand)
+    if isinstance(node, BinOp):
+        left = evaluate(node.left)
+        right = evaluate(node.right)
+        if node.op == 'PLUS':
+            return left + right
+        if node.op == 'MINUS':
+            return left - right
+        if node.op == 'STAR':
+            return left * right
+        if node.op == 'SLASH':
+            if right == 0:
+                raise EvalError("division by zero")
+            result = left / right
+            return int(result) if result == int(result) else result
+    raise EvalError(f"unknown node: {type(node).__name__}")