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

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

@@ -0,0 +1,36 @@
+from __future__ import annotations
+from calc.parser import Node, Num, BinOp, Unary
+
+
+class EvalError(Exception):
+    pass
+
+
+def evaluate(node: Node) -> int | float:
+    """Walk an AST and return its numeric value.
+
+    Uses true division (7/2 → 3.5). Division by zero raises EvalError.
+    Integer operands with integer-only operations (+ - *) return int;
+    any division always returns float. The CLI formats whole floats as int.
+    """
+    if isinstance(node, Num):
+        return node.value
+    if isinstance(node, Unary):
+        if node.op == '-':
+            return -evaluate(node.operand)
+        raise EvalError(f"unknown unary operator: {node.op!r}")
+    if isinstance(node, BinOp):
+        left = evaluate(node.left)
+        right = evaluate(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 binary operator: {node.op!r}")
+    raise EvalError(f"unknown node type: {type(node)!r}")