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

calculators/builder-adversary-min/run-04/calc/evaluator.py

@@ -0,0 +1,41 @@
+from calc.parser import Num, BinOp, Unary
+
+
+class EvalError(Exception):
+    pass
+
+
+def evaluate(node):
+    """Walk the AST and return int | float.
+
+    Result type rule: if the mathematical value is a whole number, return int;
+    otherwise return float.
+    """
+    if isinstance(node, Num):
+        return node.value
+    if isinstance(node, Unary):
+        v = evaluate(node.operand)
+        if node.op == '-':
+            return _normalize(-v)
+        raise EvalError(f"unknown unary op {node.op!r}")
+    if isinstance(node, BinOp):
+        left = evaluate(node.left)
+        right = evaluate(node.right)
+        if node.op == '+':
+            return _normalize(left + right)
+        if node.op == '-':
+            return _normalize(left - right)
+        if node.op == '*':
+            return _normalize(left * right)
+        if node.op == '/':
+            if right == 0:
+                raise EvalError("division by zero")
+            return _normalize(left / right)
+        raise EvalError(f"unknown binary op {node.op!r}")
+    raise EvalError(f"unknown node type {type(node).__name__}")
+
+
+def _normalize(v):
+    if isinstance(v, float) and v == int(v):
+        return int(v)
+    return v