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

calculators/builder-adversary-deferred/run-03/calc/evaluator.py

@@ -0,0 +1,44 @@
+"""Evaluator: walks an AST (from calc.parser) and returns int | float.
+
+Result-type rule: if the result is whole-valued (no fractional part), return int;
+otherwise return float. This means 4/2 → 2 (int) and 7/2 → 3.5 (float).
+"""
+from __future__ import annotations
+from calc.parser import Num, BinOp, Unary, Node
+
+
+class EvalError(Exception):
+    pass
+
+
+def _normalize(v: int | float) -> int | float:
+    if isinstance(v, float) and v == int(v):
+        return int(v)
+    return v
+
+
+def evaluate(node: Node) -> int | float:
+    if isinstance(node, Num):
+        return _normalize(node.value)
+    if isinstance(node, Unary):
+        val = evaluate(node.operand)
+        if node.op == '-':
+            return _normalize(-val)
+        raise EvalError(f"unknown unary operator: {node.op!r}")
+    if isinstance(node, BinOp):
+        left = evaluate(node.left)
+        right = evaluate(node.right)
+        if node.op == '+':
+            result = left + right
+        elif node.op == '-':
+            result = left - right
+        elif node.op == '*':
+            result = left * right
+        elif node.op == '/':
+            if right == 0:
+                raise EvalError("division by zero")
+            result = left / right
+        else:
+            raise EvalError(f"unknown operator: {node.op!r}")
+        return _normalize(result)
+    raise EvalError(f"unknown node type: {type(node).__name__}")