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

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

@@ -0,0 +1,42 @@
+"""Evaluator for calc AST nodes.
+
+evaluate(node) -> int | float
+
+Result-type rule: whole-valued results are returned as int;
+fractional results as float. So 4/2 -> 2, 7/2 -> 3.5.
+"""
+
+from calc.parser import Num, BinOp, Unary
+
+
+class EvalError(Exception):
+    pass
+
+
+def _normalize(value):
+    """Convert a whole-valued float to int; leave everything else alone."""
+    if isinstance(value, float) and value.is_integer():
+        return int(value)
+    return value
+
+
+def evaluate(node):
+    """Walk an AST node and return its numeric value."""
+    if isinstance(node, Num):
+        return _normalize(node.value)
+    if isinstance(node, Unary):
+        return _normalize(-evaluate(node.operand))
+    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 node type: {type(node).__name__}')