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

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

@@ -0,0 +1,47 @@
+"""Evaluator for the arithmetic AST produced by calc.parser.
+
+Result-type rule: if a computation yields a float that is whole-valued
+(e.g. 4/2 == 2.0), it is coerced to int before returning.  Non-whole
+floats (e.g. 7/2 == 3.5) are returned as float.
+"""
+from .parser import BinOp, Num, Unary
+
+
+class EvalError(Exception):
+    """Raised on a runtime evaluation error (e.g. division by zero)."""
+
+
+def _coerce(value):
+    if isinstance(value, float) and value == int(value):
+        return int(value)
+    return value
+
+
+def evaluate(node):
+    """Walk an AST node and return int | float.
+
+    Raises:
+        EvalError: on division by zero.
+    """
+    if isinstance(node, Num):
+        return _coerce(node.value)
+
+    if isinstance(node, Unary):
+        return _coerce(-evaluate(node.operand))
+
+    if isinstance(node, BinOp):
+        left = evaluate(node.left)
+        right = evaluate(node.right)
+        op = node.op
+        if op == '+':
+            return _coerce(left + right)
+        if op == '-':
+            return _coerce(left - right)
+        if op == '*':
+            return _coerce(left * right)
+        if op == '/':
+            if right == 0:
+                raise EvalError("division by zero")
+            return _coerce(left / right)
+
+    raise EvalError(f"unknown node type: {type(node).__name__}")