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

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

@@ -0,0 +1,37 @@
+from calc.parser import Num, BinOp, Unary
+
+
+class EvalError(Exception):
+    pass
+
+
+def evaluate(node):
+    """Walk the AST returned by parse() and return int | float."""
+    if isinstance(node, Num):
+        return node.value
+    if isinstance(node, Unary):
+        if node.op == '-':
+            return -evaluate(node.operand)
+        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 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 op {node.op!r}")
+    raise EvalError(f"unknown AST node type {type(node).__name__!r}")
+
+
+def format_result(value) -> str:
+    """Format a numeric result: whole-valued floats print without '.0', others as-is."""
+    if isinstance(value, float) and value == int(value):
+        return str(int(value))
+    return str(value)