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

calculators/builder-solo/run-05/calc/evaluator.py

@@ -0,0 +1,53 @@
+"""Evaluator for the arithmetic AST produced by calc.parser.
+
+evaluate(node) -> int | float
+
+Result-type rule: if the mathematical result is whole-valued (no fractional
+part), it is returned as int; otherwise as float. This ensures '4/2' → 2
+and '7/2' → 3.5 without a trailing .0 on whole results.
+"""
+
+from calc.parser import BinOp, Num, Unary
+
+
+class EvalError(Exception):
+    pass
+
+
+def evaluate(node):
+    """Walk an AST node and return int or float.
+
+    Raises EvalError on semantic errors (e.g. division by zero).
+    """
+    if isinstance(node, Num):
+        return node.value
+
+    if isinstance(node, Unary):
+        operand = evaluate(node.operand)
+        if node.op == '-':
+            return _normalize(-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 _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 AST node: {node!r}")
+
+
+def _normalize(v):
+    """Return int if v is a whole-valued float, else return v unchanged."""
+    if isinstance(v, float) and v == int(v):
+        return int(v)
+    return v