agent-orchestrator-benchmark/calculators/builder-solo/run-02/machine-docs/JOURNAL-eval.md

JOURNAL — eval phase

Build

1. Read calc/parser.py and calc/lexer.py to understand AST node contracts (Num, BinOp, Unary) and Token/ParseError types.

2. Wrote calc/evaluator.py:

   • EvalError(Exception) wraps all evaluation failures.
   • evaluate(node) walks the AST recursively.
   • Division by zero raises EvalError("division by zero").
   • Result-type rule: float.is_integer() → cast to int; otherwise keep float.

3. Wrote calc.py (top-level CLI):

   • Accepts exactly one argument (the expression string).
   • Chains tokenize → parse → evaluate, prints result.
   • Catches LexError | ParseError | EvalError, prints error: <msg> to stderr, exits 1.
   • No traceback surfaces.

4. Wrote calc/test_evaluator.py (unittest):

   • TestArithmetic — D1: +, -, *, /, precedence, parens, unary minus.
   • TestDivision — D2: true division, EvalError on /0, confirms no bare ZeroDivisionError.
   • TestResultType — D3: 4/2 → int(2), 7/2 → float(3.5).
   • TestCLI — D4: subprocess smoke tests for valid and invalid CLI invocations.

Verification

All plan Verify commands run from a clean working directory:

python -m unittest -q       → Ran 51 tests, OK
python calc.py "2+3*4"      → 14   (exit 0)
python calc.py "(2+3)*4"    → 20   (exit 0)
python calc.py "7/2"        → 3.5  (exit 0)
python calc.py "4/2"        → 2    (exit 0, no trailing .0)
python calc.py "1/0"        → error: division by zero  (exit 1, stderr)
python calc.py "1 +"        → error: unexpected end of expression  (exit 1, stderr)

Additional D1 edge cases verified:

python calc.py "8-3-2"      → 3
python calc.py "-2+5"       → 3
python calc.py "2*-3"       → -6

All DoD gates confirmed PASS. Committed as f083f901.