agent-orchestrator-benchmark/calculators/builder-adversary-deferred/run-05/machine-docs/JOURNAL-parse.md

JOURNAL — parse phase

Session 1 (2026-06-16)

Starting parse phase. Lex phase complete (11 tests green).

Design: recursive-descent parser

Grammar chosen:

expr    := term  (('+' | '-') term)*
term    := unary (('*' | '/') unary)*
unary   := '-' unary | primary
primary := NUMBER | '(' expr ')'

Why iterative (not right-recursive) for expr/term: gives natural left-associativity. Why unary is right-recursive: - chains right, e.g. --5 = -(-(5)).

Test run results (2026-06-16)

python -m unittest -v
Ran 35 tests in 0.001s
OK

All 24 parser tests + 11 lexer tests green on first attempt.

Verified shapes:

• 1+2*3 → BinOp('+', Num(1), BinOp('*', Num(2), Num(3))) ✓ D1
• 8-3-2 → BinOp('-', BinOp('-', Num(8), Num(3)), Num(2)) ✓ D2
• (1+2)*3 → BinOp('*', BinOp('+', Num(1), Num(2)), Num(3)) ✓ D3
• -5 → Unary('-', Num(5)) ✓ D4
• 3 * -2 → BinOp('*', Num(3), Unary('-', Num(2))) ✓ D4
• 1 + → ParseError: unexpected end of input ✓ D5

AST nodes (dataclasses):

• Num(value: int | float) — leaf
• BinOp(op: str, left: Node, right: Node) — binary operation
• Unary(op: str, operand: Node) — unary minus (op='-')