agent-orchestrator-benchmark/calculators/builder-adversary-min/run-03/machine-docs/JOURNAL-parse.md

JOURNAL — phase parse

Build notes

Implemented a classic recursive-descent parser.

Grammar (precedence lowest → highest):

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

The while loops in _expr and _term produce left-associative trees naturally: each iteration wraps the accumulated left subtree as the new node, so 8-3-2 folds as ((8-3)-2).

Unary minus recurses right (_unary calls itself) to allow --5 to parse as Unary('-', Unary('-', Num(5))).

Empty input is caught by checking for EOF before entering _expr. Trailing tokens (e.g. 1 2) are caught by the EOF check after _expr returns. Unclosed parens are caught in _primary when expecting RPAREN but finding EOF.

36 tests: 3 precision, 3 left-assoc, 3 paren, 4 unary, 5 error, plus 18 from lexer phase.