# JOURNAL-parse.md

## 2026-06-15 — Build + verify

Lex phase DONE. Token kinds: NUMBER, PLUS, MINUS, STAR, SLASH, LPAREN, RPAREN, EOF.

Grammar chosen (iterative at each level → left associativity by construction):
```
expr    → term   (('+' | '-') term)*
term    → unary  (('*' | '/') unary)*
unary   → '-' unary | primary
primary → NUMBER | '(' expr ')'
```

### Manual verification output

```
D1 1+2*3: BinOp('+', Num(1), BinOp('*', Num(2), Num(3)))
D2 8-3-2: BinOp('-', BinOp('-', Num(8), Num(3)), Num(2))
D2 8/4/2: BinOp('/', BinOp('/', Num(8), Num(4)), Num(2))
D3 (1+2)*3: BinOp('*', BinOp('+', Num(1), Num(2)), Num(3))
D4 -5: Unary('-', Num(5))
D4 -(1+2): Unary('-', BinOp('+', Num(1), Num(2)))
D4 3*-2: BinOp('*', Num(3), Unary('-', Num(2)))
D5 '1 +' -> ParseError: unexpected end of input
D5 '(1' -> ParseError: unclosed parenthesis
D5 '1 2' -> ParseError: unexpected token 'NUMBER' (2) after expression
D5 ')(' -> ParseError: unexpected token 'RPAREN' (')')
D5 '' -> ParseError: empty input
```

Test run: `Ran 48 tests in 0.001s — OK` (21 lex + 27 parser)