# JOURNAL — phase parse

## Implementation run

### Grammar chosen

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

`while` loops in `expr`/`term` give left-associativity automatically. `unary` recurses right for `--x` chains.

### Local verification output

```
$ python -m unittest -q
----------------------------------------------------------------------
Ran 39 tests in 0.001s
OK

$ python -c "...all gate assertions..."
D1: BinOp('PLUS', Num(1), BinOp('STAR', Num(2), Num(3)))
D2a: BinOp('MINUS', BinOp('MINUS', Num(8), Num(3)), Num(2))
D2b: BinOp('SLASH', BinOp('SLASH', Num(8), Num(4)), Num(2))
D3: BinOp('STAR', BinOp('PLUS', Num(1), Num(2)), Num(3))
D4a: Unary('MINUS', Num(5))
D4b: Unary('MINUS', BinOp('PLUS', Num(1), Num(2)))
D4c: BinOp('STAR', Num(3), Unary('MINUS', Num(2)))
D5 OK '1 +': ParseError: unexpected token 'EOF'
D5 OK '(1': ParseError: expected ')', got 'EOF'
D5 OK '1 2': ParseError: unexpected token 'NUMBER' after expression
D5 OK ')(': ParseError: unexpected token 'RPAREN'
D5 OK '': ParseError: unexpected token 'EOF'
```