# JOURNAL-lex

## 2026-06-15

### Build
- Created `calc/__init__.py` (empty package marker)
- Created `calc/lexer.py`: `Token` (NamedTuple with `kind` and `value`), `LexError`, `tokenize(src)`
  - Handles integers (int), floats (float, including `.5` and `10.` edge cases)
  - Single-char operators: `+ - * / ( )`
  - Whitespace (space, tab) skipped
  - Invalid chars raise `LexError` with char repr and position
  - Appends `EOF` token at end
- Created `calc/test_lexer.py`: 14 unittest cases covering D1–D3

### Verification
- `python -m unittest -q` → 14 tests, 0 failures — PASS
- `tokenize('3.5*(1-2)')` → correct 8-token sequence — PASS
- `tokenize('1 @ 2')` → raises `LexError: unexpected character '@' at position 2` — PASS

### Commit
`7ac5cdaded6af3b635d6d638f9c20082b5648393`