Specctra's SpecCharASCII includes / and *, and an Identifier may start with /,
so KiCad emits hierarchical net names such as /*52 and /53. The tokenizer
treated any /* as a block-comment start and raised 'unterminated comment' when
no */ followed — rejecting real KiCad DSN. Match FreeRouting's JFlex rule-order
resolution: /* is a comment only when a closing */ exists; otherwise it is an
ordinary name run. Validated against a KiCad 10.0.4 pcbnew-exported DSN (78 nets
incl. /*52, /53).
Ports the read path of FreeRouting's io/specctra/parser package to a
Java-free Python implementation:
- tokenizer: S-expression lexer mirroring SpecctraFileDescription.flex
(comments, quoted strings, the string_quote IGNORE_QUOTE directive,
case-insensitive keywords, and hash-prefixed names)
- sexp: nested S-expression tree builder
- shapes: rect/circle/polygon/path plus area-with-holes scopes
- model: typed dataclasses for layers, padstacks, images, placements,
nets, net classes, rules, keepouts
- reader: recursive-descent scope readers producing a DsnBoard, one
_read_* function per FreeRouting read_scope method
46 pytest cases cover the tokenizer, tree, shapes, and end-to-end
parsing against hand-crafted fixtures modeled on FreeRouting's own
test DSN files. Parses 90 of 91 upstream fixtures (the one failure is
a binary OLE file, not text DSN).
