2 releases

0.1.1 Oct 14, 2022
0.1.0 Apr 16, 2022

#1533 in Parser implementations

47 downloads per month

MIT/Apache

45KB
1K SLoC

s-expr

Rust library for S-expression like parsing and printing

  • parser keeps track of spans, and representation (e.g. number base)
  • number and decimal don't limit size
  • only 1 dependency on unicode-xid

S-expressions features

Extra features which are not in usual s-expressions (cannot be turned off):

  • binary and hexadecimal number, when starting a number with the prefixes respectively 0b or 0x.
  • _ characters in number, e.g. 0xfedc__1240__abcd or 100_000_000 to improve legibility

Currently unsupported:

  • symbol with spaces
  • negative literal integral and decimal, currently -123 will be tokenized as the ident - followed by number 123.
  • scientific notation for decimal numbers 6.022e23 will be parsed as decimal 6.022 then ident e, then number 23

There's lots of variant of S-expression, so the parser allow to parse various different optional features that can be enabled/disabled depending on the user wishes:

  • semi-colon line comment
  • byte string of the format : #8BADF00D#
  • braces { } and bracket [ ] group, which behave like ( ) but provide equivalent grouping balancing check and flavor of grouping

Dependencies