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