sexpr-plus ![npm package][1] ![CI status][2]

Recursive descent parser for S-expressions, with features useful for writing an
S-expr-based programming language. Written for [eslisp][3], but generalisable.

Outputs an array containing objects representing parsed forms:

- Lists are parsed to { type: "list", content: [ ... ] }.
- Atoms are parsed to { type: "atom", content: "" }.
- Strings (delimited with "s) are parsed to { type: "string", content:
"" }. They support the same escape sequences as JavaScript
strings: \", \\, \n, \r, \t, \f, and \b.
- Supports quote, quasiquote, unquote and unquote-splicing, with ', `
`, , and ,@. They're turned into the appropriate atoms.
- Comments are from ; til end of line. They are not present in the output.

Empty inputs or inputs containing only comments produce an empty array.

Forked from the more minimal [fwg/s-expression][4].

Node locations

All output nodes also have a location property, showing where in the input
that node originated:

{
start : { offset, line, column },
end : { offset, line, column }
}

All are integers: offset is the number of characters since the input, line
and column are 1-based and self-explanatory.

These may be handy for constructing source maps or showing more detailed error
messages.

Usage

npm i sexpr-plus

`js
var parse = require("sexpr-plus").parse;
`

Call parse with a string containing code to parse.

If you need to catch and distinguish between different types of Error with
instanceof while parsing, the syntax error prototype is available at
require("sexpr-plus").SyntaxError`.

License

[MIT][5].

[1]: https://www.npmjs.com/package/sexpr-plus
[2]: https://travis-ci.org/anko/sexpr-plus
[3]: https://github.com/anko/eslisp
[4]: https://github.com/fwg/s-expression
[5]: LICENSE