Hocon

LALR grammar based HOCON-like configuration Parser for Erlang/OTP.

Spec

HOCON spec for reference: https://lightbend.github.io/config/

Divergence from Spec and Caveats

• No unicode support (at least not verified).
• The forbidden character @ is allowed in unquoted strings.
• Value concatenation is not allowed in keys e.g. a b c : 42 is invalid.
• Newlines do not prevent concatenation.
  • String (All below are parsed to the same result, which is #{key => <<"value1value2">>})
    • "key=value1 value2"
    • "key=value1value2"
    • "key=\"value1\" \"value2\""
    • "key=value1\nvalue2"
  • Array (#{key => [1,2,3,4]})
    • key=[1, 2] [3, 4]
    • key=[1, 2]\n[3, 4]
    • key=[1,2,3,4]
  • Object (#{key => #{a => 1,b => 2}}):
    • key={a: 1} {b: 2}
    • key={a: 1}\n{b: 2}
    • key={a=1, b=2}
• url()/file()/classpath() includes are not supported

Schema

HOCON schema (hocon_schema) is a type-safe data validation framework. which is compatible to basho cuttlefish

See more information in SCHEMA.md

Test Data

Files in sample-configs are collected from https://github.com/lightbend/config/tree/v1.4.1

TODO

• Upload to hex.pm

Reference

• https://en.wikipedia.org/wiki/Lexical_analysis#Evaluator
• https://www.crockford.com/mckeeman.html
• https://en.wikipedia.org/wiki/Backus–Naur_form

License

Apache License 2.0, see LICENSE.

Authors

EMQ X team