EXPERIMENT: Rusty Object Notation reboot

Experimental implementation of a new parser for RON using small functional parsers for individual syntax elements over a stateful parser.

This experiment started off as "RON + nom", but is now using its own parsers & combinators inspired by nom.

Motivation

The current ron parsing suffers from the following problems:

• parsing is done in both parse.rs and the deserializer itself
  • bad code organization
  • hard to maintain
  • limits reuse
• serde's data model stops us from accurately reflecting struct / map and struct names

Benefits

Stateless / functional parsers are

• easier to maintain
• easier to reuse
• much easier to test

An abstract syntax tree (AST)...

• makes the deserializer much easier & cleaner to implement
• allows reporting locations of syntax & type errors
• can be reused by multiple deserializer implementations (serde::Deserializer, our_own::Deserializer, ron-edit)

Error reporting

The old RON deserializer produced errors that were often hard to understand. ron-reboot is meant to change that; this is the output of a deserialization error as of 2021-10-15:

error: invalid type: boolean `true`, expected a string
 --> string:3:9
  |
3 |       y: true,
  |          ^^^^
  |

or with a multi-line expression:

error: invalid type: map, expected a string
 --> string:3:9
  |
3 |       y: (
  |  ________^
4 | |         this: "is",
5 | |         not: "the right type",
6 | |     ),
  | |______^
  |

Goals / Progress

Contributions

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, shall be licensed according to the license of this project (Apache-2.0), without any additional terms or conditions.