modprog / rsn

rsn - Rust Notation

This crate is very early in development and is not ready for consumption.

A UTF-8 based text format that looks very similar to valid Rust code.

The syntax differs from valid Rust code for:

• Map literals. Rust has no syntax for map literals.
• Enum Variants being used without the type name -- Red vs Color::Red
  • This is technically valid Rust syntax if use Color::* is present.
• Infinity and Not-A-Number floats are represented as +Inf/-Inf/+NaN/-NaN.

The rules for parsing literals should match Rust's rules as closely as possible.

no_std support

This crate supports no_std targets that support the alloc crate.

Data Types

• Integers (42, 0xFF, 0o77, ob101)

• Floats (42., 3.14, `)

• Bool (true, false)

• Character ('a', '\'')

• Byte (b'a', b'\'')

• String ("hello, world")

• Raw Strings (r#"They said, "Hello World!""#)

• Byte Strings (b"hello, world")

• Struct

  • Ident or Raw Ident (r#foo)
  • Map or Tuple

• Map

  • List of <Value>: <Value> pairs, delimited by comma
  • Trailing comma is optional

• Tuple (empty tuple = Unit)

  • List of <Value>s, delimited by comma
  • Trailing comma is optional

• Array

  • List of <Value>s, delimited by comma
  • Trailing comma is optional

• Comments // and /* */

• Potential Extensions via #[] syntax

  • Semi-strict comma-delimited list
  • #[foo(...), bar = ...,]
  • All braces/brackets/parens must be paired correctly?

Why not Ron?

Ron is a great format. There were a few design decisions that led to this very-similar-yet-not-the-same format being invented:

• ron differentiates between Tuples and Lists, while rsn treats all sequences the same.
• ron uses a different syntax for structures and maps. rsn uses the same syntax for both concepts.
• ron has special support for Option<T>. rsn treats Option<T> like any other enum.
• ron's parsing rules are close but not the same as Rust, while rsn attempts to match implementations:
  • Rust allows unicode identifiers
  • Rust allows additional whitespace characters
  • Rust allows _ in float literals
  • Rust allows for raw line endings to be escaped in string literals.
  • Rust supports multi-line comments /* ... */
  • Rust supports byte strings and byte literals, while Ron elected to use base64 encoded strings for byte values.