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rsn Syntax Reference

This document aims to describe the accepted syntax for parsing rsn. Currently, it is more of a TODO list than actual documentation.

An rsn payload contains a single Value, which can be one of these types:

  • Integer: 123; -123_456; 0x0123_aBc; 0o123_777; 0b1010_1111
  • Float: 1.; -2_000.123_456; 1e-2
  • Boolean: true; false
  • Character: 'a'; '\''
  • Byte: b'a'; b'\''
  • String: "hello, world"; r#"raw "strings""#
  • Byte String: b"hello, world"; br#"raw "strings""#
  • Map: {key: "value"}; {a: 1, b: true,}
  • List: [1, 2, 3]; ["a", "b",]
  • Tuple: (1, false); (2, true,)
  • Identified: Name; Name { a: 1 }; Name(1)

Integer

Just like in Rust, integers can be represented in four different representations: decimal (base 10), binary (base 2), octal (base 8), and hexadecimal (base 16). Integer parsing ignores underscores (_) to allow large literals to be grouped however the user prefers.

If an integer has no explicit sign, it will be parsed as a usize. If the value overflows, it will be promoted to the "large integer size". If the integer128 feature is enabled, the "large integer size" is a u128. If the feature is not enabled, the "large integer size" is a u64.

If either a + or - sign is present, the integer will be parsed as an isize with the appropriate sign applied. If the value overflows, it will be promoted to the "large integer size". If the integer128 feature is enabled, the "large integer size" is a i128. If the feature is not enabled, the "large integer size" is a i64.

Syntax

Integer values always begin with a digit (0-9) or a sign (+/-).

  1. If a sign (+ or -) is encountered, the literal is parsed as a signed number.
  2. At least one digit (0-9) must be present.
    1. If the first digit is a 0 and it is followed by an x or 'X', parse the remainder of this literal as a hexadecimal number.
    2. If the first digit is a 0 and it is followed by a b or 'B', parse the remainder of this literal as a binary number.
    3. If the first digit is a 0 and it is followed by an o or 'O', parse the remainder of this literal as an octal number.
  3. Continue reading digits (0-9) or underscores (_) until a non-matching character is encountered.
  4. If the first non-matching character is either a ., e or E, switch to parsing this numerical value as a float.

Hexadecimal Syntax

Hexadecimal values are parsed after encountering 0x while parsing an integer. After this prefix, parsing is done by reading hexadecimal digits (0-9, a-f, A-F) or underscores (_) until a non-matching character is encountered.

Octal Syntax

Octal values are parsed after encountering 0o while parsing an integer. After this prefix, parsing is done by reading octal digits (0-7) or underscores (_) until a non-matching character is encountered.

Binary Syntax

Binary values are parsed after encountering 0b while parsing an integer. After this prefix, parsing is done by reading binary digits (0 or 1) or underscores (_) until a non-matching character is encountered.

Float

  • Tokenizer support
    • inf/NaN support
  • Parser support
  • Deserializer Support
  • Documentation
  • Grammar Spec

Boolean

  • Tokenizer support
  • Parser support
  • Deserializer Support
  • Documentation

Character

  • Tokenizer support
  • Parser support
  • Deserializer Support
  • Documentation

Byte

  • Tokenizer support
  • Parser support
  • Deserializer Support
  • Documentation

String

  • Tokenizer support
    • Support same whitespace rules on raw line ending escaping.
    • Error-by-default on multiple line ending removal with raw line ending escaping, just like rustc, but allow a parsing option that prevents the errors.
  • Parser support
  • Deserializer Support
  • Documentation

Byte String

  • Tokenizer support
    • b64 prefixed base64-encoded byte strings
  • Parser support
  • Deserializer Support
  • Documentation

Map

  • Tokenizer support
  • Parser support
  • Deserializer Support
  • Documentation

List

  • Tokenizer support
  • Parser support
  • Deserializer Support
  • Documentation

Tuple

  • Tokenizer support
  • Parser support
  • Deserializer Support
  • Documentation

Identified

  • Tokenizer support
  • Parser support
  • Deserializer Support
  • Documentation