tree-sitter-rust-format-args

A grammar for Rust's format_args!.

Why?

It's desirable to have syntax highlighting for arguments in format macros, like format!, write!, etc.

tree-sitter-rust decided not to add this feature to their parser, so this grammar exists to be separately used and injected by editors in Rust.

Showcase

Example

It can parse the format_args! spec, so for instance, the following contents:

empty: {}
variable name: {testing}
padding and alignment: {:>5} {:a<5} {:0^5}
floating points: {:10.2}
hexadecimal and binary: {:b} {:x} {:X}
debug: {:?} {:#?} {hello:#?}
Numbers: {:e} {:E} {:+} {: } {:-}
Escape: {{ these are literal }}

Will be parsed as this tree:

(format_string [0, 0] - [8, 0]
  (text [0, 0] - [0, 7])
  (format [0, 7] - [0, 9])
  (text [0, 9] - [1, 15])
  (format [1, 15] - [1, 24]
    (argument [1, 16] - [1, 23]
      (identifier [1, 16] - [1, 23])))
  (text [1, 24] - [2, 23])
  (format [2, 23] - [2, 28]
    (colon [2, 24] - [2, 25])
    (align [2, 25] - [2, 26])
    (width [2, 26] - [2, 27]
      (number [2, 26] - [2, 27])))
  (text [2, 28] - [2, 29])
  (format [2, 29] - [2, 35]
    (colon [2, 30] - [2, 31])
    (fill [2, 31] - [2, 32])
    (align [2, 32] - [2, 33])
    (width [2, 33] - [2, 34]
      (number [2, 33] - [2, 34])))
  (text [2, 35] - [2, 36])
  (format [2, 36] - [2, 42]
    (colon [2, 37] - [2, 38])
    (fill [2, 38] - [2, 39])
    (align [2, 39] - [2, 40])
    (width [2, 40] - [2, 41]
      (number [2, 40] - [2, 41])))
  (text [2, 42] - [3, 17])
  (format [3, 17] - [3, 24]
    (colon [3, 18] - [3, 19])
    (width [3, 19] - [3, 21]
      (number [3, 19] - [3, 21]))
    (number [3, 21] - [3, 22])
    (number [3, 22] - [3, 23]
      (number [3, 22] - [3, 23])))
  (text [3, 24] - [4, 24])
  (format [4, 24] - [4, 28]
    (colon [4, 25] - [4, 26])
    (type [4, 26] - [4, 27]))
  (text [4, 28] - [4, 29])
  (format [4, 29] - [4, 33]
    (colon [4, 30] - [4, 31])
    (type [4, 31] - [4, 32]))
  (text [4, 33] - [4, 34])
  (format [4, 34] - [4, 38]
    (colon [4, 35] - [4, 36])
    (type [4, 36] - [4, 37]))
  (text [4, 38] - [5, 7])
  (format [5, 7] - [5, 11]
    (colon [5, 8] - [5, 9])
    (type [5, 9] - [5, 10]))
  (text [5, 11] - [5, 12])
  (format [5, 12] - [5, 17]
    (colon [5, 13] - [5, 14])
    (type [5, 15] - [5, 16]))
  (text [5, 17] - [5, 18])
  (format [5, 18] - [5, 28]
    (argument [5, 19] - [5, 24]
      (identifier [5, 19] - [5, 24]))
    (colon [5, 24] - [5, 25])
    (type [5, 26] - [5, 27]))
  (text [5, 28] - [6, 9])
  (format [6, 9] - [6, 13]
    (colon [6, 10] - [6, 11])
    (type [6, 11] - [6, 12]))
  (text [6, 13] - [6, 14])
  (format [6, 14] - [6, 18]
    (colon [6, 15] - [6, 16])
    (type [6, 16] - [6, 17]))
  (text [6, 18] - [6, 19])
  (format [6, 19] - [6, 23]
    (colon [6, 20] - [6, 21])
    (sign [6, 21] - [6, 22]))
  (text [6, 23] - [6, 24])
  (format [6, 24] - [6, 28]
    (colon [6, 25] - [6, 26]))
  (text [6, 28] - [6, 29])
  (format [6, 29] - [6, 33]
    (colon [6, 30] - [6, 31])
    (sign [6, 31] - [6, 32]))
  (text [6, 33] - [7, 8])
  (escaped [7, 8] - [7, 10])
  (text [7, 10] - [7, 29])
  (escaped [7, 29] - [7, 31])
  (text [7, 31] - [8, 0]))```