$ cargo install sbnfc

$ cargo install --path cli

NAME = `simplec`

prototype : ( ~comment )* ;

comment : '(//+).*\n?'{comment.line, 1: punctuation.definition.comment} ;

main : ( variable-declaration | function-definition )* ;

IDENTIFIER = '\b[A-Za-z_]+\b'

function-definition{meta.function}
: type
  IDENTIFIER{entity.name.function}
  `(`
  `)`
  block
;

block{meta.block} : '{' statement* '}' ;

statement : variable-declaration
          | value ';'
          | block
          ;

variable-declaration : type IDENTIFIER{variable} ( '=' value )? ';' ;

type : IDENTIFIER{storage.type} ;

value : '[0-9]+'{constant.numeric}
      | function-call
      ;

# Function calls don't have arguments :)
function-call{meta.function-call}
: IDENTIFIER{variable.function meta.path} `(` `)` ;

%YAML 1.2
---
# https://text.sublime.net.cn/docs/syntax.html
version: 2
name: simplec
scope: source.simplec
contexts:
  # Rule: block
  block|0:
    - meta_content_scope: meta.block.simplec
    - match: '{'
      scope: meta.block.simplec
      set: block|1
    - match: '\S'
      scope: invalid.illegal.simplec
      pop: true
  # Rule: block
  block|1:
    - meta_content_scope: meta.block.simplec
    - include: include!block@1
    - match: '[0-9]+'
      scope: meta.block.simplec constant.numeric.simplec
      push: [block|meta, statement|0]
    - match: '{'
      scope: meta.block.simplec meta.block.simplec
      push: [block|meta, block|1]
    - match: '}'
      scope: meta.block.simplec
      pop: true
    - match: '\S'
      scope: invalid.illegal.simplec
      pop: true
  # Rule: block
  #  For branch point 'block@1'
  block|2|block@1:
    - match: '\b[A-Za-z_]+\b'
      scope: meta.block.simplec variable.simplec
      set: [block|meta, variable-declaration|2]
    - match: '\S'
      fail: block@1
  # Rule: block
  #  For branch point 'block@1'
  block|3|block@1:
    - match: '\('
      scope: meta.block.simplec meta.function-call.simplec
      set: [block|meta, statement|0, function-call|1]
    - match: '\S'
      scope: invalid.illegal.simplec
      pop: true
  # Meta scope context for block
  block|meta:
    - meta_content_scope: meta.block.simplec
    - match: ''
      pop: true
  # Rule: function-call
  function-call|0:
    - meta_content_scope: meta.function-call.simplec
    - match: '\('
      scope: meta.function-call.simplec
      set: function-call|1
    - match: '\S'
      scope: invalid.illegal.simplec
      pop: true
  # Rule: function-call
  function-call|1:
    - meta_content_scope: meta.function-call.simplec
    - match: '\)'
      scope: meta.function-call.simplec
      pop: true
    - match: '\S'
      scope: invalid.illegal.simplec
      pop: true
  function-call|2|block@1:
    - meta_include_prototype: false
    - match: '\b[A-Za-z_]+\b'
      scope: meta.function-call.simplec variable.function.simplec meta.path.simplec
      push: block|3|block@1
      pop: true
  # Rule: function-definition
  function-definition|0:
    - meta_content_scope: meta.function.simplec
    - match: '\)'
      scope: meta.function.simplec
      set: [function-definition|meta, block|0]
    - match: '\S'
      scope: invalid.illegal.simplec
      pop: true
  # Meta scope context for function-definition
  function-definition|meta:
    - meta_content_scope: meta.function.simplec
    - match: ''
      pop: true
  # Include context for branch point block@1
  include!block@1:
    - match: '(?=\b[A-Za-z_]+\b)'
      branch_point: block@1
      branch:
        - type|2|block@1
        - function-call|2|block@1
  # Include context for branch point main@1
  include!main@1:
    - match: '(?=\b[A-Za-z_]+\b)'
      branch_point: main@1
      branch:
        - type|0|main@1
        - type|1|main@1
  # Rule: main
  main:
    - include: include!main@1
    - match: '\S'
      scope: invalid.illegal.simplec
  # Rule: main
  #  For branch point 'main@1'
  main|0|main@1:
    - match: '\b[A-Za-z_]+\b'
      scope: variable.simplec
      push: main|2|main@1
      pop: true
    - match: '\S'
      fail: main@1
  # Rule: main
  #  For branch point 'main@1'
  main|1|main@1:
    - match: '\b[A-Za-z_]+\b'
      scope: meta.function.simplec entity.name.function.simplec
      push: main|3|main@1
      pop: true
    - match: '\S'
      scope: invalid.illegal.simplec
      pop: true
  # Rule: main
  #  For branch point 'main@1'
  main|2|main@1:
    - match: '='
      set: variable-declaration|0
    - match: ';'
      pop: true
    - match: '\S'
      fail: main@1
  # Rule: main
  #  For branch point 'main@1'
  main|3|main@1:
    - match: '\('
      scope: meta.function.simplec
      set: function-definition|0
    - match: '\S'
      scope: invalid.illegal.simplec
      pop: true
  # Rule: prototype
  prototype:
    - match: '(//+).*\n?'
      scope: comment.line.simplec
      captures:
        1: punctuation.definition.comment.simplec
  # Rule: statement
  statement|0:
    - match: ';'
      pop: true
    - match: '\S'
      scope: invalid.illegal.simplec
      pop: true
  type|0|main@1:
    - meta_include_prototype: false
    - match: '\b[A-Za-z_]+\b'
      scope: storage.type.simplec
      push: main|0|main@1
      pop: true
  type|1|main@1:
    - meta_include_prototype: false
    - match: '\b[A-Za-z_]+\b'
      scope: meta.function.simplec storage.type.simplec
      push: main|1|main@1
      pop: true
  type|2|block@1:
    - meta_include_prototype: false
    - match: '\b[A-Za-z_]+\b'
      scope: storage.type.simplec
      push: block|2|block@1
      pop: true
  # Rule: variable-declaration
  variable-declaration|0:
    - match: '[0-9]+'
      scope: constant.numeric.simplec
      set: variable-declaration|1
    - match: '\b[A-Za-z_]+\b'
      scope: meta.function-call.simplec variable.function.simplec meta.path.simplec
      set: [variable-declaration|1, function-call|0]
    - match: '\S'
      scope: invalid.illegal.simplec
      pop: true
  # Rule: variable-declaration
  variable-declaration|1:
    - match: ';'
      pop: true
    - match: '\S'
      scope: invalid.illegal.simplec
      pop: true
  # Rule: variable-declaration
  variable-declaration|2:
    - match: '='
      set: variable-declaration|0
    - match: ';'
      pop: true
    - match: '\S'
      scope: invalid.illegal.simplec
      pop: true

NAME = `SBNF`
EXTENSIONS = `sbnf`
# Don't need this, as this is already the default
# SCOPE = `source.sbnf`

a : 'a' ;
b{source.b} : 'b' ;
c[S] : 'c'{#[S]} ;
d[S]{text.d} : a b c[S] ;

main
: a['a'] # instantiates rule 1
| a[a]   # instantiates rule 2
| a['b'] # instantiates rule 3
| b['b'] # error: Ambiguous instantiation
;

# Rule 1.
a['a'] : 'a' ;

# Rule 2.
a[a] : 'a' ;

# Rule 3.
a[A] : 'a' ;

b[A] : 'a' ;
b[B] : 'b' ;

# Declares a single global parameter
[TYPE]

# Can be used in clauses
NAME = 'd-#[TYPE]'

# As well as rules
main : '#[TYPE]' ;

# 'dmd' is passed to TYPE when compiled
$ sbnf syntax.sbnf dmd

# This is a basic implementation of the html script tag embedding the javascript
# syntax.
script
: '<script>'{tag.begin.script}
  %embed['</script>']{scope:source.js, embedded.js, 0: tag.end.script}
;

# The above translates to the following context
script:
  - match: '<script>'
    scope: tag.begin.script.example
    embed: scope:source.js
    embed_scope: embedded.js.example
    escape: '</script>'
    escape_captures:
      0: tag.end.script.example
    pop: true
  - match: '\S'
    scope: invalid.illegal.example

# This is a basic implementation of a regex string. It has a prototype rule that
# extends the regex syntax with an escape sequence for the string.

regex-prototype{include-prototype: false}
: ( ~`\'`{constant.character.escape} )*
  # A lookahead is required here, as otherwise we would only pop one context
  # The same is required in a sublime-syntax file
  ~'(?=\')'
;

regex-string{string.quoted}
: `'`{punctuation.definition.string.begin}
  %include[regex-prototype]{scope:source.regexp}
  `'`{punctuation.definition.string.end}
;

# The above translates to the following contexts
regex-string:
  - meta_content_scope: string.quoted.example
  - match: ''''
    scope: string.quoted.example punctuation.definition.string.begin.example
    set: [regex-string|0, regex-string|1]
  - match: '\S'
    scope: invalid.illegal.example
regex-string|0:
  - meta_content_scope: string.quoted.example
  - match: ''''
    scope: string.quoted.example punctuation.definition.string.end.example
    pop: true
  - match: '\S'
    scope: invalid.illegal.example
    pop: true
regex-string|1:
  - meta_include_prototype: false
  - match: ''
    set: scope:source.regexp
    with_prototype:
      - include: regex-prototype|0
regex-prototype|0:
  - meta_include_prototype: false
  - match: '\\'''
    scope: constant.character.escape.example
  - match: '(?='')'
    pop: true

$ sbnf --help
SBNF compiler 0.4.0

USAGE:
    sbnf [FLAGS] [OPTIONS] <INPUT> [ARGS]...

FLAGS:
    -g               Compile with debug scopes
    -h, --help       Prints help information
    -q               Do not display warnings
    -V, --version    Prints version information

OPTIONS:
    -o <output>        The file to write the compiled sublime-syntax to. Defaults to $INPUT.sublime-syntax if left out. Use a single dash `-` to write to stdout instead.

ARGS:
    <INPUT>      The SBNF file to compile
    <ARGS>...    Arguments to pass to the main and prototype rules

main : 'aa?'{scope1} 'b'
     | 'a'{scope2} 'c'
     ;

main : 'aa'{scope1} 'b'
     | 'a'{scope1} 'b'
     | 'a'{scope2} 'c'
     ;