source ../plugin/vimpeg.vim
let p = Vimpeg({'skip_white': 1})

" # Hierarchical syntax {{{
" Grammar <- Spacing Definition+ EndOfFile
" Definition <- Identifier LEFTARROW Expression
" Expression <- Sequence (SLASH Sequence)*
" Sequence <- Prefix*
" Prefix <- (AND / NOT)? Suffix
" Suffix <- Primary (QUESTION / STAR / PLUS)?
" Primary <- Identifier !LEFTARROW / OPEN Expression CLOSE / Literal / Class / DOT
" # Lexical syntax
" Identifier <- IdentStart IdentCont* Spacing
" IdentStart <- [a-zA-Z_]
" IdentCont <- IdentStart / [0-9]
" Literal <- [’] (![’] Char)* [’] Spacing / ["] (!["] Char)* ["] Spacing
" Class <- ’[’ (!’]’ Range)* ’]’ Spacing
" Range <- Char ’-’ Char / Char
" Char <- ’\\’ [nrt’"\[\]\\] / ’\\’ [0-2][0-7][0-7] / ’\\’ [0-7][0-7]?  / !’\\’ .
" LEFTARROW <- ’<-’ Spacing
" SLASH <- ’/’ Spacing
" AND <- ’&’ Spacing
" NOT <- ’!’ Spacing
" QUESTION <- ’?’ Spacing
" STAR <- ’*’ Spacing
" PLUS <- ’+’ Spacing
" OPEN <- ’(’ Spacing
" CLOSE <- ’)’ Spacing
" DOT <- ’.’ Spacing
" Spacing <- (Space / Comment)*
" Comment <- ’#’ (!EndOfLine .)* EndOfLine
" Space <- ’ ’ / ’\t’ / EndOfLine
" EndOfLine <- ’\r\n’ / ’\n’ / ’\r’
" EndOfFile <- !.
" }}}

" <definition>    ::= <label> <mallet> <expression>
" <expression>    ::= <sequence> ( <or> <sequence> )*
" <sequence>      ::= <prefix>*
" <prefix>        ::= ( <and> | <not> )? <suffix>
" <suffix>        ::= <primary> ( <question> | <star> | <plus> )?
" <primary>       ::= <label> !<mallet> | <open> <expression> <close> | <regex>
" <label>         ::= <lt> <identifier> <gt>
" <identifier>    ::= <ident_start> <ident_cont>*
" <ident_cont>    ::= '\w'
" <ident_start>   ::= '\h'
" <regex>         ::= <squote> ( '[^']' | <double_squote> )* <squote>
" <double-squote> ::= "''"
" <squote>        ::= "'"
" <mallet>        ::= '::='
" <or>            ::= '|'
" <and>           ::= '&'
" <not>           ::= '!'
" <question>      ::= '?'
" <star>          ::= '\*'
" <plus>          ::= '+'
" <close>         ::= ')'
" <open>          ::= '('
" <gt>            ::= '>'
" <lt>            ::= '<'
" <spacing>       ::= '\s'

" Parser grammar {{{
let expr = p.and(['label', 'mallet', 'expression'],
      \{'id': 'definition', 'on_match': 'Definition'})
call p.and(['sequence', p.maybe_many(p.and(['or', 'sequence']))],
      \{'id': 'expression', 'on_match': 'Expression'})
call p.maybe_many('prefix',
      \{'id': 'sequence', 'on_match': 'Sequence'})
call p.and([p.maybe_one(p.or(['and', 'not'])), 'suffix'],
      \{'id': 'prefix', 'on_match': 'Prefix'})
call p.and(['primary', p.maybe_one(p.or(['question', 'star', 'plus']))],
      \{'id': 'suffix', 'on_match': 'Suffix'})
call p.or([p.and(['label', p.not_has('mallet')]), p.and(['open', 'expression', 'close']), 'regex'],
      \{'id': 'primary', 'on_match': 'Primary'})
call p.and(['lt', 'identifier', 'gt'],
      \{'id': 'label', 'on_match': 'Label'})
call p.and(['ident_start', p.many('ident_cont')],
      \{'id': 'identifier', 'on_match': 'Identifier'})
call p.e('\w',
      \{'id': 'ident_cont'})
call p.e('\h',
      \{'id': 'ident_start'})
call p.and(['squote', p.maybe_many(p.or([p.e('[^'']'),'double_squote'])), 'squote'],
      \{'id': 'regex', 'on_match': 'Regex'})
call p.e("''",
      \{'id': 'double_squote', 'on_match': 'Double_squote'})
call p.e("'",
      \{'id': 'squote', 'on_match': 'Squote'})
call p.e('::=',
      \{'id': 'mallet', 'on_match': 'Mallet'})
call p.e('|',
      \{'id': 'or', 'on_match': 'Or'})
call p.e('&',
      \{'id': 'and', 'on_match': 'And'})
call p.e('!',
      \{'id': 'not', 'on_match': 'Not'})
call p.e('?',
      \{'id': 'question', 'on_match': 'Question'})
call p.e('\*',
      \{'id': 'star', 'on_match': 'Star'})
call p.e('+',
      \{'id': 'plus', 'on_match': 'Plus'})
call p.e(')',
      \{'id': 'close', 'on_match': 'Close'})
call p.e('(',
      \{'id': 'open', 'on_match': 'Open'})
call p.e('>',
      \{'id': 'gt', 'on_match': 'Gt'})
call p.e('<',
      \{'id': 'lt', 'on_match': 'Lt'})
" }}}

" Callback functions {{{
function! Definition(elems)
  echom string(a:elems)
  let def = 'call '.string(a:elems[2][0])."{'id':'".a:elems[0][0]."'})"
  echom 'Definition: ' . string(def)
  return def
endfunction
function! Expression(elems)
  echom 'Expression: ' . string(a:elems)
  return a:elems
endfunction
function! Sequence(elems)
  echom 'Sequence: ' . string(a:elems)
  return a:elems
endfunction
function! Prefix(elems)
  echom 'Prefix: ' . string(a:elems)
  return a:elems
endfunction
function! Suffix(elems)
  echom 'Suffix: ' . string(a:elems)
  return a:elems
endfunction
function! Primary(elems)
  echom 'Primary: ' . string(a:elems)
  return a:elems
endfunction
function! Label(elems)
  let res = a:elems[1]
  echom 'Label: ' . string(res)
  return res
endfunction
function! Identifier(elems)
  let id = [a:elems[0].join(a:elems[1], '')]
  echom 'Identifier: ' . string(id)
  return id
endfunction
function! Regex(elems)
  echom 'Regex: ' . string(a:elems)
  return a:elems
endfunction
function! Double_squote(elems)
  echom 'Double_squote: ' . string(a:elems)
  return a:elems
endfunction
function! Squote(elems)
  echom 'Squote: ' . string(a:elems)
  return a:elems
endfunction
function! Mallet(elems)
  echom 'Mallet: ' . string(a:elems)
  return a:elems
endfunction
function! Or(elems)
  echom 'Or: ' . string(a:elems)
  return a:elems
endfunction
function! And(elems)
  echom 'And: ' . string(a:elems)
  return a:elems
endfunction
function! Not(elems)
  echom 'Not: ' . string(a:elems)
  return a:elems
endfunction
function! Question(elems)
  echom 'Question: ' . string(a:elems)
  return a:elems
endfunction
function! Star(elems)
  echom 'Star: ' . string(a:elems)
  return a:elems
endfunction
function! Plus(elems)
  echom 'Plus: ' . string(a:elems)
  return a:elems
endfunction
function! Close(elems)
  echom 'Close: ' . string(a:elems)
  return a:elems
endfunction
function! Open(elems)
  echom 'Open: ' . string(a:elems)
  return a:elems
endfunction
function! Gt(elems)
  echom 'Gt: ' . string(a:elems)
  return a:elems
endfunction
function! Lt(elems)
  echom 'Lt: ' . string(a:elems)
  return a:elems
endfunction
" }}}

function! Test(expr)
  let expr = substitute(a:expr, '^"\s*', '', '')
  echom expr
  return string(g:expr.match(expr).value)
endfunction

nore <leader><leader> :w<bar>so %<bar>echo Test(getline('.'))<CR>
finish

" <hola> ::= 'mundo'