vis

a vi-like editor based on Plan 9's structural regular expressions
rc.lua

(1556B)
      1 -- Copyright 2017-2025 Michael Forney. See LICENSE.
      2 -- rc LPeg lexer.
      3 
      4 local lexer = require('lexer')
      5 local token, word_match = lexer.token, lexer.word_match
      6 local P, S = lpeg.P, lpeg.S
      7 
      8 local lex = lexer.new('rc')
      9 
     10 -- Whitespace.
     11 lex:add_rule('whitespace', token(lexer.WHITESPACE, lexer.space^1))
     12 
     13 -- Keywords.
     14 lex:add_rule('keyword', token(lexer.KEYWORD, word_match{
     15 	'for', 'in', 'while', 'if', 'not', 'switch', 'case', 'fn', 'builtin', 'cd', 'eval', 'exec',
     16 	'exit', 'flag', 'rfork', 'shift', 'ulimit', 'umask', 'wait', 'whatis', '.', '~'
     17 }))
     18 
     19 -- Identifiers.
     20 lex:add_rule('identifier', token(lexer.IDENTIFIER, lexer.word))
     21 
     22 -- Strings.
     23 local str = lexer.range("'", false, false)
     24 local heredoc = '<<' * P(function(input, index)
     25 	local s, e, _, delimiter = input:find('[ \t]*(["\']?)([%w!"%%+,-./:?@_~]+)%1', index)
     26 	if s == index and delimiter then
     27 		delimiter = delimiter:gsub('[%%+-.?]', '%%%1')
     28 		e = select(2, input:find('[\n\r]' .. delimiter .. '[\n\r]', e))
     29 		return e and e + 1 or #input + 1
     30 	end
     31 end)
     32 lex:add_rule('string', token(lexer.STRING, str + heredoc))
     33 
     34 -- Comments.
     35 lex:add_rule('comment', token(lexer.COMMENT, lexer.to_eol('#')))
     36 
     37 -- Numbers.
     38 lex:add_rule('number', token(lexer.NUMBER, lexer.number))
     39 
     40 -- Variables.
     41 lex:add_rule('variable',
     42 	token(lexer.VARIABLE, '$' * S('"#')^-1 * ('*' + lexer.digit^1 + lexer.word)))
     43 
     44 -- Operators.
     45 lex:add_rule('operator', token(lexer.OPERATOR, S('@`=!<>*&^|;?()[]{}') + '\\\n'))
     46 
     47 -- Fold points.
     48 lex:add_fold_point(lexer.OPERATOR, '{', '}')
     49 
     50 lexer.property['scintillua.comment'] = '#'
     51 
     52 return lex