lexers/tcl.lua

   1 -- Copyright 2014-2015 Joshua Krämer. See LICENSE.
   2 -- Tcl LPeg lexer.
   3 -- This lexer follows the TCL dodekalogue (http://wiki.tcl.tk/10259).
   4 -- It is based on the previous lexer by Mitchell.
   5
   6 local l = require('lexer')
   7 local token, word_match = l.token, l.word_match
   8 local P, R, S = lpeg.P, lpeg.R, lpeg.S
   9
  10 local M = {_NAME = 'tcl'}
  11
  12 -- Whitespace.
  13 local whitespace = token(l.WHITESPACE, l.space^1)
  14
  15 -- Separator (semicolon).
  16 local separator = token(l.CLASS, P(';'))
  17
  18 -- Delimiters.
  19 local braces = token(l.KEYWORD, S('{}'))
  20 local quotes = token(l.FUNCTION, '"')
  21 local brackets = token(l.VARIABLE, S('[]'))
  22
  23 -- Argument expander.
  24 local expander = token(l.LABEL, P('{*}'))
  25
  26 -- Variable substitution.
  27 local variable = token(l.STRING, '$' * (l.alnum + '_' + P(':')^2)^0)
  28
  29 -- Backslash substitution.
  30 local backslash = token(l.TYPE, '\\' * ((l.digit * l.digit^-2) +
  31                         ('x' * l.xdigit^1) + ('u' * l.xdigit * l.xdigit^-3) +
  32                         ('U' * l.xdigit * l.xdigit^-7) + P(1)))
  33
  34 -- Comment.
  35 local comment = token(l.COMMENT, '#' * P(function(input, index)
  36   local i = index - 2
  37   while i > 0 and input:find('^[ \t]', i) do i = i - 1 end
  38   if i < 1 or input:find('^[\r\n;]', i) then return index end
  39 end) * l.nonnewline^0)
  40
  41 M._rules = {
  42   {'whitespace', whitespace},
  43   {'comment', comment},
  44   {'separator', separator},
  45   {'expander', expander},
  46   {'braces', braces},
  47   {'quotes', quotes},
  48   {'brackets', brackets},
  49   {'variable', variable},
  50   {'backslash', backslash},
  51 }
  52
  53 M._foldsymbols = {
  54   _patterns = {'[{}]', '#'},
  55   [l.KEYWORD] = {['{'] = 1, ['}'] = -1},
  56   [l.COMMENT] = {['#'] = l.fold_line_comments('#')}
  57 }
  58
  59 return M