lexers/latex.lua

   1 -- Copyright 2006-2016 Mitchell mitchell.att.foicica.com. See LICENSE.
   2 -- Latex LPeg lexer.
   3 -- Modified by Brian Schott.
   4 -- Modified by Robert Gieseke.
   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 = 'latex'}
  11
  12 -- Whitespace.
  13 local ws = token(l.WHITESPACE, l.space^1)
  14
  15 -- Comments.
  16 local line_comment = '%' * l.nonnewline^0
  17 local block_comment = '\\begin' * P(' ')^0 * '{comment}' *
  18                       (l.any - '\\end' * P(' ')^0 * '{comment}')^0 *
  19                       P('\\end' * P(' ')^0 * '{comment}')^-1
  20 -- Note: need block_comment before line_comment or LPeg cannot compile rule.
  21 local comment = token(l.COMMENT, block_comment + line_comment)
  22
  23 -- Sections.
  24 local section = token('section', '\\' * word_match{
  25   'part', 'chapter', 'section', 'subsection', 'subsubsection', 'paragraph',
  26   'subparagraph'
  27 } * P('*')^-1)
  28
  29 -- Math environments.
  30 local math_word = word_match{
  31   'align', 'displaymath', 'eqnarray', 'equation', 'gather', 'math', 'multline'
  32 }
  33 local math_begin_end = (P('begin') + P('end')) * P(' ')^0 *
  34                        '{' * math_word * P('*')^-1 * '}'
  35 local math = token('math', '$' + '\\' * (S('[]()') + math_begin_end))
  36
  37 -- LaTeX environments.
  38 local environment = token('environment', '\\' * (P('begin') + P('end')) *
  39                                          P(' ')^0 *
  40                                          '{' * l.word * P('*')^-1 * '}')
  41
  42 -- Commands.
  43 local command = token(l.KEYWORD, '\\' * (l.alpha^1 + S('#$&~_^%{}')))
  44
  45 -- Operators.
  46 local operator = token(l.OPERATOR, S('&#{}[]'))
  47
  48 M._rules = {
  49   {'whitespace', ws},
  50   {'comment', comment},
  51   {'math', math},
  52   {'environment', environment},
  53   {'section', section},
  54   {'keyword', command},
  55   {'operator', operator},
  56 }
  57
  58 M._tokenstyles = {
  59   environment = l.STYLE_KEYWORD,
  60   math = l.STYLE_FUNCTION,
  61   section = l.STYLE_CLASS
  62 }
  63
  64 M._foldsymbols = {
  65   _patterns = {'\\[a-z]+', '[{}]', '%%'},
  66   [l.COMMENT] = {
  67     ['\\begin'] = 1, ['\\end'] = -1, ['%'] = l.fold_line_comments('%')
  68   },
  69   ['environment'] = {['\\begin'] = 1, ['\\end'] = -1},
  70   [l.OPERATOR] = {['{'] = 1, ['}'] = -1}
  71 }
  72
  73 return M