lexers/haskell.lua

   1 -- Copyright 2006-2015 Mitchell mitchell.att.foicica.com. See LICENSE.
   2 -- Haskell LPeg lexer.
   3 -- Modified by Alex Suraci.
   4
   5 local l = require('lexer')
   6 local token, word_match = l.token, l.word_match
   7 local P, R, S = lpeg.P, lpeg.R, lpeg.S
   8
   9 local M = {_NAME = 'haskell'}
  10
  11 -- Whitespace.
  12 local ws = token(l.WHITESPACE, l.space^1)
  13
  14 -- Comments.
  15 local line_comment = '--' * l.nonnewline_esc^0
  16 local block_comment = '{-' * (l.any - '-}')^0 * P('-}')^-1
  17 local comment = token(l.COMMENT, line_comment + block_comment)
  18
  19 -- Strings.
  20 local string = token(l.STRING, l.delimited_range('"'))
  21
  22 -- Chars.
  23 local char = token(l.STRING, l.delimited_range("'", true))
  24
  25 -- Numbers.
  26 local number = token(l.NUMBER, l.float + l.integer)
  27
  28 -- Keywords.
  29 local keyword = token(l.KEYWORD, word_match{
  30   'case', 'class', 'data', 'default', 'deriving', 'do', 'else', 'if', 'import',
  31   'in', 'infix', 'infixl', 'infixr', 'instance', 'let', 'module', 'newtype',
  32   'of', 'then', 'type', 'where', '_', 'as', 'qualified', 'hiding'
  33 })
  34
  35 -- Identifiers.
  36 local word = (l.alnum + S("._'#"))^0
  37 local identifier = token(l.IDENTIFIER, (l.alpha + '_') * word)
  38
  39 -- Operators.
  40 local op = l.punct - S('()[]{}')
  41 local operator = token(l.OPERATOR, op)
  42
  43 -- Types & type constructors.
  44 local constructor = token(l.TYPE, (l.upper * word) + (P(":") * (op^1 - P(":"))))
  45
  46 M._rules = {
  47   {'whitespace', ws},
  48   {'keyword', keyword},
  49   {'type', constructor},
  50   {'identifier', identifier},
  51   {'string', string},
  52   {'char', char},
  53   {'comment', comment},
  54   {'number', number},
  55   {'operator', operator},
  56 }
  57
  58 M._FOLDBYINDENTATION = true
  59
  60 return M