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-- Copyright 2014-2015 Joshua Krämer. See LICENSE.
-- Tcl LPeg lexer.
-- This lexer follows the TCL dodekalogue (http://wiki.tcl.tk/10259).
-- It is based on the previous lexer by Mitchell.
local l = require('lexer')
local token, word_match = l.token, l.word_match
local P, R, S = lpeg.P, lpeg.R, lpeg.S
local M = {_NAME = 'tcl'}
-- Whitespace.
local whitespace = token(l.WHITESPACE, l.space^1)
-- Separator (semicolon).
local separator = token(l.CLASS, P(';'))
-- Delimiters.
local braces = token(l.KEYWORD, S('{}'))
local quotes = token(l.FUNCTION, '"')
local brackets = token(l.VARIABLE, S('[]'))
-- Argument expander.
local expander = token(l.LABEL, P('{*}'))
-- Variable substitution.
local variable = token(l.STRING, '$' * (l.alnum + '_' + P(':')^2)^0)
-- Backslash substitution.
local backslash = token(l.TYPE, '\\' * ((l.digit * l.digit^-2) +
('x' * l.xdigit^1) + ('u' * l.xdigit * l.xdigit^-3) +
('U' * l.xdigit * l.xdigit^-7) + P(1)))
-- Comment.
local comment = token(l.COMMENT, '#' * P(function(input, index)
local i = index - 2
while i > 0 and input:find('^[ \t]', i) do i = i - 1 end
if i < 1 or input:find('^[\r\n;]', i) then return index end
end) * l.nonnewline^0)
M._rules = {
{'whitespace', whitespace},
{'comment', comment},
{'separator', separator},
{'expander', expander},
{'braces', braces},
{'quotes', quotes},
{'brackets', brackets},
{'variable', variable},
{'backslash', backslash},
}
M._foldsymbols = {
_patterns = {'[{}]', '#'},
[l.KEYWORD] = {['{'] = 1, ['}'] = -1},
[l.COMMENT] = {['#'] = l.fold_line_comments('#')}
}
return M
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