50 lines
1.7 KiB
Lua
50 lines
1.7 KiB
Lua
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-- Copyright 2014-2019 Joshua Krämer. See License.txt.
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-- Tcl LPeg lexer.
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-- This lexer follows the TCL dodekalogue (http://wiki.tcl.tk/10259).
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-- It is based on the previous lexer by Mitchell.
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local lexer = require('lexer')
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local token, word_match = lexer.token, lexer.word_match
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local P, R, S = lpeg.P, lpeg.R, lpeg.S
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local lex = lexer.new('tcl')
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-- Whitespace.
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lex:add_rule('whitespace', token(lexer.WHITESPACE, lexer.space^1))
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-- Comment.
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lex:add_rule('comment', token(lexer.COMMENT, '#' * P(function(input, index)
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local i = index - 2
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while i > 0 and input:find('^[ \t]', i) do i = i - 1 end
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if i < 1 or input:find('^[\r\n;]', i) then return index end
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end) * lexer.nonnewline^0))
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-- Separator (semicolon).
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lex:add_rule('separator', token(lexer.CLASS, P(';')))
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-- Argument expander.
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lex:add_rule('expander', token(lexer.LABEL, P('{*}')))
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-- Delimiters.
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lex:add_rule('braces', token(lexer.KEYWORD, S('{}')))
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lex:add_rule('quotes', token(lexer.FUNCTION, '"'))
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lex:add_rule('brackets', token(lexer.VARIABLE, S('[]')))
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-- Variable substitution.
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lex:add_rule('variable', token(lexer.STRING, '$' *
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(lexer.alnum + '_' + P(':')^2)^0))
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-- Backslash substitution.
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lex:add_rule('backslash', token(lexer.TYPE,
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'\\' * (lexer.digit * lexer.digit^-2 +
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'x' * lexer.xdigit^1 +
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'u' * lexer.xdigit * lexer.xdigit^-3 +
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'U' * lexer.xdigit * lexer.xdigit^-7 +
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1)))
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-- Fold points.
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lex:add_fold_point(lexer.KEYWORD, '{', '}')
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lex:add_fold_point(lexer.COMMENT, '#', lexer.fold_line_comments('#'))
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return lex
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