-- Copyright 2006-2018 Mitchell mitchell.att.foicica.com. See License.txt.
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-- Gap LPeg lexer.
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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('gap')
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-- Whitespace.
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lex:add_rule('whitespace', token(lexer.WHITESPACE, lexer.space^1))
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-- Keywords.
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lex:add_rule('keyword', token(lexer.KEYWORD, word_match[[
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and break continue do elif else end fail false fi for function if in infinity
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local not od or rec repeat return then true until while
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]]))
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-- Identifiers.
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lex:add_rule('identifier', token(lexer.IDENTIFIER, lexer.word))
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-- Strings.
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lex:add_rule('string', token(lexer.STRING, lexer.delimited_range("'", true) +
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lexer.delimited_range('"', true)))
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-- Comments.
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lex:add_rule('comment', token(lexer.COMMENT, '#' * lexer.nonnewline^0))
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-- Numbers.
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lex:add_rule('number', token(lexer.NUMBER, lexer.digit^1 * -lexer.alpha))
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-- Operators.
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lex:add_rule('operator', token(lexer.OPERATOR, S('*+-,./:;<=>~^#()[]{}')))
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-- Fold points.
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lex:add_fold_point(lexer.KEYWORD, 'function', 'end')
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lex:add_fold_point(lexer.KEYWORD, 'do', 'od')
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lex:add_fold_point(lexer.KEYWORD, 'if', 'fi')
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lex:add_fold_point(lexer.KEYWORD, 'repeat', 'until')
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lex:add_fold_point(lexer.COMMENT, '#', lexer.fold_line_comments('#'))
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return lex
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