-- Copyright 2006-2018 Brian "Sir Alaran" Schott. See License.txt.
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-- Dot LPeg lexer.
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-- Based off of lexer code 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('dot')
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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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graph node edge digraph fontsize rankdir fontname shape label arrowhead
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arrowtail arrowsize color comment constraint decorate dir headlabel headport
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headURL labelangle labeldistance labelfloat labelfontcolor labelfontname
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labelfontsize layer lhead ltail minlen samehead sametail style taillabel
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tailport tailURL weight subgraph
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]]))
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-- Types.
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lex:add_rule('type', token(lexer.TYPE, word_match[[
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box polygon ellipse circle point egg triangle plaintext diamond trapezium
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parallelogram house pentagon hexagon septagon octagon doublecircle
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doubleoctagon tripleoctagon invtriangle invtrapezium invhouse Mdiamond Msquare
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Mcircle rect rectangle none note tab folder box3d record
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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("'") +
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lexer.delimited_range('"')))
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-- Comments.
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local line_comment = '//' * lexer.nonnewline_esc^0
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local block_comment = '/*' * (lexer.any - '*/')^0 * P('*/')^-1
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lex:add_rule('comment', token(lexer.COMMENT, line_comment + block_comment))
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-- Numbers.
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lex:add_rule('number', token(lexer.NUMBER, lexer.digit^1 + lexer.float))
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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.OPERATOR, '{', '}')
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lex:add_fold_point(lexer.COMMENT, '/*', '*/')
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lex:add_fold_point(lexer.COMMENT, '//', lexer.fold_line_comments('//'))
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return lex
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