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-- Copyright 2006-2022 Brian "Sir Alaran" Schott. See LICENSE.
-- Dot LPeg lexer.
-- Based off of lexer code by Mitchell.
local lexer = require('lexer')
local token, word_match = lexer.token, lexer.word_match
local P, S = lpeg.P, lpeg.S
local lex = lexer.new('dot')
-- Whitespace.
lex:add_rule('whitespace', token(lexer.WHITESPACE, lexer.space^1))
-- Keywords.
lex:add_rule('keyword', token(lexer.KEYWORD, word_match{
'graph', 'node', 'edge', 'digraph', 'fontsize', 'rankdir', 'fontname', 'shape', 'label',
'arrowhead', 'arrowtail', 'arrowsize', 'color', 'comment', 'constraint', 'decorate', 'dir',
'headlabel', 'headport', 'headURL', 'labelangle', 'labeldistance', 'labelfloat', 'labelfontcolor',
'labelfontname', 'labelfontsize', 'layer', 'lhead', 'ltail', 'minlen', 'samehead', 'sametail',
'style', 'taillabel', 'tailport', 'tailURL', 'weight', 'subgraph'
}))
-- Types.
lex:add_rule('type', token(lexer.TYPE, word_match{
' box', 'polygon', 'ellipse', 'circle', 'point', 'egg', 'triangle', 'plaintext', 'diamond',
'trapezium', 'parallelogram', 'house', 'pentagon', 'hexagon', 'septagon', 'octagon',
'doublecircle', 'doubleoctagon', 'tripleoctagon', 'invtriangle', 'invtrapezium', 'invhouse',
'Mdiamond', 'Msquare', 'Mcircle', 'rect', 'rectangle', 'none', 'note', 'tab', 'folder', 'box3d',
'record'
}))
-- Identifiers.
lex:add_rule('identifier', token(lexer.IDENTIFIER, lexer.word))
-- Strings.
local sq_str = lexer.range("'")
local dq_str = lexer.range('"')
lex:add_rule('string', token(lexer.STRING, sq_str + dq_str))
-- Comments.
local line_comment = lexer.to_eol('//', true)
local block_comment = lexer.range('/*', '*/')
lex:add_rule('comment', token(lexer.COMMENT, line_comment + block_comment))
-- Numbers.
lex:add_rule('number', token(lexer.NUMBER, lexer.dec_num + lexer.float))
-- Operators.
lex:add_rule('operator', token(lexer.OPERATOR, S('->()[]{};')))
-- Fold points.
lex:add_fold_point(lexer.OPERATOR, '{', '}')
lex:add_fold_point(lexer.COMMENT, '/*', '*/')
lex:add_fold_point(lexer.COMMENT, lexer.fold_consecutive_lines('//'))
return lex
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