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-- Copyright 2006-2022 Mitchell. See LICENSE.
-- R LPeg lexer.
local lexer = require('lexer')
local token, word_match = lexer.token, lexer.word_match
local P, S = lpeg.P, lpeg.S
local lex = lexer.new('rstats')
-- Whitespace.
lex:add_rule('whitespace', token(lexer.WHITESPACE, lexer.space^1))
-- Keywords.
lex:add_rule('keyword', token(lexer.KEYWORD, word_match{
'break', 'else', 'for', 'if', 'in', 'next', 'repeat', 'return', 'switch', 'try', 'while', --
'Inf', 'NA', 'NaN', 'NULL', 'FALSE', 'TRUE', 'F', 'T',
-- Frequently used operators.
'|>', '%%', '%*%', '%/%', '%in%', '%o%', '%x%'
}))
-- Types.
lex:add_rule('type', token(lexer.TYPE, word_match{
'array', 'character', 'closure', 'complex', 'data.frame', 'double', 'environment', 'expression',
'externalptr', 'factor', 'function', 'integer', 'list', 'logical', 'matrix', 'numeric',
'pairlist', 'promise', 'raw', 'symbol', 'vector'
}))
-- Identifiers.
lex:add_rule('identifier', token(lexer.IDENTIFIER, lexer.word))
-- Strings.
local sq_str = lexer.range("'", true)
local dq_str = lexer.range('"', true)
lex:add_rule('string', token(lexer.STRING, sq_str + dq_str))
-- Comments.
lex:add_rule('comment', token(lexer.COMMENT, lexer.to_eol('#')))
-- Numbers.
lex:add_rule('number', token(lexer.NUMBER, (lexer.number * P('i')^-1) * P('L')^-1))
-- Operators.
lex:add_rule('operator', token(lexer.OPERATOR, S('<->+*/^=.,:;|$()[]{}')))
-- Folding
lex:add_fold_point(lexer.OPERATOR, '(', ')')
lex:add_fold_point(lexer.OPERATOR, '[', ']')
lex:add_fold_point(lexer.OPERATOR, '{', '}')
lex:add_fold_point(lexer.COMMENT, lexer.fold_consecutive_lines('#'))
return lex
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