51 lines
1.6 KiB
Lua
Executable File
51 lines
1.6 KiB
Lua
Executable File
-- Copyright 2015-2019 David B. Lamkins <david@lamkins.net>. See License.txt.
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-- pure LPeg lexer, see http://purelang.bitbucket.org/
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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('pure')
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-- Whitespace.
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lex:add_rule('whitespace', token(lexer.WHITESPACE, lexer.space^1))
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-- Comments.
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local line_comment = '//' * lexer.nonnewline^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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-- Pragmas.
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local hashbang = lexer.starts_line('#!') * (lexer.nonnewline - '//')^0
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lex:add_rule('pragma', token(lexer.PREPROCESSOR, hashbang))
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-- Keywords.
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lex:add_rule('keyword', token(lexer.KEYWORD, word_match[[
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namespace with end using interface extern let const def type public private
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nonfix outfix infix infixl infixr prefix postfix if otherwise when case of
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then else
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]]))
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-- Numbers.
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local bin = '0' * S('Bb') * S('01')^1
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local hex = '0' * S('Xx') * (R('09') + R('af') + R('AF'))^1
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local dec = R('09')^1
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local int = (bin + hex + dec) * P('L')^-1
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local rad = P('.') - '..'
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local exp = (S('Ee') * S('+-')^-1 * int)^-1
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local flt = int * (rad * dec)^-1 * exp + int^-1 * rad * dec * exp
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lex:add_rule('number', token(lexer.NUMBER, flt + int))
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-- Operators.
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local punct = S('+-/*%<>~!=^&|?~:;,.()[]{}@#$`\\\'')
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local dots = P('..')
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lex:add_rule('operator', token(lexer.OPERATOR, dots + punct))
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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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return lex
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