-- Copyright 2017-2018 Michael Forney. See License.txt
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-- Myrddin 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, V = lpeg.P, lpeg.R, lpeg.S, lpeg.V
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local lex = lexer.new('myrddin')
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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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break const continue elif else extern false for generic goto if impl in match
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pkg pkglocal sizeof struct trait true type union use var while
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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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void bool char byte int uint int8 uint8 int16 uint16 int32 uint32 int64 uint64
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flt32 flt64
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]] + '@' * lexer.word))
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-- Identifiers.
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lex:add_rule('identifier', token(lexer.IDENTIFIER, lexer.word))
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-- Comments.
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local line_comment = '//' * lexer.nonnewline_esc^0
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local block_comment = P{
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V'part' * P'*/'^-1,
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part = '/*' * (V'full' + (lexer.any - '/*' - '*/'))^0,
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full = V'part' * '*/',
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}
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lex:add_rule('comment', token(lexer.COMMENT, line_comment + block_comment))
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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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-- Numbers.
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local digit = lexer.digit + '_'
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local bdigit = R'01' + '_'
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local xdigit = lexer.xdigit + '_'
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local odigit = R'07' + '_'
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local integer = '0x' * xdigit^1 + '0o' * odigit^1 + '0b' * bdigit^1 + digit^1
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local float = digit^1 * (('.' * digit^1) * (S'eE' * S'+-'^-1 * digit^1)^-1 +
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('.' * digit^1)^-1 * S'eE' * S'+-'^-1 * digit^1)
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lex:add_rule('number', token(lexer.NUMBER, float + integer))
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-- Operators.
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lex:add_rule('operator', token(lexer.OPERATOR, S'`#_+-/*%<>~!=^&|~:;,.()[]{}'))
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return lex
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