46 lines
1.5 KiB
Lua
46 lines
1.5 KiB
Lua
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-- Copyright 2006-2019 Mitchell mitchell.att.foicica.com. See License.txt.
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-- Haskell LPeg lexer.
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-- Modified by Alex Suraci.
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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('haskell', {fold_by_indentation = true})
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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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case class data default deriving do else if import in infix infixl infixr
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instance let module newtype of then type where _ as qualified hiding
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]]))
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local word = (lexer.alnum + S("._'#"))^0
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local op = lexer.punct - S('()[]{}')
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-- Types & type constructors.
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lex:add_rule('type', token(lexer.TYPE, (lexer.upper * word) +
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(":" * (op^1 - ":"))))
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-- Identifiers.
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lex:add_rule('identifier', token(lexer.IDENTIFIER, (lexer.alpha + '_') * 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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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.float + lexer.integer))
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-- Operators.
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lex:add_rule('operator', token(lexer.OPERATOR, op))
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return lex
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