vis

a vi-like editor based on Plan 9's structural regular expressions
pure.lua

(1660B)
      1 -- Copyright 2015-2025 David B. Lamkins <david@lamkins.net>. See LICENSE.
      2 -- pure LPeg lexer, see http://purelang.bitbucket.org/
      3 
      4 local lexer = require('lexer')
      5 local token, word_match = lexer.token, lexer.word_match
      6 local P, S = lpeg.P, lpeg.S
      7 
      8 local lex = lexer.new('pure')
      9 
     10 -- Whitespace.
     11 lex:add_rule('whitespace', token(lexer.WHITESPACE, lexer.space^1))
     12 
     13 -- Keywords.
     14 lex:add_rule('keyword', token(lexer.KEYWORD, word_match{
     15 	'namespace', 'with', 'end', 'using', 'interface', 'extern', 'let', 'const', 'def', 'type',
     16 	'public', 'private', 'nonfix', 'outfix', 'infix', 'infixl', 'infixr', 'prefix', 'postfix', 'if',
     17 	'otherwise', 'when', 'case', 'of', 'then', 'else'
     18 }))
     19 
     20 -- Identifiers.
     21 lex:add_rule('identifier', token(lexer.IDENTIFIER, lexer.word))
     22 
     23 -- Strings.
     24 lex:add_rule('string', token(lexer.STRING, lexer.range('"', true)))
     25 
     26 -- Comments.
     27 local line_comment = lexer.to_eol('//')
     28 local block_comment = lexer.range('/*', '*/')
     29 lex:add_rule('comment', token(lexer.COMMENT, line_comment + block_comment))
     30 
     31 -- Numbers.
     32 local bin = '0' * S('Bb') * S('01')^1
     33 local hex = lexer.hex_num
     34 local dec = lexer.dec_num
     35 local int = (bin + hex + dec) * P('L')^-1
     36 local rad = P('.') - '..'
     37 local exp = (S('Ee') * S('+-')^-1 * int)^-1
     38 local flt = int * (rad * dec)^-1 * exp + int^-1 * rad * dec * exp
     39 lex:add_rule('number', token(lexer.NUMBER, flt + int))
     40 
     41 -- Pragmas.
     42 local hashbang = lexer.starts_line('#!') * (lexer.nonnewline - '//')^0
     43 lex:add_rule('pragma', token(lexer.PREPROCESSOR, hashbang))
     44 
     45 -- Operators.
     46 lex:add_rule('operator', token(lexer.OPERATOR, '..' + S('+-/*%<>~!=^&|?~:;,.()[]{}@#$`\\\'')))
     47 
     48 lexer.property['scintillua.comment'] = '//'
     49 
     50 return lex