vis

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

(3913B)
      1 -- Copyright 2006-2025 Mitchell. See LICENSE.
      2 -- Copyright 2017 Michel Martens.
      3 -- Crystal LPeg lexer (based on Ruby).
      4 
      5 local lexer = require('lexer')
      6 local token, word_match = lexer.token, lexer.word_match
      7 local P, S = lpeg.P, lpeg.S
      8 
      9 local lex = lexer.new('crystal')
     10 
     11 -- Whitespace.
     12 lex:add_rule('whitespace', token(lexer.WHITESPACE, lexer.space^1))
     13 
     14 -- Keywords.
     15 lex:add_rule('keyword', token(lexer.KEYWORD, word_match{
     16 	'alias', 'begin', 'break', 'case', 'class', 'def', 'defined?', 'do', 'else', 'elsif', 'end',
     17 	'ensure', 'false', 'for', 'if', 'in', 'module', 'next', 'nil', 'not', 'redo', 'rescue', 'retry',
     18 	'return', 'self', 'super', 'then', 'true', 'undef', 'unless', 'until', 'when', 'while', 'yield',
     19 	'__FILE__', '__LINE__'
     20 }))
     21 
     22 -- Functions.
     23 lex:add_rule('function', token(lexer.FUNCTION, word_match{
     24 	'abort', 'at_exit', 'caller', 'delay', 'exit', 'fork', 'future', 'get_stack_top', 'gets', 'lazy',
     25 	'loop', 'main', 'p', 'print', 'printf', 'puts', 'raise', 'rand', 'read_line', 'require', 'sleep',
     26 	'spawn', 'sprintf', 'system', 'with_color',
     27 	-- Macros.
     28 	'assert_responds_to', 'debugger', 'parallel', 'pp', 'record', 'redefine_main'
     29 }) * -S('.:|'))
     30 
     31 -- Identifiers.
     32 local word_char = lexer.alnum + S('_!?')
     33 local word = (lexer.alpha + '_') * word_char^0
     34 lex:add_rule('identifier', token(lexer.IDENTIFIER, word))
     35 
     36 -- Comments.
     37 lex:add_rule('comment', token(lexer.COMMENT, lexer.to_eol('#', true)))
     38 
     39 -- Strings.
     40 local cmd_str = lexer.range('`')
     41 local sq_str = lexer.range("'")
     42 local dq_str = lexer.range('"')
     43 local heredoc = '<<' * P(function(input, index)
     44 	local _, e, indented, _, delimiter = input:find('^(%-?)(["`]?)([%a_][%w_]*)%2[\n\r\f;]+', index)
     45 	if not delimiter then return end
     46 	local end_heredoc = (#indented > 0 and '[\n\r\f]+ *' or '[\n\r\f]+')
     47 	_, e = input:find(end_heredoc .. delimiter, e)
     48 	return e and e + 1 or #input + 1
     49 end)
     50 local string = token(lexer.STRING, (sq_str + dq_str + heredoc + cmd_str) * S('f')^-1)
     51 -- TODO: regex_str fails with `obj.method /patt/` syntax.
     52 local regex_str = lexer.after_set('!%^&*([{-=+|:;,?<>~', lexer.range('/', true) * S('iomx')^0)
     53 local regex = token(lexer.REGEX, regex_str)
     54 lex:add_rule('string', string + regex)
     55 
     56 -- Numbers.
     57 local numeric_literal = '?' * (lexer.any - lexer.space) * -word_char -- TODO: meta, control, etc.
     58 lex:add_rule('number', token(lexer.NUMBER, lexer.number_('_') * S('ri')^-1 + numeric_literal))
     59 
     60 -- Variables.
     61 local global_var = '$' *
     62 	(word + S('!@L+`\'=~/\\,.;<>_*"$?:') + lexer.digit + '-' * S('0FadiIKlpvw'))
     63 local class_var = '@@' * word
     64 local inst_var = '@' * word
     65 lex:add_rule('variable', token(lexer.VARIABLE, global_var + class_var + inst_var))
     66 
     67 -- Symbols.
     68 lex:add_rule('symbol', token('symbol', ':' * P(function(input, index)
     69 	if input:sub(index - 2, index - 2) ~= ':' then return true end
     70 end) * (word_char^1 + sq_str + dq_str)))
     71 lex:add_style('symbol', lexer.styles.constant)
     72 
     73 -- Operators.
     74 lex:add_rule('operator', token(lexer.OPERATOR, S('!%^&*()[]{}-=+/|:;.,?<>~')))
     75 
     76 -- Fold points.
     77 local function disambiguate(text, pos, line, s)
     78 	return line:sub(1, s - 1):match('^%s*$') and not text:sub(1, pos - 1):match('\\[ \t]*\r?\n$') and
     79 		1 or 0
     80 end
     81 lex:add_fold_point(lexer.KEYWORD, 'begin', 'end')
     82 lex:add_fold_point(lexer.KEYWORD, 'case', 'end')
     83 lex:add_fold_point(lexer.KEYWORD, 'class', 'end')
     84 lex:add_fold_point(lexer.KEYWORD, 'def', 'end')
     85 lex:add_fold_point(lexer.KEYWORD, 'do', 'end')
     86 lex:add_fold_point(lexer.KEYWORD, 'for', 'end')
     87 lex:add_fold_point(lexer.KEYWORD, 'module', 'end')
     88 lex:add_fold_point(lexer.KEYWORD, 'if', disambiguate)
     89 lex:add_fold_point(lexer.KEYWORD, 'while', disambiguate)
     90 lex:add_fold_point(lexer.KEYWORD, 'unless', disambiguate)
     91 lex:add_fold_point(lexer.KEYWORD, 'until', disambiguate)
     92 lex:add_fold_point(lexer.OPERATOR, '(', ')')
     93 lex:add_fold_point(lexer.OPERATOR, '[', ']')
     94 lex:add_fold_point(lexer.OPERATOR, '{', '}')
     95 
     96 lexer.property['scintillua.comment'] = '#'
     97 
     98 return lex