-- Copyright 2006-2025 Mitchell. See LICENSE.
-- Fennel LPeg lexer.
-- Contributed by Momohime Honda.

local lexer = require('lexer')
local token, word_match = lexer.token, lexer.word_match
local P, S = lpeg.P, lpeg.S

local lex = lexer.new('fennel', {inherit = lexer.load('lua')})

-- Whitespace.
lex:add_rule('whitespace', token(lexer.WHITESPACE, lexer.space^1))

-- Keywords.
lex:modify_rule('keyword', token(lexer.KEYWORD, word_match{
	'#', '%', '*', '+', '-', '->>', '->', '-?>>', '-?>', '..', '.', '//', '/', ':', '<=', '<', '=',
	'>=', '>', '?.', '^', '~=', 'λ', 'accumulate', 'and', 'band', 'bnot', 'bor', 'bxor', 'collect',
	'comment', 'do', 'doto', 'each', 'eval-compiler', 'fn', 'for', 'global', 'hashfn', 'icollect',
	'if', 'import-macros', 'include', 'lambda', 'length', 'let', 'local', 'lshift', 'lua', 'macro',
	'macrodebug', 'macros', 'match', 'not', 'not=', 'or', 'partial', 'pick-args', 'pick-values',
	'quote', 'require-macros', 'rshift', 'set', 'set-forcibly!', 'tset', 'values', 'var', 'when',
	'while', 'with-open'
}))

-- Identifiers.
local initial = lexer.alpha + S('|$%&#*+-/<=>?~^_λ!')
local subsequent = initial + lexer.digit
lex:modify_rule('identifier', token(lexer.IDENTIFIER, initial * subsequent^0 * P('#')^-1))

-- Strings.
local dq_str = lexer.range('"')
local kw_str = lpeg.B(1 - subsequent) * ':' * subsequent^1
lex:modify_rule('string', token(lexer.STRING, dq_str + kw_str))

-- Comments.
lex:modify_rule('comment', token(lexer.COMMENT, lexer.to_eol(';')))

-- Ignore these rules.
-- lex:modify_rule('longstring', P(false))
lex:modify_rule('label', P(false))
lex:modify_rule('operator', P(false))

lexer.property['scintillua.comment'] = ';'

return lex