-- Copyright 2015-2023 David B. Lamkins <david@lamkins.net>. See LICENSE.
-- Faust LPeg lexer, see http://faust.grame.fr/
local lexer = require('lexer')
local token, word_match = lexer.token, lexer.word_match
local P, S = lpeg.P, lpeg.S

local lex = lexer.new('faust')

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

-- Keywords.
lex:add_rule('keyword', token(lexer.KEYWORD, word_match {
    'declare', 'import', 'mdoctags', 'dependencies', 'distributed', 'inputs',
    'outputs', 'par', 'seq', 'sum', 'prod', 'xor', 'with', 'environment',
    'library', 'component', 'ffunction', 'fvariable', 'fconstant', 'int',
    'float', 'case', 'waveform', 'h:', 'v:', 't:'
}))

-- Identifiers.
lex:add_rule('identifier', token(lexer.IDENTIFIER, lexer.word))

-- Strings.
lex:add_rule('string', token(lexer.STRING, lexer.range('"', true)))

-- Comments.
local line_comment = lexer.to_eol('//')
local block_comment = lexer.range('/*', '*/')
lex:add_rule('comment', token(lexer.COMMENT, line_comment + block_comment))

-- Numbers.
local int = lexer.digit ^ 1
local rad = P('.')
local exp = (P('e') * S('+-') ^ -1 * int) ^ -1
local flt = int * (rad * int) ^ -1 * exp + int ^ -1 * rad * int * exp
lex:add_rule('number', token(lexer.NUMBER, flt + int))

-- Pragmas.
lex:add_rule('pragma',
             token(lexer.PREPROCESSOR, lexer.range('<mdoc>', '</mdoc>')))

-- Operators.
lex:add_rule('operator',
             token(lexer.OPERATOR, S('+-/*%<>~!=^&|?~:;,.()[]{}@#$`\\\'')))

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

return lex
