-- Copyright 2006-2023 Mitchell. See LICENSE.
-- Erlang LPeg lexer.
local lexer = require('lexer')
local token, word_match = lexer.token, lexer.word_match
local P, S = lpeg.P, lpeg.S

local lex = lexer.new('erlang')

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

-- Keywords.
lex:add_rule('keyword', token(lexer.KEYWORD, word_match {
    'after', 'begin', 'case', 'catch', 'cond', 'end', 'fun', 'if', 'let', 'of',
    'query', 'receive', 'try', 'when', -- Operators.
    'div', 'rem', 'or', 'xor', 'bor', 'bxor', 'bsl', 'bsr', 'and', 'band',
    'not', 'bnot', 'badarg', 'nocookie', 'orelse', 'andalso', 'false', 'true'
}))

-- Functions.
lex:add_rule('function', token(lexer.FUNCTION, word_match {
    'abs', 'alive', 'apply', 'atom_to_list', 'binary_to_list', 'binary_to_term',
    'concat_binary', 'date', 'disconnect_node', 'element', 'erase', 'exit',
    'float', 'float_to_list', 'get', 'get_keys', 'group_leader', 'halt', 'hd',
    'integer_to_list', 'is_alive', 'is_record', 'length', 'link',
    'list_to_atom', 'list_to_binary', 'list_to_float', 'list_to_integer',
    'list_to_pid', 'list_to_tuple', 'load_module', 'make_ref', 'monitor_node',
    'node', 'nodes', 'now', 'open_port', 'pid_to_list', 'process_flag',
    'process_info', 'process', 'put', 'register', 'registered', 'round', 'self',
    'setelement', 'size', 'spawn', 'spawn_link', 'split_binary', 'statistics',
    'term_to_binary', 'throw', 'time', 'tl', 'trunc', 'tuple_to_list', 'unlink',
    'unregister', 'whereis', -- Others.
    'any', 'atom', 'binary', 'bitstring', 'byte', 'constant', 'function',
    'integer', 'list', 'map', 'mfa', 'non_neg_integer', 'number', 'pid',
    'ports', 'port_close', 'port_info', 'pos_integer', 'reference', 'record',
    -- Erlang.
    'check_process_code', 'delete_module', 'get_cookie', 'hash', 'math',
    'module_loaded', 'preloaded', 'processes', 'purge_module', 'set_cookie',
    'set_node', -- Math.
    'acos', 'asin', 'atan', 'atan2', 'cos', 'cosh', 'exp', 'log', 'log10',
    'min', 'max', 'pi', 'pow', 'power', 'sin', 'sinh', 'sqrt', 'tan', 'tanh'
}))

-- Identifiers.
lex:add_rule('identifier',
             token(lexer.IDENTIFIER, lexer.lower * ('_' + lexer.alnum) ^ 0))

-- Variables.
lex:add_rule('variable', token(lexer.VARIABLE, P('_') ^ 0 * lexer.upper *
                                   ('_' + lexer.alnum) ^ 0))

-- Directives.
lex:add_rule('directive', token(lexer.PREPROCESSOR, '-' * word_match {
    'author', 'behaviour', 'behavior', 'compile', 'copyright', 'define', 'doc',
    'else', 'endif', 'export', 'file', 'ifdef', 'ifndef', 'import', 'include',
    'include_lib', 'module', 'record', 'spec', 'type', 'undef'
}))

-- Strings.
local sq_str = lexer.range("'", true)
local dq_str = lexer.range('"')
lex:add_rule('string', token(lexer.STRING, sq_str + dq_str + '$' * lexer.any *
                                 lexer.alnum ^ 0))

-- Comments.
lex:add_rule('comment', token(lexer.COMMENT, lexer.to_eol('%')))

-- Numbers.
lex:add_rule('number', token(lexer.NUMBER, lexer.number))

-- Operators.
lex:add_rule('operator', token(lexer.OPERATOR, S('-<>.;=/|+*:,!()[]{}')))

-- Preprocessor.
lex:add_rule('preprocessor', token(lexer.TYPE, '?' * lexer.word))

-- Records.
lex:add_rule('type', token(lexer.TYPE, '#' * lexer.word))

-- Fold points.
lex:add_fold_point(lexer.KEYWORD, 'case', 'end')
lex:add_fold_point(lexer.KEYWORD, 'fun', 'end')
lex:add_fold_point(lexer.KEYWORD, 'if', 'end')
lex:add_fold_point(lexer.KEYWORD, 'query', 'end')
lex:add_fold_point(lexer.KEYWORD, 'receive', 'end')
lex:add_fold_point(lexer.OPERATOR, '(', ')')
lex:add_fold_point(lexer.OPERATOR, '[', ']')
lex:add_fold_point(lexer.OPERATOR, '{', '}')

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

return lex
