-- Copyright 2006-2022 Mitchell. See LICENSE.
-- C 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('ansi_c')

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

-- Keywords.
lex:add_rule('keyword', token(lexer.KEYWORD, word_match{
  'auto', 'break', 'case', 'const', 'continue', 'default', 'do', 'else', 'enum', 'extern', 'for',
  'goto', 'if', 'inline', 'register', 'restrict', 'return', 'sizeof', 'static', 'switch', 'typedef',
  'volatile', 'while',
  -- C99.
  'false', 'true',
  -- C11.
  '_Alignas', '_Alignof', '_Atomic', '_Generic', '_Noreturn', '_Static_assert', '_Thread_local',
  -- Compiler.
  'asm', '__asm', '__asm__', '__restrict__', '__inline', '__inline__', '__attribute__', '__declspec'
}))

-- Types.
lex:add_rule('type', token(lexer.TYPE, word_match{
  'bool', 'char', 'double', 'float', 'int', 'long', 'short', 'signed', 'struct', 'union',
  'unsigned', 'void', '_Bool', '_Complex', '_Imaginary',
  -- Stdlib types.
  'ptrdiff_t', 'size_t', 'max_align_t', 'wchar_t', 'intptr_t', 'uintptr_t', 'intmax_t', 'uintmax_t'
} + P('u')^-1 * 'int' * (P('_least') + '_fast')^-1 * lexer.digit^1 * '_t'))

-- Constants.
lex:add_rule('constants', token(lexer.CONSTANT, word_match{
  'NULL',
  -- Preprocessor.
  '__DATE__', '__FILE__', '__LINE__', '__TIME__', '__func__',
  -- errno.h.
  'E2BIG', 'EACCES', 'EADDRINUSE', 'EADDRNOTAVAIL', 'EAFNOSUPPORT', 'EAGAIN', 'EALREADY', 'EBADF',
  'EBADMSG', 'EBUSY', 'ECANCELED', 'ECHILD', 'ECONNABORTED', 'ECONNREFUSED', 'ECONNRESET',
  'EDEADLK', 'EDESTADDRREQ', 'EDOM', 'EDQUOT', 'EEXIST', 'EFAULT', 'EFBIG', 'EHOSTUNREACH', 'EIDRM',
  'EILSEQ', 'EINPROGRESS', 'EINTR', 'EINVAL', 'EIO', 'EISCONN', 'EISDIR', 'ELOOP', 'EMFILE',
  'EMLINK', 'EMSGSIZE', 'EMULTIHOP', 'ENAMETOOLONG', 'ENETDOWN', 'ENETRESET', 'ENETUNREACH',
  'ENFILE', 'ENOBUFS', 'ENODATA', 'ENODEV', 'ENOENT', 'ENOEXEC', 'ENOLCK', 'ENOLINK', 'ENOMEM',
  'ENOMSG', 'ENOPROTOOPT', 'ENOSPC', 'ENOSR', 'ENOSTR', 'ENOSYS', 'ENOTCONN', 'ENOTDIR',
  'ENOTEMPTY', 'ENOTRECOVERABLE', 'ENOTSOCK', 'ENOTSUP', 'ENOTTY', 'ENXIO', 'EOPNOTSUPP',
  'EOVERFLOW', 'EOWNERDEAD', 'EPERM', 'EPIPE', 'EPROTO', 'EPROTONOSUPPORT', 'EPROTOTYPE', 'ERANGE',
  'EROFS', 'ESPIPE', 'ESRCH', 'ESTALE', 'ETIME', 'ETIMEDOUT', 'ETXTBSY', 'EWOULDBLOCK', 'EXDEV',
  -- stdint.h.
  'PTRDIFF_MIN', 'PTRDIFF_MAX', 'SIZE_MAX', 'SIG_ATOMIC_MIN', 'SIG_ATOMIC_MAX', 'WINT_MIN',
  'WINT_MAX', 'WCHAR_MIN', 'WCHAR_MAX'
} + P('U')^-1 * 'INT' * ((P('_LEAST') + '_FAST')^-1 * lexer.digit^1 + 'PTR' + 'MAX') *
  (P('_MIN') + '_MAX')))

-- Labels.
lex:add_rule('label', token(lexer.LABEL, lexer.starts_line(lexer.word * ':')))

-- Strings.
local sq_str = P('L')^-1 * lexer.range("'", true)
local dq_str = P('L')^-1 * lexer.range('"', true)
lex:add_rule('string', token(lexer.STRING, sq_str + dq_str))

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

-- Comments.
local line_comment = lexer.to_eol('//', true)
local block_comment = lexer.range('/*', '*/') +
  lexer.range('#if' * S(' \t')^0 * '0' * lexer.space, '#endif')
lex:add_rule('comment', token(lexer.COMMENT, line_comment + block_comment))

-- Numbers.
local integer = lexer.integer * word_match('u l ll ul ull lu llu', true)^-1
local float = lexer.float * P('f')^-1
lex:add_rule('number', token(lexer.NUMBER, float + integer))

-- Preprocessor.
local include = token(lexer.PREPROCESSOR, '#' * S('\t ')^0 * 'include') *
  (ws * token(lexer.STRING, lexer.range('<', '>', true)))^-1
local preproc = token(lexer.PREPROCESSOR, '#' * S('\t ')^0 *
  word_match('define elif else endif if ifdef ifndef line pragma undef'))
lex:add_rule('preprocessor', include + preproc)

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

-- Fold points.
lex:add_fold_point(lexer.PREPROCESSOR, '#if', '#endif')
lex:add_fold_point(lexer.PREPROCESSOR, '#ifdef', '#endif')
lex:add_fold_point(lexer.PREPROCESSOR, '#ifndef', '#endif')
lex:add_fold_point(lexer.OPERATOR, '{', '}')
lex:add_fold_point(lexer.COMMENT, '/*', '*/')
lex:add_fold_point(lexer.COMMENT, lexer.fold_consecutive_lines('//'))

return lex