-- Copyright 2016-2020 Alejandro Baez (https://keybase.io/baez). See LICENSE.
-- Moonscript 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('moonscript', {fold_by_indentation = true})

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

-- Keywords.
lex:add_rule('keyword', token(lexer.KEYWORD, word_match[[
  -- Lua.
  and break do else elseif false for if in local nil not or return then true
  while
  -- Moonscript.
  continue class export extends from import super switch unless using when with
]]))

-- Error words.
lex:add_rule('error', token(lexer.ERROR, word_match[[function end]]))

-- Self reference.
lex:add_rule('self_ref', token('self_ref', '@' * lexer.word + 'self'))
lex:add_style('self_ref', lexer.styles.label)

-- Functions.
lex:add_rule('function', token(lexer.FUNCTION, word_match[[
  assert collectgarbage dofile error getmetatable ipairs load loadfile next
  pairs pcall print rawequal rawget rawset require select setmetatable tonumber
  tostring type xpcall
  -- Added in 5.2.
  rawlen
]]))

-- Constants.
lex:add_rule('constant', token(lexer.CONSTANT, word_match[[
  _G _VERSION
  -- Added in 5.2.
  _ENV
]]))

-- Libraries.
lex:add_rule('library', token('library', word_match[[
  -- Coroutine.
  coroutine coroutine.create coroutine.resume coroutine.running coroutine.status
  coroutine.wrap coroutine.yield
  -- Coroutine added in 5.3.
  coroutine.isyieldable
  -- Module.
  package package.cpath package.loaded package.loadlib package.path
  package.preload
  -- Module added in 5.2.
  package.config package.searchers package.searchpath
  -- UTF-8 added in 5.3.
  utf8 utf8.char utf8.charpattern utf8.codepoint utf8.codes utf8.len utf8.offset
  -- String.
  string string.byte string.char string.dump string.find string.format
  string.gmatch string.gsub string.len string.lower string.match string.rep
  string.reverse string.sub string.upper
  -- String added in 5.3.
  string.pack string.packsize string.unpack
  -- Table.
  table table.concat table.insert table.remove table.sort
  -- Table added in 5.2.
  table.pack table.unpack
  -- Table added in 5.3.
  table.move
  -- Math.
  math math.abs math.acos math.asin math.atan math.ceil math.cos math.deg
  math.exp math.floor math.fmod math.huge math.log math.max math.min math.modf
  math.pi math.rad math.random math.randomseed math.sin math.sqrt math.tan
  -- Math added in 5.3.
  math.maxinteger math.mininteger math.tointeger math.type math.ult
  -- IO.
  io io.close io.flush io.input io.lines io.open io.output io.popen io.read
  io.stderr io.stdin io.stdout io.tmpfile io.type io.write
  -- OS.
  os os.clock os.date os.difftime os.execute os.exit os.getenv os.remove
  os.rename os.setlocale os.time os.tmpname
  -- Debug.
  debug debug.debug debug.gethook debug.getinfo debug.getlocal
  debug.getmetatable debug.getregistry debug.getupvalue debug.sethook
  debug.setlocal debug.setmetatable debug.setupvalue debug.traceback
  -- Debug added in 5.2.
  debug.getuservalue debug.setuservalue debug.upvalueid debug.upvaluejoin

  --- MoonScript 0.3.1 standard library.
  -- Printing functions.
  p
  -- Table functions.
  run_with_scope defaultbl extend copy
  -- Class/object functions.
  is_object bind_methods mixin mixin_object mixin_table
  -- Misc functions.
  fold
  -- Debug functions.
  debug.upvalue
]]))
lex:add_style('library', lexer.styles.type)

-- Identifiers.
local identifier = token(lexer.IDENTIFIER, lexer.word)
local proper_ident = token('proper_ident', lexer.upper * lexer.word)
local tbl_key = token('tbl_key', lexer.word * ':' + ':' * lexer.word )
lex:add_rule('identifier', tbl_key + proper_ident + identifier)
lex:add_style('proper_ident', lexer.styles.class)
lex:add_style('tbl_key', lexer.styles.regex)

local longstring = lpeg.Cmt('[' * lpeg.C(P('=')^0) * '[',
  function(input, index, eq)
    local _, e = input:find(']' .. eq .. ']', index, true)
    return (e or #input) + 1
  end)

-- Strings.
local sq_str = lexer.range("'", false, false)
local dq_str = lexer.range('"', false, false)
lex:add_rule('string', token(lexer.STRING, sq_str + dq_str) +
  token('longstring', longstring))
lex:add_style('longstring', lexer.styles.string)

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

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

-- Function definition.
lex:add_rule('fndef', token('fndef', P('->') + '=>'))
lex:add_style('fndef', lexer.styles.preprocessor)

-- Operators.
lex:add_rule('operator', token(lexer.OPERATOR, S('+-*!\\/%^#=<>;:,.')))
lex:add_rule('symbol', token('symbol', S('(){}[]')))
lex:add_style('symbol', lexer.styles.embedded)

return lex
