Move all lua related files to lua/ subfolder

Also remove the lexers sub directory from the Lua search path.
As a result we attempt to open fewer files during startup:

 $ strace -e open -o log ./vis +q config.h && wc -l log

In order to avoid having to modifiy all lexers which `require('lexer')`
we instead place a symlink in the top level directory.

 $ ./configure --disable-lua
 $ rm -rf lua

Should result in a source tree with most lua specifc functionality
removed.

1 files changed, 190 insertions, 0 deletions

diff --git a/lua/lexers/lua.lua b/lua/lexers/lua.lua
new file mode 100644
index 0000000..fba4600
--- /dev/null
+++ b/lua/lexers/lua.lua
@@ -0,0 +1,190 @@
+-- Copyright 2006-2016 Mitchell mitchell.att.foicica.com. See LICENSE.
+-- Lua LPeg lexer.
+-- Original written by Peter Odding, 2007/04/04.
+
+local l = require('lexer')
+local token, word_match = l.token, l.word_match
+local P, R, S = lpeg.P, lpeg.R, lpeg.S
+
+local M = {_NAME = 'lua'}
+
+-- Whitespace.
+local ws = token(l.WHITESPACE, l.space^1)
+
+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)
+
+-- Comments.
+local line_comment = '--' * l.nonnewline^0
+local block_comment = '--' * longstring
+local comment = token(l.COMMENT, block_comment + line_comment)
+
+-- Strings.
+local sq_str = l.delimited_range("'")
+local dq_str = l.delimited_range('"')
+local string = token(l.STRING, sq_str + dq_str) +
+               token('longstring', longstring)
+
+-- Numbers.
+local lua_integer = P('-')^-1 * (l.hex_num + l.dec_num)
+local number = token(l.NUMBER, l.float + lua_integer)
+
+-- Keywords.
+local keyword = token(l.KEYWORD, word_match{
+  'and', 'break', 'do', 'else', 'elseif', 'end', 'false', 'for', 'function',
+  'goto', 'if', 'in', 'local', 'nil', 'not', 'or', 'repeat', 'return', 'then',
+  'true', 'until', 'while'
+})
+
+-- Functions.
+local func = token(l.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'
+})
+
+-- Deprecated functions.
+local deprecated_func = token('deprecated_function', word_match{
+  -- Deprecated in 5.2.
+  'getfenv', 'loadstring', 'module', 'setfenv', 'unpack'
+})
+
+-- Constants.
+local constant = token(l.CONSTANT, word_match{
+  '_G', '_VERSION',
+  -- Added in 5.2.
+  '_ENV'
+})
+
+-- Libraries.
+local 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',
+}, '.'))
+
+-- Deprecated libraries.
+local deprecated_library = token('deprecated_library', word_match({
+  -- Module deprecated in 5.2.
+  'package.loaders', 'package.seeall',
+  -- Table deprecated in 5.2.
+  'table.maxn',
+  -- Math deprecated in 5.2.
+  'math.log10',
+  -- Math deprecated in 5.3.
+  'math.atan2', 'math.cosh', 'math.frexp', 'math.ldexp', 'math.pow',
+  'math.sinh', 'math.tanh',
+  -- Bit32 deprecated in 5.3.
+  'bit32', 'bit32.arshift', 'bit32.band', 'bit32.bnot', 'bit32.bor',
+  'bit32.btest', 'bit32.extract', 'bit32.lrotate', 'bit32.lshift',
+  'bit32.replace', 'bit32.rrotate', 'bit32.rshift', 'bit32.xor',
+  -- Debug deprecated in 5.2.
+  'debug.getfenv', 'debug.setfenv'
+}, '.'))
+
+-- Identifiers.
+local identifier = token(l.IDENTIFIER, l.word)
+
+-- Labels.
+local label = token(l.LABEL, '::' * l.word * '::')
+
+-- Operators.
+local operator = token(l.OPERATOR, S('+-*/%^#=<>&|~;:,.{}[]()'))
+
+M._rules = {
+  {'whitespace', ws},
+  {'keyword', keyword},
+  {'function', func + deprecated_func},
+  {'constant', constant},
+  {'library', library + deprecated_library},
+  {'identifier', identifier},
+  {'string', string},
+  {'comment', comment},
+  {'number', number},
+  {'label', label},
+  {'operator', operator},
+}
+
+M._tokenstyles = {
+  longstring = l.STYLE_STRING,
+  deprecated_function = l.STYLE_FUNCTION..',italics',
+  library = l.STYLE_TYPE,
+  deprecated_library = l.STYLE_TYPE..',italics'
+}
+
+local function fold_longcomment(text, pos, line, s, match)
+  if match == '[' then
+    if line:find('^%[=*%[', s) then return 1 end
+  elseif match == ']' then
+    if line:find('^%]=*%]', s) then return -1 end
+  end
+  return 0
+end
+
+M._foldsymbols = {
+  _patterns = {'%l+', '[%({%)}]', '[%[%]]', '%-%-'},
+  [l.KEYWORD] = {
+    ['if'] = 1, ['do'] = 1, ['function'] = 1, ['end'] = -1, ['repeat'] = 1,
+    ['until'] = -1
+  },
+  [l.COMMENT] = {
+    ['['] = fold_longcomment, [']'] = fold_longcomment,
+    ['--'] = l.fold_line_comments('--')
+  },
+  longstring = {['['] = 1, [']'] = -1},
+  [l.OPERATOR] = {['('] = 1, ['{'] = 1, [')'] = -1, ['}'] = -1}
+}
+
+return M