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, 52 insertions, 0 deletions

diff --git a/lua/lexers/ini.lua b/lua/lexers/ini.lua
new file mode 100644
index 0000000..e5df55a
--- /dev/null
+++ b/lua/lexers/ini.lua
@@ -0,0 +1,52 @@
+-- Copyright 2006-2016 Mitchell mitchell.att.foicica.com. See LICENSE.
+-- Ini LPeg lexer.
+
+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 = 'ini'}
+
+-- Whitespace.
+local ws = token(l.WHITESPACE, l.space^1)
+
+-- Comments.
+local comment = token(l.COMMENT, l.starts_line(S(';#')) * l.nonnewline^0)
+
+-- Strings.
+local sq_str = l.delimited_range("'")
+local dq_str = l.delimited_range('"')
+local label = l.delimited_range('[]', true, true)
+local string = token(l.STRING, sq_str + dq_str + label)
+
+-- Numbers.
+local dec = l.digit^1 * ('_' * l.digit^1)^0
+local oct_num = '0' * S('01234567_')^1
+local integer = S('+-')^-1 * (l.hex_num + oct_num + dec)
+local number = token(l.NUMBER, (l.float + integer))
+
+-- Keywords.
+local keyword = token(l.KEYWORD, word_match{
+  'true', 'false', 'on', 'off', 'yes', 'no'
+})
+
+-- Identifiers.
+local word = (l.alpha + '_') * (l.alnum + S('_.'))^0
+local identifier = token(l.IDENTIFIER, word)
+
+-- Operators.
+local operator = token(l.OPERATOR, '=')
+
+M._rules = {
+  {'whitespace', ws},
+  {'keyword', keyword},
+  {'identifier', identifier},
+  {'string', string},
+  {'comment', comment},
+  {'number', number},
+  {'operator', operator},
+}
+
+M._LEXBYLINE = true
+
+return M