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, 62 insertions, 0 deletions

diff --git a/lua/lexers/desktop.lua b/lua/lexers/desktop.lua
new file mode 100644
index 0000000..22c95f3
--- /dev/null
+++ b/lua/lexers/desktop.lua
@@ -0,0 +1,62 @@
+-- Copyright 2006-2016 Mitchell mitchell.att.foicica.com. See LICENSE.
+-- Desktop Entry 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 = 'desktop'}
+
+-- Whitespace.
+local ws = token(l.WHITESPACE, l.space^1)
+
+-- Comments.
+local comment = token(l.COMMENT, '#' * l.nonnewline^0)
+
+-- Strings.
+local string = token(l.STRING, l.delimited_range('"'))
+
+-- Group headers.
+local group_header = l.starts_line(token(l.STRING,
+                                         l.delimited_range('[]', false, true)))
+
+-- Numbers.
+local number = token(l.NUMBER, (l.float + l.integer))
+
+-- Keywords.
+local keyword = token(l.KEYWORD, word_match{'true', 'false'})
+
+-- Locales.
+local locale = token(l.CLASS, l.delimited_range('[]', false, true))
+
+-- Keys.
+local key = token(l.VARIABLE, word_match{
+  'Type', 'Version', 'Name', 'GenericName', 'NoDisplay', 'Comment', 'Icon',
+  'Hidden', 'OnlyShowIn', 'NotShowIn', 'TryExec', 'Exec', 'Exec', 'Path',
+  'Terminal', 'MimeType', 'Categories', 'StartupNotify', 'StartupWMClass', 'URL'
+})
+
+-- Field codes.
+local code = l.token(l.CONSTANT, P('%') * S('fFuUdDnNickvm'))
+
+-- Identifiers.
+local identifier = l.token(l.IDENTIFIER, l.alpha * (l.alnum + S('_-'))^0)
+
+-- Operators.
+local operator = token(l.OPERATOR, S('='))
+
+M._rules = {
+  {'whitespace', ws},
+  {'keyword', keyword},
+  {'key', key},
+  {'identifier', identifier},
+  {'group_header', group_header},
+  {'locale', locale},
+  {'string', string},
+  {'comment', comment},
+  {'number', number},
+  {'code', code},
+  {'operator', operator},
+}
+
+return M