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, 39 insertions, 0 deletions

diff --git a/lua/lexers/gettext.lua b/lua/lexers/gettext.lua
new file mode 100644
index 0000000..8556d01
--- /dev/null
+++ b/lua/lexers/gettext.lua
@@ -0,0 +1,39 @@
+-- Copyright 2006-2016 Mitchell mitchell.att.foicica.com. See LICENSE.
+-- Gettext 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 = 'gettext'}
+
+-- Whitespace.
+local ws = token(l.WHITESPACE, l.space^1)
+
+-- Comments.
+local comment = token(l.COMMENT, '#' * S(': .~') * l.nonnewline^0)
+
+-- Strings.
+local string = token(l.STRING, l.delimited_range('"', true))
+
+-- Keywords.
+local keyword = token(l.KEYWORD, word_match({
+  'msgid', 'msgid_plural', 'msgstr', 'fuzzy', 'c-format', 'no-c-format'
+}, '-', true))
+
+-- Identifiers.
+local identifier = token(l.IDENTIFIER, l.word)
+
+-- Variables.
+local variable = token(l.VARIABLE, S('%$@') * l.word)
+
+M._rules = {
+  {'whitespace', ws},
+  {'comment', comment},
+  {'string', string},
+  {'keyword', keyword},
+  {'identifier', identifier},
+  {'variable', variable},
+}
+
+return M