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, 32 insertions, 0 deletions

diff --git a/lua/lexers/sass.lua b/lua/lexers/sass.lua
new file mode 100644
index 0000000..002df27
--- /dev/null
+++ b/lua/lexers/sass.lua
@@ -0,0 +1,32 @@
+-- Copyright 2006-2013 Robert Gieseke. See LICENSE.
+-- Sass CSS preprocessor LPeg lexer.
+-- http://sass-lang.com
+
+local l = require('lexer')
+local token = l.token
+local P, S = lpeg.P, lpeg.S
+
+local M = {_NAME = 'sass'}
+
+-- Line comments.
+local line_comment = token(l.COMMENT, '//' * l.nonnewline^0)
+
+-- Variables.
+local variable = token(l.VARIABLE, '$' * (l.alnum + S('_-'))^1)
+
+-- Mixins.
+local mixin = token('mixin', P('@') * l.word)
+
+local css = l.load('css')
+local _rules = css._rules
+table.insert(_rules, #_rules - 1, {'mixin', mixin})
+table.insert(_rules, #_rules - 1, {'line_comment', line_comment})
+table.insert(_rules, #_rules - 1, {'variable', variable})
+M._rules = _rules
+
+M._tokenstyles = css._tokenstyles
+M._tokenstyles['mixin'] = l.STYLE_FUNCTION
+
+M._foldsymbols = css._foldsymbols
+
+return M