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, 47 insertions, 0 deletions

diff --git a/lua/lexers/json.lua b/lua/lexers/json.lua
new file mode 100644
index 0000000..6dcebec
--- /dev/null
+++ b/lua/lexers/json.lua
@@ -0,0 +1,47 @@
+-- Copyright 2006-2013 Brian "Sir Alaran" Schott. See LICENSE.
+-- JSON LPeg lexer.
+-- Based off of lexer code by Mitchell.
+
+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 = 'json'}
+
+-- Whitespace.
+local ws = token(l.WHITESPACE, l.space^1)
+
+-- Comments.
+local comment = token(l.COMMENT, '/*' * (l.any - '*/')^0 * P('*/')^-1)
+
+-- Strings.
+local sq_str = P('u')^-1 * l.delimited_range("'", true)
+local dq_str = P('U')^-1 * l.delimited_range('"', true)
+local string = token(l.STRING, sq_str + dq_str)
+
+-- Numbers.
+local integer = S('+-')^-1 * l.digit^1 * S('Ll')^-1
+local number = token(l.NUMBER, l.float + integer)
+
+-- Keywords.
+local keyword = token(l.KEYWORD, word_match{"true", "false", "null"})
+
+-- Operators.
+local operator = token(l.OPERATOR, S('[]{}:,'))
+
+M._rules = {
+  {'whitespace', ws},
+  {'comment', comment},
+  {'string', string},
+  {'number', number},
+  {'keyword', keyword},
+  {'operator', operator},
+}
+
+M._foldsymbols = {
+  _patterns = {'[%[%]{}]', '/%*', '%*/'},
+  [l.OPERATOR] = {['['] = 1, [']'] = -1, ['{'] = 1, ['}'] = -1},
+  [l.COMMENT] = {['/*'] = 1, ['*/'] = -1}
+}
+
+return M