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, 77 insertions, 0 deletions

diff --git a/lua/lexers/django.lua b/lua/lexers/django.lua
new file mode 100644
index 0000000..19bcc05
--- /dev/null
+++ b/lua/lexers/django.lua
@@ -0,0 +1,77 @@
+-- Copyright 2006-2016 Mitchell mitchell.att.foicica.com. See LICENSE.
+-- Django LPeg lexer.
+
+local l = require('lexer')
+local token, word_match = l.token, l.word_match
+local P, R, S, V = lpeg.P, lpeg.R, lpeg.S, lpeg.V
+
+local M = {_NAME = 'django'}
+
+-- Whitespace.
+local ws = token(l.WHITESPACE, l.space^1)
+
+-- Comments.
+local comment = token(l.COMMENT, '{#' * (l.any - l.newline - '#}')^0 *
+                                 P('#}')^-1)
+
+-- Strings.
+local string = token(l.STRING, l.delimited_range('"', false, true))
+
+-- Keywords.
+local keyword = token(l.KEYWORD, word_match{
+  'as', 'block', 'blocktrans', 'by', 'endblock', 'endblocktrans', 'comment',
+  'endcomment', 'cycle', 'date', 'debug', 'else', 'extends', 'filter',
+  'endfilter', 'firstof', 'for', 'endfor', 'if', 'endif', 'ifchanged',
+  'endifchanged', 'ifnotequal', 'endifnotequal', 'in', 'load', 'not', 'now',
+  'or', 'parsed', 'regroup', 'ssi', 'trans', 'with', 'widthratio'
+})
+
+-- Functions.
+local func = token(l.FUNCTION, word_match{
+  'add', 'addslashes', 'capfirst', 'center', 'cut', 'date', 'default',
+  'dictsort', 'dictsortreversed', 'divisibleby', 'escape', 'filesizeformat',
+  'first', 'fix_ampersands', 'floatformat', 'get_digit', 'join', 'length',
+  'length_is', 'linebreaks', 'linebreaksbr', 'linenumbers', 'ljust', 'lower',
+  'make_list', 'phone2numeric', 'pluralize', 'pprint', 'random', 'removetags',
+  'rjust', 'slice', 'slugify', 'stringformat', 'striptags', 'time', 'timesince',
+  'title', 'truncatewords', 'unordered_list', 'upper', 'urlencode', 'urlize',
+  'urlizetrunc', 'wordcount', 'wordwrap', 'yesno',
+})
+
+-- Identifiers.
+local identifier = token(l.IDENTIFIER, l.word)
+
+-- Operators.
+local operator = token(l.OPERATOR, S(':,.|'))
+
+M._rules = {
+  {'whitespace', ws},
+  {'keyword', keyword},
+  {'function', func},
+  {'identifier', identifier},
+  {'string', string},
+  {'comment', comment},
+  {'operator', operator},
+}
+
+-- Embedded in HTML.
+local html = l.load('html')
+
+-- Embedded Django.
+local django_start_rule = token('django_tag', '{' * S('{%'))
+local django_end_rule = token('django_tag', S('%}') * '}')
+l.embed_lexer(html, M, django_start_rule, django_end_rule)
+-- Modify HTML patterns to embed Django.
+html._RULES['comment'] = html._RULES['comment'] + comment
+
+M._tokenstyles = {
+  django_tag = l.STYLE_EMBEDDED
+}
+
+local _foldsymbols = html._foldsymbols
+_foldsymbols._patterns[#_foldsymbols._patterns + 1] = '{[%%{]'
+_foldsymbols._patterns[#_foldsymbols._patterns + 1] = '[%%}]}'
+_foldsymbols.django_tag = {['{{'] = 1, ['}}'] = -1, ['{%'] = 1, ['%}'] = -1}
+M._foldsymbols = _foldsymbols
+
+return M