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, 73 insertions, 0 deletions

diff --git a/lua/lexers/latex.lua b/lua/lexers/latex.lua
new file mode 100644
index 0000000..f1febe9
--- /dev/null
+++ b/lua/lexers/latex.lua
@@ -0,0 +1,73 @@
+-- Copyright 2006-2016 Mitchell mitchell.att.foicica.com. See LICENSE.
+-- Latex LPeg lexer.
+-- Modified by Brian Schott.
+-- Modified by Robert Gieseke.
+
+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 = 'latex'}
+
+-- Whitespace.
+local ws = token(l.WHITESPACE, l.space^1)
+
+-- Comments.
+local line_comment = '%' * l.nonnewline^0
+local block_comment = '\\begin' * P(' ')^0 * '{comment}' *
+                      (l.any - '\\end' * P(' ')^0 * '{comment}')^0 *
+                      P('\\end' * P(' ')^0 * '{comment}')^-1
+-- Note: need block_comment before line_comment or LPeg cannot compile rule.
+local comment = token(l.COMMENT, block_comment + line_comment)
+
+-- Sections.
+local section = token('section', '\\' * word_match{
+  'part', 'chapter', 'section', 'subsection', 'subsubsection', 'paragraph',
+  'subparagraph'
+} * P('*')^-1)
+
+-- Math environments.
+local math_word = word_match{
+  'align', 'displaymath', 'eqnarray', 'equation', 'gather', 'math', 'multline'
+}
+local math_begin_end = (P('begin') + P('end')) * P(' ')^0 *
+                       '{' * math_word * P('*')^-1 * '}'
+local math = token('math', '$' + '\\' * (S('[]()') + math_begin_end))
+
+-- LaTeX environments.
+local environment = token('environment', '\\' * (P('begin') + P('end')) *
+                                         P(' ')^0 *
+                                         '{' * l.word * P('*')^-1 * '}')
+
+-- Commands.
+local command = token(l.KEYWORD, '\\' * (l.alpha^1 + S('#$&~_^%{}')))
+
+-- Operators.
+local operator = token(l.OPERATOR, S('&#{}[]'))
+
+M._rules = {
+  {'whitespace', ws},
+  {'comment', comment},
+  {'math', math},
+  {'environment', environment},
+  {'section', section},
+  {'keyword', command},
+  {'operator', operator},
+}
+
+M._tokenstyles = {
+  environment = l.STYLE_KEYWORD,
+  math = l.STYLE_FUNCTION,
+  section = l.STYLE_CLASS
+}
+
+M._foldsymbols = {
+  _patterns = {'\\[a-z]+', '[{}]', '%%'},
+  [l.COMMENT] = {
+    ['\\begin'] = 1, ['\\end'] = -1, ['%'] = l.fold_line_comments('%')
+  },
+  ['environment'] = {['\\begin'] = 1, ['\\end'] = -1},
+  [l.OPERATOR] = {['{'] = 1, ['}'] = -1}
+}
+
+return M