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, 59 insertions, 0 deletions

diff --git a/lua/lexers/tcl.lua b/lua/lexers/tcl.lua
new file mode 100644
index 0000000..f76e6ee
--- /dev/null
+++ b/lua/lexers/tcl.lua
@@ -0,0 +1,59 @@
+-- Copyright 2014-2016 Joshua Krämer. See LICENSE.
+-- Tcl LPeg lexer.
+-- This lexer follows the TCL dodekalogue (http://wiki.tcl.tk/10259).
+-- It is based on the previous lexer 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 = 'tcl'}
+
+-- Whitespace.
+local whitespace = token(l.WHITESPACE, l.space^1)
+
+-- Separator (semicolon).
+local separator = token(l.CLASS, P(';'))
+
+-- Delimiters.
+local braces = token(l.KEYWORD, S('{}'))
+local quotes = token(l.FUNCTION, '"')
+local brackets = token(l.VARIABLE, S('[]'))
+
+-- Argument expander.
+local expander = token(l.LABEL, P('{*}'))
+
+-- Variable substitution.
+local variable = token(l.STRING, '$' * (l.alnum + '_' + P(':')^2)^0)
+
+-- Backslash substitution.
+local backslash = token(l.TYPE, '\\' * ((l.digit * l.digit^-2) +
+                        ('x' * l.xdigit^1) + ('u' * l.xdigit * l.xdigit^-3) +
+                        ('U' * l.xdigit * l.xdigit^-7) + P(1)))
+
+-- Comment.
+local comment = token(l.COMMENT, '#' * P(function(input, index)
+  local i = index - 2
+  while i > 0 and input:find('^[ \t]', i) do i = i - 1 end
+  if i < 1 or input:find('^[\r\n;]', i) then return index end
+end) * l.nonnewline^0)
+
+M._rules = {
+  {'whitespace', whitespace},
+  {'comment', comment},
+  {'separator', separator},
+  {'expander', expander},
+  {'braces', braces},
+  {'quotes', quotes},
+  {'brackets', brackets},
+  {'variable', variable},
+  {'backslash', backslash},
+}
+
+M._foldsymbols = {
+  _patterns = {'[{}]', '#'},
+  [l.KEYWORD] = {['{'] = 1, ['}'] = -1},
+  [l.COMMENT] = {['#'] = l.fold_line_comments('#')}
+}
+
+return M