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, 74 insertions, 0 deletions

diff --git a/lua/lexers/bash.lua b/lua/lexers/bash.lua
new file mode 100644
index 0000000..7bf7957
--- /dev/null
+++ b/lua/lexers/bash.lua
@@ -0,0 +1,74 @@
+-- Copyright 2006-2016 Mitchell mitchell.att.foicica.com. See LICENSE.
+-- Shell LPeg lexer.
+
+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 = 'bash'}
+
+-- Whitespace.
+local ws = token(l.WHITESPACE, l.space^1)
+
+-- Comments.
+local comment = token(l.COMMENT, '#' * l.nonnewline^0)
+
+-- Strings.
+local sq_str = l.delimited_range("'", false, true)
+local dq_str = l.delimited_range('"')
+local ex_str = l.delimited_range('`')
+local heredoc = '<<' * P(function(input, index)
+  local s, e, _, delimiter =
+    input:find('%-?(["\']?)([%a_][%w_]*)%1[\n\r\f;]+', index)
+  if s == index and delimiter then
+    local _, e = input:find('[\n\r\f]+'..delimiter, e)
+    return e and e + 1 or #input + 1
+  end
+end)
+local string = token(l.STRING, sq_str + dq_str + ex_str + heredoc)
+
+-- Numbers.
+local number = token(l.NUMBER, l.float + l.integer)
+
+-- Keywords.
+local keyword = token(l.KEYWORD, word_match({
+  'if', 'then', 'elif', 'else', 'fi', 'case', 'in', 'esac', 'while', 'for',
+  'do', 'done', 'continue', 'local', 'return', 'select',
+  -- Operators.
+  '-a', '-b', '-c', '-d', '-e', '-f', '-g', '-h', '-k', '-p', '-r', '-s', '-t',
+  '-u', '-w', '-x', '-O', '-G', '-L', '-S', '-N', '-nt', '-ot', '-ef', '-o',
+  '-z', '-n', '-eq', '-ne', '-lt', '-le', '-gt', '-ge'
+}, '-'))
+
+-- Identifiers.
+local identifier = token(l.IDENTIFIER, l.word)
+
+-- Variables.
+local variable = token(l.VARIABLE,
+                       '$' * (S('!#?*@$') + l.digit^1 + l.word +
+                              l.delimited_range('{}', true, true)))
+
+-- Operators.
+local operator = token(l.OPERATOR, S('=!<>+-/*^&|~.,:;?()[]{}'))
+
+M._rules = {
+  {'whitespace', ws},
+  {'keyword', keyword},
+  {'identifier', identifier},
+  {'string', string},
+  {'comment', comment},
+  {'number', number},
+  {'variable', variable},
+  {'operator', operator},
+}
+
+M._foldsymbols = {
+  _patterns = {'[a-z]+', '[{}]', '#'},
+  [l.KEYWORD] = {
+    ['if'] = 1, fi = -1, case = 1, esac = -1, ['do'] = 1, done = -1
+  },
+  [l.OPERATOR] = {['{'] = 1, ['}'] = -1},
+  [l.COMMENT] = {['#'] = l.fold_line_comments('#')}
+}
+
+return M