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, 55 insertions, 0 deletions

diff --git a/lua/lexers/dockerfile.lua b/lua/lexers/dockerfile.lua
new file mode 100644
index 0000000..3f6ca7f
--- /dev/null
+++ b/lua/lexers/dockerfile.lua
@@ -0,0 +1,55 @@
+-- Copyright 2016 Alejandro Baez (https://keybase.io/baez). See LICENSE.
+-- Dockerfile 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 = 'dockerfile'}
+
+-- Whitespace
+local indent = #l.starts_line(S(' \t')) *
+               (token(l.WHITESPACE, ' ') + token('indent_error', '\t'))^1
+local ws = token(l.WHITESPACE, S(' \t')^1 + l.newline^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 string = token(l.STRING, sq_str + dq_str)
+
+-- Numbers.
+local number = token(l.NUMBER, l.float + l.integer)
+
+-- Keywords.
+local keyword = token(l.KEYWORD, word_match{
+  'ADD', 'ARG', 'CMD', 'COPY', 'ENTRYPOINT', 'ENV', 'EXPOSE', 'FROM', 'LABEL',
+  'MAINTAINER', 'ONBUILD', 'RUN', 'STOPSIGNAL', 'USER', 'VOLUME', 'WORKDIR'
+})
+
+-- Identifiers.
+local identifier = token(l.IDENTIFIER, l.word)
+
+-- Variable.
+local variable = token(l.VARIABLE,
+                       S('$')^1 * (S('{')^1 * l.word * S('}')^1 + l.word))
+
+-- Operators.
+local operator = token(l.OPERATOR, S('\\[],=:{}'))
+
+M._rules = {
+  {'whitespace', ws},
+  {'keyword', keyword},
+  {'variable', variable},
+  {'identifier', identifier},
+  {'string', string},
+  {'comment', comment},
+  {'number', number},
+  {'operator', operator},
+}
+
+M._FOLDBYINDENTATION = true
+
+return M