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, 53 insertions, 0 deletions

diff --git a/lua/lexers/rstats.lua b/lua/lexers/rstats.lua
new file mode 100644
index 0000000..19e43e8
--- /dev/null
+++ b/lua/lexers/rstats.lua
@@ -0,0 +1,53 @@
+-- Copyright 2006-2016 Mitchell mitchell.att.foicica.com. See LICENSE.
+-- R 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 = 'rstats'}
+
+-- 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("'", true)
+local dq_str = l.delimited_range('"', true)
+local string = token(l.STRING, sq_str + dq_str)
+
+-- Numbers.
+local number = token(l.NUMBER, (l.float + l.integer) * P('i')^-1)
+
+-- Keywords.
+local keyword = token(l.KEYWORD, word_match{
+  'break', 'else', 'for', 'if', 'in', 'next', 'repeat', 'return', 'switch',
+  'try', 'while', 'Inf', 'NA', 'NaN', 'NULL', 'FALSE', 'TRUE'
+})
+
+-- Types.
+local type = token(l.TYPE, word_match{
+  'array', 'character', 'complex', 'data.frame', 'double', 'factor', 'function',
+  'integer', 'list', 'logical', 'matrix', 'numeric', 'vector'
+})
+
+-- Identifiers.
+local identifier = token(l.IDENTIFIER, l.word)
+
+-- Operators.
+local operator = token(l.OPERATOR, S('<->+*/^=.,:;|$()[]{}'))
+
+M._rules = {
+  {'whitespace', ws},
+  {'keyword', keyword},
+  {'type', type},
+  {'identifier', identifier},
+  {'string', string},
+  {'comment', comment},
+  {'number', number},
+  {'operator', operator},
+}
+
+return M