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, 84 insertions, 0 deletions

diff --git a/lua/lexers/lisp.lua b/lua/lexers/lisp.lua
new file mode 100644
index 0000000..2d8a907
--- /dev/null
+++ b/lua/lexers/lisp.lua
@@ -0,0 +1,84 @@
+-- Copyright 2006-2016 Mitchell mitchell.att.foicica.com. See LICENSE.
+-- Lisp 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 = 'lisp'}
+
+-- Whitespace.
+local ws = token(l.WHITESPACE, l.space^1)
+
+-- Comments.
+local line_comment = ';' * l.nonnewline^0
+local block_comment = '#|' * (l.any - '|#')^0 * P('|#')^-1
+local comment = token(l.COMMENT, line_comment + block_comment)
+
+local word = l.alpha * (l.alnum + '_' + '-')^0
+
+-- Strings.
+local literal = "'" * word
+local dq_str = l.delimited_range('"')
+local string = token(l.STRING, literal + dq_str)
+
+-- Numbers.
+local number = token(l.NUMBER, P('-')^-1 * l.digit^1 * (S('./') * l.digit^1)^-1)
+
+-- Keywords.
+local keyword = token(l.KEYWORD, word_match({
+  'defclass', 'defconstant', 'defgeneric', 'define-compiler-macro',
+  'define-condition', 'define-method-combination', 'define-modify-macro',
+  'define-setf-expander', 'define-symbol-macro', 'defmacro', 'defmethod',
+  'defpackage', 'defparameter', 'defsetf', 'defstruct', 'deftype', 'defun',
+  'defvar',
+  'abort', 'assert', 'block', 'break', 'case', 'catch', 'ccase', 'cerror',
+  'cond', 'ctypecase', 'declaim', 'declare', 'do', 'do*', 'do-all-symbols',
+  'do-external-symbols', 'do-symbols', 'dolist', 'dotimes', 'ecase', 'error',
+  'etypecase', 'eval-when', 'flet', 'handler-bind', 'handler-case', 'if',
+  'ignore-errors', 'in-package', 'labels', 'lambda', 'let', 'let*', 'locally',
+  'loop', 'macrolet', 'multiple-value-bind', 'proclaim', 'prog', 'prog*',
+  'prog1', 'prog2', 'progn', 'progv', 'provide', 'require', 'restart-bind',
+  'restart-case', 'restart-name', 'return', 'return-from', 'signal',
+  'symbol-macrolet', 'tagbody', 'the', 'throw', 'typecase', 'unless',
+  'unwind-protect', 'when', 'with-accessors', 'with-compilation-unit',
+  'with-condition-restarts', 'with-hash-table-iterator',
+  'with-input-from-string', 'with-open-file', 'with-open-stream',
+  'with-output-to-string', 'with-package-iterator', 'with-simple-restart',
+  'with-slots', 'with-standard-io-syntax',
+  't', 'nil'
+}, '-'))
+
+-- Identifiers.
+local identifier = token(l.IDENTIFIER, word)
+
+-- Operators.
+local operator = token(l.OPERATOR, S('<>=*/+-`@%()'))
+
+-- Entities.
+local entity = token('entity', '&' * word)
+
+M._rules = {
+  {'whitespace', ws},
+  {'keyword', keyword},
+  {'identifier', identifier},
+  {'string', string},
+  {'comment', comment},
+  {'number', number},
+  {'operator', operator},
+  {'entity', entity},
+}
+
+M._tokenstyles = {
+  entity = l.STYLE_VARIABLE
+}
+
+M._foldsymbols = {
+  _patterns = {'[%(%)%[%]{}]', '#|', '|#', ';'},
+  [l.OPERATOR] = {
+    ['('] = 1, [')'] = -1, ['['] = 1, [']'] = -1, ['{'] = 1, ['}'] = -1
+  },
+  [l.COMMENT] = {['#|'] = 1, ['|#'] = -1, [';'] = l.fold_line_comments(';')}
+}
+
+return M