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, 112 insertions, 0 deletions

diff --git a/lua/lexers/xtend.lua b/lua/lexers/xtend.lua
new file mode 100644
index 0000000..cc2bf8e
--- /dev/null
+++ b/lua/lexers/xtend.lua
@@ -0,0 +1,112 @@
+-- Copyright (c) 2014-2016 Piotr Orzechowski [drzewo.org]. See LICENSE.
+-- Xtend 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 = 'xtend'}
+
+-- Whitespace.
+local ws = token(l.WHITESPACE, l.space^1)
+
+-- Comments.
+local line_comment = '//' * l.nonnewline_esc^0
+local block_comment = '/*' * (l.any - '*/')^0 * P('*/')^-1
+local comment = token(l.COMMENT, line_comment + block_comment)
+
+-- Strings.
+local sq_str = l.delimited_range("'", true)
+local dq_str = l.delimited_range('"', true)
+local string = token(l.STRING, sq_str + dq_str)
+
+-- Templates.
+local templ_str = "'''" * (l.any - P("'''"))^0 * P("'''")^-1
+local template = token('template', templ_str, true)
+
+-- Numbers.
+local small_suff = S('lL')
+local med_suff = P(S('bB') * S('iI'))
+local large_suff = S('dD') + S('fF') + P(S('bB') * S('dD'))
+local exp = S('eE') * l.digit^1
+
+local dec_inf = ('_' * l.digit^1)^0
+local hex_inf = ('_' * l.xdigit^1)^0
+local float_pref = l.digit^1 * '.' * l.digit^1
+local float_suff = exp^-1 * med_suff^-1 * large_suff^-1
+
+local dec = l.digit * dec_inf * (small_suff^-1 + float_suff)
+local hex = l.hex_num * hex_inf * P('#' * (small_suff + med_suff))^-1
+local float = float_pref * dec_inf * float_suff
+
+local number = token(l.NUMBER, float + hex + dec)
+
+-- Keywords.
+local keyword = token(l.KEYWORD, word_match{
+  -- General.
+  'abstract', 'annotation', 'as', 'case', 'catch', 'class', 'create', 'def',
+  'default', 'dispatch', 'do', 'else', 'enum', 'extends', 'extension', 'final',
+  'finally', 'for', 'if', 'implements', 'import', 'interface', 'instanceof',
+  'it', 'new', 'override', 'package', 'private', 'protected', 'public',
+  'return', 'self', 'static', 'super', 'switch', 'synchronized', 'this',
+  'throw', 'throws', 'try', 'typeof', 'val', 'var', 'while',
+  -- Templates.
+  -- 'AFTER', 'BEFORE', 'ENDFOR', 'ENDIF', 'FOR', 'IF', 'SEPARATOR',
+  -- Literals.
+  'true', 'false', 'null'
+})
+
+-- Types.
+local type = token(l.TYPE, word_match{
+  'boolean', 'byte', 'char', 'double', 'float', 'int', 'long', 'short', 'void',
+  'Boolean', 'Byte', 'Character', 'Double', 'Float', 'Integer', 'Long', 'Short',
+  'String'
+})
+
+-- Identifiers.
+local identifier = token(l.IDENTIFIER, l.word)
+
+-- Operators.
+local operator = token(l.OPERATOR, S('+-/*%<>!=^&|?~:;.()[]{}#'))
+
+-- Annotations.
+local annotation = token('annotation', '@' * l.word)
+
+-- Functions.
+local func = token(l.FUNCTION, l.word) * #P('(')
+
+-- Classes.
+local class = token(l.KEYWORD, P('class')) * ws^1 * token(l.CLASS, l.word)
+
+-- Rules.
+M._rules = {
+  {'whitespace', ws},
+  {'class', class},
+  {'keyword', keyword},
+  {'type', type},
+  {'function', func},
+  {'identifier', identifier},
+  {'template', template},
+  {'string', string},
+  {'comment', comment},
+  {'number', number},
+  {'annotation', annotation},
+  {'operator', operator},
+  {'error', token(l.ERROR, l.any)},
+}
+
+-- Token styles.
+M._tokenstyles = {
+  annotation = l.STYLE_PREPROCESSOR,
+  template = l.STYLE_EMBEDDED
+}
+
+-- Folding.
+M._foldsymbols = {
+  _patterns = {'[{}]', '/%*', '%*/', '//', 'import'},
+  [l.OPERATOR] = {['{'] = 1, ['}'] = -1},
+  [l.COMMENT] = {['/*'] = 1, ['*/'] = -1, ['//'] = l.fold_line_comments('//')},
+  [l.KEYWORD] = {['import'] = l.fold_line_comments('import')}
+}
+
+return M