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, 64 insertions, 0 deletions

diff --git a/lua/lexers/snobol4.lua b/lua/lexers/snobol4.lua
new file mode 100644
index 0000000..08e5a9b
--- /dev/null
+++ b/lua/lexers/snobol4.lua
@@ -0,0 +1,64 @@
+-- Copyright 2013-2016 Michael T. Richter. See LICENSE.
+-- SNOBOL4 lexer.
+-- This lexer works with classic SNOBOL4 as well as the CSNOBOL4 extensions.
+
+local l = require 'lexer'
+local token, word_match = l.token, l.word_match
+local B, P, R, S, V = lpeg.B, lpeg.P, lpeg.R, lpeg.S, lpeg.V
+
+local M = { _NAME = 'snobol4' }
+
+-- Helper patterns.
+local dotted_id = l.word * (P'.' * l.word)^0
+
+local dq_str = l.delimited_range('"', true, true)
+local sq_str = l.delimited_range("'", true, true)
+
+local branch = B(l.space * P':(') * dotted_id * #P')'
+local sbranch = B(l.space * P':' * S'SF' * '(') * dotted_id * #P')'
+local sbranchx = B(P')' * S'SF' * P'(') * dotted_id * #P')'
+
+-- Token definitions.
+local bif = token(l.FUNCTION, l.word_match({
+  'APPLY', 'ARRAY', 'CHAR', 'CONVERT', 'COPY', 'DATA', 'DATE', 'DIFFER', 'DUPL',
+  'EQ', 'EVAL', 'FILE_ABSPATH', 'FILE_ISDIR', 'FREEZE', 'FUNCTION', 'GE', 'GT',
+  'HOST', 'IDENT', 'INTEGER', 'IO_FINDUNIT', 'ITEM', 'LABEL', 'LOAD', 'LPAD',
+  'LE', 'LGT', 'LT', 'NE', 'OPSYN', 'ORD', 'PROTOTYPE', 'REMDR', 'REPLACE',
+  'REVERSE', 'RPAD', 'RSORT', 'SERV_LISTEN', 'SET', 'SETEXIT', 'SIZE', 'SORT',
+  'SQRT', 'SSET', 'SUBSTR', 'TABLE', 'THAW', 'TIME', 'TRACE', 'TRIM', 'UNLOAD',
+  'VALUE', 'VDIFFER',
+}, '', true) * #l.delimited_range('()', false, true, true))
+local comment = token(l.COMMENT, l.starts_line(S'*#|;!' * l.nonnewline^0))
+local control = token(l.PREPROCESSOR, l.starts_line(P'-' * l.word))
+local identifier = token(l.DEFAULT, dotted_id)
+local keyword = token(l.KEYWORD, l.word_match({
+  'ABORT', 'ARRAY', 'CONTINUE', 'DEFINE', 'END', 'FRETURN', 'INPUT', 'NRETURN',
+  'OUTPUT', 'PUNCH', 'RETURN', 'SCONTINUE', 'TABLE',
+}, '', true) + P'&' * l.word)
+local label = token(l.LABEL, l.starts_line(dotted_id))
+local number = token(l.NUMBER, l.float + l.integer)
+local operator = token(l.OPERATOR, S'¬?$.!%*/#+-@⊥&^~\\=')
+local pattern = l.token(l.CLASS, l.word_match({ -- "class" to keep distinct
+  'ABORT', 'ANY', 'ARB', 'ARBNO', 'BAL', 'BREAK', 'BREAKX', 'FAIL', 'FENCE',
+  'LEN', 'NOTANY', 'POS', 'REM', 'RPOS', 'RTAB', 'SPAN', 'SUCCEED', 'TAB',
+}, '', true) * #l.delimited_range('()', false, true, true))
+local str = token(l.STRING, sq_str + dq_str)
+local target = token(l.LABEL, branch + sbranch + sbranchx)
+local ws = token(l.WHITESPACE, l.space^1)
+
+M._rules = {
+  { 'comment',    comment     },
+  { 'control',    control     },
+  { 'string',     str         },
+  { 'number',     number      },
+  { 'keyword',    keyword     },
+  { 'label',      label       },
+  { 'target',     target      },
+  { 'pattern',    pattern     },
+  { 'built-in',   bif         },
+  { 'operator',   operator    },
+  { 'identifier', identifier  },
+  { 'whitespace', ws          },
+}
+
+return M