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, 0 insertions, 64 deletions

diff --git a/lexers/prolog.lua b/lexers/prolog.lua
deleted file mode 100644
index bda9b53..0000000
--- a/lexers/prolog.lua
+++ /dev/null
@@ -1,64 +0,0 @@
--- Copyright 2006-2016 Mitchell mitchell.att.foicica.com. See LICENSE.
--- Prolog 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 = 'prolog'}
-
--- 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)
-
--- 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.digit^1 * ('.' * l.digit^1)^-1)
-
--- Keywords.
-local keyword = token(l.KEYWORD, word_match{
-  'module', 'meta_predicate', 'multifile', 'dynamic', 'abolish',
-  'current_output', 'peek_code', 'append', 'current_predicate', 'put_byte',
-  'arg', 'current_prolog_flag', 'put_char', 'asserta', 'assert', 'fail',
-  'put_code', 'assertz', 'findall', 'read', 'at_end_of_stream', 'float',
-  'read_term', 'atom', 'flush_output', 'repeat', 'atom_chars', 'functor',
-  'retract', 'atom_codes', 'get_byte', 'set_input', 'atom_concat', 'get_char',
-  'set_output', 'atom_length', 'get_code', 'set_prolog_flag', 'atomic', 'halt',
-  'set_stream_position', 'bagof', 'integer', 'setof', 'call', 'is',
-  'stream_property', 'catch', 'nl', 'sub_atom', 'char_code', 'nonvar', 'throw',
-  'char_conversion', 'number', 'clause', 'number_chars',
-  'unify_with_occurs_check', 'close', 'number_codes', 'var', 'compound', 'once',
-  'copy_term', 'op', 'write', 'writeln', 'write_canonical', 'write_term',
-  'writeq', 'current_char_conversion', 'open', 'current_input', 'peek_byte',
-  'current_op', 'peek_char', 'false', 'true', 'consult', 'member', 'memberchk',
-  'reverse', 'permutation', 'delete',
-  -- Math.
-  'mod', 'div', 'abs', 'exp', 'ln', 'log', 'sqrt', 'round', 'trunc', 'val',
-  'cos', 'sin', 'tan', 'arctan', 'random', 'randominit'
-})
-
--- Identifiers.
-local identifier = token(l.IDENTIFIER, l.word)
-
--- Operators.
-local operator = token(l.OPERATOR, S('-!+\\|=:;&<>()[]{}'))
-
-M._rules = {
-  {'whitespace', ws},
-  {'keyword', keyword},
-  {'identifier', identifier},
-  {'string', string},
-  {'comment', comment},
-  {'number', number},
-  {'operator', operator},
-}
-
-return M