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, 57 insertions, 0 deletions

diff --git a/lua/lexers/forth.lua b/lua/lexers/forth.lua
new file mode 100644
index 0000000..d61aa55
--- /dev/null
+++ b/lua/lexers/forth.lua
@@ -0,0 +1,57 @@
+-- Copyright 2006-2016 Mitchell mitchell.att.foicica.com. See LICENSE.
+-- Forth 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 = 'forth'}
+
+-- Whitespace.
+local ws = token(l.WHITESPACE, l.space^1)
+
+-- Comments.
+local line_comment = S('|\\') * l.nonnewline^0
+local block_comment = '(*' * (l.any - '*)')^0 * P('*)')^-1
+local comment = token(l.COMMENT, line_comment + block_comment)
+
+-- Strings.
+local s_str = 's' * l.delimited_range('"', true, true)
+local dot_str = '.' * l.delimited_range('"', true, true)
+local f_str = 'f' * l.delimited_range('"', true, true)
+local dq_str = l.delimited_range('"', true, true)
+local string = token(l.STRING, s_str + dot_str + f_str + 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({
+  'swap', 'drop', 'dup', 'nip', 'over', 'rot', '-rot', '2dup', '2drop', '2over',
+  '2swap', '>r', 'r>',
+  'and', 'or', 'xor', '>>', '<<', 'not', 'negate', 'mod', '/mod', '1+', '1-',
+  'base', 'hex', 'decimal', 'binary', 'octal',
+  '@', '!', 'c@', 'c!', '+!', 'cell+', 'cells', 'char+', 'chars',
+  'create', 'does>', 'variable', 'variable,', 'literal', 'last', '1,', '2,',
+  '3,', ',', 'here', 'allot', 'parse', 'find', 'compile',
+  -- Operators.
+  'if', '=if', '<if', '>if', '<>if', 'then', 'repeat', 'until', 'forth', 'macro'
+}, '2><1-@!+3,='))
+
+-- Identifiers.
+local identifier = token(l.IDENTIFIER, (l.alnum + S('+-*=<>.?/\'%,_$'))^1)
+
+-- Operators.
+local operator = token(l.OPERATOR, S(':;<>+*-/()[]'))
+
+M._rules = {
+  {'whitespace', ws},
+  {'keyword', keyword},
+  {'string', string},
+  {'identifier', identifier},
+  {'comment', comment},
+  {'number', number},
+  {'operator', operator},
+}
+
+return M