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/ledger.lua b/lua/lexers/ledger.lua
new file mode 100644
index 0000000..1632241
--- /dev/null
+++ b/lua/lexers/ledger.lua
@@ -0,0 +1,57 @@
+-- Copyright 2015-2016 Charles Lehner. See LICENSE.
+-- ledger journal LPeg lexer, see http://www.ledger-cli.org/
+
+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 = 'ledger'}
+
+local delim = P('\t') + P('  ')
+
+-- Whitespace.
+local ws = token(l.WHITESPACE, l.space^1)
+
+-- Comments.
+local comment = token(l.COMMENT, S(';#') * l.nonnewline^0)
+
+-- Strings.
+local sq_str = l.delimited_range("'")
+local dq_str = l.delimited_range('"')
+local label = l.delimited_range('[]', true, true)
+local string = token(l.STRING, sq_str + dq_str + label)
+
+-- Date.
+local date = token(l.CONSTANT, l.starts_line((l.digit + S('/-')) ^1))
+
+-- Account.
+local account = token(l.VARIABLE,
+                      l.starts_line(S(' \t')^1 * (l.print - delim)^1))
+
+-- Amount.
+local amount = token(l.NUMBER, delim * (1 - S(';\r\n'))^1)
+
+-- Automated transactions.
+local auto_tx = token(l.PREPROCESSOR, l.starts_line(S('=~') * l.nonnewline^0))
+
+-- Directives.
+local directive_word = word_match{
+	'account', 'alias', 'assert', 'bucket', 'capture', 'check', 'comment',
+	'commodity', 'define', 'end', 'fixed', 'endfixed', 'include', 'payee',
+	'apply', 'tag', 'test', 'year'
+} + S('AYNDCIiOobh')
+local directive = token(l.KEYWORD, l.starts_line(S('!@')^-1 * directive_word))
+
+M._rules = {
+  {'account', account},
+  {'amount', amount},
+  {'comment', comment},
+  {'whitespace', ws},
+  {'date', date},
+  {'auto_tx', auto_tx},
+  {'directive', directive},
+}
+
+M._LEXBYLINE = true
+
+return M