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, 76 insertions, 0 deletions

diff --git a/lua/lexers/fish.lua b/lua/lexers/fish.lua
new file mode 100644
index 0000000..24ee2df
--- /dev/null
+++ b/lua/lexers/fish.lua
@@ -0,0 +1,76 @@
+-- Copyright 2015-2016 Jason Schindler. See LICENSE.
+-- Fish (http://fishshell.com/) script 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 = 'fish'}
+
+-- Whitespace.
+local ws = token(l.WHITESPACE, l.space^1)
+
+-- shebang
+local shebang = token('shebang', '#!/' * l.nonnewline^0)
+
+-- Comments.
+local comment = token(l.COMMENT, '#' * l.nonnewline^0)
+
+-- Strings.
+local sq_str = l.delimited_range("'", false, true)
+local dq_str = l.delimited_range('"')
+
+local string = token(l.STRING, sq_str + dq_str)
+
+-- Numbers.
+local number = token(l.NUMBER, l.float + l.integer)
+
+-- Keywords.
+local keyword = token(l.KEYWORD, word_match{
+  'alias', 'and', 'begin', 'bg', 'bind', 'block', 'break', 'breakpoint',
+  'builtin', 'case', 'cd', 'command', 'commandline', 'complete', 'contains',
+  'continue', 'count', 'dirh', 'dirs', 'echo', 'else', 'emit', 'end', 'eval',
+  'exec', 'exit', 'fg', 'fish', 'fish_config', 'fish_indent', 'fish_pager',
+  'fish_prompt', 'fish_right_prompt', 'fish_update_completions', 'fishd', 'for',
+  'funced', 'funcsave', 'function', 'functions', 'help', 'history', 'if', 'in',
+  'isatty', 'jobs', 'math', 'mimedb', 'nextd', 'not', 'open', 'or', 'popd',
+  'prevd', 'psub', 'pushd', 'pwd', 'random', 'read', 'return', 'set',
+  'set_color', 'source', 'status', 'switch', 'test', 'trap', 'type', 'ulimit',
+  'umask', 'vared', 'while'
+})
+
+-- Identifiers.
+local identifier = token(l.IDENTIFIER, l.word)
+
+-- Variables.
+local variable = token(l.VARIABLE,
+                       '$' * l.word + '$' * l.delimited_range('{}', true, true))
+
+-- Operators.
+local operator = token(l.OPERATOR, S('=!<>+-/*^&|~.,:;?()[]{}'))
+
+M._rules = {
+  {'whitespace', ws},
+  {'shebang', shebang},
+  {'keyword', keyword},
+  {'identifier', identifier},
+  {'variable', variable},
+  {'string', string},
+  {'comment', comment},
+  {'number', number},
+  {'operator', operator},
+}
+
+M._tokenstyles = {
+  shebang = l.STYLE_LABEL
+}
+
+M._foldsymbols = {
+  _patterns = {'%l+'},
+  [l.KEYWORD] = {
+    begin = 1, ['for'] = 1, ['function'] = 1, ['if'] = 1, switch = 1,
+    ['while'] = 1, ['end'] = -1
+  }
+}
+
+return M