Add :OldFileSearch command to filter a list of :oldfiles and
regular buffers and display a selection menu to open one of them.
The displayed files must exist and must match all patterns in their
full paths and at least one pattern in their tail name.  The patterns
are matched as 'nomagic' regular expressions.  The search is case
insensitive unless there is an upper-case character in the pattern.
The matching files are displayed together with their oldfile index
#<n or with buffer number #n when already loaded in the editor.
Note: As of Vim 8 a similar selection can be accomplished using
the built-in command :filter /pattern/ browse oldfiles.  In a subtle
difference the :OldFileSearch command presents only the existing
files, makes it easier to use several patterns and allows to match
a plain / or . without backslash quoting.
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To access more old files increase the 'entry in the'viminfo'option. For example to remember the last 500 edited files, add the following line to your .vimrclet &viminfo = substitute(&viminfo, "'\\zs\\d*", "500", "") 
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The response time of the initial call of :OldFileSearch can be improved with let g:oldfilesearch_enable_warm_up = 1which checks existence of old files in a background after vim startup. This makes a notable difference for old files residing on network or other lower-latency devices. The response is also improved for the fzf :History command. 
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The :OldFileSearchcommand also supports<Tab>completion which allows to cycle over the matching files.:OldFileSearch plugin/ .vim<Tab> 
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Select old files that contain vimrcin their name::OldFileSearch vimrc 
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Select oldfiles that contain both ftplandpython.vimin their full path. This should match~/.vim/ftplugin/python.vimif present in:oldfiles.:OldFileSearch ftpl python.vim 
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Select oldfiles that reside in some bindirectory::OldFileSearch /bin/
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Select oldfiles that reside under the .vimdirectory. Here the$pattern is always a match within file tail therefore.vim/may match anywhere in its full path.:OldFileSearch .vim/ $ 
Copyright (c) Pavol Juhas.  Distributed under the same terms as Vim itself
(see :help license).