14. Filters
There are two kinds of filters in WinMerge: file filters for filtering files and directories in directory compare and line filters for ignoring lines from files before comparing.
14.1. Regular expressions
Filters are based on regular expressions (regexps). Each line filter or file filter rule is regexp which is matched against file/directory name or line.
Regexps can be very complex to read. Luckily most file filtering needs are for file extensions. Filters installed with WinMerge show how to filter file extensions.
14.1.1. Help with regexps
There are many guides and help sites in Web:
- Good site devoted for regexps:
- Good HOWTO document for regexps:
- Tutorial:
- PDF quick reference:
14.2. File filters
A file filter is a set of rules saved to one file. Every file and directory is tested against all these rules before comparing. Files and directories that match the rules are excluded if it is an inclusive filter, or included if it is an exclusive filter.
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Ignored items have "Skipped" status in directory compare. User can select them to visible or hidden from menu. Usually its wise to keep skipped items hidden. |
WinMerge's filtering system allows only one filter set to be active at a time. Active filter set can be selected from Open-dialog or from menu: ->. Also empty filter can be selected when no directories or files are ignored.
14.2.1. Filter files
Filter files are normal text files, with an extension of .flt. Filter files must be placed in either:
-
"Filters" subdirectory in the WinMerge program directory. This is the recommended place.
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"Winmerge/Filters" subdirectory in user profile. Under Windows XP, this might be C:\Documents And Settings\username\Local Settings\Application Data\WinMerge\Filters or C:\Documents And Settings\username\Application Data\WinMerge\Filters. This can be used to store personal filters for the individual user, or for a user who lacks the ability to write to the WinMerge program directory. This also is appropriate if backup & restore from an individual profile directory is desired.
First part of filter file defines name and basic functionality of the filter:
name: Example filter def: include |
def: is:
-
include- inclusive filter. This filter type filters out files and directories that match rules in filter. -
exclude- exclusive filter. This filter type lets through files and directories that match rules in filter.
d: \\*$ ## Subdirectories |
There can be one filter rule in one line. And rule cannot be split to several lines. Common format for one filter line is like this:
f: \.ext$ ## Match files *.ext |
or
d: \\directory$ ## Match given directory name |
Rule begins with "f:" if it
matches for filenames and "d:" if it
matches for directory names. Filenames are given to filter as is,
there are no special characters added. But for directory names
there must be "\\" in begin of
directory name. This is done clearly to separate directory names
and filenames. "##" is a comment
separator, all characters in line after that are ignored by
WinMerge.
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File filter rules are case-insensitive. Rule |
So simple filters can be for example:
Example 6. Simple filefilter rules
f: \.cpp$ ## Match *.cpp files f: \.h$ ## Match *.h files f: ^My ## Match My*.* files f: Dlg\. ## Match *Dlg.* files d: \\test$ ## Match 'test' directories |
Line begin or -end marker ("^" or
"$") is usually required filter to
work correctly. Dot in filename must be "escaped" with "\" so "\." means
dot in filename.
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Don't forget " |
Since file filter rules are regular expressions more complex rules are also possible. Following few rules show some possibilities for more complex rules:
Example 7. More complex file filter rules
f: ^\.#.*$ ## .#filename.version files f: Dlg\.c(pp)?$ ## *Dlg.c & *Dlg.cpp files f: ^I.*\.h$ ## I*.h files f: Srv[1-9]\.def$ ## *Srv1.def - *Srv9.def files f: ^[h,k,m] ## h*.* & k*.* & m*.* files |
WinMerge ignores most whitespace characters in rules definition
lines. However comment must always start with one or more
whitespace character (space or tabulator) and comment-marker
(##). ## can be used as part of rule if there is no
whitespace character before it.
14.3. Line filters
Line filters can be used to ignore single lines from compared files. Line filters are handy when user doesn't want to compare comments or certain generated code. For example version control system (time)stamps.
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Line filter rule ignores single line it matches. It is not possible to ignore partial lines or several lines with file filter rule. |
In file compare ignored lines are shown with own colors to differentiate them from other differences. User can see these differences but cannot select or merge them.
Line filter rules are regular expressions like file filter
rules. Since filter matches if any part of line matches it is
usually recommended to add begin ("^") or end ("$")
marker to rule. Or both markers if exact line is wanted to
filtered.
|
There are some troubles with "$" and end-of-line. One way to work-around these troubles is to use "\W$" when possible. |
Rules can be added and edited in Filters-dialog (Menu: ->). In editbox, give one rule per line. Compare results are not updated automatically after changing line filter rules. User can update compare results by selecting -> or F5.
Maximum length for linefilter (all lines in dialog) is 255 characters.
Example 8. Some example line filters
^MYTAG$ |
- Filters out lines being exactly "MYTAG"
^:: |
- Filters out lines beginning with "::"
^/\**.\*/$ |
- Filters out lines beginning with "/*" and ending with "*/"
^[1-5]00 |
- Filters out lines beginning with numbers 100, 200, 300, 400 & 500