All Comparisons > Text Filters
Find it under Settings > New Comparisons > All Comparisons > Text Filters. The tab of an active text or folder comparison has the same page, for that comparison alone.
Use this page to set up the filters, based on regular expressions, that DeltaWalker Classic applies when it compares text files as text.
The text filters are part of the All Comparisons settings because they come into play in two cases:
- When comparing text files. Text filters, if any are on, are always applied when text files are opened for comparison in the text editors.
- When comparing folders by content with Use text comparison selected (see the Folder Comparisons page). As DeltaWalker Classic goes through the folders, it determines the content type of every file, and compares the files it finds to be text with the text comparison algorithm, applying the text filters.
Filters ignore text you are not interested in, which makes the comparison more useful: they narrow the gap between the way computers represent text and what the text means to you.
A common case is source code whose formatting does not matter. Options such as ignoring whitespace or line endings appear in the user interface as checkboxes, but they are in fact text filters.
Software developers can also use text filters to ignore code comments when comparing source files.
The table lists the filters with their Description, Expression and Target; check a filter to apply it, uncheck it to leave it out. Use New, Edit and Delete to add, change and remove filters in the Text Comparison Filter dialog.
The page
Filters at a glance
You can define many filters and use the ones that suit the comparison at hand. Filters are written as regular expressions, in their standard syntax, and each has a human-readable description, so that you can focus on the comparison rather than on the notation. The checkboxes of the table let you choose which of the filters you have defined are applied.
Filters give you fine-grained control over the text to ignore, from entire lines to specific character sequences.
Filters by example
Blank lines vs. sequences of “blank” characters
Consider the following regular expression, which matches lines that are empty or contain only spaces and tabs (often called blanks):
^[ \t]*$
A filter with this expression and Report a line same if any part of it matches the expression selected makes the comparison ignore such lines: differences made up only of matching lines are discarded.
In contrast, a filter with the same expression and Ignore character sequences that match the expression selected keeps a matching line, and its meaning, as the basis for a difference, but lets it correspond to another line that may not be blank as it stands but is blank once filtered.