RegEx to ignore beginning of line

Support for our DiffMerge utility.

Moderator: SourceGear


Posts: 1
Joined: Fri Sep 24, 2010 5:07 pm
PostPosted: Fri Sep 24, 2010 5:17 pm
I am trying to figure out how to ignore the first 4 characters of each line when comparing two files. I know that the 5th character will be a space, so it seems like I should be able to accomplish this by setting the context boundaries in a ruleset, but I can't get it to work. I've tried several RegEx variations, and unchecked the "Classify differences as Important", but nothing works. Any guidance would be appreciated.

Posts: 534
Joined: Tue Jun 05, 2007 11:37 am
Location: SourceGear
PostPosted: Mon Sep 27, 2010 1:39 pm
Sorry, but we don't support ignoring or excluding data by columns.

There are 2 ways to think of this feature:
[1] strip the columns out of the line before comparing them.
(the "ignore whitespace when matching lines" feature does
that, but it only handles whitespace.)
[2] don't strip them in the line-compare phase, but rather use the
"classify differences as important" feature to not color/not-color
them during the drawing phase. (the "hide unimportant differences"
feature does this.)

I'm guessing that you want [1]. I've had several requests to be
able to ignore columns, such as 1-7 and/or 72-80 for Fortran or
Cobol source code.

In fact, you probably want a combination of both [1] and [2] -- that is,
ignore them for in the line-matching (vertical alignment) and then
ignore them again in the coloring/highlight.

Getting the RegEx right to use just [2] is problematic. Using something
with a leading "^", for example doesn't work correctly right now because
of a bug in how I'm resetting the pattern within a line (so that I can
identify the start of multiple comments within a line).

Sorry I don't have a better answer for you right now (and sorry to
make this so complicated (both the code and the description of the
problem)).

jeff hostetler


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