PR: Better feedback for regexp errors in find/replace

[timhoffm]

Based on [#5386] in which the user did not realize that he was searching with an invalid regular expression.

This patch gives feedback on invalid regular expressions by coloring the search field and adding a tooltip.

[goanpeca]

@timhoffm thanks a lot for this. could you paste a couple of screenshots to better visualize the changes made by this PR?

[ccordoba12]

@rlaverde, please review this one.

[timhoffm]

Here's a screenshot illustrating the changes for invalid regular expressions.

Top: "no matches" in a normal search
Bottom: invalid regular expression with tooltip.

[rlaverde]

It looks good, maybe some refactoring is needed.

[rlaverde]

This code could be refactored, It has repeated calls to rexexp_error_msg, also both "if" are checking for the error message:

            stylesheet = self.STYLE[found]
            tooltip = self.TOOLTIP[found]
            if not found and regexp:
                error_msg = rexexp_error_msg(text)    
                if error_msg:
                    stylesheet = self.STYLE['regexp_error']
                    tooltip = "{}: {}".format(self.TOOLTIP['regexp_error'], error_msg)

            self.search_text.lineEdit().setStyleSheet(stylesheet)
            self.search_text.setToolTip(tooltip)

[timhoffm]

Thanks that's a more readable version (Note that calling rexexp_error_msg() twice would not have been a big deal in itself since re.compile() is cached).

I've applied your suggestion with the exception of not switching the string formatting. IMHO "{}: {}".format( is not making it more readable in this case (And also I don't want pep8 to moan again about the line length).

[ccordoba12]

Could we add some alpha here to tone down a bit this red? I mean, as it is, it's a bit too strong for the eye (in my opinion).

[timhoffm]

Feel free to choose any shade of red you want. I didn't put any effort in chosing the color. IMO it should be a little stronger than the color for "not found".

There's no need for alpha though because it's the background anyway. Just adapt the rgb values.

[ccordoba12]

@timhoffm, I left a minor comment. The rest looks good to me.