Search pattern for an if statement that isn't followed by curly brace on the next line

Question

How would I formulate a search pattern for matching if statements that don't have an opening curly brace on the next line? I assume it requires the use of something like [^{] or \@!, but I'm having trouble getting things to work correctly.

I'd like to match:

    if(some_condition)
        return;

but not:

    if(some_condition)
    {
        return;
    }

The if and { may be indented one or more levels and I think trying to account for the indentation is what's causing my problems.

My first attempt was to use this pattern:

if(.*\n\s*[^{]

This works if things aren't indented, but once they are it matches any if statement regardless of whether the first non-white space character on the next line is a {.

Answer 1

Of course just before clicking the submit button, I thought of a way to do it:

^\(\s*\)\zsif(.*\ze\n\1[^{]

This works by capturing any white space before the if and searching for the same amount of white space at the start of the next line (using \1). Note that this assumes that the white space before the { exactly matches the white space before the if.

The \zs and \ze just limit the highlighting to the actual if line.