condition in regular expression qt

Question

I wrote a regular expression for find the scopes('{'|'}'). I want to find the scopes that wasn't commented, but I don't understand where I have mistake. Here are a fragment of code:

    while (start >= 0 && end >=0) {
        start = text.indexOf("\n", start);
        end  = text.indexOf(QRegExp("^.*[{](?!=[//]|[/*]|[*]))"),start);
        end2  = text.indexOf(QRegExp("^.*[}](?!=[//]|[/*]|[*]))"), start);
        if (end < end2) {
            text.replace(end,"\n{\n");
        }
        else  text.replace(end2,"\n}\n");
        ++start;
   }

For example, we have some text:

//dfsdkfj ksjdfksjdf {  <- this symbol should be skipped
public SystemBlock()
{  //<- this symbol should be found. 
    this.producer = "none";
    this.motherBoard = "none";
    this.processor = "none";
    this.ram = "none";
    this.gpu = "none";
    this.price = 0;
    this.eventSupport = null;
}

At first, escape curly braces: `\\{` and'\\}'. They may be interpreted as quantificators. — ilotXXI, Oct 24 '16 at 14:32

score 0 · Answer 1 · edited May 23 '17 at 10:27

0

First of all, it is generally impossible to correctly parse C++ code with regular expressions. Think about nested comments, line continuations, strings containing "//", "/*" etc.!

Secondly, it is generally hard to have a regex not match something. See this question for more details.

But your specific example can be parsed with a regex like this: ^(?!(//|/\*))*{ :

    end  = text.indexOf(QRegExp("^(?!(//|/\\*))*\\{"),start);
    end2  = text.indexOf(QRegExp("^(?!(//|/\\*))*\\}"), start);

edited May 23 '17 at 10:27

Community

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answered Oct 24 '16 at 13:59

rustyx

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thanks for your answer, but it still doesn't work. It expression always returned -1. – Max Oct 24 '16 at 14:14
Also qt regexp doesn't parse "{" as lonely symbol, we must use sequence scopes "[{]" and symbol '{' will correctly parsed after that this operation. – Max Oct 24 '16 at 14:19
Then escape it: `\\{` – rustyx Oct 24 '16 at 14:31
thanks at all, I escaped scopes, but without results. – Max Oct 24 '16 at 15:48

condition in regular expression qt

1 Answers1