Re: remove_if with a mask

From:

Victor Bazarov <v.bazarov@comcast.invalid>

Newsgroups:

comp.lang.c++

Date:

Tue, 08 Jun 2010 11:55:29 -0400

Message-ID:

<hulp73$5b5$1@news.eternal-september.org>

On 6/8/2010 11:43 AM, eLVa wrote:

[..] I tried :

template<class Z> struct maskChecker {
     public:
         maskChecker(const vector<bool> &mask) : it(mask.begin()) {}
         bool operator()(Z&) const { return *it ++; }
     private:
         vector<bool>::const_iterator⁢
};

template<class T> template<class Z>
void Selector<T>::compact(vector<Z> &data, const vector<bool> &mask) {
     if (data.size() != mask.size()) throw UnmatchedSize(data.size(),
mask.size());
     typename vector<Z>::iterator end = remove_if(data.begin(),
data.end(), maskChecker<Z>(mask));
     data.erase(end, data.end());
}

This does not compile ...
I know this is about it being initialized by a temporary variable
returned by mask.begin() ..
Should I directly pass a reference to the iterator to the constructor
of maskChecker rather than the vector itself ?

Yes, the iterator has to be created outside (next to the call to
'remove_if'), and it needs to be an lvalue. Only then you can
initialize a ref to non-const with it.

V
--
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