Re: Functor to find a key in a vector

From:

Victor Bazarov <v.Abazarov@comAcast.net>

Newsgroups:

comp.lang.c++

Date:

Thu, 30 Oct 2008 14:03:56 -0400

Message-ID:

<gecsub$i1k$1@news.datemas.de>

John Doe wrote:

Hi,

I have a vector of struct called ViewList defined like this :

class CViewMgr : public CSingleton<CViewMgr>
{
    friend class CSingleton<CViewMgr>;

    // Constructor
    CViewMgr(): m_pCurView(NULL) {}
    CViewMgr(CViewMgr const&) {}
    virtual ~CViewMgr(void) {}

protected:
    CMobidjinnView m_MobidjinnView;

public:
    struct ViewInfo
    {
        ViewInfo(const GString& view, const CViewBase* a_pViewBase)
            : m_viewname(view), m_pView(a_pViewBase)
        {
        }

        GString m_viewname;
        const CViewBase* m_pView;
    };
    typedef std::vector<ViewInfo> ViewList;

    void Init()
    {
        m_viewlist.push_back(ViewInfo(_T("SelectModuleView"),
&m_MobidjinnView));
    }

    CViewBase* SwitchView(const GString& strViewName)
    {
                // I want to search in the ViewList an element
                // with a m_viewname matching strViewName
        CViewBase* pView = ?????????????????????????;
                pView = find_if( m_viewlist.begin(), m_viewlist.end(),
    ... ) );

        return NULL;
    }

protected:
    ViewList m_viewlist;
    CViewBase* m_pCurView;

};

static inline CViewMgr& ViewMgr() { return *(CViewMgr::GetInstance()); }

and I would like to search my vector for a particular value matching the
  m_viewname value.
How should I declare my functor ?

Your functor needs to return 'true' when the value of the 'ViewInfo's
name coincides with the name the functor is given at its construction,
something like

     struct EqualNameFunctor {
         GString nameToLookFor;
         EqualNameFunctor(GString const& n) : nameToLookFor(n) {}
         bool operator()(ViewInfo const& vi) {
             return vi.m_viewname == nameToLookFor;
         }
     };

and then call it like so

   ViewList::iterator found = find_if(m_viewlist.begin(),
                                      m_viewlist.end(),
                                      EqualNameFunctor(strViewName));
   pView = found == m_viewlist.end() ? NULL : found->m_pView;

V
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