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Lambda 表达式递归用法实例

2018-06-17 23:35:23来源：未知阅读 ()

注意：使用Lambda表达式会增加额外开销，但却有时候又蛮方便的。

Windows下查找子孙窗口实例：

HWND FindDescendantWindows(HWND hWndParent, LPCTSTR lpClassName, LPCTSTR lpWindowName)
{
    HWND hFind = nullptr;

    UINT nCompare = 0;
    nCompare += (lpClassName != nullptr) ? 1 : 0;
    nCompare += (lpWindowName != nullptr) ? 1 : 0;

    if (nCompare == 0)
        return nullptr;

    TCHAR szClass[MAX_CLASS_NAME];
    TCHAR szTitle[MAX_PATH];
    std::function< HWND(HWND hWndParent, LPCTSTR lpClassName, LPCTSTR lpWindowName)> _FindDescendantWindows;
    _FindDescendantWindows = [&](HWND hWndParent, LPCTSTR lpClassName, LPCTSTR lpWindowName)->HWND {

        HWND hChild = ::GetWindow(hWndParent, GW_CHILD);
        while (hChild != NULL)
        {
            UINT cmp = 0;
            ::GetClassName(hChild, szClass, MAX_CLASS_NAME);
            if (_tcsicmp(szClass, lpClassName) == 0) 
                cmp++;
            if (cmp == nCompare)
                return hChild;

            ::GetWindowText(hChild, szTitle, MAX_PATH);
            if (_tcsicmp(szTitle, lpWindowName) == 0)
                cmp++;
            if (cmp == nCompare)
                return hChild;

            HWND hFind = _FindDescendantWindows(hChild, lpClassName, lpWindowName);
            if (hFind != nullptr)
                return hFind;

            hChild = ::GetWindow(hChild, GW_HWNDNEXT);
        }
        return nullptr;
    };
    return _FindDescendantWindows(hWndParent, lpClassName, lpWindowName);
}