Question

我尝试使用boost :: variant

std::vector<boost::variant<mesh::Entity&, mesh::Vertex, mesh::Edge> > 
    xField::getZeros(const mesh::Region& s, char *EntityS) const
{
//Vertex  
  if( EntityS == "V" )
  {
    std::vector<mesh::Vertex> zeros;
    for(Region::vertexIterator itv = s.beginVertex(); 
        itv != s.endVertex(); ++itv )
    {
      if( abs(getVal(*itv)) < 1.e-12 )      
      zeros.push_back(*itv);
    }
      return zeros;    
  }
 else if ..

但我收到错误：错误：从'std :: vector'转换为非标量类型'std :: vector＆gt;'请求

修改

zeroVector xField::getZeros(const mesh::Region& s, char *EntityS) const
{
//Vertex  
  if( EntityS == "V" )
  {
    zeroVector zeros;
    for(Region::vertexIterator itv = s.beginVertex(); itv != s.endVertex(); ++itv )
    {
      if( abs(getVal(*itv)) < 1.e-12 )      
      zeros.push_back( zeroVariant(*itv) );
    }
      return zeros;

我在.h文件中定义了typedef

typedef boost::variant<mesh::Entity&, mesh::Vertex, mesh::Edge> zeroVariant;
typedef std::vector<zeroVariant> zeroVector;

现在我有以下错误：

/softs/boost/1.53.0/64/gcc/4.5.1/include/boost/detail/reference_content.hpp：在成员函数'void boost :: detail :: variant :: assign_storage :: internal_visit（T＆amp; ;，int）const [with T = boost :: detail :: reference_content]'： /softs/boost/1.53.0/64/gcc/4.5.1/include/boost/variant/detail/visitation_impl.hpp:130:9：从'typename Visitor :: result_type boost :: detail :: variant ::实例化visitation_impl_invoke_impl（int，Visitor＆amp;，VoidPtrCV，T *，mpl _ :: true_）[与Visitor = boost :: detail :: variant :: assign_storage，VoidPtrCV = void *，T = boost :: detail :: reference_content，typename Visitor：：result_type = void，mpl _ :: true_ = mpl _ :: bool_]' /softs/boost/1.53.0/64/gcc/4.5.1/include/boost/variant/detail/visitation_impl.hpp:173:9：从'typename Visitor :: result_type boost :: detail :: variant ::实例化visitation_impl_invoke（int，Visitor＆amp;，VoidPtrCV，T *，NoBackupFlag，int）[与Visitor = boost :: detail :: variant :: assign_storage，VoidPtrCV = void *，T = boost :: detail :: reference_content，NoBackupFlag = boost：：variant :: has_fallback_type_，typename Visitor :: result_type = void]' /softs/boost/1.53.0/64/gcc/4.5.1/include/boost/variant/detail/visitation_impl.hpp:260:1：从'typename Visitor :: result_type boost :: detail :: variant ::实例化visitation_impl（int，int，Visitor＆amp;，VoidPtrCV，mpl _ :: false_，NoBackupFlag，which *，step0 *）[with which = mpl _ :: int_＆lt; 0＆gt ;, step0 = boost :: detail :: variant :: visitation_impl_step，boost :: detail :: reference_content，boost :: mpl :: l_item，mesh :: Vertex，boost :: mpl :: l_item，mesh :: Edge，boost :: mpl :: l_end＆gt; ＆GT; ＆GT; ＆gt;，boost :: mpl :: l_iter＆gt ;, Visitor = boost :: detail :: variant :: assign_storage，VoidPtrCV = void *，NoBackupFlag = boost :: variant :: has_fallback_type_，typename Visitor :: result_type = void，mpl_ :: false_ = mpl _ :: bool_]' /softs/boost/1.53.0/64/gcc/4.5.1/include/boost/variant/variant.hpp:2326:13：从'static typename实例化访问者:: result_type boost :: variant :: internal_apply_visitor_impl（int， int，Visitor＆amp;，VoidPtrCV）[与Visitor = boost :: detail :: variant :: assign_storage，VoidPtrCV = void *，T0_ = mesh :: Entity＆amp;，T1 = mesh :: Vertex，T2 = mesh :: Edge，T3 = boost :: detail :: variant :: void_，T4 = boost :: detail :: variant :: void_，T5 = boost :: detail :: variant :: void_，T6 = boost :: detail :: variant :: void_ ，T7 = boost :: detail :: variant :: void_，T8 = boost :: detail :: variant :: void_，T9 = boost :: detail :: variant :: void_，T10 = boost :: detail :: variant：：void_，T11 = boost :: detail :: variant :: void_，T12 = boost :: detail :: variant :: void_，T13 = boost :: detail :: variant :: void_，T14 = boost :: detail :: variant :: void_，T15 = boost :: detail :: variant :: void_，T16 = boost :: detail :: variant :: void_，T17 = boost :: detail :: variant :: void_，T18 = boost :: detail :: variant :: void_，T19 = boost :: detail :: variant :: void_，typename Visitor :: result_ty pe = void]' /softs/boost/1.53.0/64/gcc/4.5.1/include/boost/variant/variant.hpp:2337:13：从'typename Visitor :: result_type boost :: variant :: internal_apply_visitor（Visitor＆amp;）实例化[与Visitor = boost :: detail :: variant :: assign_storage，T0_ = mesh :: Entity＆amp;，T1 = mesh :: Vertex，T2 = mesh :: Edge，T3 = boost :: detail :: variant :: void_， T4 = boost :: detail :: variant :: void_，T5 = boost :: detail :: variant :: void_，T6 = boost :: detail :: variant :: void_，T7 = boost :: detail :: variant :: void_，T8 = boost :: detail :: variant :: void_，T9 = boost :: detail :: variant :: void_，T10 = boost :: detail :: variant :: void_，T11 = boost :: detail :: variant :: void_，T12 = boost :: detail :: variant :: void_，T13 = boost :: detail :: variant :: void_，T14 = boost :: detail :: variant :: void_，T15 = boost :: detail：：variant :: void_，T16 = boost :: detail :: variant :: void_，T17 = boost :: detail :: variant :: void_，T18 = boost :: detail :: variant :: void_，T19 = boost :: detail :: variant :: void_，typename Visitor :: result_type = void]' /softs/boost/1.53.0/64/gcc/4.5.1/include/boost/variant/variant.hpp:2085:13：从'void boost :: variant :: variant_assign（const boost :: variant＆amp;）实例化[使用T0_ = mesh :: Entity＆amp;，T1 = mesh :: Vertex，T2 = mesh :: Edge，T3 = boost :: detail :: variant :: void_，T4 = boost :: detail :: variant :: void_， T5 = boost :: detail :: variant :: void_，T6 = boost :: detail :: variant :: void_，T7 = boost :: detail :: variant :: void_，T8 = boost :: detail :: variant :: void_，T9 = boost :: detail :: variant :: void_，T10 = boost :: detail :: variant :: void_，T11 = boost :: detail :: variant :: void_，T12 = boost :: detail :: variant :: void_，T13 = boost :: detail :: variant :: void_，T14 = boost :: detail :: variant :: void_，T15 = boost :: detail :: variant :: void_，T16 = boost :: detail：：variant :: void_，T17 = boost :: detail :: variant :: void_，T18 = boost :: detail :: variant :: void_，T19 = boost :: detail :: variant :: void_，boost :: variant =提高::变种]” /softs/boost/1.53.0/64/gcc/4.5.1/include/boost/variant/variant.hpp:2175:9：从'boost :: variant＆amp; amp;实例化boost :: variant :: operator =（const boost :: variant＆amp;）[with T0_ = mesh :: Entity＆amp;，T1 = mesh :: Vertex，T2 = mesh :: Edge，T3 = boost :: detail :: variant：：void_，T4 = boost :: detail :: variant :: void_，T5 = boost :: detail :: variant :: void_，T6 = boost :: detail :: variant :: void_，T7 = boost :: detail :: variant :: void_，T8 = boost :: detail :: variant :: void_，T9 = boost :: detail :: variant :: void_，T10 = boost :: detail :: variant :: void_，T11 = boost :: detail :: variant :: void_，T12 = boost :: detail :: variant :: void_，T13 = boost :: detail :: variant :: void_，T14 = boost :: detail :: variant :: void_，T15 = boost：：detail :: variant :: void_，T16 = boost :: detail :: variant :: void_，T17 = boost :: detail :: variant :: void_，T18 = boost :: detail :: variant :: void_，T19 = boost :: detail :: variant :: void_，boost :: variant = boost :: variant]' /usr/include/c++/4.5/bits/vector.tcc:312:4：从'void std :: vector＆lt; _Tp，_Alloc＆gt; :: _ M_insert_aux实例化（std :: vector＆lt; _Tp，_Alloc＆gt; :: iterator，const _Tp＆amp;）[with _Tp = boost :: variant，_Alloc = std :: allocator＆gt;，std :: vector＆lt; _Tp，_Alloc＆gt; :: iterator = __gnu_cxx :: __ normal_iterator *，std :: vector＆gt; ＆gt;，typename std :: _ Vector_base＆lt; _Tp，_Alloc＆gt; :: _ Tp_alloc_type :: pointer = boost :: variant *]' /usr/include/c++/4.5/bits/stl_vector.h:749:4：从'void std :: vector＆lt; _Tp，_Alloc＆gt; :: push_back（const value_type＆amp;）实例化[with _Tp = boost :: variant，_Alloc = std :: allocator＆gt;，value_type = boost :: variant]' /home/mycode.cc:128:42：从这里实例化 /softs/boost/1.53.0/64/gcc/4.5.1/include/boost/detail/reference_content.hpp:62:24：错误：'boost :: detail :: reference_content＆amp; boost :: detail :: reference_content :: operator =（const boost :: detail :: reference_content＆amp;）[with RefT = mesh :: Entity＆amp;，boost :: detail :: reference_content = boost :: detail :: reference_content]'is私人的 /softs/boost/1.53.0/64/gcc/4.5.1/include/boost/variant/variant.hpp:526:9：错误：在此上下文中

提前致谢!!!!!

Answer 1

您需要更改“零”的类型 - 它无法从std::vector<mesh::Vertex>转换为您的变体类型的向量。使用一些typedef也可以使代码更简洁：

typedef boost::variant<mesh::Entity&, mesh::Vertex, mesh::Edge> EvVariant;
typedef std::vector<EvVariant> EvVariantVector;

EvVariantVector xField::getZeros(const mesh::Region& s, char *EntityS) const
{
//Vertex  
  if( EntityS == "V" ) // This line is probably a bug!
  {
    EvVariantVector zeros; // Use the return type here!
    for(Region::vertexIterator itv = s.beginVertex(); itv != s.endVertex(); ++itv )
    {
      if( abs(getVal(*itv)) < 1.e-12 )      
      zeros.push_back(EvVariant(*itv));
    }
      return zeros;    
  }
 else if ..

行if (EntityS == "V")也不正确，可能会失败。使用strcmp或只比较字符串的第一个字符。

矢量的助推变体

1 个答案: