自学教程：C++ visit函数代码示例

 void visit(ast::TypeCall * node) override {     s << "type";     visit(static_cast<ast::SpecialCall*>(node)); }

voidVisitor::visit(Type* t) {  switch (t->kind) {  case typename_type: return visit(as<Typename_type>(t));  case unit_type: return visit(as<Unit_type>(t));  case bool_type: return visit(as<Bool_type>(t));  case nat_type: return visit(as<Nat_type>(t));  case int_type: return visit(as<Int_type>(t));  case char_type: return visit(as<Char_type>(t));  case fn_type: return visit(as<Fn_type>(t));  case range_type: return visit(as<Range_type>(t));  case bitfield_type: return visit(as<Bitfield_type>(t));  case record_type: return visit(as<Record_type>(t));  case variant_type: return visit(as<Variant_type>(t));  case dep_variant_type: return visit(as<Dep_variant_type>(t));  case enum_type: return visit(as<Enum_type>(t));  case array_type: return visit(as<Array_type>(t));  case dep_type: return visit(as<Dep_type>(t));  case module_type: return visit(as<Module>(t));  case net_str_type: return visit(as<Net_str_type>(t));  case net_seq_type: return visit(as<Net_seq_type>(t));  default: return no_such_visitor(t);  }}

voidVisitor::visit(Stmt* s) {  if (Decl* d = as<Decl>(s))    return visit(d);  return no_such_visitor(s);}

void Label::visit(Renderer *renderer, const Mat4 &parentTransform, uint32_t parentFlags){    if (! _visible || (_utf8Text.empty() && _children.empty()) )    {        return;    }        if (_systemFontDirty || _contentDirty)    {        updateContent();    }        uint32_t flags = processParentFlags(parentTransform, parentFlags);    if (!_utf8Text.empty() && _shadowEnabled && (_shadowDirty || (flags & FLAGS_DIRTY_MASK)))    {        _position.x += _shadowOffset.width;        _position.y += _shadowOffset.height;        _transformDirty = _inverseDirty = true;        _shadowTransform = transform(parentTransform);        _position.x -= _shadowOffset.width;        _position.y -= _shadowOffset.height;        _transformDirty = _inverseDirty = true;        _shadowDirty = false;    }    bool visibleByCamera = isVisitableByVisitingCamera();    if (_children.empty() && !_textSprite && !visibleByCamera)    {        return;    }    // IMPORTANT:    // To ease the migration to v3.0, we still support the Mat4 stack,    // but it is deprecated and your code should not rely on it    _director->pushMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);    _director->loadMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW, _modelViewTransform);        if (!_children.empty())    {        sortAllChildren();        int i = 0;        // draw children zOrder < 0        for (; i < _children.size(); i++)        {            auto node = _children.at(i);            if (node && node->getLocalZOrder() < 0)                node->visit(renderer, _modelViewTransform, flags);            else                break;        }                this->drawSelf(visibleByCamera, renderer, flags);        for (auto it = _children.cbegin() + i; it != _children.cend(); ++it)        {            (*it)->visit(renderer, _modelViewTransform, flags);        }                }    else    {        this->drawSelf(visibleByCamera, renderer, flags);    }    _director->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);}

void LatexDocVisitor::visitPre(DocParamList *pl){  if (m_hide) return;  DocParamSect::Type parentType = DocParamSect::Unknown;  DocParamSect *sect = 0;  if (pl->parent() && pl->parent()->kind()==DocNode::Kind_ParamSect)  {    parentType = ((DocParamSect*)pl->parent())->type();    sect=(DocParamSect*)pl->parent();  }  bool useTable = parentType==DocParamSect::Param ||                  parentType==DocParamSect::RetVal ||                  parentType==DocParamSect::Exception ||                  parentType==DocParamSect::TemplateParam;  if (!useTable)  {    m_t << "//item[";  }  if (sect && sect->hasInOutSpecifier())  {    if (pl->direction()!=DocParamSect::Unspecified)    {      m_t << "//mbox{//tt ";      if (pl->direction()==DocParamSect::In)      {        m_t << "in";      }      else if (pl->direction()==DocParamSect::Out)      {        m_t << "out";      }      else if (pl->direction()==DocParamSect::InOut)      {        m_t << "in,out";      }      m_t << "} ";    }    if (useTable) m_t << " & ";  }  if (sect && sect->hasTypeSpecifier())  {    QListIterator<DocNode> li(pl->paramTypes());    DocNode *type;    bool first=TRUE;    for (li.toFirst();(type=li.current());++li)    {      if (!first) m_t << " | "; else first=FALSE;      if (type->kind()==DocNode::Kind_Word)      {        visit((DocWord*)type);       }      else if (type->kind()==DocNode::Kind_LinkedWord)      {        visit((DocLinkedWord*)type);       }    }    if (useTable) m_t << " & ";  }  m_t << "{//em ";  //QStrListIterator li(pl->parameters());  //const char *s;  QListIterator<DocNode> li(pl->parameters());  DocNode *param;  bool first=TRUE;  for (li.toFirst();(param=li.current());++li)  {    if (!first) m_t << ","; else first=FALSE;    m_insideItem=TRUE;    if (param->kind()==DocNode::Kind_Word)    {      visit((DocWord*)param);     }    else if (param->kind()==DocNode::Kind_LinkedWord)    {      visit((DocLinkedWord*)param);     }    m_insideItem=FALSE;  }  m_t << "}";  if (useTable)  {    m_t << " & ";  }  else  {    m_t << "]";  }}

 void visit(TypeAArray *t) {     t->index->accept(this);     visit((TypeNext *)t); }

expr replace_visitor::visit_app(expr const & e) {    lean_assert(is_app(e));    return update_app(e, visit(app_fn(e)), visit(app_arg(e)));}

void link_traverse(void (*visit)(link_t)){    link_t p;    for(p = head->next; p!= tail; p = p->next)        visit(p);}

static void visitmethod(const upb_refcounted *r, upb_refcounted_visit *visit,                        void *closure) {  const upb_pbdecodermethod *m = (const upb_pbdecodermethod*)r;  visit(r, m->group, closure);}

void ClippingNode::visit(Renderer *renderer, const Mat4 &parentTransform, uint32_t parentFlags){    if (!_visible || !hasContent())        return;        uint32_t flags = processParentFlags(parentTransform, parentFlags);    // IMPORTANT:    // To ease the migration to v3.0, we still support the Mat4 stack,    // but it is deprecated and your code should not rely on it    Director* director = Director::getInstance();    CCASSERT(nullptr != director, "Director is null when seting matrix stack");    director->pushMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);    director->loadMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW, _modelViewTransform);    //Add group command            _groupCommand.init(_globalZOrder);    renderer->addCommand(&_groupCommand);    renderer->pushGroup(_groupCommand.getRenderQueueID());    _beforeVisitCmd.init(_globalZOrder);    _beforeVisitCmd.func = CC_CALLBACK_0(ClippingNode::onBeforeVisit, this);    renderer->addCommand(&_beforeVisitCmd);    if (_alphaThreshold < 1)    {#if (CC_TARGET_PLATFORM == CC_PLATFORM_MAC || CC_TARGET_PLATFORM == CC_PLATFORM_WIN32 || CC_TARGET_PLATFORM == CC_PLATFORM_LINUX)#else        // since glAlphaTest do not exists in OES, use a shader that writes        // pixel only if greater than an alpha threshold        GLProgram *program = GLProgramCache::getInstance()->getGLProgram(GLProgram::SHADER_NAME_POSITION_TEXTURE_ALPHA_TEST_NO_MV);        GLint alphaValueLocation = glGetUniformLocation(program->getProgram(), GLProgram::UNIFORM_NAME_ALPHA_TEST_VALUE);        // set our alphaThreshold        program->use();        program->setUniformLocationWith1f(alphaValueLocation, _alphaThreshold);        // we need to recursively apply this shader to all the nodes in the stencil node        // FIXME: we should have a way to apply shader to all nodes without having to do this        setProgram(_stencil, program);        #endif    }    _stencil->visit(renderer, _modelViewTransform, flags);    _afterDrawStencilCmd.init(_globalZOrder);    _afterDrawStencilCmd.func = CC_CALLBACK_0(ClippingNode::onAfterDrawStencil, this);    renderer->addCommand(&_afterDrawStencilCmd);    int i = 0;    bool visibleByCamera = isVisitableByVisitingCamera();        if(!_children.empty())    {        sortAllChildren();        // draw children zOrder < 0        for(auto size = _children.size(); i < size; i++)        {            auto node = _children.at(i);                        if ( node && node->getLocalZOrder() < 0 )                node->visit(renderer, _modelViewTransform, flags);            else                break;        }        // self draw        if (visibleByCamera)            this->draw(renderer, _modelViewTransform, flags);                for(auto it=_children.cbegin()+i, itCend = _children.cend(); it != itCend; ++it)            (*it)->visit(renderer, _modelViewTransform, flags);    }    else if (visibleByCamera)    {        this->draw(renderer, _modelViewTransform, flags);    }    _afterVisitCmd.init(_globalZOrder);    _afterVisitCmd.func = CC_CALLBACK_0(ClippingNode::onAfterVisit, this);    renderer->addCommand(&_afterVisitCmd);    renderer->popGroup();        director->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);}

std::string Value::getDescription(){    std::string ret("/n");    ret += visit(*this, 0);    return ret;}

void Scale9Sprite::visit(Renderer *renderer, const Mat4 &parentTransform, uint32_t parentFlags){        // quick return if not visible. children won't be drawn.    if (!_visible)    {        return;    }        uint32_t flags = processParentFlags(parentTransform, parentFlags);        // IMPORTANT:    // To ease the migration to v3.0, we still support the Mat4 stack,    // but it is deprecated and your code should not rely on it    Director* director = Director::getInstance();    CCASSERT(nullptr != director, "Director is null when seting matrix stack");    director->pushMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);    director->loadMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW, _modelViewTransform);        int i = 0;      // used by _children    int j = 0;      // used by _protectedChildren        sortAllChildren();    sortAllProtectedChildren();        //    // draw children and protectedChildren zOrder < 0    //    for( ; i < _children.size(); i++ )    {        auto node = _children.at(i);                if ( node && node->getLocalZOrder() < 0 )            node->visit(renderer, _modelViewTransform, flags);        else            break;    }    //    if (_scale9Enabled)//    {//        for( ; j < _protectedChildren.size(); j++ )//        {//            auto node = _protectedChildren.at(j);//            //            if ( node && node->getLocalZOrder() < 0 )//                node->visit(renderer, _modelViewTransform, flags);//            else//                break;//        }//    }//    else//    {//        if (_scale9Image && _scale9Image->getLocalZOrder() < 0 )//        {//            _scale9Image->visit(renderer, _modelViewTransform, flags);//        }//    }        //    // draw self    ////    if (isVisitableByVisitingCamera())//        this->draw(renderer, _modelViewTransform, flags);        //    // draw children and protectedChildren zOrder >= 0    ////    if (_scale9Enabled)//    {//        for(auto it=_protectedChildren.cbegin()+j; it != _protectedChildren.cend(); ++it)//            (*it)->visit(renderer, _modelViewTransform, flags);//    }//    else//    {//        if (_scale9Image && _scale9Image->getLocalZOrder() >= 0 )//        {//            _scale9Image->visit(renderer, _modelViewTransform, flags);//        }//    }            for(auto it=_children.cbegin()+i; it != _children.cend(); ++it)        (*it)->visit(renderer, _modelViewTransform, flags);        // FIX ME: Why need to set _orderOfArrival to 0??    // Please refer to https://github.com/cocos2d/cocos2d-x/pull/6920    // setOrderOfArrival(0);        director->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);    }

int main(int argc, char *argv[]){  element_type test_array[20];  int i;  BTREE T = init_tree();  TREE_NODE p;  int height;     for(i=0; i<20; i++){    test_array[i]= random(200);    printf("%d, ", test_array[i]);  }  printf("/n");  T =  creat_tree(test_array, sizeof(test_array)/sizeof(test_array[0]), T);  height = height_recursive(T);  printf("height is %d/n", height);  printf("preorder:/n");  preorder_recursive(T);   printf("/n");  printf("inoder:/n");  inorder_recursive(T);  printf("/n");  printf("postorder:/n");  postorder_recursive(T);  printf("/n");  printf("preorder nonrec:/n");  preorder_norecursive(T);  printf("/n");  printf("inorder nonrec:/n");  inorder_norecursive(T);  printf("/n");  printf("postorder nonrec:/n");  postorder_norcursive(T);  printf("/n");   printf("levelorder:/n");  levelorder(T);  printf("/n");  printf("print leaf recursive:/n");  output_leaf_recursive(T);  printf("/n");   printf("print leaf norecursive/n");  output_leaf_norecursive(T);  printf("/n");  printf("find an element/n");  if(find_tree(177, T) == NULL)    printf("no such element/n");  else    preorder_recursive(find_tree(177, T));  printf("/n");  printf("min node/n");  visit(find_min(T)->element);  printf("/n");    printf("max node/n");  visit(find_max(T)->element);  printf("/n");  printf("delet:/n");  tree_delete(115, T);  preorder_recursive(T);  printf("/n");    printf("exchange tree:/n");  exchange_recursive(T);  preorder_recursive(T);  printf("/n");  printf("exchange tree norecursive:/n");  exchange_norecursive(T);  preorder_recursive(T);  printf("/n");  free_tree(T);   return 0;}

void RTFDocVisitor::visitPre(DocParamList *pl){  static int columnPos[4][5] =   { { 2, 25, 100, 100, 100 }, // no inout, no type    { 3, 14,  35, 100, 100 }, // inout, no type    { 3, 25,  50, 100, 100 }, // no inout, type    { 4, 14,  35, 55,  100 }, // inout, type  };  int config=0;  if (m_hide) return;  DBG_RTF("{//comment RTFDocVisitor::visitPre(DocParamList)}/n");  DocParamSect::Type parentType = DocParamSect::Unknown;  DocParamSect *sect = 0;  if (pl->parent() && pl->parent()->kind()==DocNode::Kind_ParamSect)  {    parentType = ((DocParamSect*)pl->parent())->type();    sect=(DocParamSect*)pl->parent();  }  bool useTable = parentType==DocParamSect::Param ||                  parentType==DocParamSect::RetVal ||                  parentType==DocParamSect::Exception ||                  parentType==DocParamSect::TemplateParam;  if (sect && sect->hasInOutSpecifier()) config+=1;  if (sect && sect->hasTypeSpecifier())  config+=2;  if (useTable)  {    int i;    m_t << "//trowd //trgaph108//trleft426//tblind426"         "//trbrdrt//brdrs//brdrw10//brdrcf15 "         "//trbrdrl//brdrs//brdrw10//brdrcf15 "         "//trbrdrb//brdrs//brdrw10//brdrcf15 "         "//trbrdrr//brdrs//brdrw10//brdrcf15 "         "//trbrdrh//brdrs//brdrw10//brdrcf15 "         "//trbrdrv//brdrs//brdrw10//brdrcf15 "<< endl;    for (i=0;i<columnPos[config][0];i++)    {      m_t << "//clvertalt//clbrdrt//brdrs//brdrw10//brdrcf15 "           "//clbrdrl//brdrs//brdrw10//brdrcf15 "           "//clbrdrb//brdrs//brdrw10//brdrcf15 "           "//clbrdrr //brdrs//brdrw10//brdrcf15 "           "//cltxlrtb "           "//cellx" << (rtf_pageWidth*columnPos[config][i+1]/100) << endl;    }    m_t << "//pard //widctlpar//intbl//adjustright" << endl;  }  if (sect && sect->hasInOutSpecifier())  {    if (useTable)    {      m_t << "{";    }    // Put in the direction: in/out/in,out if specified.    if (pl->direction()!=DocParamSect::Unspecified)    {      if (pl->direction()==DocParamSect::In)      {        m_t << "in";      }      else if (pl->direction()==DocParamSect::Out)      {        m_t << "out";      }      else if (pl->direction()==DocParamSect::InOut)      {        m_t << "in,out";      }    }    if (useTable)    {      m_t << "//cell }";    }  }  if (sect && sect->hasTypeSpecifier())  {    if (useTable)    {      m_t << "{";    }    QListIterator<DocNode> li(pl->paramTypes());    DocNode *type;    bool first=TRUE;    for (li.toFirst();(type=li.current());++li)    {      if (!first) m_t << " | "; else first=FALSE;      if (type->kind()==DocNode::Kind_Word)      {        visit((DocWord*)type);       }      else if (type->kind()==DocNode::Kind_LinkedWord)      {        visit((DocLinkedWord*)type);       }    }    if (useTable)    {//.........这里部分代码省略.........

 expr operator()(expr const & e) { return visit(e); }

//.........这里部分代码省略.........                                               (struct sockaddr*) peer_interfaces[j]->ipv6_address,                                               local_interfaces[i]->ipv6_netmask)) {                    weights[i][j] = CQ_PUBLIC_SAME_NETWORK;                } else {                    weights[i][j] = CQ_PUBLIC_DIFFERENT_NETWORK;                }                best_addr[i][j] = peer_interfaces[j]->ipv6_endpoint_addr;            }         } /* for each peer interface */    } /* for each local interface */    /*     * determine the size of the set to permute (max number of     * interfaces     */    best_assignment = (unsigned int *) malloc (perm_size * sizeof(int));    a = (int *) malloc(perm_size * sizeof(int));    if (NULL == a) {        return OMPI_ERR_OUT_OF_RESOURCE;    }    /* Can only find the best set of connections when the number of     * interfaces is not too big.  When it gets larger, we fall back     * to a simpler and faster (and not as optimal) algorithm.      * See ticket https://svn.open-mpi.org/trac/ompi/ticket/2031      * for more details about this issue.  */    if (perm_size <= MAX_PERMUTATION_INTERFACES) {        memset(a, 0, perm_size * sizeof(int));        max_assignment_cardinality = -1;        max_assignment_weight = -1;        visit(0, -1, perm_size, a);        rc = OMPI_ERR_UNREACH;        for(i = 0; i < perm_size; ++i) {            if(best_assignment[i] > num_peer_interfaces               || weights[i][best_assignment[i]] == CQ_NO_CONNECTION               || peer_interfaces[best_assignment[i]]->inuse                || NULL == peer_interfaces[best_assignment[i]]) {                continue;            }             peer_interfaces[best_assignment[i]]->inuse++;            btl_endpoint->endpoint_addr = best_addr[i][best_assignment[i]];            btl_endpoint->endpoint_addr->addr_inuse++;            rc = OMPI_SUCCESS;            break;        }    } else {        enum mca_btl_tcp2_connection_quality max;        int i_max = 0, j_max = 0;        /* Find the best connection that is not in use.  Save away         * the indices of the best location. */        max = CQ_NO_CONNECTION;        for(i=0; i<num_local_interfaces; ++i) {            for(j=0; j<num_peer_interfaces; ++j) {                if (!peer_interfaces[j]->inuse) {                    if (weights[i][j] > max) {                        max = weights[i][j];                        i_max = i;                        j_max = j;                    }                }            }        }

 expr visit_app(expr const & e) {     expr new_f = visit(app_fn(e));     expr new_v = visit(app_arg(e));     return update_app(e, new_f, new_v); }

void CtrGenerator::visit(const P_ConstraintList& list) {	for (vector<P_NumConstraint*>::const_iterator it=list.ctrs.begin(); it!=list.ctrs.end(); it++) {		visit(**it);	}}

void XmlDocVisitor::visitPre(DocParamList *pl){  if (m_hide) return;  m_t << "<parameteritem>" << endl;  m_t << "<parameternamelist>" << endl;  //QStrListIterator li(pl->parameters());  //const char *s;  QListIterator<DocNode> li(pl->parameters());  DocNode *param;  for (li.toFirst();(param=li.current());++li)  {    if (pl->paramTypes().count()>0)    {      QListIterator<DocNode> li(pl->paramTypes());      DocNode *type;      for (li.toFirst();(type=li.current());++li)      {        m_t << "<parametertype>";        if (type->kind()==DocNode::Kind_Word)        {          visit((DocWord*)type);         }        else if (type->kind()==DocNode::Kind_LinkedWord)        {          visit((DocLinkedWord*)type);         }        m_t << "</parametertype>" << endl;      }    }    m_t << "<parametername";    if (pl->direction()!=DocParamSect::Unspecified)    {      m_t << " direction=/"";      if (pl->direction()==DocParamSect::In)      {        m_t << "in";      }      else if (pl->direction()==DocParamSect::Out)      {        m_t << "out";      }      else if (pl->direction()==DocParamSect::InOut)      {        m_t << "inout";      }      m_t << "/"";    }    m_t << ">";    if (param->kind()==DocNode::Kind_Word)    {      visit((DocWord*)param);     }    else if (param->kind()==DocNode::Kind_LinkedWord)    {      visit((DocLinkedWord*)param);     }    m_t << "</parametername>" << endl;  }  m_t << "</parameternamelist>" << endl;  m_t << "<parameterdescription>" << endl;}

void insertAsserts(IRUnit& unit) {    // Note: it doesn't matter what order we visit the blocks for this pass.    for (auto& block : poSortCfg(unit)) visit(unit, block);}