visitor

问题 For various reasons I use a Visitor for the HIR tree traversal instead of relying on the lint context to walk the tree. However, this means my lint ignores #[allow/warn/deny(..)] annotations in the source. How can I get this back? I know of ctxt.levels , but those don't appear to help. The other functions (like with_lint_attrs(..) are private to the context. 回答1: Since there was no solution with the Rust we had, I created the necessary callbacks in Rustc: With tonight's nightly, our

问题 I need to overwrite the default visitorID, that's automatically set by Adobe Analytics s_code, with a custom value. As explained here, I may set the s.visitorID variable for this purpose but It's not clear to me how, and overall when, doing so. I guess this variable should be set into the s_code itself but I fear that the automatic visitorID would be used anyway for the first s.t() call, in the place of the custom value I'd like to use. In fact, I want that since the first automatic request

问题 I'm trying to implement a simple abstract syntax tree (AST) in C++ using the visitor pattern. Usually a visitor pattern does not handle return value. But in my AST there are expressions nodes which care about the return type and value of its children node. For example, I have a Node structure like this: class AstNode { public: virtual void accept(AstNodeVisitor&) = 0; void addChild(AstNode* child); AstNode* left() { return m_left; } AstNode* right() { return m_right; } ... private: AstNode* m

问题 Suppose I have a bunch of fruit: class Fruit { ... }; class Apple : public Fruit { ... }; class Orange: public Fruit { ... }; And some polymorphic functions that operate on said fruit: void Eat(Fruit* f, Pesticide* p) { ... } void Eat(Apple* f, Pesticide* p) { ingest(f,p); } void Eat(Orange* f, Pesticide* p) { peel(f,p); ingest(f,p); } OK, wait. Stop right there. Note at this point that any sane person would make Eat() a virtual member function of the Fruit classes. But that's not an option,

问题 Is the following java implementation of the visitor pattern using generics, general enough to be useful? (I suppose it is). Could it be improved in some way? It's important to be easily call-able using anonymous classes. Thanks. (Example of use): Vector<Number> numbers = new Vector<Number>(); numbers.add(new Double(1.2)); numbers.add(new Float(-1.2)); numbers.add(new Double(4.8)); numbers.add(new Float(-3.4)); numbers.add(new Long(123456)); numbers.add(new Short("14")); For.each(numbers, new

问题 I'm studying Visitor Pattern advantages, and quoting Design Patterns: But an iteratorcan't work across object structures with different types of elements. Forexample, the Iterator interface defined on page 295 can access only objects of type Item: template <class Item> clas Iterator { // ... Item CurrentItem() const; }; This implies that all elements the iterator can visit have a common parentclass Item. Visitor does not have this restriction... class Visitor { public: // ... void VisitMyType

问题 The Visitor pattern allows operations on objects to be written without extending the object class. Sure. But why not just write a global function, or a static class, that manipulates my object collection from the outside? Basically, in a language like java, an accept() method is needed for technical reasons; but in a language where I can implement the same design without an accept() method, does the Visitor pattern become trivial? Explanation: In the Visitor pattern, visitable classes

问题 I am a beginner of antlr. I was trying to use visitor in my code and following the instruction on the net. However, I found out that the visitor was not entering the method I create at all. May anyone tell me what I did wrong? This is my visitor: import java.util.LinkedList; import org.antlr.v4.runtime.misc.NotNull; /* * To change this template, choose Tools | Templates * and open the template in the editor. */ /** * * @author Sherwood */ public class ExtractMicroBaseVisitor extends

问题 Since C++11 we can make template functions which can accept any sequence of arguments: template <typename... Ts> void func(Ts &&... ts) { step_one(std::forward<Ts>(ts)...); step_two(std::forward<Ts>(ts)...); } However, suppose that it really only makes sense to call my function in the case where each argument has the same type -- any number of arguments would be okay though. What's the best way to do that, i.e. is there a good way to constrain the templates to make a nice error message in

问题 Imagine that we have three classes like this: public class ParentType { private ParentType() {} public int Id { get; protected set; } public SubType Sub { get; protected set; } } public class SubType{ private SubType(){} public int Id { get; protected set; } public ICollection<ColSubType> ColSubs{get; protected set;} } public class ColSubType{ private ColSubType(){} public int Id { get; protected set; } public SubType SubType { get; set; } } I have an anonymous Expression like this: x => new