d04序化数组

快来打我* 2022-09-15 11:43 100阅读 0赞

[原地址][Link 1]  
`Person`之后仍为`构`.

JSONValue serialise(T)(T value)
    {     
        ...
        else static if(isDynamicArray!T)
        { //在类与构后面.检查`动态数组`.
            JSONValue toReturn = parseJSON("[]");
        //这样创建动态数组,`std.json`有点过时了.
            foreach(element; value)
            { 
                toReturn.array~=serialise(element);
            }
            
            return toReturn;
        }
        else
        {  /**/ }
    }

注意,`串`在`D`中为`immutable(char)[]`.因而`串`也会匹配`动态数组`.这里`串`在`动态处理`前处理.`wstring和dstring`忽略了.  
`区间`中`std.range#ElementType`来获取`元素类型`.因而前面要用`import std.range;`导入.

T deserialise(T)(JSONValue json)
    {     
        ...
        else static if(isDynamicArray!T)
        { //同样在`类/构`后.
            T toReturn;
            alias ElementT = ElementType!T;
            //这是类型计算.元编程必备
            foreach(element; json.array)
            { 
                toReturn ~= deserialise!ElementT(element);
            }
            
            return toReturn;
        }
        else
        {  /**/ }
    }

注意,如果`ElementType`为`串`类,则总是返回`dchar`,有点烦人.而`ElementEncodingType`会返回相应`char,wchar,和dchar`,测试:

void main()
    { 
        import std.stdio : writeln;
    
        auto json = ["a", "b", "c"].serialise();
        writeln(json); 
        writeln(json.deserialise!(string[]));
        /* 输出: ["a","b","c"] ["a", "b", "c"] */
    }

# 关联数组(AA) #

在`动态数组`后`序化`,`静态数组`作为作业了:

JSONValue serialise(T)(T value)
    {     
        ...
        else static if(isAssociativeArray!T)
        { 
            JSONValue toReturn;
            
            alias KeyT = KeyType!T;//键型
            static assert(is(KeyT == string), "仅支持`串`: " ~ KeyT.stringof);
            
            foreach(key, element; value)
            { 
                toReturn[key] = serialise(element);
            }
    
            return toReturn;
        }
        ...
    }
    //反序
    T deserialise(T)(JSONValue json)
    {     
        ...//同样在动态数组后.
        else static if(isAssociativeArray!T)
        { 
            T toReturn;
            
            alias KeyT   = KeyType!T;//键型
            alias ValueT = ValueType!T; //值型
            
            static assert(is(KeyT == string), "仅支持串,非: " ~ KeyT.stringof);
            
            foreach(key, element; json.object)
            { 
                toReturn[key] = deserialise!ValueT(element);
            }
                
            return toReturn;
        }
        else
        {  /**/ }
    }

测试:

void main()
    { 
        import std.stdio : writeln;
    
        auto json = 
        [
            "bradley": Person("Bradley", 20, PersonType.Student), 
            "andy":    Person("Andy", 100, PersonType.Staff)
        ].serialise();
    
        writeln(json);
        writeln(json.deserialise!(Person[string]));
    
        /* 输出: {"andy":{"age":100,"name":"Andy","type":"Staff"},"bradley":{"age":20,"name":"Bradley","type":"Student"}} ["andy":Person("Andy", 100, Staff), "bradley":Person("Bradley", 20, Student)] */
    }

[Link 1]: https://bradley.chatha.dev/blog/dlang-json-serialiser-4