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Nested Structs (Solution)

Code

module main;

import std.stdio;
import std.metastrings;

static template StructNestType(string S, string name, alias C = "__ClassNameFix", alias dummy = "__NestLevelFix") 
{
			
	enum string Temp1 = `mixin(StructNestType2!("`~S~`", "`~name~`", `;
	static if (C == "__ClassNameFix")
		static if (dummy == "__NestLevelFix")
			enum string StructNestType	= Temp1~C~`, `~dummy~`));`;
		else
			enum string StructNestType	= Temp1~C~`, "`~dummy~`"));`;
	else
		static if (dummy == "__NestLevelFix")
			enum string StructNestType	= Temp1~C~`", `~dummy~`));`;
		else
			enum string StructNestType	= Temp1~C~`", "`~dummy~`"));`;
}
static template StructNestType2(string S, string name, alias C, alias dummy) 
{ 	
	static if (std.string.indexOf(S, ")") > 0)
	{
		enum string S2 = S[0..S.length-1];
		static if (std.string.indexOf(S2, ",") > 0)
			enum string StructNestType2 = "static if (!"~dummy~") "~S2~", 1000000) "~name~"; else "~S2~", "~C~"!"~dummy~")."~name~".offsetof) "~name~";"; 			
		else
			enum string StructNestType2 = "static if (!"~dummy~") "~S2~", 1000000) "~name~"; else "~S2~", "~C~"!"~dummy~")."~name~".offsetof) "~name~";"; 			
	}
	else
	{
		enum string StructNestType2 = "static if (!"~dummy~") "~S~"!(1000000) "~name~"; else "~S~"!("~C~"!"~dummy~")."~name~".offsetof) "~name~";"; 
	}
}

static template StructNestParent(string name, alias C = "__ClassNameFix", alias dummy = "__NestLevelFix")  
{ 	
	enum string Temp1 = `mixin(StructNestParent2!("`~name~`", `;

static if (C == "__ClassNameFix")
		static if (dummy == "__NestLevelFix")
			enum string StructNestParent	= Temp1~C~`, `~dummy~`));`;
		else
			enum string StructNestParent	= Temp1~C~`, "`~dummy~`"));`;
	else
		static if (dummy == "__NestLevelFix")
			enum string StructNestParent	= Temp1~C~`", `~dummy~`));`;
		else
			enum string StructNestParent	= Temp1~C~`", "`~dummy~`"));`;
}

static template StructNestParent2(string name, alias C, alias dummy) 
{ 	
	enum string StructNestParent2 = `static if (_Offset == 0) { `~C~dummy~`) `~name~`; } else { pure nothrow `~C~dummy~`) _`~name~`_func_`~name~`() { return cast(`~C~dummy~`))(cast(void *)&this - _Offset); } alias _`~name~`_func_`~name~` `~name~`; }`;
}

class _A(bool _NestLevel = true)
{

enum string __ClassNameFix = "_A!("; enum string __NestLevelFix = "_NestLevel";

public:
		struct B(int _Offset)  {
			mixin(StructNestParent!("Parent"));
			void Do() { writeln(Parent.Name); }

static if (_Offset == 0)
				B!(0) opAssign(T)(ref T b) 
				{ 
					B!(0) a; 
					a.Parent = b.Parent;
					this.Parent = b.Parent;
					return a; 
				}
			else
				B!(_Offset) opAssign(T)(ref T b) { return cast(B!(_Offset))b; }
			
		}

mixin(StructNestType!("B", "b1"));
		mixin(StructNestType!("B", "b2"));

string Name;

static if (_NestLevel)
		{
			this() { Name = "Class"; }
		}
} alias _A!() A;

int main(string[] argv)
{
	
	
	
	auto asize = A.classinfo.init.length;
	auto bsize = A.B!(0).sizeof;
	A a = new A();

// Demonstrate that the two B fields in A have the same parent(yet contain no ptr to the parent)

auto x = a.b1.Parent;
	auto y = a.b2.Parent;
	
	auto s1 = A.init.b1.offsetof;
	auto s2 = A.init.b2.offsetof;

auto a_ptr = cast(void*)a;
	auto x_ptr = cast(void*)x;
	auto y_ptr = cast(void*)y;

assert(a_ptr == x_ptr);
	assert(x_ptr == y_ptr);

// Show that each parent of b2(a,x,y) are all the same(or at least all have the same b2.Do)
	auto p1 = &(a.b2.Do);
	auto p2 = &(x.b2.Do);
	auto p3 = &(y.b2.Do);
	
	assert(p1 == p2);
	assert(p2 == p3);

a.b2.Do();
	x.b2.Do();
	y.b2.Do();
	writeln(a.Name, x.Name, y.Name);

// Nested struct to nested struct assignment with implicit cast
	a.b1 = a.b2;
	assert(a.b1.Parent == a.b2.Parent);
	a.b1.Do();

// "orphaned" struct which contains a ptr to parent
	A.B!(0) b1;
	b1 = a.b1;
	assert(b1.Parent == a.b1.Parent);
	b1.Do();

getchar();
	return 0;
}

Application output:

Class
Class
Class
ClassClassClass
Class
Class

Paste info

Author: js.mdnq

Views: 167

Private: no

Expires: Never

Uploaded: 12.12.12 22:59

Votes: 0

Compilation

Compiler: DMD 2.060

Pointer size: m32

Code

Application output:

Paste info

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