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NotNull struct & test

Code

import std.stdio;

alias clear destroy;

class RefCounter {
private:
	uint _refc;

public:
	this() {
		this._refc = 1;
	}

void inc() {
		this._refc++;
	}

void dec() {
		if (this._refc > 0) {
			this._refc--;
		}
	}

bool valid() const {
		return this._refc > 0;
	}

@property
	uint use_count() const {
		return this._refc;
	}
}

struct not_null(T) {
private:
	T _obj;

RefCounter _refc;

bool _is_copy;
	
public:
	@disable
	this();

@disable
	this(typeof(null));
	
	this(T obj, string filename = __FILE__, uint line = __LINE__) {
		if (obj is null) {
			throw new Exception("Null Object.", filename, line);
		}

this._obj = obj;
		this._refc = new RefCounter();
	}

this(ref T obj, string filename = __FILE__, uint line = __LINE__) {
		if (obj is null) {
			throw new Exception("Null Object.", filename, line);
		}

this._obj = obj;
		this._refc = new RefCounter();
	}

this(T* ptr, string filename = __FILE__, uint line = __LINE__) {
		if (*ptr is null) {
			throw new Exception("Null Object.", filename, line);
		}

this._obj = *ptr;
		this._refc = new RefCounter();
	}

this(this) {
		this._obj = _obj;
		
		this._refc = _refc;
		this._refc.inc();

this._is_copy = true;
	}

~this() {
		if (this._refc !is null && this._obj !is null) {
			this._refc.dec();

if (!this._refc.valid()) {
				destroy(this._obj);
				
				this._obj = null;
			}
		}
	}

ref not_null!(T) opAssign(T obj, string filename = __FILE__, uint line = __LINE__) {
		if (obj is null) {
			throw new Exception("Null Object.", filename, line);
		}

this._obj = obj;

return this;
	}
	
	ref not_null!(T) opAssign(ref T obj, string filename = __FILE__, uint line = __LINE__) {
		if (obj is null) {
			throw new Exception("Null Object.", filename, line);
		}

this._obj = obj;

return this;
	}
	
	ref not_null!(T) opAssign(T* ptr, string filename = __FILE__, uint line = __LINE__) {
		if (*ptr is null) {
			throw new Exception("Null Object.", filename, line);
		}

this._obj = *ptr;

return this;
	}

bool IsCopy() const {
		return this._is_copy;
	}
	
	void Release(string filename = __FILE__, uint line = __LINE__) {
		if (this._is_copy) {
			throw new Exception("Versuchte Freigabe der Ressource bei einer Kopie!", filename, line);
		}
		
		destroy(this._obj);

this._obj = null;
	}

@property
	uint Count() const {
		return this._refc.use_count;
	}

@property
	inout(T) GetObj(string filename = __FILE__, uint line = __LINE__) inout in {
		if (this._obj is null) {
			throw new Exception("Null Object.", filename, line);
		}
	} body {
		return this._obj;
	}

alias GetObj this;
}

void some_function(not_null!(Foo) nnf) {
	writefln(" --> use count: %d", nnf.Count);
	nnf.echo();

//nnf.Release();
}

void some_other_function(ref Foo f) {
	f.echo();
}

void some_other_function2(Foo f) {
	f.echo();
}

class Foo {
public:
	void echo() const {
		writeln("I'm Foo. King of Kings.");
	}
}

void main() {
	not_null!(Foo) nnf = new Foo();
	writefln("#1 use count: %d", nnf.Count);

{
		not_null!(Foo) nnfc = nnf;
		writefln("#2 use count: %d, %d", nnf.Count, nnfc.Count);
	}

writefln("#3 use count: %d", nnf.Count);

some_function(nnf);
	some_function(not_null!(Foo)(new Foo()));
	//some_function(null);

Foo f1 = new Foo();
	
	some_other_function(f1);
	//some_other_function(null);
	//some_other_function(not_null!(Foo)(f1));
	
	some_other_function2(new Foo());
	some_other_function2(not_null!(Foo)(f1));
	some_other_function2(null);
}

Application output:

#1 use count: 1
#2 use count: 2, 2
#3 use count: 1
--> use count: 2
I'm Foo. King of Kings.
--> use count: 1

Paste info

Author: Namespace

Views: 140

Private: no

Expires: Never

Uploaded: 28.07.12 19:48

Votes: 0

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Compiler: DMD 2.062

Pointer size: m64

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Application output:

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