nxt.appender_stack source code

1 module nxt.appender_stack;
2 
3 /** Stack using `std.array.Appender`.
4  *
5  * See_Also: http://forum.dlang.org/thread/wswbtzakdvpgaebuhbom@forum.dlang.org
6  */
7 struct Stack(T) {
8 	import std.array : Appender;
9 
10 	ref inout(T) top() inout @property => _app.data[$ - 1];
11 	bool empty() const @property => _app.data.length == 0;
12 
13 	/// Pop back value.
14 	void pop() => _app.shrinkTo(_app.data.length - 1);
15 
16 	/// Pop back value and return it.
17 	T takeBack() {
18 		T value = top;
19 		_app.shrinkTo(_app.data.length - 1);
20 		return value;
21 	}
22 
23 	void push(T t) => _app.put(t);
24 
25 	private Appender!(T[]) _app;
26 }
27 
28 pure @safe unittest {
29 	alias T = uint;
30 
31 	Stack!T s;
32 	assert(s.empty);
33 
34 	// pushBack:
35 
36 	s.push(13);
37 	assert(!s.empty);
38 	assert(s.top == 13);
39 
40 	s.push(14);
41 	assert(!s.empty);
42 	assert(s.top == 14);
43 
44 	s.push(15);
45 	assert(!s.empty);
46 	assert(s.top == 15);
47 
48 	// pop:
49 
50 	s.pop();
51 	assert(!s.empty);
52 	assert(s.top == 14);
53 
54 	s.pop();
55 	assert(!s.empty);
56 	assert(s.top == 13);
57 
58 	s.pop();
59 	assert(s.empty);
60 
61 	// push:
62 
63 	s.push(13);
64 	s.push(14);
65 	s.push(15);
66 	assert(!s.empty);
67 	assert(s.top == 15);
68 
69 	// takeBack:
70 
71 	assert(s.takeBack() == 15);
72 	assert(s.takeBack() == 14);
73 	assert(s.takeBack() == 13);
74 
75 	assert(s.empty);
76 }