ddash.algorithm.flatmap source code

1 /// Flatmaps a range
2 module ddash.algorithm.flatmap;
3 import ddash.common;
4 
5 ///
6 unittest {
7     auto dup(int n) {
8         return [n, n];
9     }
10 
11     assert([1, 2].flatMap!dup.equal([1, 1, 2, 2]));
12 
13     import optional: some, no;
14 
15     assert([
16         no!int,
17         some(3),
18         no!int,
19         some(7),
20     ].flatMap!"a".equal(
21         [3, 7]
22     ));
23 }
24 
25 /**
26     Flatmaps a range of elemenents
27 
28     Params:
29         unaryPred = unary mapping function
30         range = an input range
31 
32     Returns:
33         New range that has been mapped and flattened
34 
35     Since:
36         0.0.1
37 */
38 auto flatMap(alias unaryPred, Range)(Range range) if (from!"std.range".isInputRange!Range) {
39     import std.algorithm: map;
40     import ddash.algorithm: flatten;
41     return range
42         .map!unaryPred
43         .flatten;
44 }
45 
46 unittest {
47     import optional: some, no;
48     auto optionalArray = [
49         no!int,
50         some(3),
51         no!int,
52         some(7),
53     ];
54     assert(optionalArray.flatMap!(a => a).equal([3, 7]));
55 }
56 
57 unittest {
58     auto intArray = [
59         3,
60         7,
61     ];
62     assert(intArray.flatMap!(a => a).equal([3, 7]));
63 }
64 
65 unittest {
66     auto intArrayOfArrays = [
67         [3],
68         [],
69         [7, 8],
70         [],
71     ];
72     assert(intArrayOfArrays.flatMap!(a => a).equal([3, 7, 8]));
73 }