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03ac148f SK |
1 | %%%---------------------------------------------------------------------------- |
2 | %%% Equivalent to stdlib's orddict, but with a pretty (IMO), uniform interface. | |
3 | %%%---------------------------------------------------------------------------- | |
4 | -module(hope_kv_list). | |
5 | ||
6 | -behavior(hope_dictionary). | |
7 | ||
8 | -export_type( | |
9 | [ t/2 | |
10 | ]). | |
11 | ||
12 | -export( | |
13 | [ empty/0 | |
14 | , get/2 | |
15 | , set/3 | |
16 | , update/3 | |
70cf8e86 | 17 | , pop/2 |
03ac148f SK |
18 | , iter/2 |
19 | , map/2 | |
20 | , filter/2 | |
21 | , fold/3 | |
22 | , of_kv_list/1 | |
23 | , to_kv_list/1 | |
24 | ]). | |
25 | ||
26 | ||
27 | -type t(K, V) :: | |
28 | [{K, V}]. | |
29 | ||
30 | ||
31 | %% ============================================================================ | |
32 | %% API | |
33 | %% ============================================================================ | |
34 | ||
35 | -spec empty() -> | |
36 | []. | |
37 | empty() -> | |
38 | []. | |
39 | ||
95c3c2a7 PO |
40 | -spec get(t(K, V), K) -> |
41 | hope_option:t(V). | |
03ac148f SK |
42 | get(T, K) -> |
43 | case lists:keyfind(K, 1, T) | |
44 | of false -> none | |
45 | ; {K, V} -> {some, V} | |
46 | end. | |
47 | ||
95c3c2a7 PO |
48 | -spec set(t(K, V), K, V) -> |
49 | t(K, V). | |
03ac148f SK |
50 | set(T, K, V) -> |
51 | lists:keystore(K, 1, T, {K, V}). | |
52 | ||
95c3c2a7 PO |
53 | -spec update(t(K, V), K, fun((hope_option:t(V)) -> V)) -> |
54 | t(K, V). | |
03ac148f SK |
55 | update(T, K, F) -> |
56 | V1Opt = get(T, K), | |
57 | V2 = F(V1Opt), | |
37c6e98b | 58 | % TODO: Eliminate the 2nd lookup. |
03ac148f SK |
59 | set(T, K, V2). |
60 | ||
95c3c2a7 PO |
61 | -spec pop(t(K, V), K) -> |
62 | {hope_option:t(V), t(K, V)}. | |
70cf8e86 SK |
63 | pop(T1, K) -> |
64 | case lists:keytake(K, 1, T1) | |
65 | of {value, {K, V}, T2} -> {{some, V}, T2} | |
66 | ; false -> {none , T1} | |
67 | end. | |
68 | ||
95c3c2a7 PO |
69 | -spec iter(t(K, V), fun((K, V) -> ok)) -> |
70 | ok. | |
c1672ac4 | 71 | iter(T, F1) -> |
d10156b0 | 72 | F2 = lift_map(F1), |
c1672ac4 | 73 | lists:foreach(F2, T). |
03ac148f | 74 | |
95c3c2a7 PO |
75 | -spec map(t(K, V), fun((K, V) -> V)) -> |
76 | t(K, V). | |
c1672ac4 | 77 | map(T, F1) -> |
d10156b0 SK |
78 | F2 = fun ({K, _}=X) -> {K, apply_map(F1, X)} end, |
79 | lists:map(F2, T). | |
03ac148f | 80 | |
95c3c2a7 PO |
81 | -spec filter(t(K, V), fun((K, V) -> boolean())) -> |
82 | t(K, V). | |
c1672ac4 | 83 | filter(T, F1) -> |
d10156b0 | 84 | F2 = lift_map(F1), |
c1672ac4 | 85 | lists:filter(F2, T). |
03ac148f | 86 | |
95c3c2a7 PO |
87 | -spec fold(t(K, V), fun((K, V, Acc) -> Acc), Acc) -> |
88 | Acc. | |
03ac148f SK |
89 | fold(T, F1, Accumulator) -> |
90 | F2 = fun ({K, V}, Acc) -> F1(K, V, Acc) end, | |
097a2aa3 | 91 | lists:foldl(F2, Accumulator, T). |
03ac148f | 92 | |
95c3c2a7 PO |
93 | -spec to_kv_list(t(K, V)) -> |
94 | [{K, V}]. | |
03ac148f SK |
95 | to_kv_list(T) -> |
96 | T. | |
97 | ||
95c3c2a7 PO |
98 | -spec of_kv_list([{K, V}]) -> |
99 | t(K, V). | |
03ac148f | 100 | of_kv_list(List) -> |
37c6e98b | 101 | % TODO: Decide if validation is to be done here. Do so if yes. |
03ac148f SK |
102 | List. |
103 | ||
104 | ||
105 | %% ============================================================================ | |
106 | %% Helpers | |
107 | %% ============================================================================ | |
108 | ||
48371999 SK |
109 | -spec lift_map(F) -> |
110 | G | |
111 | when F :: fun(( K, V1 ) -> V2) | |
112 | , G :: fun(({K, V1}) -> V2) | |
113 | . | |
d10156b0 SK |
114 | lift_map(F) -> |
115 | fun (X) -> apply_map(F, X) end. | |
116 | ||
48371999 SK |
117 | -spec apply_map(fun((K, V1) -> V2), {K, V1}) -> |
118 | V2. | |
d10156b0 SK |
119 | apply_map(F, {K, V}) -> |
120 | F(K, V). |