-
Notifications
You must be signed in to change notification settings - Fork 100
/
ec_lists.erl
246 lines (216 loc) · 7.29 KB
/
ec_lists.erl
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
%%% vi:ts=4 sw=4 et
%%%-------------------------------------------------------------------
%%% @copyright (C) 2011, Erlware LLC
%%% @doc
%%% Provides useful functionionality on standard lists that are
%%% not provided in the standard library.
%%% @end
%%%-------------------------------------------------------------------
-module(ec_lists).
%% API
-export([find/2,
fetch/2,
search/2]).
%%%===================================================================
%%% API
%%%===================================================================
%% @doc Search each value in the list with the specified
%% function. When the function returns a value of {ok, term()} the
%% search function stops and returns a tuple of {ok, term(), term()},
%% where the second value is the term returned from the function and
%% the third value is the element passed to the function. The purpose
%% of this is to allow a list to be searched where some internal state
%% is important while the input element is not.
-spec search(fun(), list()) -> {ok, Result::term(), Element::term()} | not_found.
search(Fun, [H|T]) ->
case Fun(H) of
{ok, Value} ->
{ok, Value, H};
not_found ->
search(Fun, T)
end;
search(_, []) ->
not_found.
%% @doc Find a value in the list with the specified function. If the
%% function returns the atom true, the value is returned as {ok,
%% term()} and processing is aborted, if the function returns false,
%% processing continues until the end of the list. If the end is found
%% and the function never returns true the atom error is returned.
-spec find(fun(), list()) -> {ok, term()} | error.
find(Fun, [Head|Tail]) when is_function(Fun) ->
case Fun(Head) of
true ->
{ok, Head};
false ->
find(Fun, Tail)
end;
find(_Fun, []) ->
error.
%% @doc Fetch a value from the list. If the function returns true the
%% value is returned. If processing reaches the end of the list and
%% the function has never returned true an exception not_found is
%% thrown.
-spec fetch(fun(), list()) -> term().
fetch(Fun, List) when is_list(List), is_function(Fun) ->
case find(Fun, List) of
{ok, Head} ->
Head;
error ->
throw(not_found)
end.
%%%===================================================================
%%% Test Functions
%%%===================================================================
-ifdef(TEST).
-include_lib("eunit/include/eunit.hrl").
find1_test() ->
TestData = [1, 2, 3, 4, 5, 6],
Result = find(fun(5) ->
true;
(_) ->
false
end,
TestData),
?assertMatch({ok, 5}, Result),
Result2 = find(fun(37) ->
true;
(_) ->
false
end,
TestData),
?assertMatch(error, Result2).
find2_test() ->
TestData = ["one", "two", "three", "four", "five", "six"],
Result = find(fun("five") ->
true;
(_) ->
false
end,
TestData),
?assertMatch({ok, "five"}, Result),
Result2 = find(fun(super_duper) ->
true;
(_) ->
false
end,
TestData),
?assertMatch(error, Result2).
find3_test() ->
TestData = [{"one", 1}, {"two", 2}, {"three", 3}, {"four", 5}, {"five", 5},
{"six", 6}],
Result = find(fun({"one", 1}) ->
true;
(_) ->
false
end,
TestData),
?assertMatch({ok, {"one", 1}}, Result),
Result2 = find(fun([fo, bar, baz]) ->
true;
({"onehundred", 100}) ->
true;
(_) ->
false
end,
TestData),
?assertMatch(error, Result2).
fetch1_test() ->
TestData = [1, 2, 3, 4, 5, 6],
Result = fetch(fun(5) ->
true;
(_) ->
false
end,
TestData),
?assertMatch(5, Result),
?assertThrow(not_found,
fetch(fun(37) ->
true;
(_) ->
false
end,
TestData)).
fetch2_test() ->
TestData = ["one", "two", "three", "four", "five", "six"],
Result = fetch(fun("five") ->
true;
(_) ->
false
end,
TestData),
?assertMatch("five", Result),
?assertThrow(not_found,
fetch(fun(super_duper) ->
true;
(_) ->
false
end,
TestData)).
fetch3_test() ->
TestData = [{"one", 1}, {"two", 2}, {"three", 3}, {"four", 5}, {"five", 5},
{"six", 6}],
Result = fetch(fun({"one", 1}) ->
true;
(_) ->
false
end,
TestData),
?assertMatch({"one", 1}, Result),
?assertThrow(not_found,
fetch(fun([fo, bar, baz]) ->
true;
({"onehundred", 100}) ->
true;
(_) ->
false
end,
TestData)).
search1_test() ->
TestData = [1, 2, 3, 4, 5, 6],
Result = search(fun(5) ->
{ok, 5};
(_) ->
not_found
end,
TestData),
?assertMatch({ok, 5, 5}, Result),
Result2 = search(fun(37) ->
{ok, 37};
(_) ->
not_found
end,
TestData),
?assertMatch(not_found, Result2).
search2_test() ->
TestData = [1, 2, 3, 4, 5, 6],
Result = search(fun(1) ->
{ok, 10};
(_) ->
not_found
end,
TestData),
?assertMatch({ok, 10, 1}, Result),
Result2 = search(fun(6) ->
{ok, 37};
(_) ->
not_found
end,
TestData),
?assertMatch({ok, 37, 6}, Result2).
search3_test() ->
TestData = [1, 2, 3, 4, 5, 6],
Result = search(fun(10) ->
{ok, 10};
(_) ->
not_found
end,
TestData),
?assertMatch(not_found, Result),
Result2 = search(fun(-1) ->
{ok, 37};
(_) ->
not_found
end,
TestData),
?assertMatch(not_found, Result2).
-endif.