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mythzmythz
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Add new Func utils + treat nulls as empty collections
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  • src/AndroidClient/client/src/main/java/net/servicestack/client

1 file changed

+86
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lines changed

‎src/AndroidClient/client/src/main/java/net/servicestack/client/Func.java‎

Lines changed: 86 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -7,6 +7,10 @@
77
import java.util.Iterator;
88

99
public class Func {
10+
public static interface Each<T> {
11+
public void apply(T t);
12+
}
13+
1014
public static interface Function<T,R> {
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public R apply(T t);
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}
@@ -17,15 +21,42 @@ public static interface Reducer<T,E> {
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public static <T,R> ArrayList<R> map(Iterable<T> xs, Function<T,R> f) {
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ArrayList<R> to = new ArrayList<>();
24+
if (xs == null) return to;
25+
2026
for (T x : xs) {
2127
R ret = f.apply(x);
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to.add(ret);
2329
}
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return to;
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}
2632

33+
public static <T> void each(Iterable<T> xs, Each<T> f) {
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if (xs == null) return;
35+
for (T x : xs) {
36+
f.apply(x);
37+
}
38+
}
39+
40+
public static ArrayList<Integer> toList(int... xs){
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ArrayList<Integer> to = new ArrayList<>();
42+
for (int x : xs) {
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to.add(x);
44+
}
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return to;
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}
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48+
public static <T> ArrayList<T> toList(T... xs){
49+
ArrayList<T> to = new ArrayList<>();
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for (T x : xs) {
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to.add(x);
52+
}
53+
return to;
54+
}
55+
2756
public static <T> ArrayList<T> toList(Iterable<T> xs){
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ArrayList<T> to = new ArrayList<>();
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if (xs == null) return to;
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for (T x : xs) {
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to.add(x);
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}
@@ -34,6 +65,8 @@ public static <T> ArrayList<T> toList(Iterable<T> xs){
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public static <T> ArrayList<T> filter(Iterable<T> xs, Predicate<T> predicate){
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ArrayList<T> to = new ArrayList<>();
68+
if (xs == null) return to;
69+
3770
for (T x : xs) {
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if (predicate.apply(x)){
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to.add(x);
@@ -43,6 +76,8 @@ public static <T> ArrayList<T> filter(Iterable<T> xs, Predicate<T> predicate){
4376
}
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public static <T> T first(Iterable<T> xs, Predicate<T> predicate){
79+
if (xs == null) return null;
80+
4681
for (T x : xs) {
4782
if (predicate.apply(x)){
4883
return x;
@@ -51,7 +86,22 @@ public static <T> T first(Iterable<T> xs, Predicate<T> predicate){
5186
return null;
5287
}
5388

89+
public static <T> T first(Iterable<T> xs){
90+
if (xs == null) return null;
91+
92+
for (T x : xs) {
93+
return x;
94+
}
95+
return null;
96+
}
97+
98+
public static <T> T first(T[] xs) {
99+
return xs == null || xs.length == 0 ? null : xs[0];
100+
}
101+
54102
public static <T> T last(Iterable<T> xs, Predicate<T> predicate){
103+
if (xs == null) return null;
104+
55105
for (T x : reverse(xs)) {
56106
if (predicate.apply(x)){
57107
return x;
@@ -60,13 +110,29 @@ public static <T> T last(Iterable<T> xs, Predicate<T> predicate){
60110
return null;
61111
}
62112

113+
public static <T> T last(Iterable<T> xs){
114+
if (xs == null) return null;
115+
116+
T last = null;
117+
for (T x : xs) {
118+
last = x;
119+
}
120+
return last;
121+
}
122+
123+
public static <T> T last(T[] xs) {
124+
return xs == null ? null : xs[xs.length - 1];
125+
}
126+
63127
public static <T> boolean contains(Iterable<T> xs, Predicate<T> predicate){
64128
return first(xs, predicate) != null;
65129
}
66130

67131
public static <T> ArrayList<T> skip(Iterable<T> xs, int skip){
68132
int i = 0;
69133
ArrayList<T> to = new ArrayList<>();
134+
if (xs == null) return to;
135+
70136
for (T x : xs) {
71137
if (i++ >= skip){
72138
to.add(x);
@@ -77,6 +143,8 @@ public static <T> ArrayList<T> skip(Iterable<T> xs, int skip){
77143

78144
public static <T> ArrayList<T> skip(Iterable<T> xs, Predicate<T> predicate){
79145
ArrayList<T> to = new ArrayList<>();
146+
if (xs == null) return to;
147+
80148
for (T x : xs) {
81149
if (predicate.apply(x)){
82150
to.add(x);
@@ -87,6 +155,8 @@ public static <T> ArrayList<T> skip(Iterable<T> xs, Predicate<T> predicate){
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88156
public static <T> ArrayList<T> take(Iterable<T> xs, Predicate<T> predicate){
89157
ArrayList<T> to = new ArrayList<>();
158+
if (xs == null) return to;
159+
90160
for (T x : xs) {
91161
if (predicate.apply(x)){
92162
return to;
@@ -99,6 +169,8 @@ public static <T> ArrayList<T> take(Iterable<T> xs, Predicate<T> predicate){
99169
public static <T> ArrayList<T> take(Iterable<T> xs, int take){
100170
int i = 0;
101171
ArrayList<T> to = new ArrayList<>();
172+
if (xs == null) return to;
173+
102174
for (T x : xs) {
103175
if (i++ >= take){
104176
return to;
@@ -109,6 +181,8 @@ public static <T> ArrayList<T> take(Iterable<T> xs, int take){
109181
}
110182

111183
public static <T> boolean any(Iterable<T> xs, Predicate<T> predicate){
184+
if (xs == null) return false;
185+
112186
for (T x : xs) {
113187
if (predicate.apply(x)){
114188
return true;
@@ -118,6 +192,8 @@ public static <T> boolean any(Iterable<T> xs, Predicate<T> predicate){
118192
}
119193

120194
public static <T> boolean all(Iterable<T> xs, Predicate<T> predicate){
195+
if (xs == null) return false;
196+
121197
for (T x : xs) {
122198
if (!predicate.apply(x)){
123199
return false;
@@ -128,6 +204,8 @@ public static <T> boolean all(Iterable<T> xs, Predicate<T> predicate){
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129205
public static <T> ArrayList<T> expand(Iterable<T>... xss){
130206
ArrayList<T> to = new ArrayList<>();
207+
if (xss == null) return to;
208+
131209
for (Iterable<T> xs : xss) {
132210
for (T x : xs){
133211
to.add(x);
@@ -137,6 +215,8 @@ public static <T> ArrayList<T> expand(Iterable<T>... xss){
137215
}
138216

139217
public static <T> T elementAt(Iterable<T> xs, int index){
218+
if (xs == null) return null;
219+
140220
int i = 0;
141221
for (T x : xs){
142222
if (i++ == index){
@@ -147,12 +227,16 @@ public static <T> T elementAt(Iterable<T> xs, int index){
147227
}
148228

149229
public static <T> ArrayList<T> reverse(Iterable<T> xs){
230+
if (xs == null) return new ArrayList<T>();
231+
150232
ArrayList<T> clone = toList(xs);
151233
Collections.reverse(clone);
152234
return clone;
153235
}
154236

155237
public static <T,E> E reduce(Iterable<T> xs, E initialValue, Reducer<T,E> reducer){
238+
if (xs == null) return initialValue;
239+
156240
E currentValue = initialValue;
157241
for (T x : xs){
158242
currentValue = reducer.reduce(currentValue, x);
@@ -166,6 +250,8 @@ public static <T,E> E reduceRight(Iterable<T> xs, E initialValue, Reducer<T,E> r
166250

167251
public static <T> String join(Iterable<T> xs, String separator){
168252
StringBuilder sb = new StringBuilder();
253+
if (xs == null) return sb.toString();
254+
169255
for (T x : xs){
170256
if (sb.length() > 0)
171257
sb.append(separator);

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