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authorPacien TRAN-GIRARD2016-05-10 17:10:31 +0200
committerPacien TRAN-GIRARD2016-05-10 17:10:31 +0200
commit766114c05bcd0b0388988aaf606e046857e6946a (patch)
tree91ccdb1b82664c8e6d4cb5469f18da2ef08fe5e9 /src/ch/epfl
parente85032012f1d5ded1b6a49a88d345cc60a6ac88b (diff)
downloadxblast-766114c05bcd0b0388988aaf606e046857e6946a.tar.gz
Add lists and maps functions
Diffstat (limited to 'src/ch/epfl')
-rw-r--r--src/ch/epfl/xblast/Lists.java48
1 files changed, 48 insertions, 0 deletions
diff --git a/src/ch/epfl/xblast/Lists.java b/src/ch/epfl/xblast/Lists.java
index cc6a1c8..bf0cafa 100644
--- a/src/ch/epfl/xblast/Lists.java
+++ b/src/ch/epfl/xblast/Lists.java
@@ -2,6 +2,7 @@ package ch.epfl.xblast;
2 2
3import java.util.*; 3import java.util.*;
4import java.util.stream.Collectors; 4import java.util.stream.Collectors;
5import java.util.stream.IntStream;
5import java.util.stream.Stream; 6import java.util.stream.Stream;
6 7
7/** 8/**
@@ -181,4 +182,51 @@ public final class Lists {
181 .collect(Collectors.toList())); 182 .collect(Collectors.toList()));
182 } 183 }
183 184
185 /**
186 * Maps linearly two lists.
187 *
188 * @param kl the keys list
189 * @param vl the values list
190 * @param <K> the key type
191 * @param <V> the value type
192 * @return the map
193 */
194 public static <K, V> Map<K, V> linearMap(List<K> kl, List<V> vl) {
195 if (Objects.isNull(kl) || Objects.isNull(vl) || kl.size() != vl.size())
196 throw new IllegalArgumentException();
197
198 return Collections.unmodifiableMap(IntStream
199 .range(0, kl.size()).mapToObj(i -> i)
200 .filter(i -> Objects.nonNull(vl.get(i)))
201 .collect(Collectors.toMap(kl::get, vl::get)));
202 }
203
204 /**
205 * Merges two maps Map<K1, IK> and Map<IK, V> -> Map<K1, V>.
206 *
207 * @param m1 key maps
208 * @param m2 values maps
209 * @param <K> the keys type
210 * @param <IK> the intermediate keys type
211 * @param <V> the values type
212 * @return the traversing map
213 */
214 public static <K, IK, V> Map<K, V> traverseMaps(Map<K, IK> m1, Map<IK, V> m2) {
215 return Collections.unmodifiableMap(m1.entrySet().stream()
216 .collect(Collectors.toMap(Map.Entry::getKey, e -> m2.get(e.getValue()))));
217 }
218
219 /**
220 * Returns an inverted copy of a bijective map.
221 *
222 * @param m the map to invert
223 * @param <K> the keys type
224 * @param <V> the values type
225 * @return the inverted map
226 */
227 public static <K, V> Map<K, V> invertMap(Map<V, K> m) {
228 return Collections.unmodifiableMap(m.entrySet().stream()
229 .collect(Collectors.toMap(Map.Entry::getValue, Map.Entry::getKey)));
230 }
231
184} 232}