Improved some methods in CharSeq, Vector, TreeSet and HashSet classes… (#2208)

NataliiaPrivezentseva · danieldietrich · commit b080ce70342e · 2019-01-06T23:33:12.000+01:00
* Improved some methods in CharSeq, Vector, TreeSet and HashSet classes using Collections.isEmpty(Iterable) method (#1958) * Reverted changes in addAll(Iterable) methods in TreeSet and HashSet classes * Fixed ofAll(Iterable) method in Vector class in order to pass Euler67 and Euler18 tests
diff --git a/vavr/src/main/java/io/vavr/collection/CharSeq.java b/vavr/src/main/java/io/vavr/collection/CharSeq.java
@@ -134,14 +134,17 @@ public static CharSeq of(char... characters) {
      */
     public static CharSeq ofAll(Iterable<? extends Character> elements) {
         Objects.requireNonNull(elements, "elements is null");
+        if (Collections.isEmpty(elements)){
+            return EMPTY;
+        }
         if (elements instanceof CharSeq) {
             return (CharSeq) elements;
         }
         final StringBuilder sb = new StringBuilder();
         for (char character : elements) {
             sb.append(character);
         }
-        return sb.length() == 0 ? EMPTY : of(sb);
+        return of(sb);
     }
 
     /**
@@ -772,12 +775,18 @@ public CharSeq prepend(Character element) {
     @Override
     public CharSeq prependAll(Iterable<? extends Character> elements) {
         Objects.requireNonNull(elements, "elements is null");
-        final StringBuilder sb = new StringBuilder();
-        for (char element : elements) {
-            sb.append(element);
+        if (Collections.isEmpty(elements)) {
+            return this;
+        } else if (isEmpty()) {
+            return ofAll(elements);
+        } else {
+            final StringBuilder sb = new StringBuilder();
+            for (char element : elements) {
+                sb.append(element);
+            }
+            sb.append(back);
+            return CharSeq.of(sb);
         }
-        sb.append(back);
-        return sb.length() == 0 ? EMPTY : of(sb);
     }
 
     @Override
diff --git a/vavr/src/main/java/io/vavr/collection/Vector.java b/vavr/src/main/java/io/vavr/collection/Vector.java
@@ -28,6 +28,7 @@
 import java.util.function.*;
 import java.util.stream.Collector;
 
+import static io.vavr.collection.Collections.removeAll;
 import static io.vavr.collection.Collections.withSize;
 import static io.vavr.collection.JavaConverters.ChangePolicy.IMMUTABLE;
 import static io.vavr.collection.JavaConverters.ChangePolicy.MUTABLE;
@@ -170,12 +171,14 @@ public static <T> Vector<T> fill(int n, Supplier<? extends T> s) {
     @SuppressWarnings("unchecked")
     public static <T> Vector<T> ofAll(Iterable<? extends T> iterable) {
         Objects.requireNonNull(iterable, "iterable is null");
+        if (iterable instanceof Traversable && io.vavr.collection.Collections.isEmpty(iterable)){
+            return empty();
+        }
         if (iterable instanceof Vector) {
             return (Vector<T>) iterable;
-        } else {
-            final Object[] values = withSize(iterable).toArray();
-            return ofAll(BitMappedTrie.ofAll(values));
         }
+        final Object[] values = withSize(iterable).toArray();
+        return ofAll(BitMappedTrie.ofAll(values));
     }
 
     /**
@@ -606,10 +609,11 @@ public Vector<T> appendAll(Iterable<? extends T> iterable) {
         Objects.requireNonNull(iterable, "iterable is null");
         if (isEmpty()) {
             return ofAll(iterable);
-        } else {
-            final BitMappedTrie<T> that = trie.appendAll(iterable);
-            return (that == trie) ? this : new Vector<>(that);
         }
+        if (io.vavr.collection.Collections.isEmpty(iterable)){
+            return this;
+        }
+        return new Vector<>(trie.appendAll(iterable));
     }
 
     @GwtIncompatible
@@ -918,10 +922,11 @@ public Vector<T> prependAll(Iterable<? extends T> iterable) {
         Objects.requireNonNull(iterable, "iterable is null");
         if (isEmpty()) {
             return ofAll(iterable);
-        } else {
-            final BitMappedTrie<T> that = trie.prependAll(iterable);
-            return (that == trie) ? this : new Vector<>(that);
         }
+        if (io.vavr.collection.Collections.isEmpty(iterable)){
+            return this;
+        }
+        return new Vector<>(trie.prependAll(iterable));
     }
 
     @Override
