BUG-7464: Optimize LNode operations

[yangtools.git] / third-party / triemap / src / main / java / org / opendaylight / yangtools / triemap / LNodeEntries.java

diff --git a/third-party/triemap/src/main/java/org/opendaylight/yangtools/triemap/LNodeEntries.java b/third-party/triemap/src/main/java/org/opendaylight/yangtools/triemap/LNodeEntries.java
new file mode 100644 (file)
index 0000000..93382a9
--- /dev/null
+++ b/third-party/triemap/src/main/java/org/opendaylight/yangtools/triemap/LNodeEntries.java
@@ -0,0 +1,133 @@
+/*
+ * (C) Copyright 2016 Pantheon Technologies, s.r.o. and others.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.opendaylight.yangtools.triemap;
+
+import java.util.AbstractMap.SimpleImmutableEntry;
+import java.util.Iterator;
+import java.util.Map.Entry;
+import java.util.NoSuchElementException;
+import java.util.Optional;
+
+/**
+ * Similar to Scala's ListMap. Stores a linked set of entries, guaranteed to contain unique entry keys.
+ *
+ * @author Robert Varga
+ *
+ * @param <K> the type of keys
+ * @param <V> the type of values
+ */
+final class LNodeEntries<K, V> extends LNodeEntry<K, V> {
+    // Modified during remove0 only
+    private LNodeEntries<K, V> next;
+
+    private LNodeEntries(final K k, final V v) {
+        this(k, v, null);
+    }
+
+    private LNodeEntries(final K k, final V v, final LNodeEntries<K, V> next) {
+        super(k, v);
+        this.next = next;
+    }
+
+    static <K,V> LNodeEntries<K, V> map(final K k1, final V v1, final K k2, final V v2) {
+        return new LNodeEntries<>(k1, v1, new LNodeEntries<>(k2, v2));
+    }
+
+    Optional<Entry<K, V>> maybeSingleton() {
+        return next != null ? Optional.empty() : Optional.of(new SimpleImmutableEntry<>(key(), value()));
+    }
+
+    int size() {
+        int sz = 1;
+        for (LNodeEntries<?, ?> wlk = next; wlk != null; wlk = wlk.next) {
+            sz++;
+        }
+        return sz;
+    }
+
+    LNodeEntry<K, V> findEntry(final Equivalence<? super K> equiv, final K key) {
+        // We do not perform recursion on purpose here, so we do not run out of stack if the key hashing fails.
+        LNodeEntries<K, V> head = this;
+        do {
+            if (equiv.equivalent(head.key(), key)) {
+                return head;
+            }
+
+            head = head.next;
+        } while (head != null);
+
+        return null;
+    }
+
+    LNodeEntries<K,V> insert(final K key, final V value) {
+        return new LNodeEntries<>(key, value, this);
+    }
+
+    LNodeEntries<K, V> replace(final LNodeEntry<K, V> entry, final V v) {
+        return new LNodeEntries<>(entry.key(), v, remove(entry));
+    }
+
+    LNodeEntries<K, V> remove(final LNodeEntry<K, V> entry) {
+        if (entry == this) {
+            return next;
+        }
+
+        final LNodeEntries<K, V> ret = new LNodeEntries<>(key(), value());
+
+        LNodeEntries<K, V> last = ret;
+        LNodeEntries<K, V> cur = next;
+        while (cur != null) {
+            if (entry.equals(cur)) {
+                last.next = cur.next;
+                return ret;
+            }
+
+            last.next = new LNodeEntries<>(cur.key(), cur.value());
+            last = last.next;
+            cur = cur.next;
+        }
+
+        throw new IllegalStateException("Entry " + entry + " not found in entries " + this);
+    }
+
+    Iterator<Entry<K, V>> iterator() {
+        return new NodeIterator<>(this);
+    }
+
+    static final class NodeIterator<K,V> implements Iterator<Entry<K, V>> {
+        private LNodeEntries<K, V> n;
+
+        NodeIterator(final LNodeEntries<K, V> n) {
+            this.n = n;
+        }
+
+        @Override
+        public boolean hasNext() {
+            return n != null;
+        }
+
+        @Override
+        public Entry<K, V> next() {
+            if (n == null) {
+                throw new NoSuchElementException();
+            }
+
+            final Entry<K, V> res = new SimpleImmutableEntry<>(n.key(), n.value());
+            n = n.next;
+            return res;
+        }
+    }
+}