[#70] Implement a helper Map implementation for ConfigSources to use

smallrye · Dec 15, 2018 · 89bca78 · 89bca78
1 parent cc0fc35
commit 89bca78
Show file tree

Hide file tree

Showing 3 changed files with 497 additions and 0 deletions.
diff --git a/implementation/pom.xml b/implementation/pom.xml
@@ -69,6 +69,50 @@
           <forkMode>once</forkMode>
         </configuration>
       </plugin>
+      <plugin>
+        <artifactId>maven-javadoc-plugin</artifactId>
+        <configuration>
+          <!-- Support for @apiNote, @implSpec, @implNote -->
+          <tags>
+            <tag>
+              <name>apiNote</name>
+              <placement>a</placement>
+              <head>API Note:</head>
+            </tag>
+            <tag>
+              <name>implSpec</name>
+              <placement>a</placement>
+              <head>Implementation Requirements:</head>
+            </tag>
+            <tag>
+              <name>implNote</name>
+              <placement>a</placement>
+              <head>Implementation Note:</head>
+            </tag>
+            <tag>
+              <name>param</name>
+            </tag>
+            <tag>
+              <name>return</name>
+            </tag>
+            <tag>
+              <name>throws</name>
+            </tag>
+            <tag>
+              <name>since</name>
+            </tag>
+            <tag>
+              <name>version</name>
+            </tag>
+            <tag>
+              <name>serialData</name>
+            </tag>
+            <tag>
+              <name>see</name>
+            </tag>
+          </tags>
+        </configuration>
+      </plugin>
     </plugins>
   </build>
 </project>
diff --git a/implementation/src/main/java/io/smallrye/config/ConfigSourceMap.java b/implementation/src/main/java/io/smallrye/config/ConfigSourceMap.java
@@ -0,0 +1,180 @@
+/*
+ * Copyright 2018 Red Hat, Inc.
+ *
+ * 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 io.smallrye.config;
+
+import java.util.AbstractCollection;
+import java.util.AbstractMap;
+import java.util.AbstractSet;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+import java.util.function.BiConsumer;
+
+import org.eclipse.microprofile.config.spi.ConfigSource;
+
+/**
+ * A {@link Map Map&lt;String, String>} which is backed by a {@link ConfigSource}.
+ * This should not be used to implement {@link ConfigSource#getProperties()} on {@code ConfigSource}
+ * instances which do not override {@code getPropertyNames()}, as this will result in infinite recursion.
+ *
+ * @implNote The key set of the map is the result of calling {@link ConfigSource#getPropertyNames()}; the rest
+ * of the map operations are derived from this method and {@link ConfigSource#getValue(String)}.
+ * The values collection and entry set are instantiated lazily and cached.
+ * The implementation attempts to make no assumptions about the efficiency of the backing implementation and
+ * prefers the most direct access possible.
+ * <p>
+ * Some mutate operations are supported (specifically removals), where they can be performed on the backing key set, if
+ * the backing implementation allows them.
+ * Keys cannot be added to the map, nor values assigned, under any circumstances.
+ */
+public class ConfigSourceMap extends AbstractMap<String, String> implements Map<String, String> {
+    private final ConfigSource delegate;
+    private Values values;
+    private EntrySet entrySet;
+
+    /**
+     * Construct a new instance.
+     *
+     * @param delegate the delegate configuration source (must not be {@code null})
+     */
+    public ConfigSourceMap(final ConfigSource delegate) {
+        this.delegate = Objects.requireNonNull(delegate, "delegate must not be null");
+    }
+
+    public int size() {
+        return delegate.getPropertyNames().size();
+    }
+
+    public boolean isEmpty() {
+        // may be cheaper in some cases
+        return delegate.getPropertyNames().isEmpty();
+    }
+
+    public boolean containsKey(final Object key) {
+        //noinspection SuspiciousMethodCalls - it's OK in this case
+        return delegate.getPropertyNames().contains(key);
+    }
+
+    public String get(final Object key) {
+        return key instanceof String ? delegate.getValue((String) key) : null;
+    }
+
+    public Set<String> keySet() {
+        return delegate.getPropertyNames();
+    }
+
+    public void clear() {
+        delegate.getPropertyNames().clear();
+    }
+
+    public String remove(final Object key) {
+        final String value = get(key);
+        //noinspection SuspiciousMethodCalls - it's OK in this case
+        return delegate.getPropertyNames().remove(key) ? value : null;
+    }
+
+    public Collection<String> values() {
+        Values values = this.values;
+        if (values == null) return this.values = new Values();
+        return values;
+    }
+
+    public Set<Entry<String, String>> entrySet() {
+        EntrySet entrySet = this.entrySet;
+        if (entrySet == null) return this.entrySet = new EntrySet();
+        return entrySet;
+    }
+
+    public void forEach(final BiConsumer<? super String, ? super String> action) {
+        // superclass is implemented in terms of entry set - expensive!
+        for (String name : keySet()) {
+            action.accept(name, delegate.getValue(name));
+        }
+    }
+
+    final class Values extends AbstractCollection<String> implements Collection<String> {
+        public Iterator<String> iterator() {
+            return new Itr(delegate.getPropertyNames().iterator());
+        }
+
+        public int size() {
+            return delegate.getPropertyNames().size();
+        }
+
+        public boolean isEmpty() {
+            // may be cheaper in some cases
+            return delegate.getPropertyNames().isEmpty();
+        }
+
+        final class Itr implements Iterator<String> {
+            private final Iterator<String> iterator;
+
+            Itr(final Iterator<String> iterator) {
+                this.iterator = iterator;
+            }
+
+            public boolean hasNext() {
+                return iterator.hasNext();
+            }
+
+            public String next() {
+                return delegate.getValue(iterator.next());
+            }
+
+            public void remove() {
+                iterator.remove();
+            }
+        }
+    }
+
+    final class EntrySet extends AbstractSet<Entry<String, String>> {
+        public Iterator<Entry<String, String>> iterator() {
+            return new Itr(delegate.getPropertyNames().iterator());
+        }
+
+        public int size() {
+            return delegate.getPropertyNames().size();
+        }
+
+        public boolean isEmpty() {
+            // may be cheaper in some cases
+            return delegate.getPropertyNames().isEmpty();
+        }
+
+        final class Itr implements Iterator<Entry<String, String>> {
+            private final Iterator<String> iterator;
+
+            Itr(final Iterator<String> iterator) {
+                this.iterator = iterator;
+            }
+
+            public boolean hasNext() {
+                return iterator.hasNext();
+            }
+
+            public Entry<String, String> next() {
+                String name = iterator.next();
+                return new SimpleImmutableEntry<>(name, delegate.getValue(name));
+            }
+            public void remove() {
+                iterator.remove();
+            }
+        }
+    }
+}