Introduce Mapping abstraction. (#64)

Intended as a shared type for records and map values.

metafix/src/main/java/org/metafacture/metafix/Mapping.java

@@ -0,0 +1,146 @@
+/*
+ * Copyright 2021 hbz NRW
+ *
+ * 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.metafacture.metafix;
+
+import java.util.Collection;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.function.BiConsumer;
+
+/**
+ * Represents a mapping of metadata fields and values.
+ */
+public class Mapping {
+
+    private static final String EMPTY = "";
+
+    private final Map<String, Object> map = new LinkedHashMap<>();
+
+    /**
+     * Creates an empty instance of {@link Mapping}.
+     */
+    public Mapping() {
+    }
+
+    /**
+     * Checks whether this mapping contains the metadata field.
+     *
+     * @param field the field name
+     * @return true if this mapping contains the metadata field, false otherwise
+     */
+    public boolean containsField(final String field) {
+        return map.containsKey(field);
+    }
+
+    /**
+     * Checks whether this mapping is empty.
+     *
+     * @return true if this mapping is empty, false otherwise
+     */
+    public boolean isEmpty() {
+        return map.isEmpty();
+    }
+
+    /**
+     * Gets the number of field/value pairs in this mapping.
+     *
+     * @return the number of field/value pairs in this mapping
+     */
+    public int size() {
+        return map.size();
+    }
+
+    /**
+     * Adds a field/value pair to this mapping, provided it's not {@code null}.
+     *
+     * @param field the field name
+     * @param value the metadata value
+     */
+    public void put(final String field, final Object value) {
+        if (value != null) {
+            map.put(field, value);
+        }
+    }
+
+    /**
+     * {@link #put(String, Object) Replaces} a field/value pair in this mapping,
+     * provided the field name is already {@link #containsField(String) present}.
+     *
+     * @param field the field name
+     * @param value the metadata value
+     */
+    public void replace(final String field, final Object value) {
+        if (containsField(field)) {
+            put(field, value);
+        }
+    }
+
+    /**
+     * Retrieves the field value from this mapping.
+     *
+     * @param field the field name
+     * @return the metadata value
+     */
+    public Object get(final String field) {
+        return map.get(field);
+    }
+
+    /**
+     * Removes the given field/value pair from this mapping.
+     *
+     * @param field the field name
+     */
+    public void remove(final String field) {
+        map.remove(field);
+    }
+
+    /**
+     * Retains only the given field/value pairs in this mapping.
+     *
+     * @param fields the field names
+     */
+    public void retainFields(final Collection<String> fields) {
+        map.keySet().retainAll(fields);
+    }
+
+    /**
+     * Removes all field/value pairs from this mapping whose value is empty.
+     */
+    public void removeEmptyValues() {
+        map.values().removeIf(EMPTY::equals);
+    }
+
+    /**
+     * Iterates over all field/value pairs in this mapping.
+     *
+     * @param consumer the action to be performed for each field/value pair
+     */
+    public void forEach(final BiConsumer<String, Object> consumer) {
+        map.forEach(consumer);
+    }
+
+    @Override
+    public String toString() {
+        return map.toString();
+    }
+
+    // TODO: Replace map accesses with record operations!
+    public Map<String, Object> temporarilyGetMap() {
+        return map;
+    }
+
+}

metafix/src/main/java/org/metafacture/metafix/Record.java

@@ -16,19 +16,10 @@
 
 package org.metafacture.metafix;
 
-import java.util.Collection;
-import java.util.LinkedHashMap;
-import java.util.Map;
-import java.util.function.BiConsumer;
-
 /**
- * Represents a metadata record, i.e., a mapping of fields and values.
+ * Represents a metadata record, i.e., a {@link Mapping} of fields and values.
  */
-public class Record {
-
-    private static final String EMPTY = "";
-
-    private final Map<String, Object> map = new LinkedHashMap<>();
+public class Record extends Mapping {
 
     private boolean reject;
 
@@ -70,112 +61,10 @@ public boolean getReject() {
         return reject;
     }
 
-    /**
-     * Checks whether this record contains the metadata field.
-     *
-     * @param field the field name
-     * @return true if this record contains the metadata field, false otherwise
-     */
-    public boolean containsField(final String field) {
-        return map.containsKey(field);
-    }
-
-    /**
-     * Checks whether this record is empty.
-     *
-     * @return true if this record is empty, false otherwise
-     */
-    public boolean isEmpty() {
-        return map.isEmpty();
-    }
-
-    /**
-     * Gets the number of field/value pairs in this record.
-     *
-     * @return the number of field/value pairs in this record
-     */
-    public int size() {
-        return map.size();
-    }
-
-    /**
-     * Adds a field/value pair to this record, provided it's not {@code null}.
-     *
-     * @param field the field name
-     * @param value the metadata value
-     */
-    public void put(final String field, final Object value) {
-        if (value != null) {
-            map.put(field, value);
-        }
-    }
-
-    /**
-     * {@link #put(String, Object) Replaces} a field/value pair in this record,
-     * provided the field name is already {@link #containsField(String) present}.
-     *
-     * @param field the field name
-     * @param value the metadata value
-     */
-    public void replace(final String field, final Object value) {
-        if (containsField(field)) {
-            put(field, value);
-        }
-    }
-
-    /**
-     * Retrieves the field value from this record.
-     *
-     * @param field the field name
-     * @return the metadata value
-     */
-    public Object get(final String field) {
-        return map.get(field);
-    }
-
-    /**
-     * Removes the given field/value pair from this record.
-     *
-     * @param field the field name
-     */
-    public void remove(final String field) {
-        map.remove(field);
-    }
-
-    /**
-     * Retains only the given field/value pairs in this record.
-     *
-     * @param fields the field names
-     */
-    public void retainFields(final Collection<String> fields) {
-        map.keySet().retainAll(fields);
-    }
-
-    /**
-     * Removes all field/value pairs from this record whose value is empty.
-     */
-    public void removeEmptyValues() {
-        map.values().removeIf(EMPTY::equals);
-    }
-
-    /**
-     * Iterates over all field/value pairs in this record.
-     *
-     * @param consumer the action to be performed for each field/value pair
-     */
-    public void forEach(final BiConsumer<String, Object> consumer) {
-        map.forEach(consumer);
-    }
-
     @Override
     public String toString() {
         // TODO: Improve string representation? Include reject status, etc.?
-        return map.toString();
-    }
-
-    // TODO: Replace map accesses with record operations!
-    public Map<String, Object> temporarilyGetMap() {
-        return map;
+        return super.toString();
     }
 
 }