[MNG-8490] Combine XmlNode and XmlNodeImpl.

api/maven-api-xml/pom.xml

@@ -35,6 +35,14 @@
       <groupId>org.apache.maven</groupId>
       <artifactId>maven-api-annotations</artifactId>
     </dependency>
+    <dependency>
+      <groupId>com.fasterxml.woodstox</groupId>
+      <artifactId>woodstox-core</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.codehaus.woodstox</groupId>
+      <artifactId>stax2-api</artifactId>
+    </dependency>
   </dependencies>
 
 </project>

impl/maven-xml/src/main/java/org/apache/maven/internal/xml/ImmutableCollections.java → api/maven-api-xml/src/main/java/org/apache/maven/api/xml/ImmutableCollections.java

@@ -16,7 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
-package org.apache.maven.internal.xml;
+package org.apache.maven.api.xml;
 
 import java.io.Serializable;
 import java.util.AbstractList;

api/maven-api-xml/src/main/java/org/apache/maven/api/xml/XmlNode.java

@@ -18,121 +18,204 @@
  */
 package org.apache.maven.api.xml;
 
+import javax.xml.stream.XMLStreamException;
+
+import java.io.Serializable;
+import java.io.StringWriter;
 import java.util.List;
+import java.util.ListIterator;
 import java.util.Map;
-
-import org.apache.maven.api.annotations.Experimental;
-import org.apache.maven.api.annotations.Immutable;
-import org.apache.maven.api.annotations.Nonnull;
-import org.apache.maven.api.annotations.Nullable;
-import org.apache.maven.api.annotations.ThreadSafe;
+import java.util.Objects;
+import java.util.function.Function;
 
 /**
- * An immutable xml node.
- *
- * @since 4.0.0
+ *  NOTE: remove all the util code in here when separated, this class should be pure data.
  */
-@Experimental
-@ThreadSafe
-@Immutable
-public interface XmlNode {
+public class XmlNode implements Serializable {
+    private static final long serialVersionUID = 2567894443061173996L;
 
-    String CHILDREN_COMBINATION_MODE_ATTRIBUTE = "combine.children";
+    protected final String prefix;
 
-    String CHILDREN_COMBINATION_MERGE = "merge";
+    protected final String namespaceUri;
 
-    String CHILDREN_COMBINATION_APPEND = "append";
+    protected final String name;
 
-    /**
-     * This default mode for combining children DOMs during merge means that where element names match, the process will
-     * try to merge the element data, rather than putting the dominant and recessive elements (which share the same
-     * element name) as siblings in the resulting DOM.
-     */
-    String DEFAULT_CHILDREN_COMBINATION_MODE = CHILDREN_COMBINATION_MERGE;
+    protected final String value;
 
-    String SELF_COMBINATION_MODE_ATTRIBUTE = "combine.self";
+    protected final Map<String, String> attributes;
 
-    String SELF_COMBINATION_OVERRIDE = "override";
+    protected final List<XmlNode> children;
 
-    String SELF_COMBINATION_MERGE = "merge";
+    protected final Object location;
 
-    String SELF_COMBINATION_REMOVE = "remove";
+    public XmlNode(String name) {
+        this(name, null, null, null, null);
+    }
 
-    /**
-     * In case of complex XML structures, combining can be done based on id.
-     */
-    String ID_COMBINATION_MODE_ATTRIBUTE = "combine.id";
+    public XmlNode(String name, String value) {
+        this(name, value, null, null, null);
+    }
 
-    /**
-     * In case of complex XML structures, combining can be done based on keys.
-     * This is a comma separated list of attribute names.
-     */
-    String KEYS_COMBINATION_MODE_ATTRIBUTE = "combine.keys";
+    public XmlNode(XmlNode from, String name) {
+        this(name, from.getValue(), from.getAttributes(), from.getChildren(), from.getInputLocation());
+    }
 
-    /**
-     * This default mode for combining a DOM node during merge means that where element names match, the process will
-     * try to merge the element attributes and values, rather than overriding the recessive element completely with the
-     * dominant one. This means that wherever the dominant element doesn't provide the value or a particular attribute,
-     * that value or attribute will be set from the recessive DOM node.
-     */
-    String DEFAULT_SELF_COMBINATION_MODE = SELF_COMBINATION_MERGE;
+    public XmlNode(String name, String value, Map<String, String> attributes, List<XmlNode> children, Object location) {
+        this("", "", name, value, attributes, children, location);
+    }
 
-    @Nonnull
-    String getName();
+    public XmlNode(
+            String prefix,
+            String namespaceUri,
+            String name,
+            String value,
+            Map<String, String> attributes,
+            List<XmlNode> children,
+            Object location) {
+        this.prefix = prefix == null ? "" : prefix;
+        this.namespaceUri = namespaceUri == null ? "" : namespaceUri;
+        this.name = Objects.requireNonNull(name);
+        this.value = value;
+        this.attributes = ImmutableCollections.copy(attributes);
+        this.children = ImmutableCollections.copy(children);
+        this.location = location;
+    }
+    // ----------------------------------------------------------------------
+    // Name handling
+    // ----------------------------------------------------------------------
+
+    public String getPrefix() {
+        return prefix;
+    }
+
+    public String getNamespaceUri() {
+        return namespaceUri;
+    }
 
-    @Nonnull
-    String getNamespaceUri();
+    public String getName() {
+        return name;
+    }
 
-    @Nonnull
-    String getPrefix();
+    // ----------------------------------------------------------------------
+    // Value handling
+    // ----------------------------------------------------------------------
 
-    @Nullable
-    String getValue();
+    public String getValue() {
+        return value;
+    }
 
-    @Nonnull
-    Map<String, String> getAttributes();
+    // ----------------------------------------------------------------------
+    // Attribute handling
+    // ----------------------------------------------------------------------
 
-    @Nullable
-    String getAttribute(@Nonnull String name);
+    public Map<String, String> getAttributes() {
+        return attributes;
+    }
 
-    @Nonnull
-    List<XmlNode> getChildren();
+    public String getAttribute(String name) {
+        return attributes.get(name);
+    }
 
-    @Nullable
-    XmlNode getChild(String name);
+    // ----------------------------------------------------------------------
+    // Child handling
+    // ----------------------------------------------------------------------
+
+    public XmlNode getChild(String name) {
+        if (name != null) {
+            ListIterator<XmlNode> it = children.listIterator(children.size());
+            while (it.hasPrevious()) {
+                XmlNode child = it.previous();
+                if (name.equals(child.getName())) {
+                    return child;
+                }
+            }
+        }
+        return null;
+    }
 
-    @Nullable
-    Object getInputLocation();
+    public List<XmlNode> getChildren() {
+        return children;
+    }
 
-    default XmlNode merge(@Nullable XmlNode source) {
-        return merge(source, (Boolean) null);
+    public int getChildCount() {
+        return children.size();
     }
 
-    XmlNode merge(@Nullable XmlNode source, @Nullable Boolean childMergeOverride);
+    // ----------------------------------------------------------------------
+    // Input location handling
+    // ----------------------------------------------------------------------
 
     /**
-     * Merge recessive into dominant and return either {@code dominant}
-     * with merged information or a clone of {@code recessive} if
-     * {@code dominant} is {@code null}.
-     *
-     * @param dominant the node
-     * @param recessive if {@code null}, nothing will happen
-     * @return the merged node
+     * @since 3.2.0
+     * @return input location
      */
-    @Nullable
-    static XmlNode merge(@Nullable XmlNode dominant, @Nullable XmlNode recessive) {
-        return merge(dominant, recessive, null);
+    public Object getInputLocation() {
+        return location;
+    }
+
+    // ----------------------------------------------------------------------
+    // Standard object handling
+    // ----------------------------------------------------------------------
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        XmlNode that = (XmlNode) o;
+        return Objects.equals(this.name, that.name)
+                && Objects.equals(this.value, that.value)
+                && Objects.equals(this.attributes, that.attributes)
+                && Objects.equals(this.children, that.children);
     }
 
-    @Nullable
-    static XmlNode merge(
-            @Nullable XmlNode dominant, @Nullable XmlNode recessive, @Nullable Boolean childMergeOverride) {
-        if (recessive == null) {
-            return dominant;
+    @Override
+    public int hashCode() {
+        return Objects.hash(name, value, attributes, children);
+    }
+
+    @Override
+    public String toString() {
+        try {
+            return toStringXml();
+        } catch (XMLStreamException e) {
+            return toStringObject();
         }
-        if (dominant == null) {
-            return recessive;
+    }
+
+    public String toStringXml() throws XMLStreamException {
+        StringWriter writer = new StringWriter();
+        XmlNodeWriter.write(writer, this);
+        return writer.toString();
+    }
+
+    public String toStringObject() {
+        StringBuilder sb = new StringBuilder();
+        sb.append("XmlNode[");
+        boolean w = false;
+        w = addToStringField(sb, prefix, o -> !o.isEmpty(), "prefix", w);
+        w = addToStringField(sb, namespaceUri, o -> !o.isEmpty(), "namespaceUri", w);
+        w = addToStringField(sb, name, o -> !o.isEmpty(), "name", w);
+        w = addToStringField(sb, value, o -> !o.isEmpty(), "value", w);
+        w = addToStringField(sb, attributes, o -> !o.isEmpty(), "attributes", w);
+        w = addToStringField(sb, children, o -> !o.isEmpty(), "children", w);
+        w = addToStringField(sb, location, Objects::nonNull, "location", w);
+        sb.append("]");
+        return sb.toString();
+    }
+
+    private static <T> boolean addToStringField(StringBuilder sb, T o, Function<T, Boolean> p, String n, boolean w) {
+        if (!p.apply(o)) {
+            if (w) {
+                sb.append(", ");
+            } else {
+                w = true;
+            }
+            sb.append(n).append("='").append(o).append('\'');
         }
-        return dominant.merge(recessive, childMergeOverride);
+        return w;
     }
 }

impl/maven-xml/src/main/java/org/apache/maven/internal/xml/XmlNodeWriter.java → api/maven-api-xml/src/main/java/org/apache/maven/api/xml/XmlNodeWriter.java

@@ -16,7 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
-package org.apache.maven.internal.xml;
+package org.apache.maven.api.xml;
 
 import javax.xml.stream.XMLOutputFactory;
 import javax.xml.stream.XMLStreamException;
@@ -25,7 +25,6 @@
 import java.io.Writer;
 import java.util.Map;
 
-import org.apache.maven.api.xml.XmlNode;
 import org.codehaus.stax2.util.StreamWriterDelegate;
 
 /**

compat/maven-embedder/src/main/java/org/apache/maven/cli/ExtensionConfigurationModule.java

@@ -27,7 +27,6 @@
 import org.apache.maven.api.xml.XmlNode;
 import org.apache.maven.extension.internal.CoreExtensionEntry;
 import org.apache.maven.internal.impl.model.DefaultInterpolator;
-import org.apache.maven.internal.xml.XmlNodeImpl;
 import org.apache.maven.internal.xml.XmlPlexusConfiguration;
 import org.apache.maven.model.v4.MavenTransformer;
 import org.codehaus.plexus.configuration.PlexusConfiguration;
@@ -49,7 +48,7 @@ public void configure(Binder binder) {
         if (extension.getKey() != null) {
             XmlNode configuration = extension.getConfiguration();
             if (configuration == null) {
-                configuration = new XmlNodeImpl("configuration");
+                configuration = new XmlNode("configuration");
             }
             Function<String, String> cb = Interpolator.memoize(callback);
             Function<String, String> it = s -> interpolator.interpolate(s, cb);

compat/maven-model-builder/src/main/java/org/apache/maven/model/plugin/DefaultPluginConfigurationExpander.java

@@ -24,6 +24,7 @@
 import java.util.List;
 
 import org.apache.maven.api.xml.XmlNode;
+import org.apache.maven.internal.xml.XmlNodeUtil;
 import org.apache.maven.model.Build;
 import org.apache.maven.model.Model;
 import org.apache.maven.model.Plugin;
@@ -64,7 +65,7 @@ private void expand(List<Plugin> plugins) {
             if (pluginConfiguration != null) {
                 for (PluginExecution execution : plugin.getExecutions()) {
                     XmlNode executionConfiguration = execution.getDelegate().getConfiguration();
-                    executionConfiguration = XmlNode.merge(executionConfiguration, pluginConfiguration);
+                    executionConfiguration = XmlNodeUtil.merge(executionConfiguration, pluginConfiguration);
                     execution.update(execution.getDelegate().withConfiguration(executionConfiguration));
                 }
             }

compat/maven-model-builder/src/main/java/org/apache/maven/model/plugin/DefaultReportConfigurationExpander.java

@@ -22,6 +22,7 @@
 import javax.inject.Singleton;
 
 import org.apache.maven.api.xml.XmlNode;
+import org.apache.maven.internal.xml.XmlNodeUtil;
 import org.apache.maven.model.Model;
 import org.apache.maven.model.ReportPlugin;
 import org.apache.maven.model.ReportSet;
@@ -50,7 +51,7 @@ public void expandPluginConfiguration(Model model, ModelBuildingRequest request,
                 if (parentDom != null) {
                     for (ReportSet execution : reportPlugin.getReportSets()) {
                         XmlNode childDom = execution.getDelegate().getConfiguration();
-                        childDom = XmlNode.merge(childDom, parentDom);
+                        childDom = XmlNodeUtil.merge(childDom, parentDom);
                         execution.update(execution.getDelegate().withConfiguration(childDom));
                     }
                 }

compat/maven-model/src/test/java/org/apache/maven/model/v4/ModelXmlTest.java

@@ -28,7 +28,6 @@
 
 import org.apache.maven.api.model.Model;
 import org.apache.maven.api.model.Plugin;
-import org.apache.maven.api.xml.XmlNode;
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;