--- /dev/null
+/*******************************************************************************
+ * Copyright (c) 2012 Sonatype, Inc.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ * Sonatype, Inc. - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.aether.metadata;
+
+import java.io.File;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * A skeleton class for metadata.
+ */
+public abstract class AbstractMetadata
+ implements Metadata
+{
+
+ private Metadata newInstance( Map<String, String> properties, File file )
+ {
+ return new DefaultMetadata( getGroupId(), getArtifactId(), getVersion(), getType(), getNature(), file,
+ properties );
+ }
+
+ public Metadata setFile( File file )
+ {
+ File current = getFile();
+ if ( ( current == null ) ? file == null : current.equals( file ) )
+ {
+ return this;
+ }
+ return newInstance( getProperties(), file );
+ }
+
+ public Metadata setProperties( Map<String, String> properties )
+ {
+ Map<String, String> current = getProperties();
+ if ( current.equals( properties ) || ( properties == null && current.isEmpty() ) )
+ {
+ return this;
+ }
+ return newInstance( copyProperties( properties ), getFile() );
+ }
+
+ public String getProperty( String key, String defaultValue )
+ {
+ String value = getProperties().get( key );
+ return ( value != null ) ? value : defaultValue;
+ }
+
+ /**
+ * Copies the specified metadata properties. This utility method should be used when creating new metadata instances
+ * with caller-supplied properties.
+ *
+ * @param properties The properties to copy, may be {@code null}.
+ * @return The copied and read-only properties, never {@code null}.
+ */
+ protected static Map<String, String> copyProperties( Map<String, String> properties )
+ {
+ if ( properties != null && !properties.isEmpty() )
+ {
+ return Collections.unmodifiableMap( new HashMap<String, String>( properties ) );
+ }
+ else
+ {
+ return Collections.emptyMap();
+ }
+ }
+
+ @Override
+ public String toString()
+ {
+ StringBuilder buffer = new StringBuilder( 128 );
+ if ( getGroupId().length() > 0 )
+ {
+ buffer.append( getGroupId() );
+ }
+ if ( getArtifactId().length() > 0 )
+ {
+ buffer.append( ':' ).append( getArtifactId() );
+ }
+ if ( getVersion().length() > 0 )
+ {
+ buffer.append( ':' ).append( getVersion() );
+ }
+ buffer.append( '/' ).append( getType() );
+ return buffer.toString();
+ }
+
+ /**
+ * Compares this metadata with the specified object.
+ *
+ * @param obj The object to compare this metadata against, may be {@code null}.
+ * @return {@code true} if and only if the specified object is another {@link Metadata} with equal coordinates,
+ * type, nature, properties and file, {@code false} otherwise.
+ */
+ @Override
+ public boolean equals( Object obj )
+ {
+ if ( obj == this )
+ {
+ return true;
+ }
+ else if ( !( obj instanceof Metadata ) )
+ {
+ return false;
+ }
+
+ Metadata that = (Metadata) obj;
+
+ return getArtifactId().equals( that.getArtifactId() ) && getGroupId().equals( that.getGroupId() )
+ && getVersion().equals( that.getVersion() ) && getType().equals( that.getType() )
+ && getNature().equals( that.getNature() ) && eq( getFile(), that.getFile() )
+ && eq( getProperties(), that.getProperties() );
+ }
+
+ private static <T> boolean eq( T s1, T s2 )
+ {
+ return s1 != null ? s1.equals( s2 ) : s2 == null;
+ }
+
+ /**
+ * Returns a hash code for this metadata.
+ *
+ * @return A hash code for the metadata.
+ */
+ @Override
+ public int hashCode()
+ {
+ int hash = 17;
+ hash = hash * 31 + getGroupId().hashCode();
+ hash = hash * 31 + getArtifactId().hashCode();
+ hash = hash * 31 + getType().hashCode();
+ hash = hash * 31 + getNature().hashCode();
+ hash = hash * 31 + getVersion().hashCode();
+ hash = hash * 31 + hash( getFile() );
+ return hash;
+ }
+
+ private static int hash( Object obj )
+ {
+ return ( obj != null ) ? obj.hashCode() : 0;
+ }
+
+}