org.graalvm.options.OptionDescriptors Maven / Gradle / Ivy
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* published by the Free Software Foundation. Oracle designates this
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*
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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package org.graalvm.options;
import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
/**
* An interface to a set of {@link OptionDescriptor}s.
*
* @since 1.0
*/
public interface OptionDescriptors extends Iterable {
/**
* An empty set of option descriptors.
*
* @since 1.0
*/
OptionDescriptors EMPTY = new OptionDescriptors() {
public Iterator iterator() {
return Collections. emptyList().iterator();
}
public OptionDescriptor get(String key) {
return null;
}
};
/**
* Gets the {@link OptionDescriptor} matching a given option name or {@code null} if this option
* descriptor set does not contain a matching option name.
*
* @since 1.0
*/
OptionDescriptor get(String optionName);
/**
* Creates a union options descriptor out of multiple given descriptors. The operation
* descriptors are not checked for duplicate keys. The option descriptors are iterated in
* declaration order.
*
* @since 1.0
*/
static OptionDescriptors createUnion(OptionDescriptors... descriptors) {
if (descriptors.length == 0) {
return EMPTY;
} else if (descriptors.length == 1) {
return descriptors[0];
} else {
return new UnionOptionDescriptors(descriptors);
}
}
/**
* {@inheritDoc}
*
* @since 1.0
*/
@Override
Iterator iterator();
/**
* Creates an {@link OptionDescriptors} instance from a list. The option descriptors
* implementation is backed by a {@link LinkedHashMap} that preserves ordering.
*
* @since 1.0
*/
static OptionDescriptors create(List descriptors) {
if (descriptors == null || descriptors.isEmpty()) {
return EMPTY;
}
return new OptionDescriptorsMap(descriptors);
}
}
class OptionDescriptorsMap implements OptionDescriptors {
final Map descriptors = new LinkedHashMap<>();
OptionDescriptorsMap(List descriptorList) {
for (OptionDescriptor descriptor : descriptorList) {
descriptors.put(descriptor.getName(), descriptor);
}
}
@Override
public OptionDescriptor get(String optionName) {
return descriptors.get(optionName);
}
@Override
public Iterator iterator() {
return descriptors.values().iterator();
}
}
final class UnionOptionDescriptors implements OptionDescriptors {
final OptionDescriptors[] descriptorsList;
UnionOptionDescriptors(OptionDescriptors[] descriptors) {
// defensive copy
this.descriptorsList = Arrays.copyOf(descriptors, descriptors.length);
}
public Iterator iterator() {
return new Iterator() {
Iterator descriptors = descriptorsList[0].iterator();
int descriptorsIndex = 0;
OptionDescriptor next = null;
public boolean hasNext() {
return fetchNext() != null;
}
private OptionDescriptor fetchNext() {
if (next != null) {
return next;
}
if (descriptors.hasNext()) {
next = descriptors.next();
return next;
} else if (descriptorsIndex < descriptorsList.length - 1) {
descriptorsIndex++;
descriptors = descriptorsList[descriptorsIndex].iterator();
return fetchNext();
} else {
return null;
}
}
public OptionDescriptor next() {
OptionDescriptor fetchedNext = fetchNext();
if (fetchedNext != null) {
// consume next
this.next = null;
return fetchedNext;
} else {
throw new NoSuchElementException();
}
}
};
}
public OptionDescriptor get(String value) {
for (OptionDescriptors descriptors : descriptorsList) {
OptionDescriptor descriptor = descriptors.get(value);
if (descriptor != null) {
return descriptor;
}
}
return null;
}
}