diff options
Diffstat (limited to 'src/main/java/com/amazon/carbonado/qe/EmptyQuery.java')
| -rw-r--r-- | src/main/java/com/amazon/carbonado/qe/EmptyQuery.java | 279 |
1 files changed, 279 insertions, 0 deletions
diff --git a/src/main/java/com/amazon/carbonado/qe/EmptyQuery.java b/src/main/java/com/amazon/carbonado/qe/EmptyQuery.java new file mode 100644 index 0000000..60b027f --- /dev/null +++ b/src/main/java/com/amazon/carbonado/qe/EmptyQuery.java @@ -0,0 +1,279 @@ +/*
+ * Copyright 2006 Amazon Technologies, Inc. or its affiliates.
+ * Amazon, Amazon.com and Carbonado are trademarks or registered trademarks
+ * of Amazon Technologies, Inc. or its affiliates. All rights reserved.
+ *
+ * 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 com.amazon.carbonado.qe;
+
+import java.io.IOException;
+
+import com.amazon.carbonado.Cursor;
+import com.amazon.carbonado.FetchException;
+import com.amazon.carbonado.IsolationLevel;
+import com.amazon.carbonado.PersistNoneException;
+import com.amazon.carbonado.Storage;
+import com.amazon.carbonado.Storable;
+import com.amazon.carbonado.Query;
+
+import com.amazon.carbonado.cursor.EmptyCursor;
+
+import com.amazon.carbonado.filter.Filter;
+import com.amazon.carbonado.filter.FilterValues;
+
+import com.amazon.carbonado.info.OrderedProperty;
+
+/**
+ * Special query implementation that fetches nothing.
+ *
+ * @author Brian S O'Neill
+ */
+public final class EmptyQuery<S extends Storable> extends AbstractQuery<S> {
+ private final Storage<S> mStorage;
+
+ // Properties that this query is ordered by.
+ private final String[] mOrderings;
+
+ /**
+ * @param storage required storage object
+ * @param orderings optional order-by properties
+ */
+ public EmptyQuery(Storage<S> storage, OrderedProperty[] orderings) {
+ if (storage == null) {
+ throw new IllegalArgumentException();
+ }
+ mStorage = storage;
+ mOrderings = extractOrderingNames(orderings);
+ }
+
+ /**
+ * @param storage required storage object
+ * @param orderings optional order-by properties
+ */
+ public EmptyQuery(Storage<S> storage, String[] orderings) {
+ if (storage == null) {
+ throw new IllegalArgumentException();
+ }
+ mStorage = storage;
+ mOrderings = orderings == null ? EMPTY_ORDERINGS : orderings;
+ }
+
+ public Class<S> getStorableType() {
+ return mStorage.getStorableType();
+ }
+
+ /**
+ * Always returns a {@link com.amazon.carbonado.filter.ClosedFilter ClosedFilter}.
+ */
+ public Filter<S> getFilter() {
+ return Filter.getClosedFilter(mStorage.getStorableType());
+ }
+
+ /**
+ * Always returns null.
+ */
+ public FilterValues<S> getFilterValues() {
+ return null;
+ }
+
+ /**
+ * Always returns zero.
+ */
+ public int getBlankParameterCount() {
+ return 0;
+ }
+
+ /**
+ * Always throws an IllegalStateException.
+ */
+ public Query<S> with(int value) {
+ throw error();
+ }
+
+ /**
+ * Always throws an IllegalStateException.
+ */
+ public Query<S> with(long value) {
+ throw error();
+ }
+
+ /**
+ * Always throws an IllegalStateException.
+ */
+ public Query<S> with(float value) {
+ throw error();
+ }
+
+ /**
+ * Always throws an IllegalStateException.
+ */
+ public Query<S> with(double value) {
+ throw error();
+ }
+
+ /**
+ * Always throws an IllegalStateException.
+ */
+ public Query<S> with(boolean value) {
+ throw error();
+ }
+
+ /**
+ * Always throws an IllegalStateException.
+ */
+ public Query<S> with(char value) {
+ throw error();
+ }
+
+ /**
+ * Always throws an IllegalStateException.
+ */
+ public Query<S> with(byte value) {
+ throw error();
+ }
+
+ /**
+ * Always throws an IllegalStateException.
+ */
+ public Query<S> with(short value) {
+ throw error();
+ }
+
+ /**
+ * Always throws an IllegalStateException.
+ */
+ public Query<S> with(Object value) {
+ throw error();
+ }
+
+ /**
+ * Throws an IllegalStateException unless no values passed in.
+ */
+ public Query<S> withValues(Object... values) {
+ if (values == null || values.length == 0) {
+ return this;
+ }
+ throw error();
+ }
+
+ /**
+ * Always throws an IllegalStateException.
+ */
+ public Query<S> and(Filter<S> filter) {
+ throw new IllegalStateException("Query is already guaranteed to fetch nothing");
+ }
+
+ public Query<S> or(Filter<S> filter) throws FetchException {
+ return mStorage.query(filter);
+ }
+
+ public Query<S> not() throws FetchException {
+ Query<S> query = mStorage.query();
+ String[] orderings = mOrderings;
+ if (orderings.length > 0) {
+ query = query.orderBy(orderings);
+ }
+ return query;
+ }
+
+ public Query<S> orderBy(String property) throws FetchException {
+ // This allows property to be checked for validity.
+ return mStorage.query().orderBy(property).not();
+ }
+
+ public Query<S> orderBy(String... properties) throws FetchException {
+ // This allows properties to be checked for validity.
+ return mStorage.query().orderBy(properties).not();
+ }
+
+ /**
+ * Always returns an {@link EmptyCursor}.
+ */
+ public Cursor<S> fetch() {
+ return EmptyCursor.getEmptyCursor();
+ }
+
+ /**
+ * Always returns an {@link EmptyCursor}.
+ */
+ public Cursor<S> fetchAfter(S start) {
+ return EmptyCursor.getEmptyCursor();
+ }
+
+ /**
+ * Always throws {@link PersistNoneException}.
+ */
+ public void deleteOne() throws PersistNoneException {
+ throw new PersistNoneException();
+ }
+
+ /**
+ * Always returns false.
+ */
+ public boolean tryDeleteOne() {
+ return false;
+ }
+
+ /**
+ * Does nothing.
+ */
+ public void deleteAll() {
+ }
+
+ /**
+ * Always returns zero.
+ */
+ public long count() {
+ return 0;
+ }
+
+ public void appendTo(Appendable app) throws IOException {
+ app.append("Query {type=");
+ app.append(mStorage.getStorableType().getName());
+ app.append(", filter=");
+ getFilter().appendTo(app);
+
+ if (mOrderings != null && mOrderings.length > 0) {
+ app.append(", orderBy=[");
+ for (int i=0; i<mOrderings.length; i++) {
+ if (i > 0) {
+ app.append(", ");
+ }
+ app.append(mOrderings[i]);
+ }
+ app.append(']');
+ }
+
+ app.append('}');
+ }
+
+ /**
+ * Always returns false.
+ */
+ public boolean printNative(Appendable app, int indentLevel) {
+ return false;
+ }
+
+ /**
+ * Always returns false.
+ */
+ public boolean printPlan(Appendable app, int indentLevel) {
+ return false;
+ }
+
+ private IllegalStateException error() {
+ return new IllegalStateException("Query doesn't have any parameters");
+ }
+}
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