--- /dev/null
+package org.apache.lucene.search.function;
+
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.
+ */
+
+import org.apache.lucene.search.Explanation;
+
+/**
+ * Expert: represents field values as different types.
+ * Normally created via a
+ * {@link org.apache.lucene.search.function.ValueSource ValueSuorce}
+ * for a particular field and reader.
+ *
+ * @lucene.experimental
+ *
+ *
+ */
+public abstract class DocValues {
+ /*
+ * DocValues is distinct from ValueSource because
+ * there needs to be an object created at query evaluation time that
+ * is not referenced by the query itself because:
+ * - Query objects should be MT safe
+ * - For caching, Query objects are often used as keys... you don't
+ * want the Query carrying around big objects
+ */
+
+ /**
+ * Return doc value as a float.
+ * <P>Mandatory: every DocValues implementation must implement at least this method.
+ * @param doc document whose float value is requested.
+ */
+ public abstract float floatVal(int doc);
+
+ /**
+ * Return doc value as an int.
+ * <P>Optional: DocValues implementation can (but don't have to) override this method.
+ * @param doc document whose int value is requested.
+ */
+ public int intVal(int doc) {
+ return (int) floatVal(doc);
+ }
+
+ /**
+ * Return doc value as a long.
+ * <P>Optional: DocValues implementation can (but don't have to) override this method.
+ * @param doc document whose long value is requested.
+ */
+ public long longVal(int doc) {
+ return (long) floatVal(doc);
+ }
+
+ /**
+ * Return doc value as a double.
+ * <P>Optional: DocValues implementation can (but don't have to) override this method.
+ * @param doc document whose double value is requested.
+ */
+ public double doubleVal(int doc) {
+ return floatVal(doc);
+ }
+
+ /**
+ * Return doc value as a string.
+ * <P>Optional: DocValues implementation can (but don't have to) override this method.
+ * @param doc document whose string value is requested.
+ */
+ public String strVal(int doc) {
+ return Float.toString(floatVal(doc));
+ }
+
+ /**
+ * Return a string representation of a doc value, as required for Explanations.
+ */
+ public abstract String toString(int doc);
+
+ /**
+ * Explain the scoring value for the input doc.
+ */
+ public Explanation explain(int doc) {
+ return new Explanation(floatVal(doc), toString(doc));
+ }
+
+ /**
+ * Expert: for test purposes only, return the inner array of values, or null if not applicable.
+ * <p>
+ * Allows tests to verify that loaded values are:
+ * <ol>
+ * <li>indeed cached/reused.</li>
+ * <li>stored in the expected size/type (byte/short/int/float).</li>
+ * </ol>
+ * Note: implementations of DocValues must override this method for
+ * these test elements to be tested, Otherwise the test would not fail, just
+ * print a warning.
+ */
+ Object getInnerArray() {
+ throw new UnsupportedOperationException("this optional method is for test purposes only");
+ }
+
+ // --- some simple statistics on values
+ private float minVal = Float.NaN;
+ private float maxVal = Float.NaN;
+ private float avgVal = Float.NaN;
+ private boolean computed=false;
+ // compute optional values
+ private void compute() {
+ if (computed) {
+ return;
+ }
+ float sum = 0;
+ int n = 0;
+ while (true) {
+ float val;
+ try {
+ val = floatVal(n);
+ } catch (ArrayIndexOutOfBoundsException e) {
+ break;
+ }
+ sum += val;
+ minVal = Float.isNaN(minVal) ? val : Math.min(minVal, val);
+ maxVal = Float.isNaN(maxVal) ? val : Math.max(maxVal, val);
+ ++n;
+ }
+
+ avgVal = n == 0 ? Float.NaN : sum / n;
+ computed = true;
+ }
+
+ /**
+ * Returns the minimum of all values or <code>Float.NaN</code> if this
+ * DocValues instance does not contain any value.
+ * <p>
+ * This operation is optional
+ * </p>
+ *
+ * @return the minimum of all values or <code>Float.NaN</code> if this
+ * DocValues instance does not contain any value.
+ */
+ public float getMinValue() {
+ compute();
+ return minVal;
+ }
+
+ /**
+ * Returns the maximum of all values or <code>Float.NaN</code> if this
+ * DocValues instance does not contain any value.
+ * <p>
+ * This operation is optional
+ * </p>
+ *
+ * @return the maximum of all values or <code>Float.NaN</code> if this
+ * DocValues instance does not contain any value.
+ */
+ public float getMaxValue() {
+ compute();
+ return maxVal;
+ }
+
+ /**
+ * Returns the average of all values or <code>Float.NaN</code> if this
+ * DocValues instance does not contain any value. *
+ * <p>
+ * This operation is optional
+ * </p>
+ *
+ * @return the average of all values or <code>Float.NaN</code> if this
+ * DocValues instance does not contain any value
+ */
+ public float getAverageValue() {
+ compute();
+ return avgVal;
+ }
+
+}
fnp / pylucene.git / blobdiff