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The Java operations layer for the MongoDB Java Driver. Third parties can ' +
'wrap this layer to provide custom higher-level APIs
/*
* Copyright 2008-present MongoDB, Inc.
*
* 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.mongodb.client.model;
import com.mongodb.client.model.Windows.Bound;
import com.mongodb.lang.Nullable;
import org.bson.BsonDocument;
import org.bson.BsonDocumentWriter;
import org.bson.BsonType;
import org.bson.codecs.configuration.CodecRegistry;
import org.bson.conversions.Bson;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;
import static com.mongodb.assertions.Assertions.assertNotNull;
import static com.mongodb.assertions.Assertions.isTrueArgument;
import static org.bson.assertions.Assertions.notNull;
/**
* Builders for {@linkplain WindowOutputField window output fields} used in the
* {@link Aggregates#setWindowFields(Object, Bson, Iterable) $setWindowFields} pipeline stage
* of an aggregation pipeline. Each windowed computation is a triple:
*
* - A window function. Some functions require documents in a window to be sorted
* (see {@code sortBy} in {@link Aggregates#setWindowFields(Object, Bson, Iterable)}).
* - An optional {@linkplain Window window}, a.k.a. frame.
* Specifying {@code null} window is equivalent to specifying an unbounded window,
* i.e., a window with both ends specified as {@link Bound#UNBOUNDED}.
* Some window functions, e.g., {@link #derivative(String, Object, Window)},
* require an explicit unbounded window instead of {@code null}.
* - A path to an output field to be computed by the window function over the window.
*
* A window output field is similar to an {@linkplain Accumulators accumulator} but does not result in folding documents constituting
* the window into a single document.
*
* @mongodb.driver.manual meta/aggregation-quick-reference/#field-paths Field paths
* @since 4.3
* @mongodb.server.release 5.0
*/
public final class WindowOutputFields {
/**
* Creates a windowed output field from a document field in situations when there is no builder method that better satisfies your needs.
* This method cannot be used to validate the document field syntax.
*
* Example
* The following code creates two functionally equivalent window output fields,
* though they may not be {@linkplain #equals(Object) equal}.
*
{@code
* Window pastWeek = Windows.timeRange(-1, MongoTimeUnit.WEEK, Windows.Bound.CURRENT);
* WindowOutputField pastWeekExpenses1 = WindowOutputFields.sum("pastWeekExpenses", "$expenses", pastWeek);
* WindowOutputField pastWeekExpenses2 = WindowOutputFields.of(
* new BsonField("pastWeekExpenses", new Document("$sum", "$expenses")
* .append("window", pastWeek.toBsonDocument())));
* }
*
* @param windowOutputField A document field representing the required windowed output field.
* @return The constructed windowed output field.
*/
public static WindowOutputField of(final BsonField windowOutputField) {
return new BsonFieldWindowOutputField(notNull("windowOutputField", windowOutputField));
}
/**
* Builds a window output field of the sum of the evaluation results of the {@code expression} over the {@code window}.
*
* @param path The output field path.
* @param expression The expression.
* @param window The window.
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.dochub core/window-functions-sum $sum
*/
public static WindowOutputField sum(final String path, final TExpression expression, @Nullable final Window window) {
notNull("path", path);
notNull("expression", expression);
return simpleParameterWindowFunction(path, "$sum", expression, window);
}
/**
* Builds a window output field of the average of the evaluation results of the {@code expression} over the {@code window}.
*
* @param path The output field path.
* @param expression The expression.
* @param window The window.
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.dochub core/window-functions-avg $avg
*/
public static WindowOutputField avg(final String path, final TExpression expression, @Nullable final Window window) {
notNull("path", path);
notNull("expression", expression);
return simpleParameterWindowFunction(path, "$avg", expression, window);
}
/**
* Builds a window output field of the sample standard deviation of the evaluation results of the {@code expression} over the
* {@code window}.
*
* @param path The output field path.
* @param expression The expression.
* @param window The window.
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.dochub core/window-functions-std-dev-samp $stdDevSamp
*/
public static WindowOutputField stdDevSamp(final String path, final TExpression expression,
@Nullable final Window window) {
notNull("path", path);
notNull("expression", expression);
return simpleParameterWindowFunction(path, "$stdDevSamp", expression, window);
}
/**
* Builds a window output field of the population standard deviation of the evaluation results of the {@code expression}
* over the {@code window}.
*
* @param path The output field path.
* @param expression The expression.
* @param window The window.
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.dochub core/window-functions-std-dev-pop $stdDevPop
*/
public static WindowOutputField stdDevPop(final String path, final TExpression expression,
@Nullable final Window window) {
notNull("path", path);
notNull("expression", expression);
return simpleParameterWindowFunction(path, "$stdDevPop", expression, window);
}
/**
* Builds a window output field of the smallest of the evaluation results of the {@code expression} over the {@code window}.
*
* @param path The output field path.
* @param expression The expression.
* @param window The window.
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.manual reference/operator/aggregation/min/ $min
*/
public static WindowOutputField min(final String path, final TExpression expression, @Nullable final Window window) {
notNull("path", path);
notNull("expression", expression);
return simpleParameterWindowFunction(path, "$min", expression, window);
}
/**
* Builds a window output field of a BSON {@link org.bson.BsonType#ARRAY Array}
* of {@code N} smallest evaluation results of the {@code inExpression} over the {@code window},
* where {@code N} is the positive integral value of the {@code nExpression}.
*
* @param path The output field path.
* @param inExpression The input expression.
* @param nExpression The expression limiting the number of produced values.
* @param window The window.
* @param The type of the input expression.
* @param The type of the limiting expression.
* @return The constructed windowed output field.
* @mongodb.driver.manual reference/operator/aggregation/minN/ $minN
* @since 4.7
* @mongodb.server.release 5.2
*/
public static WindowOutputField minN(
final String path, final InExpression inExpression, final NExpression nExpression, @Nullable final Window window) {
notNull("path", path);
notNull("inExpression", inExpression);
notNull("nExpression", nExpression);
Map args = new LinkedHashMap<>(3);
args.put(ParamName.INPUT, inExpression);
args.put(ParamName.N_LOWERCASE, nExpression);
return compoundParameterWindowFunction(path, "$minN", args, window);
}
/**
* Builds a window output field of the largest of the evaluation results of the {@code expression} over the {@code window}.
*
* @param path The output field path.
* @param expression The expression.
* @param window The window.
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.manual reference/operator/aggregation/max/ $max
*/
public static WindowOutputField max(final String path, final TExpression expression, @Nullable final Window window) {
notNull("path", path);
notNull("expression", expression);
return simpleParameterWindowFunction(path, "$max", expression, window);
}
/**
* Builds a window output field of a BSON {@link org.bson.BsonType#ARRAY Array}
* of {@code N} largest evaluation results of the {@code inExpression} over the {@code window},
* where {@code N} is the positive integral value of the {@code nExpression}.
*
* @param path The output field path.
* @param inExpression The input expression.
* @param nExpression The expression limiting the number of produced values.
* @param window The window.
* @param The type of the input expression.
* @param The type of the limiting expression.
* @return The constructed windowed output field.
* @mongodb.driver.manual reference/operator/aggregation/maxN/ $maxN
* @since 4.7
* @mongodb.server.release 5.2
*/
public static WindowOutputField maxN(
final String path, final InExpression inExpression, final NExpression nExpression, @Nullable final Window window) {
notNull("path", path);
notNull("inExpression", inExpression);
notNull("nExpression", nExpression);
Map args = new LinkedHashMap<>(3);
args.put(ParamName.INPUT, inExpression);
args.put(ParamName.N_LOWERCASE, nExpression);
return compoundParameterWindowFunction(path, "$maxN", args, window);
}
/**
* Builds a window output field of the number of documents in the {@code window}.
*
* @param path The output field path.
* @param window The window.
* @return The constructed windowed output field.
* @mongodb.driver.dochub core/window-functions-count $count
*/
public static WindowOutputField count(final String path, @Nullable final Window window) {
notNull("path", path);
return simpleParameterWindowFunction(path, "$count", null, window);
}
/**
* Builds a window output field of the time derivative by subtracting the evaluation result of the {@code expression} against the last document
* and the first document in the {@code window} and dividing it by the difference in the values of the
* {@link Aggregates#setWindowFields(Object, Bson, Iterable) sortBy} field of the respective documents.
* Other documents in the {@code window} have no effect on the computation.
*
* {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) Sorting} is required.
*
* @param path The output field path.
* @param expression The expression.
* @param window The window.
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.dochub core/window-functions-derivative $derivative
*/
public static WindowOutputField derivative(final String path, final TExpression expression,
final Window window) {
notNull("path", path);
notNull("expression", expression);
notNull("window", window);
Map args = new HashMap<>(1);
args.put(ParamName.INPUT, expression);
return compoundParameterWindowFunction(path, "$derivative", args, window);
}
/**
* Builds a window output field of the time derivative by subtracting the evaluation result of the {@code expression} against the last
* document and the first document in the {@code window} and dividing it by the difference in the BSON {@link BsonType#DATE_TIME Date}
* values of the {@link Aggregates#setWindowFields(Object, Bson, Iterable) sortBy} field of the respective documents.
* Other documents in the {@code window} have no effect on the computation.
*
* {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) Sorting} is required.
*
* @param path The output field path.
* @param expression The expression.
* @param window The window.
* @param unit The desired time unit for the divisor. Allowed values are:
* {@link MongoTimeUnit#WEEK}, {@link MongoTimeUnit#DAY}, {@link MongoTimeUnit#HOUR}, {@link MongoTimeUnit#MINUTE},
* {@link MongoTimeUnit#SECOND}, {@link MongoTimeUnit#MILLISECOND}.
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.dochub core/window-functions-derivative $derivative
*/
public static WindowOutputField timeDerivative(final String path, final TExpression expression, final Window window,
final MongoTimeUnit unit) {
notNull("path", path);
notNull("expression", expression);
notNull("window", window);
notNull("unit", unit);
isTrueArgument("unit must be either of WEEK, DAY, HOUR, MINUTE, SECOND, MILLISECOND", unit.fixed());
Map args = new LinkedHashMap<>(2);
args.put(ParamName.INPUT, expression);
args.put(ParamName.UNIT, unit.value());
return compoundParameterWindowFunction(path, "$derivative", args, window);
}
/**
* Builds a window output field of the approximate integral of a function that maps values of
* the {@link Aggregates#setWindowFields(Object, Bson, Iterable) sortBy} field to evaluation results of the {@code expression}
* against the same document. The limits of integration match the {@code window} bounds.
* The approximation is done by using the
*
* trapezoidal rule.
*
* {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) Sorting} is required.
*
* @param path The output field path.
* @param expression The expression.
* @param window The window.
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.dochub core/window-functions-integral $integral
*/
public static WindowOutputField integral(final String path, final TExpression expression, final Window window) {
notNull("path", path);
notNull("expression", expression);
notNull("window", window);
Map args = new HashMap<>(1);
args.put(ParamName.INPUT, expression);
return compoundParameterWindowFunction(path, "$integral", args, window);
}
/**
* Builds a window output field of the approximate integral of a function that maps BSON {@link BsonType#DATE_TIME Date} values of
* the {@link Aggregates#setWindowFields(Object, Bson, Iterable) sortBy} field to evaluation results of the {@code expression}
* against the same document. The limits of integration match the {@code window} bounds.
* The approximation is done by using the trapezoidal rule.
*
* {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) Sorting} is required.
*
* @param path The output field path.
* @param expression The expression.
* @param window The window.
* @param unit The desired time unit for the divisor. Allowed values are:
* {@link MongoTimeUnit#WEEK}, {@link MongoTimeUnit#DAY}, {@link MongoTimeUnit#HOUR}, {@link MongoTimeUnit#MINUTE},
* {@link MongoTimeUnit#SECOND}, {@link MongoTimeUnit#MILLISECOND}.
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.dochub core/window-functions-integral $integral
*/
public static WindowOutputField timeIntegral(final String path, final TExpression expression, final Window window,
final MongoTimeUnit unit) {
notNull("path", path);
notNull("expression", expression);
notNull("window", window);
notNull("unit", unit);
isTrueArgument("unit must be either of WEEK, DAY, HOUR, MINUTE, SECOND, MILLISECOND", unit.fixed());
Map args = new LinkedHashMap<>(2);
args.put(ParamName.INPUT, expression);
args.put(ParamName.UNIT, unit.value());
return compoundParameterWindowFunction(path, "$integral", args, window);
}
/**
* Builds a window output field of the sample covariance between the evaluation results of the two expressions over the {@code window}.
*
* @param path The output field path.
* @param expression1 The first expression.
* @param expression2 The second expression.
* @param window The window.
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.dochub core/window-functions-covariance-samp $covarianceSamp
*/
public static WindowOutputField covarianceSamp(final String path, final TExpression expression1,
final TExpression expression2, @Nullable final Window window) {
notNull("path", path);
notNull("expression1", expression1);
notNull("expression2", expression2);
List expressions = new ArrayList<>(2);
expressions.add(expression1);
expressions.add(expression2);
return simpleParameterWindowFunction(path, "$covarianceSamp", expressions, window);
}
/**
* Builds a window output field of the population covariance between the evaluation results of the two expressions over the {@code window}.
*
* @param path The output field path.
* @param expression1 The first expression.
* @param expression2 The second expression.
* @param window The window.
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.dochub core/window-functions-covariance-pop $covariancePop
*/
public static WindowOutputField covariancePop(final String path, final TExpression expression1,
final TExpression expression2, @Nullable final Window window) {
notNull("path", path);
notNull("expression1", expression1);
notNull("expression2", expression2);
List expressions = new ArrayList<>(2);
expressions.add(expression1);
expressions.add(expression2);
return simpleParameterWindowFunction(path, "$covariancePop", expressions, window);
}
/**
* Builds a window output field of the exponential moving average of the evaluation results of the {@code expression} over a window
* that includes {@code n} - 1 documents preceding the current document and the current document, with more weight on documents
* closer to the current one.
*
* {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) Sorting} is required.
*
* @param path The output field path.
* @param expression The expression.
* @param n Must be positive.
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.dochub core/window-functions-exp-moving-avg $expMovingAvg
*/
public static WindowOutputField expMovingAvg(final String path, final TExpression expression, final int n) {
notNull("path", path);
notNull("expression", expression);
isTrueArgument("n > 0", n > 0);
Map args = new LinkedHashMap<>(2);
args.put(ParamName.INPUT, expression);
args.put(ParamName.N_UPPERCASE, n);
return compoundParameterWindowFunction(path, "$expMovingAvg", args, null);
}
/**
* Builds a window output field of the exponential moving average of the evaluation results of the {@code expression} over the half-bounded
* window [{@link Bound#UNBOUNDED}, {@link Bound#CURRENT}], with {@code alpha} representing the degree of weighting decrease.
*
* {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) Sorting} is required.
*
* @param path The output field path.
* @param expression The expression.
* @param alpha A parameter specifying how fast weighting decrease happens. A higher {@code alpha} discounts older observations faster.
* Must belong to the interval (0, 1).
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.dochub core/window-functions-exp-moving-avg $expMovingAvg
*/
public static WindowOutputField expMovingAvg(final String path, final TExpression expression, final double alpha) {
notNull("path", path);
notNull("expression", expression);
isTrueArgument("alpha > 0", alpha > 0);
isTrueArgument("alpha < 1", alpha < 1);
Map args = new LinkedHashMap<>(2);
args.put(ParamName.INPUT, expression);
args.put(ParamName.ALPHA, alpha);
return compoundParameterWindowFunction(path, "$expMovingAvg", args, null);
}
/**
* Builds a window output field that adds the evaluation results of the {@code expression} over the {@code window}
* to a BSON {@link org.bson.BsonType#ARRAY Array}.
* Order within the array is guaranteed if {@link Aggregates#setWindowFields(Object, Bson, Iterable) sortBy} is specified.
*
* @param path The output field path.
* @param expression The expression.
* @param window The window.
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.dochub core/window-functions-push $push
*/
public static WindowOutputField push(final String path, final TExpression expression, @Nullable final Window window) {
notNull("path", path);
notNull("expression", expression);
return simpleParameterWindowFunction(path, "$push", expression, window);
}
/**
* Builds a window output field that adds the evaluation results of the {@code expression} over the {@code window}
* to a BSON {@link org.bson.BsonType#ARRAY Array} and excludes duplicates.
* Order within the array is not specified.
*
* @param path The output field path.
* @param expression The expression.
* @param window The window.
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.dochub core/window-functions-add-to-set $addToSet
*/
public static WindowOutputField addToSet(final String path, final TExpression expression,
@Nullable final Window window) {
notNull("path", path);
notNull("expression", expression);
return simpleParameterWindowFunction(path, "$addToSet", expression, window);
}
/**
* Builds a window output field of the evaluation result of the {@code expression} against the first document in the {@code window}.
*
* {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) Sorting} is required.
*
* @param path The output field path.
* @param expression The expression.
* @param window The window.
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.manual reference/operator/aggregation/first/ $first
*/
public static WindowOutputField first(final String path, final TExpression expression, @Nullable final Window window) {
notNull("path", path);
notNull("expression", expression);
return simpleParameterWindowFunction(path, "$first", expression, window);
}
/**
* Builds a window output field of a BSON {@link org.bson.BsonType#ARRAY Array}
* of evaluation results of the {@code inExpression} against the first {@code N} documents in the {@code window},
* where {@code N} is the positive integral value of the {@code nExpression}.
*
* {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) Sorting} is required.
*
* @param path The output field path.
* @param inExpression The input expression.
* @param nExpression The expression limiting the number of produced values.
* @param window The window.
* @param The type of the input expression.
* @param The type of the limiting expression.
* @return The constructed windowed output field.
* @mongodb.driver.manual reference/operator/aggregation/firstN/ $firstN
* @since 4.7
* @mongodb.server.release 5.2
*/
public static WindowOutputField firstN(
final String path, final InExpression inExpression, final NExpression nExpression, @Nullable final Window window) {
notNull("path", path);
notNull("inExpression", inExpression);
notNull("nExpression", nExpression);
Map args = new LinkedHashMap<>(3);
args.put(ParamName.INPUT, inExpression);
args.put(ParamName.N_LOWERCASE, nExpression);
return compoundParameterWindowFunction(path, "$firstN", args, window);
}
/**
* Builds a window output field of the evaluation result of the {@code outExpression} against the top document in the {@code window}
* sorted according to the provided {@code sortBy} specification.
*
* @param path The output field path.
* @param sortBy The {@linkplain Sorts sortBy specification}. The syntax is identical to the one expected by {@link Aggregates#sort(Bson)}.
* @param outExpression The input expression.
* @param window The window.
* @param The type of the output expression.
* @return The constructed windowed output field.
* @mongodb.driver.manual reference/operator/aggregation/top/ $top
* @since 4.7
* @mongodb.server.release 5.2
*/
public static WindowOutputField top(
final String path, final Bson sortBy, final OutExpression outExpression, @Nullable final Window window) {
notNull("path", path);
notNull("sortBy", sortBy);
notNull("outExpression", outExpression);
Map args = new LinkedHashMap<>(3);
args.put(ParamName.SORT_BY, sortBy);
args.put(ParamName.OUTPUT, outExpression);
return compoundParameterWindowFunction(path, "$top", args, window);
}
/**
* Builds a window output field of a BSON {@link org.bson.BsonType#ARRAY Array}
* of evaluation results of the {@code outExpression} against the top {@code N} documents in the {@code window}
* sorted according to the provided {@code sortBy} specification,
* where {@code N} is the positive integral value of the {@code nExpression}.
*
* @param path The output field path.
* @param sortBy The {@linkplain Sorts sortBy specification}. The syntax is identical to the one expected by {@link Aggregates#sort(Bson)}.
* @param outExpression The input expression.
* @param nExpression The expression limiting the number of produced values.
* @param window The window.
* @param The type of the output expression.
* @param The type of the limiting expression.
* @return The constructed windowed output field.
* @mongodb.driver.manual reference/operator/aggregation/topN/ $topN
* @since 4.7
* @mongodb.server.release 5.2
*/
public static WindowOutputField topN(
final String path, final Bson sortBy, final OutExpression outExpression, final NExpression nExpression, @Nullable final Window window) {
notNull("path", path);
notNull("sortBy", sortBy);
notNull("outExpression", outExpression);
notNull("nExpression", nExpression);
Map args = new LinkedHashMap<>(3);
args.put(ParamName.SORT_BY, sortBy);
args.put(ParamName.OUTPUT, outExpression);
args.put(ParamName.N_LOWERCASE, nExpression);
return compoundParameterWindowFunction(path, "$topN", args, window);
}
/**
* Builds a window output field of the evaluation result of the {@code expression} against the last document in the {@code window}.
*
* {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) Sorting} is required.
*
* @param path The output field path.
* @param expression The expression.
* @param window The window.
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.manual reference/operator/aggregation/last/ $last
*/
public static WindowOutputField last(final String path, final TExpression expression, @Nullable final Window window) {
notNull("path", path);
notNull("expression", expression);
return simpleParameterWindowFunction(path, "$last", expression, window);
}
/**
* Builds a window output field of a BSON {@link org.bson.BsonType#ARRAY Array}
* of evaluation results of the {@code inExpression} against the last {@code N} documents in the {@code window},
* where {@code N} is the positive integral value of the {@code nExpression}.
*
* {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) Sorting} is required.
*
* @param path The output field path.
* @param inExpression The input expression.
* @param nExpression The expression limiting the number of produced values.
* @param window The window.
* @param The type of the input expression.
* @param The type of the limiting expression.
* @return The constructed windowed output field.
* @mongodb.driver.manual reference/operator/aggregation/lastN/ $lastN
* @since 4.7
* @mongodb.server.release 5.2
*/
public static WindowOutputField lastN(
final String path, final InExpression inExpression, final NExpression nExpression, @Nullable final Window window) {
notNull("path", path);
notNull("inExpression", inExpression);
notNull("nExpression", nExpression);
Map args = new LinkedHashMap<>(3);
args.put(ParamName.INPUT, inExpression);
args.put(ParamName.N_LOWERCASE, nExpression);
return compoundParameterWindowFunction(path, "$lastN", args, window);
}
/**
* Builds a window output field of the evaluation result of the {@code outExpression} against the bottom document in the {@code window}
* sorted according to the provided {@code sortBy} specification.
*
* @param path The output field path.
* @param sortBy The {@linkplain Sorts sortBy specification}. The syntax is identical to the one expected by {@link Aggregates#sort(Bson)}.
* @param outExpression The input expression.
* @param window The window.
* @param The type of the output expression.
* @return The constructed windowed output field.
* @mongodb.driver.manual reference/operator/aggregation/bottom/ $bottom
* @since 4.7
* @mongodb.server.release 5.2
*/
public static WindowOutputField bottom(
final String path, final Bson sortBy, final OutExpression outExpression, @Nullable final Window window) {
notNull("path", path);
notNull("sortBy", sortBy);
notNull("outExpression", outExpression);
Map args = new LinkedHashMap<>(3);
args.put(ParamName.SORT_BY, sortBy);
args.put(ParamName.OUTPUT, outExpression);
return compoundParameterWindowFunction(path, "$bottom", args, window);
}
/**
* Builds a window output field of a BSON {@link org.bson.BsonType#ARRAY Array}
* of evaluation results of the {@code outExpression} against the bottom {@code N} documents in the {@code window}
* sorted according to the provided {@code sortBy} specification,
* where {@code N} is the positive integral value of the {@code nExpression}.
*
* @param path The output field path.
* @param sortBy The {@linkplain Sorts sortBy specification}. The syntax is identical to the one expected by {@link Aggregates#sort(Bson)}.
* @param outExpression The input expression.
* @param nExpression The expression limiting the number of produced values.
* @param window The window.
* @param The type of the output expression.
* @param The type of the limiting expression.
* @return The constructed windowed output field.
* @mongodb.driver.manual reference/operator/aggregation/bottomN/ $bottomN
* @since 4.7
* @mongodb.server.release 5.2
*/
public static WindowOutputField bottomN(
final String path, final Bson sortBy, final OutExpression outExpression, final NExpression nExpression, @Nullable final Window window) {
notNull("path", path);
notNull("sortBy", sortBy);
notNull("outExpression", outExpression);
notNull("nExpression", nExpression);
Map args = new LinkedHashMap<>(3);
args.put(ParamName.SORT_BY, sortBy);
args.put(ParamName.OUTPUT, outExpression);
args.put(ParamName.N_LOWERCASE, nExpression);
return compoundParameterWindowFunction(path, "$bottomN", args, window);
}
/**
* Builds a window output field of the evaluation result of the {@code expression} for the document whose position is shifted by the given
* amount relative to the current document. If the shifted document is outside of the
* {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) partition} containing the current document,
* then the {@code defaultExpression} is used instead of the {@code expression}.
*
* {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) Sorting} is required.
*
* @param path The output field path.
* @param expression The expression.
* @param defaultExpression The default expression.
* If {@code null}, then the default expression is evaluated to BSON {@link org.bson.BsonNull null}.
* Must evaluate to a constant value.
* @param by The shift specified similarly to {@linkplain Windows rules for window bounds}:
*
* - 0 means the current document;
* - a negative value refers to the document preceding the current one;
* - a positive value refers to the document following the current one.
*
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.dochub core/window-functions-shift $shift
*/
public static WindowOutputField shift(final String path, final TExpression expression,
@Nullable final TExpression defaultExpression, final int by) {
notNull("path", path);
notNull("expression", expression);
Map args = new LinkedHashMap<>(3);
args.put(ParamName.OUTPUT, expression);
args.put(ParamName.BY, by);
if (defaultExpression != null) {
args.put(ParamName.DEFAULT, defaultExpression);
}
return compoundParameterWindowFunction(path, "$shift", args, null);
}
/**
* Builds a window output field of the order number of each document in its
* {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) partition}.
*
* {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) Sorting} is required.
*
* @param path The output field path.
* @return The constructed windowed output field.
* @mongodb.driver.dochub core/window-functions-document-number $documentNumber
*/
public static WindowOutputField documentNumber(final String path) {
notNull("path", path);
return simpleParameterWindowFunction(path, "$documentNumber", null, null);
}
/**
* Builds a window output field of the rank of each document in its
* {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) partition}.
* Documents with the same value(s) of the {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) sortBy} fields result in
* the same ranking and result in gaps in the returned ranks.
* For example, a partition with the sequence [1, 3, 3, 5] representing the values of the single {@code sortBy} field
* produces the following sequence of rank values: [1, 2, 2, 4].
*
* {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) Sorting} is required.
*
* @param path The output field path.
* @return The constructed windowed output field.
* @mongodb.driver.dochub core/window-functions-rank $rank
*/
public static WindowOutputField rank(final String path) {
notNull("path", path);
return simpleParameterWindowFunction(path, "$rank", null, null);
}
/**
* Builds a window output field of the dense rank of each document in its
* {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) partition}.
* Documents with the same value(s) of the {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) sortBy} fields result in
* the same ranking but do not result in gaps in the returned ranks.
* For example, a partition with the sequence [1, 3, 3, 5] representing the values of the single {@code sortBy} field
* produces the following sequence of rank values: [1, 2, 2, 3].
*
* {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) Sorting} is required.
*
* @param path The output field path.
* @return The constructed windowed output field.
* @mongodb.driver.dochub core/window-functions-dense-rank $denseRank
*/
public static WindowOutputField denseRank(final String path) {
notNull("path", path);
return simpleParameterWindowFunction(path, "$denseRank", null, null);
}
/**
* Builds a window output field of the last observed non-{@link BsonType#NULL Null} evaluation result of the {@code expression}.
*
* @param path The output field path.
* @param expression The expression.
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.manual reference/operator/aggregation/locf/ $locf
* @since 4.7
* @mongodb.server.release 5.2
*/
public static WindowOutputField locf(final String path, final TExpression expression) {
notNull("path", path);
notNull("expression", expression);
return simpleParameterWindowFunction(path, "$locf", expression, null);
}
/**
* Builds a window output field of a value that is equal to the evaluation result of the {@code expression} when it is non-{@link BsonType#NULL Null},
* or to the linear interpolation of surrounding evaluation results of the {@code expression} when the result is {@link BsonType#NULL Null}.
*
* {@linkplain Aggregates#setWindowFields(Object, Bson, Iterable) Sorting} is required.
*
* @param path The output field path.
* @param expression The expression.
* @param The expression type.
* @return The constructed windowed output field.
* @mongodb.driver.manual reference/operator/aggregation/linearFill/ $linearFill
* @since 4.7
* @mongodb.server.release 5.3
*/
public static WindowOutputField linearFill(final String path, final TExpression expression) {
notNull("path", path);
notNull("expression", expression);
return simpleParameterWindowFunction(path, "$linearFill", expression, null);
}
private static WindowOutputField simpleParameterWindowFunction(final String path, final String functionName,
@Nullable final Object expression,
@Nullable final Window window) {
return new BsonFieldWindowOutputField(new BsonField(path,
new SimpleParameterFunctionAndWindow(functionName, expression, window)));
}
private static WindowOutputField compoundParameterWindowFunction(final String path, final String functionName,
final Map args,
@Nullable final Window window) {
return new BsonFieldWindowOutputField(new BsonField(path,
new CompoundParameterFunctionAndWindow(functionName, args, window)));
}
private WindowOutputFields() {
throw new UnsupportedOperationException();
}
private static final class BsonFieldWindowOutputField implements WindowOutputField {
private final BsonField wrapped;
BsonFieldWindowOutputField(final BsonField field) {
wrapped = assertNotNull(field);
}
@Override
public BsonField toBsonField() {
return wrapped;
}
@Override
public boolean equals(final Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
BsonFieldWindowOutputField that = (BsonFieldWindowOutputField) o;
return wrapped.equals(that.wrapped);
}
@Override
public int hashCode() {
return wrapped.hashCode();
}
@Override
public String toString() {
return wrapped.toString();
}
}
/**
* A combination of a window function and its window.
*/
private abstract static class AbstractFunctionAndWindow implements Bson {
private final String functionName;
@Nullable
private final Window window;
AbstractFunctionAndWindow(final String functionName, @Nullable final Window window) {
this.functionName = functionName;
this.window = window;
}
final void writeWindow(final CodecRegistry codecRegistry, final BsonDocumentWriter writer) {
if (window != null) {
writer.writeName("window");
BuildersHelper.encodeValue(writer, window, codecRegistry);
}
}
final String functionName() {
return functionName;
}
final Optional window() {
return Optional.ofNullable(window);
}
}
private static final class SimpleParameterFunctionAndWindow extends AbstractFunctionAndWindow {
@Nullable
private final Object expression;
SimpleParameterFunctionAndWindow(final String functionName, @Nullable final Object expression, @Nullable final Window window) {
super(functionName, window);
this.expression = expression;
}
@Override
public BsonDocument toBsonDocument(final Class tDocumentClass, final CodecRegistry codecRegistry) {
BsonDocumentWriter writer = new BsonDocumentWriter(new BsonDocument());
writer.writeStartDocument();
writer.writeName(functionName());
if (expression == null) {
writer.writeStartDocument();
writer.writeEndDocument();
} else {
BuildersHelper.encodeValue(writer, expression, codecRegistry);
}
writeWindow(codecRegistry, writer);
writer.writeEndDocument();
return writer.getDocument();
}
@Override
public boolean equals(final Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
SimpleParameterFunctionAndWindow that = (SimpleParameterFunctionAndWindow) o;
return functionName().equals(that.functionName()) && Objects.equals(expression, that.expression)
&& window().equals(that.window());
}
@Override
public int hashCode() {
return Objects.hash(functionName(), expression, window());
}
@Override
public String toString() {
return "WindowFunction{"
+ "name='" + functionName() + '\''
+ ", expression=" + expression
+ ", window=" + window()
+ '}';
}
}
private static final class CompoundParameterFunctionAndWindow extends AbstractFunctionAndWindow {
private final Map args;
CompoundParameterFunctionAndWindow(final String functionName, final Map args,
@Nullable final Window window) {
super(functionName, window);
this.args = args;
}
@Override
public BsonDocument toBsonDocument(final Class tDocumentClass, final CodecRegistry codecRegistry) {
BsonDocumentWriter writer = new BsonDocumentWriter(new BsonDocument());
writer.writeStartDocument();
writer.writeName(functionName());
writer.writeStartDocument();
args.forEach((paramName, paramValue) -> {
writer.writeName(paramName.value());
BuildersHelper.encodeValue(writer, paramValue, codecRegistry);
});
writer.writeEndDocument();
writeWindow(codecRegistry, writer);
writer.writeEndDocument();
return writer.getDocument();
}
@Override
public boolean equals(final Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
CompoundParameterFunctionAndWindow that = (CompoundParameterFunctionAndWindow) o;
return functionName().equals(that.functionName()) && Objects.equals(args, that.args) && window().equals(that.window());
}
@Override
public int hashCode() {
return Objects.hash(functionName(), args, window());
}
@Override
public String toString() {
return "WindowFunction{"
+ "name='" + functionName() + '\''
+ ", args=" + args
+ ", window=" + window()
+ '}';
}
}
private enum ParamName {
INPUT("input"),
UNIT("unit"),
N_UPPERCASE("N"),
N_LOWERCASE("n"),
ALPHA("alpha"),
OUTPUT("output"),
BY("by"),
DEFAULT("default"),
SORT_BY("sortBy");
private final String value;
ParamName(final String value) {
this.value = value;
}
String value() {
return value;
}
}
}