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Initial implementation
+ Add unit tests with AssertJ + Add JavaDoc with examples + Add README.md
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‎.gitignore‎

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target/
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.idea/
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*.iml
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‎README.md‎

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# Java-Timestream
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A set of builders that create streams of java.time objects.
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These are fully functional streams, so you can use them like any other stream, once created.
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Once `Stream.takeWhile()` support is added in Java 9, this library will not be very useful. The lack
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of a convenient `takeWhile(Predicate<T> predicate)` method in Java 8 is what lead to the creation
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of this library.
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To get Java-Timestream, clone this repository. I am working to get this in Maven Central ASAP.
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git clone git://github.com/tginsberg/java-timestream.git
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This library can create streams of the following java.time classes:
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+ `LocalDate` via `LocalDateStream`
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+ `LocalDateTime` via `LocalDateTimeStream`
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+ `YearMonth` via `YearMonthStream`
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+ `ZonedDateTime` via `ZoneDateTimeStream`
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And has support for...
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+ Inclusive end point (`to`)
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+ Exclusive end point (`until`)
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+ Configurable period between stream elements (`every`)
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+ Streams can move forward or backward through time
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## Usage
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Every builder needs a non-null point in time to begin the stream. Therefore, each
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builder can be created using one of two methods:
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+ `.fromNow()` - Assumes 'now'
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+ `.from(T from)` - Type-specific starting point, provided by caller
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To set the point in time where the stream ends (optional!), you can call one of two methods:
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+ `.to(T to)` - Type-specific end point. Can be null to indicate forever
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+ `.to(amount, units)` - Where `amount` is a positive integer (for forward through time) or a negative integer (for backward through time), and `unit` is a valid `ChronoUnit`
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## Examples
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Create a stream of `LocalDateTime` objects, between now and hour from now, every two minutes:
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```java
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final Stream<LocalDateTime> stream = LocalDateTimeStream
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.fromNow()
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.to(1, ChronoUnit.HOURS)
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.every(2, ChronoUnit.MINUTES)
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.stream();
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```
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Or (equivalent):
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```java
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final Stream<LocalDateTime> stream = LocalDateTimeStream
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.from(LocalDateTime.now())
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.to(LocalDateTime.now().plusHours(1))
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.every(2, ChronoUnit.MINUTES)
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.stream();
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```
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Create a stream of `YearMonth` objects from today, to a year ago (backward through time), stopping before the end (exclusive),
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every month:
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```java
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final Stream<YearMonth> stream = YearMonthStream
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.fromNow()
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.until(-12, ChronoUnit.MONTHS)
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.every(1, ChronoUnit.MONTHS) // This is the default
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.stream();
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```
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## Contributing and Issues
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Please feel free to file issues for change requests or bugs. If you would like to contribute new functionality, please contact me first!

‎pom.xml‎

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<!--
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~ MIT License
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~
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~ Copyright (c) 2016 Todd Ginsberg
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~
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~ Permission is hereby granted, free of charge, to any person obtaining a copy
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~ of this software and associated documentation files (the "Software"), to deal
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~ in the Software without restriction, including without limitation the rights
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~ to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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~ copies of the Software, and to permit persons to whom the Software is
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~ furnished to do so, subject to the following conditions:
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~
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~ The above copyright notice and this permission notice shall be included in all
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~ copies or substantial portions of the Software.
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~
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~ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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~ IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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~ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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~ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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~ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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~ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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~ SOFTWARE.
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-->
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<project xmlns="http://maven.apache.org/POM/4.0.0"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<groupId>com.ginsberg</groupId>
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<artifactId>java-timestream</artifactId>
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<description>A set of builders that create streams of java.time objects</description>
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<version>1.0-SNAPSHOT</version>
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<packaging>jar</packaging>
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<licenses>
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<license>
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<name>MIT License</name>
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<url>http://www.opensource.org/licenses/mit-license.php</url>
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<distribution>repo</distribution>
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</license>
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</licenses>
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<properties>
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<java.version>1.8</java.version>
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<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
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</properties>
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<build>
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<plugins>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-compiler-plugin</artifactId>
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<version>3.5.1</version>
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<configuration>
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<source>${java.version}</source>
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<target>${java.version}</target>
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</configuration>
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</plugin>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-release-plugin</artifactId>
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<version>2.5.3</version>
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<configuration>
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<autoVersionSubmodules>true</autoVersionSubmodules>
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<useReleaseProfile>false</useReleaseProfile>
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<releaseProfiles>release</releaseProfiles>
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<goals>deploy</goals>
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</configuration>
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</plugin>
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</plugins>
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</build>
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<dependencies>
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<!-- Test dependencies -->
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<dependency>
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<groupId>org.assertj</groupId>
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<artifactId>assertj-core</artifactId>
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<version>3.4.1</version>
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<scope>test</scope>
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</dependency>
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<dependency>
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<groupId>junit</groupId>
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<artifactId>junit</artifactId>
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<version>4.12</version>
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<scope>test</scope>
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</dependency>
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</dependencies>
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<reporting>
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<plugins>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-javadoc-plugin</artifactId>
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<version>2.10.4</version>
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</plugin>
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</plugins>
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</reporting>
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</project>

‎src/main/java/com/ginsberg/timestream/AbstractComparableStream.java‎

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/*
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* MIT License
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*
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* Copyright (c) 2016 Todd Ginsberg
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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package com.ginsberg.timestream;
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import java.util.Objects;
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import java.util.function.Predicate;
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import java.util.function.UnaryOperator;
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import java.util.stream.Stream;
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import java.util.stream.StreamSupport;
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import static java.util.stream.Stream.iterate;
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/**
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* Provides generic support for open and closed-ended ranges of objects
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* that can be compared.
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*
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* @param <T> A type that implements `Comparable`.
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* @author Todd Ginsberg (todd@ginsberg.com)
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*/
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abstract class AbstractComparableStream<T extends Comparable<? super T>> {
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private final T from;
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private T to;
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private boolean closedRange = false;
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AbstractComparableStream(final T from) {
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Objects.requireNonNull(from);
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this.from = from;
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}
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void setTo(final T to) {
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this.to = to;
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this.closedRange = false;
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}
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void setUntil(final T until) {
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this.to = until;
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this.closedRange = true;
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}
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boolean isForward() {
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return to == null || from.compareTo(to) <= 0;
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}
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T getFrom() {
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return from;
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}
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/**
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* Provide an operator that returns the next value in the series.
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* @return A non-null UnaryOperator
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*/
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abstract UnaryOperator<T> next();
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/**
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* Produce a stream between the dates given, skipping
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* by the amount specified.
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*
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* @return A non-null stream of time/date.
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*/
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public Stream<T> stream() {
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return StreamSupport.stream(
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TakeWhile.of(
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iterate(from, next()).spliterator(),
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canTake()),
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false);
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}
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/**
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* Method that generates a predicate that is used by the Spliterator to
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* implement a limitation on the stream. We can take the next value in
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* the stream if one of the following are true:
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*
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* 1) There is no bound to the stream (to is null).
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* 2) We are before the end when we are moving forward through time.
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* 3) We are after the end when we are moving backward through time.
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* 4) The current time equals the end and we are not a closed range.
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*
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* @return A Predicate
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*/
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private Predicate<T> canTake() {
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return x -> {
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if (to == null) {
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return true;
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} else {
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final int compare = x.compareTo(to);
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if (compare < 0) {
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return isForward();
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} else if (compare > 0) {
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return !isForward();
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} else {
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return !closedRange;
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}
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}
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};
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}
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}

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