Initial import

.github/GitHub-Actions.org

@@ -0,0 +1,41 @@
+* Deploying using Github Actions
+
+** Actions definition: workflow/sonatype-deploy.yml
+
+When a GitHub Release is created, usually from a tag, this action will trigger.
+
+Using JDK8 the software will be packaged, including running any tests.
+
+Then the Deploy script will sign the created artifacts then deploy them according to the distributionManagement configuration in the `pom.xml`.
+
+** Deploy Script
+
+Uses a signing key provided from the GitHub Actions Secrets as an environment variable to sign the artifact(s) before they are then deployed.
+
+*** Inputs
+
+**** DEPLOY_PROJECTS (optional)
+
+An optional list of modules in a multi-module project to be deployed. If this value is not specified, then all projects will be deployed.
+
+** Maven Configuration
+
+Picks up the credentials from Environment variables for authenticating both with GPG and with the target deployment server (e.g. sonatype-nexus).
+
+*** Inputs
+
+**** NEXUS_USERNAME
+
+The username for your account on the deployment server.
+
+**** NEXUS_PASSWORD
+
+The password for your account on the deployement server.
+
+**** GPG_KEYNAME
+
+The key to use when signing.
+
+**** GPG_PASSPHRASE
+
+The passphrase to unlock the key to use when signing.

.github/NOTES

@@ -0,0 +1,53 @@
+Add subkeys:
+
+????
+
+Publish:
+
+gpg --send-keys --keyserver keyserver.ubuntu.com $KEYID
+gpg --send-keys --keyserver pgp.mit.edu $KEYID
+gpg --send-keys --keyserver pool.sks-keyservers.net $KEYID
+
+Backup:
+
+gpg --export --armor pcampbell@kemitix.net > gpg-key-backup.asc
+gpg --export-secret-keys --armor pcampbell@kemitix.net >> gpg-key-backup.asc
+
+Export sub-keys:
+
+gpg --export-secret-subkeys pcampbell@kemitix.net > subkeys
+
+Remove master keys:
+
+gpg --delete-secret-key pcampbell@kemitix.net
+
+Import sub-keys and clean up:
+
+gpg --import subkeys
+
+shred --remove subkeys
+
+Delete any encryption subkeys:
+
+gpg --edit-key pcampbell@kemitix.net
+
+2
+delkey
+save
+
+Change passphrase:
+
+gpg --edit-key pcampbell@kemitix.net
+passwd
+save
+
+Export keys:
+
+gpg --export --armor pcampbell@kemitix.net > codesigning.asc
+gpg --export-secret-keys --armor pcampbell@kemitix.net >> codesigning.asc
+
+Encrypt keys:
+
+gpg --symmetric --cipher-algo AES256 codesigning.asc
+
+shred codesigning.asc

.github/settings.xml

@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0">
+    <servers>
+        <server>
+            <id>sonatype-nexus-snapshots</id>
+            <username>${env.NEXUS_USERNAME}</username>
+            <password>${env.NEXUS_PASSWORD}</password>
+        </server>
+        <server>
+            <id>sonatype-nexus-staging</id>
+            <username>${env.NEXUS_USERNAME}</username>
+            <password>${env.NEXUS_PASSWORD}</password>
+        </server>
+    </servers>
+    <profiles>
+        <profile>
+            <id>gpg-sign</id>
+            <activation>
+                <activeByDefault>true</activeByDefault>
+            </activation>
+            <properties>
+                <gpg.executable>gpg</gpg.executable>
+                <gpg.keyname>${env.GPG_KEYNAME}</gpg.keyname>
+                <gpg.passphrase>${env.GPG_PASSPHRASE}</gpg.passphrase>
+            </properties>
+        </profile>
+    </profiles>
+</settings>

.github/workflows/maven-build.yml

@@ -0,0 +1,25 @@
+# This workflow will build a Java project with Maven
+# For more information see: https://help.github.com/actions/language-and-framework-guides/building-and-testing-java-with-maven
+
+name: Java CI with Maven
+
+on:
+  push:
+    branches: '*'
+  pull_request:
+    branches: '*'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        java: [ 8, 11, 13 ]
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up JDK ${{ matrix.java }}
+        uses: actions/setup-java@v1
+        with:
+          java-version: ${{ matrix.java }}
+      - name: Build with Maven
+        run: mvn -B install

.github/workflows/sonatype-deploy.yml

@@ -0,0 +1,38 @@
+name: Deploy to Sonatype Nexus
+
+on:
+  release:
+    types: [created]
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up JDK 1.8
+        uses: actions/setup-java@v1
+        with:
+          java-version: 1.8
+      - name: Build with Maven
+        run: mvn -B install
+      - name: Nexus Repo Publish
+        run: |
+          gpg --quiet \
+            --batch \
+            --yes \
+            --decrypt \
+            --passphrase="${{ secrets.GPG_PASSPHRASE }}" \
+            --output codesigning.asc \
+            .github/codesigning.asc.gpg
+          gpg --batch \
+            --fast-import codesigning.asc
+          mvn --settings .github/settings.xml \
+            -Dskip-Tests=true \
+            -P release \
+            -B \
+            deploy
+        env:
+          NEXUS_USERNAME: ${{ secrets.NEXUS_USERNAME }}
+          NEXUS_PASSWORD: ${{ secrets.NEXUS_PASSWORD }}
+          GPG_KEYNAME: ${{ secrets.GPG_KEYNAME }}
+          GPG_PASSPHRASE: ${{ secrets.GPG_PASSPHRASE }}

.gitignore

@@ -0,0 +1,16 @@
+*.jqwik-database*
+
+*.iml
+.idea/
+target/
+pom.xml.tag
+pom.xml.releaseBackup
+pom.xml.versionsBackup
+pom.xml.next
+release.properties
+dependency-reduced-pom.xml
+buildNumber.properties
+.mvn/timing.properties
+
+# Avoid ignoring Maven wrapper jar file (.jar files are usually ignored)
+!/.mvn/wrapper/maven-wrapper.jar

README.md

@@ -0,0 +1,37 @@
+# List Head/Tail
+
+![Sonatype Nexus (Release)](https://img.shields.io/nexus/r/https/oss.sonatype.org/net.kemitix/list-head-tail.svg?style=for-the-badge)
+![Maven Central](https://img.shields.io/maven-central/v/net.kemitix/list-head-tail.svg?style=for-the-badge)
+
+Provides a `head()` and `tail()` implementation for `List<>` objects in Java.
+
+## Usage
+
+```java
+import net.kemitix.list.HeadTail;
+import java.util.List;
+import static org.assertj.core.api.Assertions.assertThat;
+class Usage {
+  List<String> list = Arrays.asList("a", "b", "c");
+  Optional<String> head = HeadTail.head(list);      // head()
+  assertThat(head).contains("a");
+  List<String> tail = HeadTail.tail(list);          // tail()
+  assertThat(tail).containsExactly("b", "c");
+}
+```
+
+Statically importing the `head()` and `tail()` methods will be more
+readable and idiomatically FP.
+
+```java
+import static net.kemitix.list.HeadTail.*;
+import java.util.List;
+import static org.assertj.core.api.Assertions.assertThat;
+class Usage {
+  List<String> list = Arrays.asList("a", "b", "c");
+  Optional<String> head = head(list);               // head()
+  assertThat(head).contains("a");
+  List<String> tail = tail(list);                   // tail()
+  assertThat(tail).containsExactly("b", "c");
+}
+```

pom.xml

@@ -0,0 +1,59 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>net.kemitix</groupId>
+        <artifactId>kemitix-parent</artifactId>
+        <version>5.3.0</version>
+        <relativePath/>
+    </parent>
+
+    <artifactId>list-head-tail</artifactId>
+    <version>DEV-SNAPSHOT</version>
+    <inceptionYear>2020</inceptionYear>
+
+    <properties>
+        <java.version>1.8</java.version>
+        <maven.compiler.source>${java.version}</maven.compiler.source>
+        <maven.compiler.target>${java.version}</maven.compiler.target>
+        <tiles-maven-plugin.version>2.16</tiles-maven-plugin.version>
+        <kemitix-maven-tiles.version>2.5.0</kemitix-maven-tiles.version>
+        <kemitix-checkstyle-ruleset.version>5.4.0</kemitix-checkstyle-ruleset.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>5.6.1</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>3.15.0</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>io.repaint.maven</groupId>
+                <artifactId>tiles-maven-plugin</artifactId>
+                <version>${tiles-maven-plugin.version}</version>
+                <extensions>true</extensions>
+                <configuration>
+                    <tiles>
+                        <tile>net.kemitix.tiles:all:${kemitix-maven-tiles.version}</tile>
+                        <tile>net.kemitix.checkstyle:tile:${kemitix-checkstyle-ruleset.version}</tile>
+                    </tiles>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

src/main/java/net/kemitix/list/HeadTail.java

@@ -0,0 +1,62 @@
+/**
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2020 Paul Campbell
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
+ * and associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies
+ * or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+ * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
+ * AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package net.kemitix.list;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * Provides a simple implementation of head() and tail() for {@link List}s.
+ */
+public interface HeadTail {
+
+    /**
+     * Returns the first item in the list as an {@link Optional}.
+     *
+     * @param list the list
+     * @param <X> the type of the lists contents
+     * @return an Optional containing the first item in the list, or empty if
+     * the list is empty.
+     */
+    static <X> Optional<X> head(final List<X> list) {
+        if (list.isEmpty()) {
+            return Optional.empty();
+        }
+        return Optional.ofNullable(list.get(0));
+    }
+
+    /**
+     * Returns the list, minus the first item.
+     *
+     * @param list the list
+     * @param <X> the type of the lists contents
+     * @return a view of the list starting with the second item, or an empty
+     * list if the original list has less than two items.
+     */
+    static <X> List<X> tail(final List<X> list) {
+        if (list.size() < 1) {
+            return Collections.emptyList();
+        }
+        return list.subList(1, list.size());
+    }
+}

src/test/java/net/kemitix/list/HeadTailTest.java

@@ -0,0 +1,51 @@
+package net.kemitix.list;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.UUID;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class HeadTailTest {
+
+    private String headValue = "1-" + UUID.randomUUID().toString();
+    private String secondValue = "2-" +  UUID.randomUUID().toString();
+    private String thirdValue = "3-" + UUID.randomUUID().toString();
+    private List<String> emptyList = Collections.emptyList();
+    private List<String> singletonList = Collections.singletonList(headValue);
+    private List<String> aList = Arrays.asList(
+            headValue, secondValue, thirdValue
+    );
+    private List<String> tailValue = Arrays.asList(
+            secondValue, thirdValue
+    );
+
+    @Test
+    public void headOfAnEmptyListIsEmpty() {
+        assertThat(HeadTail.head(emptyList)).isEmpty();
+    }
+    @Test
+    public void headOfASingletonListIsTheItem() {
+        assertThat(HeadTail.head(singletonList)).contains(headValue);
+    }
+    @Test
+    public void headOfAListIsTheFirstItem() {
+        assertThat(HeadTail.head(aList)).contains(headValue);
+    }
+
+    @Test
+    public void tailOfAnEmptyListIsEmpty() {
+        assertThat(HeadTail.tail(emptyList)).isEmpty();
+    }
+    @Test
+    public void tailOfASingletonListIsEmpty() {
+        assertThat(HeadTail.tail(singletonList)).isEmpty();
+    }
+    @Test
+    public void tailOfAListIsMinusTheHead() {
+        assertThat(HeadTail.tail(aList)).isEqualTo(tailValue);
+    }
+}