Support version format

This commit clarifies that Version now handles two different formats,
the original one (flagged V1) and a SemVer compliant format (flagged
V2). Both Version and VersionRange can switch from one format to the
other to produce backward compatible content.

See gh-1092

initializr-generator/src/main/java/io/spring/initializr/generator/version/Version.java

@@ -23,19 +23,25 @@ import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
 import java.util.StringJoiner;
+import java.util.function.Function;
 
+import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
 /**
- * Define the version number of a module. A typical version is represented as
- * {@code MAJOR.MINOR.PATCH.QUALIFIER} where the qualifier can have an extra version.
+ * Define a version. A typical version is represented as
+ * {@code MAJOR.MINOR.PATCH[QUALIFIER]} where the qualifier is optional and can have an
+ * extra version.
  * <p>
  * For example: {@code 1.2.0.RC1} is the first release candidate of 1.2.0 and
- * {@code 1.5.0.M4} is the fourth milestone of 1.5.0. The special {@code RELEASE}
- * qualifier indicates a final release (a.k.a. GA)
+ * {@code 1.5.0-M4} is the fourth milestone of 1.5.0. The special {@code RELEASE}
+ * qualifier indicates a final release (a.k.a. GA).
  * <p>
- * The main purpose of parsing a version is to compare it with another version, see
- * {@link Comparable}.
+ * Two formats are currently supported, {@link Format#V1} that uses a dot to separate the
+ * qualifier from the version itself and {@link Format#V2} that is SemVer compliant (and
+ * therefore uses a dash to separate the qualifier).
+ * <p>
+ * The main purpose of parsing a version is to compare it with another version.
  *
  * @author Stephane Nicoll
  */
@@ -54,11 +60,68 @@ public final class Version implements Serializable, Comparable<Version> {
 
 	private final Qualifier qualifier;
 
+	private final Format format;
+
 	public Version(Integer major, Integer minor, Integer patch, Qualifier qualifier) {
 		this.major = major;
 		this.minor = minor;
 		this.patch = patch;
 		this.qualifier = qualifier;
+		this.format = determineFormat(qualifier);
+	}
+
+	private static Format determineFormat(Qualifier qualifier) {
+		if (qualifier == null) {
+			return Format.V2;
+		}
+		return (qualifier.getSeparator().equals(".")) ? Format.V1 : Format.V2;
+	}
+
+	/**
+	 * Format this version to the specified {@link Format}.
+	 * @param format the format to use
+	 * @return a version compliant with the specified format.
+	 */
+	public Version format(Format format) {
+		Assert.notNull(format, () -> "Format must not be null");
+		if (this.format == format) {
+			return this;
+		}
+		if (format == Format.V1) {
+			Qualifier qualifier = formatQualifier(".", this::toV1Qualifier);
+			return new Version(this.major, this.minor, this.patch, qualifier);
+		}
+		Qualifier qualifier = formatQualifier("-", this::toV2Qualifier);
+		return new Version(this.major, this.minor, this.patch, qualifier);
+	}
+
+	private Qualifier formatQualifier(String newSeparator, Function<String, String> idTransformer) {
+		String originalQualifier = (this.qualifier != null) ? this.qualifier.getId() : null;
+		String newId = idTransformer.apply(originalQualifier);
+		if (newId != null) {
+			return new Qualifier(newId, (this.qualifier != null) ? this.qualifier.getVersion() : null, newSeparator);
+		}
+		return null;
+	}
+
+	private String toV1Qualifier(String id) {
+		if ("SNAPSHOT".equals(id)) {
+			return "BUILD-SNAPSHOT";
+		}
+		if (id == null) {
+			return "RELEASE";
+		}
+		return id;
+	}
+
+	private String toV2Qualifier(String id) {
+		if ("BUILD-SNAPSHOT".equals(id)) {
+			return "SNAPSHOT";
+		}
+		if ("RELEASE".equals(id)) {
+			return null;
+		}
+		return id;
 	}
 
 	public Integer getMajor() {
@@ -77,6 +140,10 @@ public final class Version implements Serializable, Comparable<Version> {
 		return this.qualifier;
 	}
 
+	public Format getFormat() {
+		return this.format;
+	}
+
 	/**
 	 * Parse the string representation of a {@link Version}. Throws an
 	 * {@link InvalidVersionException} if the version could not be parsed.
@@ -262,6 +329,26 @@ public final class Version implements Serializable, Comparable<Version> {
 
 	}
 
+	/**
+	 * Define the supported version format.
+	 */
+	public enum Format {
+
+		/**
+		 * Original version format, i.e. {@code Major.Minor.Patch.Qualifier} using
+		 * {@code BUILD-SNAPSHOT} as the qualifier for snapshots and {@code RELEASE} for
+		 * GAs.
+		 */
+		V1,
+
+		/**
+		 * SemVer-compliant format, i.e. {@code Major.Minor.Patch-Qualifier} using
+		 * {@code SNAPSHOT} as the qualifier for snapshots and no qualifier for GAs.
+		 */
+		V2;
+
+	}
+
 	private static class VersionQualifierComparator implements Comparator<Qualifier> {
 
 		static final String RELEASE = "RELEASE";

initializr-generator/src/main/java/io/spring/initializr/generator/version/VersionRange.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,8 @@
 
 package io.spring.initializr.generator.version;
 
+import io.spring.initializr.generator.version.Version.Format;
+
 import org.springframework.util.Assert;
 
 /**
@@ -27,9 +29,8 @@ import org.springframework.util.Assert;
  * <ul>
  * <li>"[1.2.0.RELEASE,1.3.0.RELEASE)" version 1.2.0 and any version after this, up to,
  * but not including, version 1.3.0.</li>
- * <li>"(2.0.0.RELEASE,3.2.0.RELEASE]" any version after 2.0.0 up to and including version
- * 3.2.0.</li>
- * <li>"1.4.5.RELEASE", version 1.4.5 and all later versions.</li>
+ * <li>"(2.0.0,3.2.0]" any version after 2.0.0 up to and including version 3.2.0.</li>
+ * <li>"2.5.0-M1", the first milestone of 2.5.0 and any version after that.</li>
  * </ul>
  *
  * @author Stephane Nicoll
@@ -83,6 +84,17 @@ public class VersionRange {
 		return true;
 	}
 
+	/**
+	 * Format this version range to the specified {@link Format}.
+	 * @param format the version format to use
+	 * @return a version range whose boundaries are compliant with the specified format.
+	 */
+	public VersionRange format(Format format) {
+		Version lower = this.lowerVersion.format(format);
+		Version higher = (this.higherVersion != null) ? this.higherVersion.format(format) : null;
+		return new VersionRange(lower, this.lowerInclusive, higher, this.higherInclusive);
+	}
+
 	public Version getLowerVersion() {
 		return this.lowerVersion;
 	}

initializr-generator/src/test/java/io/spring/initializr/generator/version/VersionRangeTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,12 +19,15 @@ package io.spring.initializr.generator.version;
 import java.util.Arrays;
 import java.util.Collections;
 
+import io.spring.initializr.generator.version.Version.Format;
 import org.assertj.core.api.Condition;
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
+ * Tests for {@link VersionRange}.
+ *
  * @author Stephane Nicoll
  */
 class VersionRangeTests {
@@ -148,6 +151,34 @@ class VersionRangeTests {
 		assertThat(range.toRangeString()).isEqualTo("(1.3.5.RELEASE,1.5.5.RELEASE)");
 	}
 
+	@Test
+	void formatLowerOnlyV1toV2() {
+		VersionRange range = parse("1.2.0.RELEASE").format(Format.V2);
+		assertThat(range.toRangeString()).isEqualTo("1.2.0");
+	}
+
+	@Test
+	void formatV1toV2() {
+		VersionRange range = parse("[1.2.0.RELEASE,1.3.0.M1)").format(Format.V2);
+		assertThat(range.toRangeString()).isEqualTo("[1.2.0,1.3.0-M1)");
+	}
+
+	@Test
+	void formatLowerOnlyV2toV1() {
+		VersionRange range = parse("1.2.0").format(Format.V1);
+		assertThat(range.toRangeString()).isEqualTo("1.2.0.RELEASE");
+	}
+
+	@Test
+	void formatV2toV1() {
+		VersionRange range = parse("[1.2.0,1.3.0-M1)").format(Format.V1);
+		assertThat(range.toRangeString()).isEqualTo("[1.2.0.RELEASE,1.3.0.M1)");
+	}
+
+	private static VersionRange parse(String text) {
+		return new VersionParser(Collections.emptyList()).parseRange(text);
+	}
+
 	private static Condition<String> match(String range) {
 		return match(range, new VersionParser(Collections.emptyList()));
 	}

initializr-generator/src/test/java/io/spring/initializr/generator/version/VersionTests.java

@@ -21,11 +21,14 @@ import java.util.List;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
+import io.spring.initializr.generator.version.Version.Format;
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
+ * Tests for {@link Version}.
+ *
  * @author Stephane Nicoll
  */
 class VersionTests {
@@ -153,6 +156,54 @@ class VersionTests {
 				"2020.0.0-SNAPSHOT", "2020.0.0");
 	}
 
+	@Test
+	void formatV1toV1() {
+		Version version = Version.parse("1.2.0.RELEASE");
+		assertThat(version.format(Format.V1)).isSameAs(version);
+	}
+
+	@Test
+	void formatV1SnapshotToV2() {
+		Version version = Version.parse("1.2.0.BUILD-SNAPSHOT");
+		assertThat(version.format(Format.V2)).hasToString("1.2.0-SNAPSHOT");
+	}
+
+	@Test
+	void formatV1GAToV2() {
+		Version version = Version.parse("1.2.0.RELEASE");
+		assertThat(version.format(Format.V2)).hasToString("1.2.0");
+	}
+
+	@Test
+	void formatNoQualifierToV1() {
+		Version version = Version.parse("1.2.0");
+		assertThat(version.format(Format.V1)).hasToString("1.2.0.RELEASE");
+	}
+
+	@Test
+	void formatV2toV2() {
+		Version version = Version.parse("1.2.0-RC1");
+		assertThat(version.format(Format.V2)).isSameAs(version);
+	}
+
+	@Test
+	void formatV2SnapshotToV1() {
+		Version version = Version.parse("1.2.0-SNAPSHOT");
+		assertThat(version.format(Format.V1)).hasToString("1.2.0.BUILD-SNAPSHOT");
+	}
+
+	@Test
+	void formatV2GAToV1() {
+		Version version = Version.parse("1.2.0");
+		assertThat(version.format(Format.V1)).hasToString("1.2.0.RELEASE");
+	}
+
+	@Test
+	void formatNoQualifierToV2() {
+		Version version = Version.parse("1.2.0");
+		assertThat(version.format(Format.V2)).hasToString("1.2.0");
+	}
+
 	private Version parse(String text) {
 		return this.parser.parse(text);
 	}