support snapshot versioning (#1053)

Author: artoonie

src/main/java/com/fasterxml/jackson/core/Version.java

@@ -113,7 +113,8 @@ public String toFullString() {
     }
 
     @Override public int hashCode() {
-        return _artifactId.hashCode() ^ _groupId.hashCode() + _majorVersion - _minorVersion + _patchLevel;
+        return _artifactId.hashCode() ^ _groupId.hashCode() ^ _snapshotInfo.hashCode()
+            + _majorVersion - _minorVersion + _patchLevel;
     }
 
     @Override
@@ -126,6 +127,7 @@ public boolean equals(Object o)
         return (other._majorVersion == _majorVersion)
             && (other._minorVersion == _minorVersion)
             && (other._patchLevel == _patchLevel)
+            && other._snapshotInfo.equals(_snapshotInfo)
             && other._artifactId.equals(_artifactId)
             && other._groupId.equals(_groupId)
             ;
@@ -145,6 +147,17 @@ public int compareTo(Version other)
                     diff = _minorVersion - other._minorVersion;
                     if (diff == 0) {
                         diff = _patchLevel - other._patchLevel;
+                        if (diff == 0) {
+                          if (isSnapshot() && other.isSnapshot()) {
+                            diff = _snapshotInfo.compareTo(other._snapshotInfo);
+                          } else if (isSnapshot() && !other.isSnapshot()) {
+                            diff = -1;
+                          } else if (!isSnapshot() && other.isSnapshot()) {
+                            diff = 1;
+                          } else {
+                            diff = 0;
+                          }
+                        }
                     }
                 }
             }

src/test/java/com/fasterxml/jackson/core/VersionTest.java

@@ -51,4 +51,36 @@ public void testCompareToAndCreatesVersionTaking6ArgumentsAndUnknownVersion() {
 
       assertTrue(version.compareTo(versionTwo) < 0);
   }
+
+  @Test
+  public void testCompareToSnapshotSame() {
+      Version version = new Version(0, 0, 0, "alpha");
+      Version versionTwo = new Version(0, 0, 0, "alpha");
+
+      assertEquals(0, version.compareTo(versionTwo));
+  }
+
+  @Test
+  public void testCompareToSnapshotDifferent() {
+      Version version = new Version(0, 0, 0, "alpha");
+      Version versionTwo = new Version(0, 0, 0, "beta");
+
+      assertTrue(version.compareTo(versionTwo) < 0);
+  }
+
+  @Test
+  public void testCompareWhenOnlyFirstHasSnapshot() {
+      Version version = new Version(0, 0, 0, "beta");
+      Version versionTwo = new Version(0, 0, 0, null);
+
+      assertEquals(-1, version.compareTo(versionTwo));
+  }
+
+  @Test
+  public void testCompareWhenOnlySecondHasSnapshot() {
+      Version version = new Version(0, 0, 0, "");
+      Version versionTwo = new Version(0, 0, 0, "beta");
+
+      assertEquals(1, version.compareTo(versionTwo));
+  }
 }