Create CastingConverter

Extract trivial casting logic from DefaultConverter to a new dedicated
(high priority) CastingConverter.

Fixes issues when trying to convert to, say, Object.

Author: hinerm

src/main/java/org/scijava/convert/CastingConverter.java

@@ -0,0 +1,90 @@
+/*
+ * #%L
+ * SciJava Common shared library for SciJava software.
+ * %%
+ * Copyright (C) 2009 - 2016 Board of Regents of the University of
+ * Wisconsin-Madison, Broad Institute of MIT and Harvard, and Max Planck
+ * Institute of Molecular Cell Biology and Genetics.
+ * %%
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ * #L%
+ */
+package org.scijava.convert;
+
+import org.scijava.Priority;
+import org.scijava.plugin.Plugin;
+import org.scijava.util.ClassUtils;
+import org.scijava.util.ConversionUtils;
+import org.scijava.util.GenericUtils;
+
+/**
+ * Minimal {@link Converter} implementation to do direct casting.
+ *
+ * @author Mark Hiner hinerm at gmail.com
+ */
+@Plugin(type = Converter.class, priority = Priority.FIRST_PRIORITY - 1)
+public class CastingConverter extends AbstractConverter<Object, Object> {
+
+	@SuppressWarnings("deprecation")
+	@Override
+	public boolean canConvert(final Object src, final Class<?> dest) {
+		return ClassUtils.canCast(src, dest);
+	}
+
+	@Override
+	public boolean canConvert(final Class<?> src, final Class<?> dest) {
+		// OK if the existing object can be casted
+		if (ConversionUtils.canCast(src, dest))
+			return true;
+
+		return false;
+	}
+
+	@SuppressWarnings("unchecked")
+	@Override
+	public <T> T convert(final Object src, final Class<T> dest) {
+		// NB: Regardless of whether the destination type is an array or
+		// collection,
+		// we still want to cast directly if doing so is possible. But note that
+		// in
+		// general, this check does not detect cases of incompatible generic
+		// parameter types. If this limitation becomes a problem in the future
+		// we
+		// can extend the logic here to provide additional signatures of canCast
+		// which operate on Types in general rather than only Classes. However,
+		// the
+		// logic could become complex very quickly in various subclassing cases,
+		// generic parameters resolved vs. propagated, etc.
+		final Class<?> c = GenericUtils.getClass(dest);
+		return (T) ConversionUtils.cast(src, c);
+	}
+
+	@Override
+	public Class<Object> getOutputType() {
+		return Object.class;
+	}
+
+	@Override
+	public Class<Object> getInputType() {
+		return Object.class;
+	}
+}

src/main/java/org/scijava/convert/DefaultConverter.java

@@ -61,17 +61,6 @@ public class DefaultConverter extends AbstractConverter<Object, Object> {
 
 	@Override
 	public Object convert(final Object src, final Type dest) {
-		// NB: Regardless of whether the destination type is an array or collection,
-		// we still want to cast directly if doing so is possible. But note that in
-		// general, this check does not detect cases of incompatible generic
-		// parameter types. If this limitation becomes a problem in the future we
-		// can extend the logic here to provide additional signatures of canCast
-		// which operate on Types in general rather than only Classes. However, the
-		// logic could become complex very quickly in various subclassing cases,
-		// generic parameters resolved vs. propagated, etc.
-		final Class<?> c = GenericUtils.getClass(dest);
-		if (c != null && ConversionUtils.canCast(src, c)) return ConversionUtils
-			.cast(src, c);
 
 		// Handle array types, including generic array types.
 		if (isArray(dest)) {