DATAJPA-218 - Add Predicate based QBE implementation.

We convert a given Example to a set of and combinded Predicates using CriteriaBuilder.
Cycles within associations are not allowed and result in an InvalidDataAccessApiUsageException.
At this time only SingularAttributes are taken into concern.

Author: christophstrobl

src/main/java/org/springframework/data/domain/Example.java

@@ -0,0 +1,216 @@
+/*
+ * Copyright 2015 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.domain;
+
+import org.springframework.data.domain.Example.StringMatcher;
+import org.springframework.util.Assert;
+
+/**
+ * Define specific property handling for a Dot-Path.
+ * 
+ * @author Christoph Strobl
+ */
+public class PropertySpecifier {
+
+	private final String path;
+
+	private StringMatcher stringMatcher;
+	private Boolean ignoreCase;
+
+	private PropertyValueTransformer valueTransformer;
+
+	/**
+	 * Creates new {@link PropertySpecifier} for given path.
+	 * 
+	 * @param path Dot-Path to the property. Must not be {@literal null}.
+	 */
+	PropertySpecifier(String path) {
+
+		Assert.hasText(path, "Path must not be null/empty!");
+		this.path = path;
+	}
+
+	/**
+	 * Get the properties Dot-Path.
+	 * 
+	 * @return never {@literal null}.
+	 */
+	public String getPath() {
+		return path;
+	}
+
+	/**
+	 * Get the {@link StringMatcher}.
+	 * 
+	 * @return can be {@literal null}.
+	 */
+	public StringMatcher getStringMatcher() {
+		return stringMatcher;
+	}
+
+	/**
+	 * @return {literal true} in case {@link StringMatcher} defined.
+	 */
+	public boolean hasStringMatcher() {
+		return this.stringMatcher != null;
+	}
+
+	/**
+	 * @return {@literal null} if not set.
+	 */
+	public Boolean getIgnoreCase() {
+		return ignoreCase;
+	}
+
+	/**
+	 * Get the property transformer to be applied.
+	 * 
+	 * @return never {@literal null}.
+	 */
+	public PropertyValueTransformer getPropertyValueTransformer() {
+		return valueTransformer == null ? NoOpPropertyValueTransformer.INSTANCE : valueTransformer;
+	}
+
+	/**
+	 * Transforms a given source using the {@link PropertyValueTransformer}.
+	 * 
+	 * @param source
+	 * @return
+	 */
+	public Object transformValue(Object source) {
+		return getPropertyValueTransformer().convert(source);
+	}
+
+	/**
+	 * Creates new case ignoring {@link PropertySpecifier} for given path.
+	 * 
+	 * @param propertyPath must not be {@literal null}.
+	 * @return
+	 */
+	public static PropertySpecifier ignoreCase(String propertyPath) {
+		return new Builder(propertyPath).ignoreCase().get();
+	}
+
+	/**
+	 * Create new {@link Builder} for specifying {@link PropertySpecifier}.
+	 * 
+	 * @param propertyPath must not be {@literal null}.
+	 * @return
+	 */
+	public static Builder newPropertySpecifier(String propertyPath) {
+		return new Builder(propertyPath);
+	}
+
+	/**
+	 * Builder for specifying desired behavior of {@link PropertySpecifier}.
+	 * 
+	 * @author Christoph Strobl
+	 */
+	public static class Builder {
+
+		private PropertySpecifier specifier;
+
+		Builder(String path) {
+			specifier = new PropertySpecifier(path);
+		}
+
+		/**
+		 * Sets the {@link StringMatcher} used for {@link PropertySpecifier}.
+		 * 
+		 * @param stringMatcher
+		 * @return
+		 * @see Builder#stringMatcher(StringMatcher)
+		 */
+		public Builder with(StringMatcher stringMatcher) {
+			return stringMatcher(stringMatcher);
+		}
+
+		/**
+		 * Sets the {@link PropertyValueTransformer} used for {@link PropertySpecifier}.
+		 * 
+		 * @param valueTransformer
+		 * @return
+		 * @see Builder#valueTransformer(PropertyValueTransformer)
+		 */
+		public Builder with(PropertyValueTransformer valueTransformer) {
+			return valueTransformer(valueTransformer);
+		}
+
+		/**
+		 * Sets the {@link StringMatcher} used for {@link PropertySpecifier}.
+		 * 
+		 * @param stringMatcher
+		 * @return
+		 */
+		public Builder stringMatcher(StringMatcher stringMatcher) {
+			return stringMatcher(stringMatcher, specifier.ignoreCase);
+		}
+
+		/**
+		 * Sets the {@link StringMatcher} used for {@link PropertySpecifier}.
+		 * 
+		 * @param stringMatcher
+		 * @param ignoreCase
+		 * @return
+		 */
+		public Builder stringMatcher(StringMatcher stringMatcher, Boolean ignoreCase) {
+
+			specifier.stringMatcher = stringMatcher;
+			specifier.ignoreCase = ignoreCase;
+			return this;
+		}
+
+		/**
+		 * @return
+		 */
+		public Builder ignoreCase() {
+			specifier.ignoreCase = Boolean.TRUE;
+			return this;
+		}
+
+		/**
+		 * Sets the {@link PropertyValueTransformer} used for {@link PropertySpecifier}.
+		 * 
+		 * @param valueTransformer
+		 * @return
+		 */
+		public Builder valueTransformer(PropertyValueTransformer valueTransformer) {
+			specifier.valueTransformer = valueTransformer;
+			return this;
+		}
+
+		/**
+		 * @return {@link PropertySpecifier} as defined.
+		 */
+		public PropertySpecifier get() {
+			return this.specifier;
+		}
+	}
+
+	/**
+	 * @author Christoph Strobl
+	 */
+	static enum NoOpPropertyValueTransformer implements PropertyValueTransformer {
+
+		INSTANCE;
+
+		@Override
+		public Object convert(Object source) {
+			return source;
+		}
+
+	}
+}

src/main/java/org/springframework/data/domain/PropertySpecifier.java

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2015 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.domain;
+
+import org.springframework.core.convert.converter.Converter;
+
+/**
+ * @author Christoph Strobl
+ */
+public interface PropertyValueTransformer extends Converter<Object, Object> {
+	// TODO: should we use the converter interface directly or not at all?
+}