Add OriginCapablePropertySource interfaces

Add `OriginCapablePropertySource` interface and supporting classes so
that `PropertySource` implementations can reveal the source of any
given property.

The `TextResourcePropertyOrigin` can be used for sources that load
values from a text `Resource` and can track line/column numbers.

See gh-8517
See gh-8142

spring-boot/src/main/java/org/springframework/boot/env/OriginCapablePropertySource.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2012-2017 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.boot.env;
+
+import org.springframework.core.env.PropertySource;
+
+/**
+ * An additional interface that may be implemented by a {@link PropertySource} that can
+ * return origin information. For example a property source that's backed by a file may
+ * return origin information for line and column numbers.
+ *
+ * @author Phillip Webb
+ * @since 2.0.0
+ */
+public interface OriginCapablePropertySource {
+
+	/**
+	 * Return the origin of the given property name or {@code null} if the origin cannot
+	 * be determined.
+	 * @param name the property name
+	 * @return the origin of the property or {@code null}
+	 */
+	PropertyOrigin getPropertyOrigin(String name);
+
+}

spring-boot/src/main/java/org/springframework/boot/env/PropertyOrigin.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2012-2017 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.boot.env;
+
+import java.io.File;
+
+/**
+ * Interface that uniquely represents the origin of a property. For example, a property
+ * loaded from a {@link File} may have an origin made up of the file name along with
+ * line/column numbers.
+ * <p>
+ * Implementations must provide sensible {@link #hashCode()}, {@link #equals(Object)} and
+ * {@link #toString()} implementations.
+ *
+ * @author Madhura Bhave
+ * @author Phillip Webb
+ * @since 2.0.0
+ */
+public interface PropertyOrigin {
+
+}

spring-boot/src/main/java/org/springframework/boot/env/TextResourcePropertyOrigin.java

@@ -0,0 +1,156 @@
+/*
+ * Copyright 2012-2017 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.boot.env;
+
+import org.springframework.core.io.Resource;
+import org.springframework.util.ObjectUtils;
+
+/**
+ * {@link PropertyOrigin} for an item loaded from a text resource. Provides access to the
+ * origina {@link Resource} that loaded the text and a {@link Location} within it.
+ *
+ * @author Madhura Bhave
+ * @author Phillip Webb
+ * @since 2.0.0
+ */
+public class TextResourcePropertyOrigin implements PropertyOrigin {
+
+	private final Resource resource;
+
+	private final Location location;
+
+	public TextResourcePropertyOrigin(Resource resource, Location location) {
+		this.resource = resource;
+		this.location = location;
+	}
+
+	/**
+	 * Return the resource where the property originated.
+	 * @return the resource the text resource or {@code null}
+	 */
+	public Resource getResource() {
+		return this.resource;
+	}
+
+	/**
+	 * Return the location of the property within the source (if known).
+	 * @return the location or {@code null}
+	 */
+	public Location getLocation() {
+		return this.location;
+	}
+
+	@Override
+	public int hashCode() {
+		int result = 1;
+		result = 31 * result + ObjectUtils.nullSafeHashCode(this.resource);
+		result = 31 * result + ObjectUtils.nullSafeHashCode(this.location);
+		return result;
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj) {
+			return true;
+		}
+		if (obj == null) {
+			return false;
+		}
+		if (obj instanceof TextResourcePropertyOrigin) {
+			TextResourcePropertyOrigin other = (TextResourcePropertyOrigin) obj;
+			boolean result = true;
+			result = result && ObjectUtils.nullSafeEquals(this.resource, other.resource);
+			result = result && ObjectUtils.nullSafeEquals(this.location, other.location);
+			return result;
+		}
+		return super.equals(obj);
+	}
+
+	@Override
+	public String toString() {
+		StringBuilder result = new StringBuilder();
+		result.append(this.resource == null ? "unknown resource [?]"
+				: this.resource.getDescription());
+		if (this.location != null) {
+			result.append(":" + this.location);
+		}
+		return result.toString();
+	}
+
+	/**
+	 * A location (line and column number) within the resource.
+	 */
+	public final static class Location {
+
+		private final int line;
+
+		private final int column;
+
+		/**
+		 * Create a new {@link Location} instance.
+		 * @param line the line number (zero indexed)
+		 * @param column the column number (zero indexed)
+		 */
+		public Location(int line, int column) {
+			this.line = line;
+			this.column = column;
+		}
+
+		/**
+		 * Return the line of the text resource where the property originated.
+		 * @return the line number (zero indexed)
+		 */
+		public int getLine() {
+			return this.line;
+		}
+
+		/**
+		 * Return the column of the text resource where the property originated.
+		 * @return the column number (zero indexed)
+		 */
+		public int getColumn() {
+			return this.column;
+		}
+
+		@Override
+		public int hashCode() {
+			return (31 * this.line) + this.column;
+		}
+
+		@Override
+		public boolean equals(Object obj) {
+			if (this == obj) {
+				return true;
+			}
+			if (obj == null || getClass() != obj.getClass()) {
+				return false;
+			}
+			Location other = (Location) obj;
+			boolean result = true;
+			result = result && this.line == other.line;
+			result = result && this.column == other.column;
+			return result;
+		}
+
+		@Override
+		public String toString() {
+			return (this.line + 1) + ":" + (this.column + 1);
+		}
+
+	}
+
+}

spring-boot/src/test/java/org/springframework/boot/env/TextResourcePropertyOriginTests.java

@@ -0,0 +1,135 @@
+/*
+ * Copyright 2012-2017 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.boot.env;
+
+import org.junit.Test;
+
+import org.springframework.boot.env.TextResourcePropertyOrigin.Location;
+import org.springframework.core.io.ClassPathResource;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link TextResourcePropertyOrigin}.
+ *
+ * @author Phillip Webb
+ */
+public class TextResourcePropertyOriginTests {
+
+	@Test
+	public void createWithNullResourceShouldSetNullResource() throws Exception {
+		TextResourcePropertyOrigin origin = new TextResourcePropertyOrigin(null, null);
+		assertThat(origin.getResource()).isNull();
+	}
+
+	@Test
+	public void createWithNullLocationShouldSetNullLocation() throws Exception {
+		TextResourcePropertyOrigin origin = new TextResourcePropertyOrigin(null, null);
+		assertThat(origin.getLocation()).isNull();
+	}
+
+	@Test
+	public void getResourceShouldReturnResource() throws Exception {
+		ClassPathResource resource = new ClassPathResource("foo.txt");
+		TextResourcePropertyOrigin origin = new TextResourcePropertyOrigin(resource,
+				null);
+		assertThat(origin.getResource()).isEqualTo(resource);
+	}
+
+	@Test
+	public void getLocationShouldReturnLocation() throws Exception {
+		Location location = new Location(1, 2);
+		TextResourcePropertyOrigin origin = new TextResourcePropertyOrigin(null,
+				location);
+		assertThat(origin.getLocation()).isEqualTo(location);
+
+	}
+
+	@Test
+	public void getLocationLineShouldReturnLine() throws Exception {
+		Location location = new Location(1, 2);
+		assertThat(location.getLine()).isEqualTo(1);
+	}
+
+	@Test
+	public void getLocationColumnShouldReturnColumn() throws Exception {
+		Location location = new Location(1, 2);
+		assertThat(location.getColumn()).isEqualTo(2);
+	}
+
+	@Test
+	public void locationToStringShouldReturnNiceString() throws Exception {
+		Location location = new Location(1, 2);
+		assertThat(location.toString()).isEqualTo("2:3");
+	}
+
+	@Test
+	public void toStringShouldReturnNiceString() throws Exception {
+		ClassPathResource resource = new ClassPathResource("foo.txt");
+		Location location = new Location(1, 2);
+		TextResourcePropertyOrigin origin = new TextResourcePropertyOrigin(resource,
+				location);
+		assertThat(origin.toString()).isEqualTo("class path resource [foo.txt]:2:3");
+	}
+
+	@Test
+	public void toStringWhenResourceIsNullShouldReturnNiceString() throws Exception {
+		Location location = new Location(1, 2);
+		TextResourcePropertyOrigin origin = new TextResourcePropertyOrigin(null,
+				location);
+		assertThat(origin.toString()).isEqualTo("unknown resource [?]:2:3");
+	}
+
+	@Test
+	public void toStringWhenLocationIsNullShouldReturnNiceString() throws Exception {
+		ClassPathResource resource = new ClassPathResource("foo.txt");
+		TextResourcePropertyOrigin origin = new TextResourcePropertyOrigin(resource,
+				null);
+		assertThat(origin.toString()).isEqualTo("class path resource [foo.txt]");
+	}
+
+	@Test
+	public void locationEqualsAndHashcodeShouldUseLineAndColumn() throws Exception {
+		Location location1 = new Location(1, 2);
+		Location location2 = new Location(1, 2);
+		Location location3 = new Location(2, 2);
+		assertThat(location1.hashCode()).isEqualTo(location1.hashCode());
+		assertThat(location1.hashCode()).isEqualTo(location2.hashCode());
+		assertThat(location1).isEqualTo(location1);
+		assertThat(location1).isEqualTo(location2);
+		assertThat(location1).isNotEqualTo(location3);
+	}
+
+	@Test
+	public void equalsAndHashCodeShouldResourceAndLocation() throws Exception {
+		TextResourcePropertyOrigin origin1 = new TextResourcePropertyOrigin(
+				new ClassPathResource("foo.txt"), new Location(1, 2));
+		TextResourcePropertyOrigin origin2 = new TextResourcePropertyOrigin(
+				new ClassPathResource("foo.txt"), new Location(1, 2));
+		TextResourcePropertyOrigin origin3 = new TextResourcePropertyOrigin(
+				new ClassPathResource("foo.txt"), new Location(2, 2));
+		TextResourcePropertyOrigin origin4 = new TextResourcePropertyOrigin(
+				new ClassPathResource("foo2.txt"), new Location(1, 2));
+		assertThat(origin1.hashCode()).isEqualTo(origin1.hashCode());
+		assertThat(origin1.hashCode()).isEqualTo(origin2.hashCode());
+		assertThat(origin1).isEqualTo(origin1);
+		assertThat(origin1).isEqualTo(origin2);
+		assertThat(origin1).isNotEqualTo(origin3);
+		assertThat(origin1).isNotEqualTo(origin4);
+	}
+
+}