Add support for value provider

Improve the "hints" section of the metadata so that each hint can provide
the reference to a value provider.

A value provider defines how a tool can discover the potential values of
a property based on the context. The provider is identifed by a name and
may have an arbitrary number of parameters.

Closes gh-3303

spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationprocessor/ConfigurationMetadataAnnotationProcessorTests.java

@@ -19,6 +19,8 @@ package org.springframework.boot.configurationprocessor;
 import java.io.File;
 import java.io.FileWriter;
 import java.io.IOException;
+import java.util.Arrays;
+import java.util.Collections;
 
 import org.json.JSONArray;
 import org.json.JSONObject;
@@ -369,6 +371,20 @@ public class ConfigurationMetadataAnnotationProcessorTests {
 				containsHint("simple.the-name").withValue(0, "boot", "Bla bla"));
 	}
 
+	@Test
+	public void mergingOfHintWithProvider() throws Exception {
+		writeAdditionalHints(
+				new ItemHint("simple.theName", Collections.<ItemHint.ValueHint>emptyList(), Arrays.asList(
+						new ItemHint.ProviderHint("first", Collections.<String,Object>singletonMap("target", "org.foo")),
+						new ItemHint.ProviderHint("second", null))
+				));
+
+		ConfigurationMetadata metadata = compile(SimpleProperties.class);
+		assertThat(metadata, containsHint("simple.the-name")
+				.withProvider("first", "target", "org.foo")
+				.withProvider("second"));
+	}
+
 	@Test
 	public void incrementalBuild() throws Exception {
 		TestProject project = new TestProject(this.temporaryFolder, FooProperties.class,

spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationprocessor/ConfigurationMetadataMatchers.java

@@ -17,11 +17,14 @@
 package org.springframework.boot.configurationprocessor;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
+import java.util.Map;
 
 import org.hamcrest.BaseMatcher;
 import org.hamcrest.Description;
 import org.hamcrest.Matcher;
+import org.hamcrest.collection.IsMapContaining;
 import org.springframework.boot.configurationprocessor.metadata.ConfigurationMetadata;
 import org.springframework.boot.configurationprocessor.metadata.ItemHint;
 import org.springframework.boot.configurationprocessor.metadata.ItemMetadata;
@@ -206,13 +209,16 @@ public class ConfigurationMetadataMatchers {
 
 		private final List<ValueHintMatcher> values;
 
+		private final List<ProviderHintMatcher> providers;
+
 		public ContainsHintMatcher(String name) {
-			this(name, new ArrayList<ValueHintMatcher>());
+			this(name, new ArrayList<ValueHintMatcher>(), new ArrayList<ProviderHintMatcher>());
 		}
 
-		public ContainsHintMatcher(String name, List<ValueHintMatcher> values) {
+		public ContainsHintMatcher(String name, List<ValueHintMatcher> values, List<ProviderHintMatcher> providers) {
 			this.name = name;
 			this.values = values;
+			this.providers = providers;
 		}
 
 		@Override
@@ -230,6 +236,11 @@ public class ConfigurationMetadataMatchers {
 					return false;
 				}
 			}
+			for (ProviderHintMatcher provider : this.providers) {
+				if (!provider.matches(itemHint)) {
+					return false;
+				}
+			}
 			return true;
 		}
 
@@ -251,12 +262,29 @@ public class ConfigurationMetadataMatchers {
 			if (this.values != null) {
 				description.appendText(" values ").appendValue(this.values);
 			}
+			if (this.providers != null) {
+				description.appendText(" providers ").appendValue(this.providers);
+			}
 		}
 
 		public ContainsHintMatcher withValue(int index, Object value, String description) {
 			List<ValueHintMatcher> values = new ArrayList<ValueHintMatcher>(this.values);
 			values.add(new ValueHintMatcher(index, value, description));
-			return new ContainsHintMatcher(this.name, values);
+			return new ContainsHintMatcher(this.name, values, this.providers);
+		}
+
+		public ContainsHintMatcher withProvider(int index, String provider, Map<String,Object> parameters) {
+			List<ProviderHintMatcher> providers = new ArrayList<ProviderHintMatcher>(this.providers);
+			providers.add(new ProviderHintMatcher(index, provider, parameters));
+			return new ContainsHintMatcher(this.name, this.values, providers);
+		}
+
+		public ContainsHintMatcher withProvider(String provider, String key, Object value) {
+			return withProvider(this.providers.size(), provider, Collections.singletonMap(key, value));
+		}
+
+		public ContainsHintMatcher withProvider(String provider) {
+			return withProvider(this.providers.size(), provider, null);
 		}
 
 		private ItemHint getFirstHintWithName(ConfigurationMetadata metadata, String name) {
@@ -314,4 +342,50 @@ public class ConfigurationMetadataMatchers {
 
 	}
 
+	public static class ProviderHintMatcher extends BaseMatcher<ItemHint> {
+		private final int index;
+		private final String name;
+		private final Map<String, Object> parameters;
+
+		public ProviderHintMatcher(int index, String name, Map<String, Object> parameters) {
+			this.index = index;
+			this.name = name;
+			this.parameters = parameters;
+		}
+
+		@Override
+		public boolean matches(Object item) {
+			ItemHint hint = (ItemHint) item;
+			if (this.index + 1 > hint.getProviders().size()) {
+				return false;
+			}
+			ItemHint.ProviderHint providerHint = hint.getProviders().get(index);
+			if (this.name != null
+					&& !this.name.equals(providerHint.getName())) {
+				return false;
+			}
+			if (this.parameters != null) {
+				for (Map.Entry<String, Object> entry : this.parameters.entrySet()) {
+					if (!IsMapContaining.hasEntry(entry.getKey(), entry.getValue())
+							.matches(providerHint.getParameters())) {
+						return false;
+					}
+				}
+			}
+			return true;
+		}
+
+		@Override
+		public void describeTo(Description description) {
+			description.appendText("provider hint ");
+			if (this.name != null) {
+				description.appendText(" name ").appendValue(this.name);
+			}
+			if (this.parameters != null) {
+				description.appendText(" parameters ").appendValue(this.parameters);
+			}
+		}
+
+	}
+
 }

spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationprocessor/metadata/JsonMarshallerTests.java

@@ -20,6 +20,8 @@ import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
+import java.util.Arrays;
+import java.util.Collections;
 
 import org.junit.Test;
 
@@ -56,6 +58,9 @@ public class JsonMarshallerTests {
 		metadata.add(ItemHint.newHint("a.b"));
 		metadata.add(ItemHint.newHint("c", new ItemHint.ValueHint(123, "hey"),
 				new ItemHint.ValueHint(456, null)));
+		metadata.add(new ItemHint("d", null, Arrays.asList(
+				new ItemHint.ProviderHint("first", Collections.<String,Object>singletonMap("target", "foo")),
+				new ItemHint.ProviderHint("second", null))));
 		ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
 		JsonMarshaller marshaller = new JsonMarshaller();
 		marshaller.write(metadata, outputStream);
@@ -76,6 +81,9 @@ public class JsonMarshallerTests {
 		assertThat(read, containsHint("a.b"));
 		assertThat(read,
 				containsHint("c").withValue(0, 123, "hey").withValue(1, 456, null));
+		assertThat(read, containsHint("d")
+				.withProvider("first", "target", "foo")
+				.withProvider("second"));
 	}
 
 }