Merge some equivalent interfaces (#22816)

Remove `FromXContent` and use `CheckedFunction` instead.
Remove `FromXContentWithContext` and use `ContentParser` instead.

Author: nik9000

core/src/main/java/org/elasticsearch/common/network/NetworkModule.java

@@ -26,6 +26,7 @@
 import org.elasticsearch.cluster.routing.allocation.command.AllocationCommand;
 import org.elasticsearch.cluster.routing.allocation.command.CancelAllocationCommand;
 import org.elasticsearch.cluster.routing.allocation.command.MoveAllocationCommand;
+import org.elasticsearch.common.CheckedFunction;
 import org.elasticsearch.common.ParseField;
 import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
 import org.elasticsearch.common.io.stream.Writeable;
@@ -34,7 +35,7 @@
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.util.BigArrays;
 import org.elasticsearch.common.xcontent.NamedXContentRegistry;
-import org.elasticsearch.common.xcontent.NamedXContentRegistry.FromXContent;
+import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.http.HttpServerTransport;
 import org.elasticsearch.indices.breaker.CircuitBreakerService;
 import org.elasticsearch.plugins.NetworkPlugin;
@@ -47,6 +48,7 @@
 import org.elasticsearch.transport.TransportRequestHandler;
 import org.elasticsearch.transport.local.LocalTransport;
 
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -168,7 +170,7 @@ private void registerHttpTransport(String key, Supplier<HttpServerTransport> fac
      *        it is the name under which the command's reader is registered.
      */
     private static <T extends AllocationCommand> void registerAllocationCommand(Writeable.Reader<T> reader,
-                                                                                FromXContent<T> parser, ParseField commandName) {
+            CheckedFunction<XContentParser, T, IOException> parser, ParseField commandName) {
         namedXContents.add(new NamedXContentRegistry.Entry(AllocationCommand.class, commandName, parser));
         namedWriteables.add(new NamedWriteableRegistry.Entry(AllocationCommand.class, commandName.getPreferredName(), reader));
     }

core/src/main/java/org/elasticsearch/common/xcontent/AbstractObjectParser.java

@@ -19,6 +19,7 @@
 
 package org.elasticsearch.common.xcontent;
 
+import org.elasticsearch.common.CheckedFunction;
 import org.elasticsearch.common.ParseField;
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.xcontent.ObjectParser.ValueType;
@@ -36,26 +37,19 @@
 public abstract class AbstractObjectParser<Value, Context>
         implements BiFunction<XContentParser, Context, Value>, ContextParser<Context, Value> {
 
-    /**
-     * Reads an object right from the parser without any context.
-     */
-    @FunctionalInterface
-    public interface NoContextParser<T> {
-        T parse(XContentParser p) throws IOException;
-    }
-
     /**
      * Declare some field. Usually it is easier to use {@link #declareString(BiConsumer, ParseField)} or
      * {@link #declareObject(BiConsumer, ContextParser, ParseField)} rather than call this directly.
      */
     public abstract <T> void declareField(BiConsumer<Value, T> consumer, ContextParser<Context, T> parser, ParseField parseField,
             ValueType type);
 
-    public <T> void declareField(BiConsumer<Value, T> consumer, NoContextParser<T> parser, ParseField parseField, ValueType type) {
+    public <T> void declareField(BiConsumer<Value, T> consumer, CheckedFunction<XContentParser, T, IOException> parser,
+            ParseField parseField, ValueType type) {
         if (parser == null) {
             throw new IllegalArgumentException("[parser] is required");
         }
-        declareField(consumer, (p, c) -> parser.parse(p), parseField, type);
+        declareField(consumer, (p, c) -> parser.apply(p), parseField, type);
     }
 
     public <T> void declareObject(BiConsumer<Value, T> consumer, ContextParser<Context, T> objectParser, ParseField field) {
@@ -121,7 +115,7 @@ public void declareIntArray(BiConsumer<Value, List<Integer>> consumer, ParseFiel
     }
 
     public void declareRawObject(BiConsumer<Value, BytesReference> consumer, ParseField field) {
-        NoContextParser<BytesReference> bytesParser = p -> {
+        CheckedFunction<XContentParser, BytesReference, IOException> bytesParser = p -> {
             try (XContentBuilder builder = JsonXContent.contentBuilder()) {
                 builder.prettyPrint();
                 builder.copyCurrentStructure(p);

core/src/main/java/org/elasticsearch/common/xcontent/NamedXContentRegistry.java

@@ -20,6 +20,7 @@
 package org.elasticsearch.common.xcontent;
 
 import org.elasticsearch.ElasticsearchException;
+import org.elasticsearch.common.CheckedFunction;
 import org.elasticsearch.common.ParseField;
 import org.elasticsearch.common.ParsingException;
 import org.elasticsearch.common.io.stream.StreamInput;
@@ -47,25 +48,6 @@ public class NamedXContentRegistry {
      */
     public static final NamedXContentRegistry EMPTY = new NamedXContentRegistry(emptyList());
 
-    /**
-     * Parses an object with the type T from parser.
-     */
-    public interface FromXContent<T> {
-        /**
-         * Parses an object with the type T from parser.
-         */
-        T fromXContent(XContentParser parser) throws IOException;
-    }
-
-    /**
-     * Parses an object with the type T from parser.
-     * @deprecated prefer {@link FromXContent} if possible
-     */
-    @Deprecated
-    public interface FromXContentWithContext<T> {
-        T fromXContent(XContentParser parser, Object context) throws IOException;
-    }
-
     /**
      * An entry in the {@linkplain NamedXContentRegistry} containing the name of the object and the parser that can parse it.
      */
@@ -77,20 +59,20 @@ public static class Entry {
         public final ParseField name;
 
         /** A parser capability of parser the entry's class. */
-        private final FromXContentWithContext<?> parser;
+        private final ContextParser<Object, ?> parser;
 
         /** Creates a new entry which can be stored by the registry. */
-        public <T> Entry(Class<T> categoryClass, ParseField name, FromXContent<? extends T> parser) {
+        public <T> Entry(Class<T> categoryClass, ParseField name, CheckedFunction<XContentParser, ? extends T, IOException> parser) {
             this.categoryClass = Objects.requireNonNull(categoryClass);
             this.name = Objects.requireNonNull(name);
-            this.parser = Objects.requireNonNull((p, c) -> parser.fromXContent(p));
+            this.parser = Objects.requireNonNull((p, c) -> parser.apply(p));
         }
         /**
          * Creates a new entry which can be stored by the registry.
-         * @deprecated prefer {@link Entry#Entry(Class, ParseField, FromXContent)}. Contexts will be removed when possible
+         * @deprecated prefer {@link Entry#Entry(Class, ParseField, CheckedFunction)}. Contexts will be removed when possible
          */
         @Deprecated
-        public <T> Entry(Class<T> categoryClass, ParseField name, FromXContentWithContext<? extends T> parser) {
+        public <T> Entry(Class<T> categoryClass, ParseField name, ContextParser<Object, ? extends T> parser) {
             this.categoryClass = Objects.requireNonNull(categoryClass);
             this.name = Objects.requireNonNull(name);
             this.parser = Objects.requireNonNull(parser);
@@ -159,7 +141,7 @@ public <T, C> T parseNamedObject(Class<T> categoryClass, String name, XContentPa
             throw new ParsingException(parser.getTokenLocation(),
                     "Unknown " + categoryClass.getSimpleName() + " [" + name + "]: Parser didn't match");
         }
-        return categoryClass.cast(entry.parser.fromXContent(parser, context));
+        return categoryClass.cast(entry.parser.parse(parser, context));
     }
 
     /**

core/src/main/java/org/elasticsearch/plugins/SearchPlugin.java

@@ -22,13 +22,14 @@
 import org.apache.lucene.search.Query;
 import org.elasticsearch.action.search.SearchRequest;
 import org.elasticsearch.action.search.SearchResponse;
+import org.elasticsearch.common.CheckedFunction;
 import org.elasticsearch.common.ParseField;
 import org.elasticsearch.common.io.stream.NamedWriteable;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.lucene.search.function.ScoreFunction;
-import org.elasticsearch.common.xcontent.AbstractObjectParser.NoContextParser;
 import org.elasticsearch.common.xcontent.XContent;
+import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.query.QueryBuilder;
 import org.elasticsearch.index.query.QueryParser;
 import org.elasticsearch.index.query.functionscore.ScoreFunctionBuilder;
@@ -50,6 +51,7 @@
 import org.elasticsearch.search.suggest.Suggester;
 import org.elasticsearch.search.suggest.SuggestionBuilder;
 
+import java.io.IOException;
 import java.util.List;
 import java.util.Map;
 import java.util.TreeMap;
@@ -150,7 +152,7 @@ public ScoreFunctionSpec(String name, Writeable.Reader<T> reader, ScoreFunctionP
     /**
      * Specification for a {@link Suggester}.
      */
-    class SuggesterSpec<T extends SuggestionBuilder<T>> extends SearchExtensionSpec<T, NoContextParser<T>> {
+    class SuggesterSpec<T extends SuggestionBuilder<T>> extends SearchExtensionSpec<T, CheckedFunction<XContentParser, T, IOException>> {
         /**
          * Specification of custom {@link Suggester}.
          *
@@ -161,7 +163,7 @@ class SuggesterSpec<T extends SuggestionBuilder<T>> extends SearchExtensionSpec<
          *        {@link StreamInput}
          * @param parser the parser the reads the query suggester from xcontent
          */
-        public SuggesterSpec(ParseField name, Writeable.Reader<T> reader, NoContextParser<T> parser) {
+        public SuggesterSpec(ParseField name, Writeable.Reader<T> reader, CheckedFunction<XContentParser, T, IOException> parser) {
             super(name, reader, parser);
         }
 
@@ -174,7 +176,7 @@ public SuggesterSpec(ParseField name, Writeable.Reader<T> reader, NoContextParse
          *        {@link StreamInput}
          * @param parser the parser the reads the suggester builder from xcontent
          */
-        public SuggesterSpec(String name, Writeable.Reader<T> reader, NoContextParser<T> parser) {
+        public SuggesterSpec(String name, Writeable.Reader<T> reader, CheckedFunction<XContentParser, T, IOException> parser) {
             super(name, reader, parser);
         }
     }
@@ -347,12 +349,13 @@ public Map<String, Writeable.Reader<? extends InternalAggregation>> getResultRea
      * Specification for a {@link SearchExtBuilder} which represents an additional section that can be
      * parsed in a search request (within the ext element).
      */
-    class SearchExtSpec<T extends SearchExtBuilder> extends SearchExtensionSpec<T, NoContextParser<T>> {
-        public SearchExtSpec(ParseField name, Writeable.Reader<? extends T> reader, NoContextParser<T> parser) {
+    class SearchExtSpec<T extends SearchExtBuilder> extends SearchExtensionSpec<T, CheckedFunction<XContentParser, T, IOException>> {
+        public SearchExtSpec(ParseField name, Writeable.Reader<? extends T> reader,
+                CheckedFunction<XContentParser, T, IOException> parser) {
             super(name, reader, parser);
         }
 
-        public SearchExtSpec(String name, Writeable.Reader<? extends T> reader, NoContextParser<T> parser) {
+        public SearchExtSpec(String name, Writeable.Reader<? extends T> reader, CheckedFunction<XContentParser, T, IOException> parser) {
             super(name, reader, parser);
         }
     }

core/src/main/java/org/elasticsearch/repositories/blobstore/BlobStoreFormat.java

@@ -19,10 +19,10 @@
 package org.elasticsearch.repositories.blobstore;
 
 import org.elasticsearch.cluster.metadata.MetaData;
+import org.elasticsearch.common.CheckedFunction;
 import org.elasticsearch.common.blobstore.BlobContainer;
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.xcontent.NamedXContentRegistry;
-import org.elasticsearch.common.xcontent.NamedXContentRegistry.FromXContent;
 import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.common.xcontent.XContentHelper;
 import org.elasticsearch.common.xcontent.XContentParser;
@@ -40,7 +40,7 @@ public abstract class BlobStoreFormat<T extends ToXContent> {
 
     protected final String blobNameFormat;
 
-    protected final FromXContent<T> reader;
+    protected final CheckedFunction<XContentParser, T, IOException> reader;
 
     protected final NamedXContentRegistry namedXContentRegistry;
 
@@ -61,7 +61,8 @@ public abstract class BlobStoreFormat<T extends ToXContent> {
      * @param blobNameFormat format of the blobname in {@link String#format(Locale, String, Object...)} format
      * @param reader the prototype object that can deserialize objects with type T
      */
-    protected BlobStoreFormat(String blobNameFormat, FromXContent<T> reader, NamedXContentRegistry namedXContentRegistry) {
+    protected BlobStoreFormat(String blobNameFormat, CheckedFunction<XContentParser, T, IOException> reader,
+            NamedXContentRegistry namedXContentRegistry) {
         this.reader = reader;
         this.blobNameFormat = blobNameFormat;
         this.namedXContentRegistry = namedXContentRegistry;
@@ -109,7 +110,7 @@ protected String blobName(String name) {
 
     protected T read(BytesReference bytes) throws IOException {
         try (XContentParser parser = XContentHelper.createParser(namedXContentRegistry, bytes)) {
-            T obj = reader.fromXContent(parser);
+            T obj = reader.apply(parser);
             return obj;
         }
     }

core/src/main/java/org/elasticsearch/repositories/blobstore/ChecksumBlobStoreFormat.java

@@ -23,6 +23,7 @@
 import org.apache.lucene.index.IndexFormatTooNewException;
 import org.apache.lucene.index.IndexFormatTooOldException;
 import org.apache.lucene.store.OutputStreamIndexOutput;
+import org.elasticsearch.common.CheckedFunction;
 import org.elasticsearch.common.blobstore.BlobContainer;
 import org.elasticsearch.common.bytes.BytesArray;
 import org.elasticsearch.common.bytes.BytesReference;
@@ -33,10 +34,10 @@
 import org.elasticsearch.common.lucene.store.ByteArrayIndexInput;
 import org.elasticsearch.common.lucene.store.IndexOutputOutputStream;
 import org.elasticsearch.common.xcontent.NamedXContentRegistry;
-import org.elasticsearch.common.xcontent.NamedXContentRegistry.FromXContent;
 import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
+import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.common.xcontent.XContentType;
 import org.elasticsearch.gateway.CorruptStateException;
 
@@ -73,7 +74,7 @@ public class ChecksumBlobStoreFormat<T extends ToXContent> extends BlobStoreForm
      * @param compress       true if the content should be compressed
      * @param xContentType   content type that should be used for write operations
      */
-    public ChecksumBlobStoreFormat(String codec, String blobNameFormat, FromXContent<T> reader,
+    public ChecksumBlobStoreFormat(String codec, String blobNameFormat, CheckedFunction<XContentParser, T, IOException> reader,
                                    NamedXContentRegistry namedXContentRegistry, boolean compress, XContentType xContentType) {
         super(blobNameFormat, reader, namedXContentRegistry);
         this.xContentType = xContentType;
@@ -87,7 +88,7 @@ public ChecksumBlobStoreFormat(String codec, String blobNameFormat, FromXContent
      * @param reader         prototype object that can deserialize T from XContent
      * @param compress       true if the content should be compressed
      */
-    public ChecksumBlobStoreFormat(String codec, String blobNameFormat, FromXContent<T> reader,
+    public ChecksumBlobStoreFormat(String codec, String blobNameFormat, CheckedFunction<XContentParser, T, IOException> reader,
                                    NamedXContentRegistry namedXContentRegistry, boolean compress) {
         this(codec, blobNameFormat, reader, namedXContentRegistry, compress, DEFAULT_X_CONTENT_TYPE);
     }

core/src/main/java/org/elasticsearch/repositories/blobstore/LegacyBlobStoreFormat.java

@@ -18,11 +18,13 @@
  */
 package org.elasticsearch.repositories.blobstore;
 
+import org.elasticsearch.common.CheckedFunction;
 import org.elasticsearch.common.blobstore.BlobContainer;
 import org.elasticsearch.common.io.Streams;
 import org.elasticsearch.common.io.stream.BytesStreamOutput;
 import org.elasticsearch.common.xcontent.NamedXContentRegistry;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.XContentParser;
 
 import java.io.IOException;
 import java.io.InputStream;
@@ -36,7 +38,7 @@ public class LegacyBlobStoreFormat<T extends ToXContent> extends BlobStoreFormat
      * @param blobNameFormat format of the blobname in {@link String#format} format
      * @param reader the prototype object that can deserialize objects with type T
      */
-    public LegacyBlobStoreFormat(String blobNameFormat, NamedXContentRegistry.FromXContent<T> reader,
+    public LegacyBlobStoreFormat(String blobNameFormat, CheckedFunction<XContentParser, T, IOException> reader,
                                  NamedXContentRegistry namedXContentRegistry) {
         super(blobNameFormat, reader, namedXContentRegistry);
     }

core/src/main/java/org/elasticsearch/search/SearchExtBuilder.java

@@ -19,12 +19,12 @@
 
 package org.elasticsearch.search;
 
+import org.elasticsearch.common.CheckedFunction;
 import org.elasticsearch.common.io.stream.NamedWriteable;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.xcontent.ToXContent;
-import org.elasticsearch.common.xcontent.AbstractObjectParser.NoContextParser;
 import org.elasticsearch.plugins.SearchPlugin;
 import org.elasticsearch.plugins.SearchPlugin.SearchExtSpec;
 
@@ -35,7 +35,7 @@
  * read from the incoming stream, usually done adding a constructor that takes {@link StreamInput} as
  * an argument.
  *
- * Registration happens through {@link SearchPlugin#getSearchExts()}, which also needs a {@link NoContextParser} that's able to parse
+ * Registration happens through {@link SearchPlugin#getSearchExts()}, which also needs a {@link CheckedFunction} that's able to parse
  * the incoming request from the REST layer into the proper {@link SearchExtBuilder} subclass.
  *
  * {@link #getWriteableName()} must return the same name as the one used for the registration

core/src/main/java/org/elasticsearch/search/SearchModule.java

@@ -594,9 +594,8 @@ private void registerSuggesters(List<SearchPlugin> plugins) {
     private void registerSuggester(SuggesterSpec<?> suggester) {
         namedWriteables.add(new NamedWriteableRegistry.Entry(
                 SuggestionBuilder.class, suggester.getName().getPreferredName(), suggester.getReader()));
-        // TODO Merge NoContextParser and FromXContent
         namedXContents.add(new NamedXContentRegistry.Entry(SuggestionBuilder.class, suggester.getName(),
-                p -> suggester.getParser().parse(p)));
+                suggester.getParser()));
     }
 
     private Map<String, Highlighter> setupHighlighters(Settings settings, List<SearchPlugin> plugins) {
@@ -715,8 +714,7 @@ private void registerSearchExts(List<SearchPlugin> plugins) {
     }
 
     private void registerSearchExt(SearchExtSpec<?> spec) {
-        // TODO merge NoContextParser and ToXContent
-        namedXContents.add(new NamedXContentRegistry.Entry(SearchExtBuilder.class, spec.getName(), p -> spec.getParser().parse(p)));
+        namedXContents.add(new NamedXContentRegistry.Entry(SearchExtBuilder.class, spec.getName(), spec.getParser()));
         namedWriteables.add(new NamedWriteableRegistry.Entry(SearchExtBuilder.class, spec.getName().getPreferredName(), spec.getReader()));
     }