Convert suggestion response parsing to use NamedXContentRegistry (#23355)

We recently added parsing code to parse suggesters responses into java api objects. This was done using a switch based on the type of the returned suggestion. We can now replace the switch with using NamedXContentRegistry, which will also be used for aggs parsing.

4 files changed, 33 insertions, 34 deletions

diff --git a/core/src/main/java/org/elasticsearch/search/suggest/Suggest.java b/core/src/main/java/org/elasticsearch/search/suggest/Suggest.java
index ba5ad712f4..f85ea18109 100644
--- a/core/src/main/java/org/elasticsearch/search/suggest/Suggest.java
+++ b/core/src/main/java/org/elasticsearch/search/suggest/Suggest.java
@@ -19,6 +19,7 @@
 package org.elasticsearch.search.suggest;
 
 import org.apache.lucene.util.CollectionUtil;
+import org.elasticsearch.common.CheckedFunction;
 import org.elasticsearch.common.ParseField;
 import org.elasticsearch.common.ParsingException;
 import org.elasticsearch.common.io.stream.StreamInput;
@@ -48,7 +49,6 @@ import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
-import java.util.function.Function;
 import java.util.stream.Collectors;
 
 import static org.elasticsearch.common.xcontent.ConstructingObjectParser.constructorArg;
@@ -384,13 +384,14 @@ public class Suggest implements Iterable<Suggest.Suggestion<? extends Entry<? ex
             return builder;
         }
 
+        @SuppressWarnings("unchecked")
         public static Suggestion<? extends Entry<? extends Option>> fromXContent(XContentParser parser) throws IOException {
             ensureExpectedToken(XContentParser.Token.FIELD_NAME, parser.currentToken(), parser::getTokenLocation);
             String typeAndName = parser.currentName();
             // we need to extract the type prefix from the name and throw error if it is not present
             int delimiterPos = typeAndName.indexOf(InternalAggregation.TYPED_KEYS_DELIMITER);
-            String type = null;
-            String name = null;
+            String type;
+            String name;
             if (delimiterPos > 0) {
                 type = typeAndName.substring(0, delimiterPos);
                 name = typeAndName.substring(delimiterPos + 1);
@@ -399,35 +400,17 @@ public class Suggest implements Iterable<Suggest.Suggestion<? extends Entry<? ex
                         "Cannot parse suggestion response without type information. Set [" + RestSearchAction.TYPED_KEYS_PARAM
                                 + "] parameter on the request to ensure the type information is added to the response output");
             }
-            Suggestion suggestion = null;
-            Function<XContentParser, Entry> entryParser = null;
-            // the "size" parameter and the SortBy for TermSuggestion cannot be parsed from the response, use default values
-            // TODO investigate if we can use NamedXContentRegistry instead of this switch
-            switch (type) {
-                case Suggestion.NAME:
-                    suggestion = new Suggestion(name, -1);
-                    entryParser = Suggestion.Entry::fromXContent;
-                    break;
-                case PhraseSuggestion.NAME:
-                    suggestion = new PhraseSuggestion(name, -1);
-                    entryParser = PhraseSuggestion.Entry::fromXContent;
-                    break;
-                case TermSuggestion.NAME:
-                    suggestion = new TermSuggestion(name, -1, SortBy.SCORE);
-                    entryParser = TermSuggestion.Entry::fromXContent;
-                    break;
-                case CompletionSuggestion.NAME:
-                    suggestion = new CompletionSuggestion(name, -1);
-                    entryParser = CompletionSuggestion.Entry::fromXContent;
-                    break;
-                default:
-                    throw new ParsingException(parser.getTokenLocation(), "Unknown suggestion type [{}]", type);
-            }
+
+            return parser.namedObject(Suggestion.class, type, name);
+        }
+
+        protected static <E extends Suggestion.Entry<?>> void parseEntries(XContentParser parser, Suggestion<E> suggestion,
+                                                                           CheckedFunction<XContentParser, E, IOException> entryParser)
+                throws IOException {
             ensureExpectedToken(XContentParser.Token.START_ARRAY, parser.nextToken(), parser::getTokenLocation);
             while ((parser.nextToken()) != XContentParser.Token.END_ARRAY) {
                 suggestion.addTerm(entryParser.apply(parser));
             }
-            return suggestion;
         }
 
         /**
@@ -584,6 +567,7 @@ public class Suggest implements Iterable<Suggest.Suggestion<? extends Entry<? ex
                 }
             }
 
+            @SuppressWarnings("unchecked")
             protected O newOption(){
                 return (O) new Option();
             }
diff --git a/core/src/main/java/org/elasticsearch/search/suggest/completion/CompletionSuggestion.java b/core/src/main/java/org/elasticsearch/search/suggest/completion/CompletionSuggestion.java
index ed45104d99..229b77aad2 100644
--- a/core/src/main/java/org/elasticsearch/search/suggest/completion/CompletionSuggestion.java
+++ b/core/src/main/java/org/elasticsearch/search/suggest/completion/CompletionSuggestion.java
@@ -94,6 +94,12 @@ public final class CompletionSuggestion extends Suggest.Suggestion<CompletionSug
         return getOptions().size() > 0;
     }
 
+    public static CompletionSuggestion fromXContent(XContentParser parser, String name) throws IOException {
+        CompletionSuggestion suggestion = new CompletionSuggestion(name, -1);
+        parseEntries(parser, suggestion, CompletionSuggestion.Entry::fromXContent);
+        return suggestion;
+    }
+
     private static final class OptionPriorityQueue extends org.apache.lucene.util.PriorityQueue<Entry.Option> {
 
         private final Comparator<Suggest.Suggestion.Entry.Option> comparator;
diff --git a/core/src/main/java/org/elasticsearch/search/suggest/phrase/PhraseSuggestion.java b/core/src/main/java/org/elasticsearch/search/suggest/phrase/PhraseSuggestion.java
index fb646b03ae..bd6c828bd4 100644
--- a/core/src/main/java/org/elasticsearch/search/suggest/phrase/PhraseSuggestion.java
+++ b/core/src/main/java/org/elasticsearch/search/suggest/phrase/PhraseSuggestion.java
@@ -60,10 +60,13 @@ public class PhraseSuggestion extends Suggest.Suggestion<PhraseSuggestion.Entry>
         return new Entry();
     }
 
+    public static PhraseSuggestion fromXContent(XContentParser parser, String name) throws IOException {
+        PhraseSuggestion suggestion = new PhraseSuggestion(name, -1);
+        parseEntries(parser, suggestion, PhraseSuggestion.Entry::fromXContent);
+        return suggestion;
+    }
+
     public static class Entry extends Suggestion.Entry<Suggestion.Entry.Option> {
-        static class Fields {
-            static final String CUTOFF_SCORE = "cutoff_score";
-        }
 
         protected double cutoffScore = Double.MIN_VALUE;
 
diff --git a/core/src/main/java/org/elasticsearch/search/suggest/term/TermSuggestion.java b/core/src/main/java/org/elasticsearch/search/suggest/term/TermSuggestion.java
index 31621fb63b..185e4c76b3 100644
--- a/core/src/main/java/org/elasticsearch/search/suggest/term/TermSuggestion.java
+++ b/core/src/main/java/org/elasticsearch/search/suggest/term/TermSuggestion.java
@@ -132,6 +132,13 @@ public class TermSuggestion extends Suggestion<TermSuggestion.Entry> {
         sort.writeTo(out);
     }
 
+    public static TermSuggestion fromXContent(XContentParser parser, String name) throws IOException {
+        // the "size" parameter and the SortBy for TermSuggestion cannot be parsed from the response, use default values
+        TermSuggestion suggestion = new TermSuggestion(name, -1, SortBy.SCORE);
+        parseEntries(parser, suggestion, TermSuggestion.Entry::fromXContent);
+        return suggestion;
+    }
+
     @Override
     protected Entry newEntry() {
         return new Entry();
@@ -140,8 +147,7 @@ public class TermSuggestion extends Suggestion<TermSuggestion.Entry> {
     /**
      * Represents a part from the suggest text with suggested options.
      */
-    public static class Entry extends
-            org.elasticsearch.search.suggest.Suggest.Suggestion.Entry<TermSuggestion.Entry.Option> {
+    public static class Entry extends org.elasticsearch.search.suggest.Suggest.Suggestion.Entry<TermSuggestion.Entry.Option> {
 
         public Entry(Text text, int offset, int length) {
             super(text, offset, length);
@@ -235,7 +241,7 @@ public class TermSuggestion extends Suggestion<TermSuggestion.Entry> {
                 PARSER.declareFloat(constructorArg(), Suggestion.Entry.Option.SCORE);
             }
 
-            public static final Option fromXContent(XContentParser parser) {
+            public static Option fromXContent(XContentParser parser) {
                 return PARSER.apply(parser, null);
             }
         }