initial refactoring of completion suggester

6 files changed, 254 insertions, 97 deletions

diff --git a/core/src/main/java/org/elasticsearch/search/suggest/completion/context/CategoryContextMapping.java b/core/src/main/java/org/elasticsearch/search/suggest/completion/context/CategoryContextMapping.java
index dffbb1aa80..10ac3935cc 100644
--- a/core/src/main/java/org/elasticsearch/search/suggest/completion/context/CategoryContextMapping.java
+++ b/core/src/main/java/org/elasticsearch/search/suggest/completion/context/CategoryContextMapping.java
@@ -158,12 +158,12 @@ public class CategoryContextMapping extends ContextMapping {
         List<QueryContext> queryContexts = new ArrayList<>();
         Token token = parser.nextToken();
         if (token == Token.START_OBJECT || token == Token.VALUE_STRING) {
-            CategoryQueryContext parse = CategoryQueryContext.parse(parser);
-            queryContexts.add(new QueryContext(parse.getCategory().toString(), parse.getBoost(), parse.isPrefix()));
+            CategoryQueryContext parse = CategoryQueryContext.PROTOTYPE.fromXContext(parser);
+            queryContexts.add(new QueryContext(parse.getCategory(), parse.getBoost(), parse.isPrefix()));
         } else if (token == Token.START_ARRAY) {
             while (parser.nextToken() != Token.END_ARRAY) {
-                CategoryQueryContext parse = CategoryQueryContext.parse(parser);
-                queryContexts.add(new QueryContext(parse.getCategory().toString(), parse.getBoost(), parse.isPrefix()));
+                CategoryQueryContext parse = CategoryQueryContext.PROTOTYPE.fromXContext(parser);
+                queryContexts.add(new QueryContext(parse.getCategory(), parse.getBoost(), parse.isPrefix()));
             }
         }
         return queryContexts;
diff --git a/core/src/main/java/org/elasticsearch/search/suggest/completion/context/CategoryQueryContext.java b/core/src/main/java/org/elasticsearch/search/suggest/completion/context/CategoryQueryContext.java
index c493126577..8db9afe5ae 100644
--- a/core/src/main/java/org/elasticsearch/search/suggest/completion/context/CategoryQueryContext.java
+++ b/core/src/main/java/org/elasticsearch/search/suggest/completion/context/CategoryQueryContext.java
@@ -21,12 +21,15 @@ package org.elasticsearch.search.suggest.completion.context;
 
 import org.elasticsearch.ElasticsearchParseException;
 import org.elasticsearch.common.ParseField;
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.xcontent.ObjectParser;
-import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 
 import java.io.IOException;
+import java.util.Collections;
+import java.util.Objects;
 
 import static org.elasticsearch.search.suggest.completion.context.CategoryContextMapping.CONTEXT_BOOST;
 import static org.elasticsearch.search.suggest.completion.context.CategoryContextMapping.CONTEXT_PREFIX;
@@ -35,12 +38,15 @@ import static org.elasticsearch.search.suggest.completion.context.CategoryContex
 /**
  * Defines the query context for {@link CategoryContextMapping}
  */
-public final class CategoryQueryContext implements ToXContent {
-    private final CharSequence category;
+public final class CategoryQueryContext implements QueryContext {
+    public static final String NAME = "category";
+    public static final CategoryQueryContext PROTOTYPE = new CategoryQueryContext("", 1, false);
+
+    private final String category;
     private final boolean isPrefix;
     private final int boost;
 
-    private CategoryQueryContext(CharSequence category, int boost, boolean isPrefix) {
+    private CategoryQueryContext(String category, int boost, boolean isPrefix) {
         this.category = category;
         this.boost = boost;
         this.isPrefix = isPrefix;
@@ -49,7 +55,7 @@ public final class CategoryQueryContext implements ToXContent {
     /**
      * Returns the category of the context
      */
-    public CharSequence getCategory() {
+    public String getCategory() {
         return category;
     }
 
@@ -71,8 +77,81 @@ public final class CategoryQueryContext implements ToXContent {
         return new Builder();
     }
 
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        CategoryQueryContext that = (CategoryQueryContext) o;
+
+        if (isPrefix != that.isPrefix) return false;
+        if (boost != that.boost) return false;
+        return category != null ? category.equals(that.category) : that.category == null;
+
+    }
+
+    @Override
+    public int hashCode() {
+        int result = category != null ? category.hashCode() : 0;
+        result = 31 * result + (isPrefix ? 1 : 0);
+        result = 31 * result + boost;
+        return result;
+    }
+
+    @Override
+    public String getWriteableName() {
+        return NAME;
+    }
+
+    private static ObjectParser<Builder, Void> CATEGORY_PARSER = new ObjectParser<>(NAME, null);
+    static {
+        CATEGORY_PARSER.declareString(Builder::setCategory, new ParseField(CONTEXT_VALUE));
+        CATEGORY_PARSER.declareInt(Builder::setBoost, new ParseField(CONTEXT_BOOST));
+        CATEGORY_PARSER.declareBoolean(Builder::setPrefix, new ParseField(CONTEXT_PREFIX));
+    }
+
+    @Override
+    public CategoryQueryContext fromXContext(XContentParser parser) throws IOException {
+        XContentParser.Token token = parser.currentToken();
+        Builder builder = builder();
+        if (token == XContentParser.Token.START_OBJECT) {
+            CATEGORY_PARSER.parse(parser, builder);
+        } else if (token == XContentParser.Token.VALUE_STRING) {
+            builder.setCategory(parser.text());
+        } else {
+            throw new ElasticsearchParseException("category context must be an object or string");
+        }
+        return builder.build();
+    }
+
+    @Override
+    public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
+        builder.startObject();
+        builder.field(CONTEXT_VALUE, category);
+        builder.field(CONTEXT_BOOST, boost);
+        builder.field(CONTEXT_PREFIX, isPrefix);
+        builder.endObject();
+        return builder;
+    }
+
+    @Override
+    public void writeTo(StreamOutput out) throws IOException {
+        out.writeBoolean(isPrefix);
+        out.writeVInt(boost);
+        out.writeString(category);
+    }
+
+    @Override
+    public QueryContext readFrom(StreamInput in) throws IOException {
+        Builder builder = new Builder();
+        builder.isPrefix = in.readBoolean();
+        builder.boost = in.readVInt();
+        builder.category = in.readString();
+        return builder.build();
+    }
+
     public static class Builder {
-        private CharSequence category;
+        private String category;
         private boolean isPrefix = false;
         private int boost = 1;
 
@@ -80,11 +159,12 @@ public final class CategoryQueryContext implements ToXContent {
         }
 
         /**
-         * Sets the category of the context.
+         * Sets the category of the category.
          * This is a required field
          */
-        public Builder setCategory(CharSequence context) {
-            this.category = context;
+        public Builder setCategory(String category) {
+            Objects.requireNonNull(category, "category must not be null");
+            this.category = category;
             return this;
         }
 
@@ -102,42 +182,16 @@ public final class CategoryQueryContext implements ToXContent {
          * Defaults to 1.
          */
         public Builder setBoost(int boost) {
+            if (boost <= 0) {
+                throw new IllegalArgumentException("boost must be greater than 0");
+            }
             this.boost = boost;
             return this;
         }
 
         public CategoryQueryContext build() {
+            Objects.requireNonNull(category, "category must not be null");
             return new CategoryQueryContext(category, boost, isPrefix);
         }
     }
-
-    private static ObjectParser<Builder, Void> CATEGORY_PARSER = new ObjectParser<>("category", null);
-    static {
-        CATEGORY_PARSER.declareString(Builder::setCategory, new ParseField("context"));
-        CATEGORY_PARSER.declareInt(Builder::setBoost, new ParseField("boost"));
-        CATEGORY_PARSER.declareBoolean(Builder::setPrefix, new ParseField("prefix"));
-    }
-
-    public static CategoryQueryContext parse(XContentParser parser) throws IOException {
-        XContentParser.Token token = parser.currentToken();
-        Builder builder = builder();
-        if (token == XContentParser.Token.START_OBJECT) {
-            CATEGORY_PARSER.parse(parser, builder);
-        } else if (token == XContentParser.Token.VALUE_STRING) {
-            builder.setCategory(parser.text());
-        } else {
-            throw new ElasticsearchParseException("category context must be an object or string");
-        }
-        return builder.build();
-    }
-
-    @Override
-    public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
-        builder.startObject();
-        builder.field(CONTEXT_VALUE, category);
-        builder.field(CONTEXT_BOOST, boost);
-        builder.field(CONTEXT_PREFIX, isPrefix);
-        builder.endObject();
-        return builder;
-    }
 }
diff --git a/core/src/main/java/org/elasticsearch/search/suggest/completion/context/ContextMappings.java b/core/src/main/java/org/elasticsearch/search/suggest/completion/context/ContextMappings.java
index 9d4bed4f66..ccd4b2d584 100644
--- a/core/src/main/java/org/elasticsearch/search/suggest/completion/context/ContextMappings.java
+++ b/core/src/main/java/org/elasticsearch/search/suggest/completion/context/ContextMappings.java
@@ -43,7 +43,6 @@ import java.util.Set;
 
 import static org.elasticsearch.search.suggest.completion.context.ContextMapping.FIELD_NAME;
 import static org.elasticsearch.search.suggest.completion.context.ContextMapping.FIELD_TYPE;
-import static org.elasticsearch.search.suggest.completion.context.ContextMapping.QueryContext;
 import static org.elasticsearch.search.suggest.completion.context.ContextMapping.Type;
 
 /**
@@ -153,7 +152,7 @@ public class ContextMappings implements ToXContent {
      * @param queryContexts a map of context mapping name and collected query contexts
      * @return a context-enabled query
      */
-    public ContextQuery toContextQuery(CompletionQuery query, Map<String, List<QueryContext>> queryContexts) {
+    public ContextQuery toContextQuery(CompletionQuery query, Map<String, List<ContextMapping.QueryContext>> queryContexts) {
         ContextQuery typedContextQuery = new ContextQuery(query);
         if (queryContexts.isEmpty() == false) {
             CharsRefBuilder scratch = new CharsRefBuilder();
@@ -162,9 +161,9 @@ public class ContextMappings implements ToXContent {
                 scratch.setCharAt(0, (char) typeId);
                 scratch.setLength(1);
                 ContextMapping mapping = contextMappings.get(typeId);
-                List<QueryContext> queryContext = queryContexts.get(mapping.name());
+                List<ContextMapping.QueryContext> queryContext = queryContexts.get(mapping.name());
                 if (queryContext != null) {
-                    for (QueryContext context : queryContext) {
+                    for (ContextMapping.QueryContext context : queryContext) {
                         scratch.append(context.context);
                         typedContextQuery.addContext(scratch.toCharsRef(), context.boost, !context.isPrefix);
                         scratch.setLength(1);
diff --git a/core/src/main/java/org/elasticsearch/search/suggest/completion/context/GeoContextMapping.java b/core/src/main/java/org/elasticsearch/search/suggest/completion/context/GeoContextMapping.java
index f2f3d10215..2c90429302 100644
--- a/core/src/main/java/org/elasticsearch/search/suggest/completion/context/GeoContextMapping.java
+++ b/core/src/main/java/org/elasticsearch/search/suggest/completion/context/GeoContextMapping.java
@@ -247,18 +247,15 @@ public class GeoContextMapping extends ContextMapping {
         List<GeoQueryContext> queryContexts = new ArrayList<>();
         Token token = parser.nextToken();
         if (token == Token.START_OBJECT || token == Token.VALUE_STRING) {
-            queryContexts.add(GeoQueryContext.parse(parser));
+            queryContexts.add(GeoQueryContext.PROTOTYPE.fromXContext(parser));
         } else if (token == Token.START_ARRAY) {
             while (parser.nextToken() != Token.END_ARRAY) {
-                queryContexts.add(GeoQueryContext.parse(parser));
+                queryContexts.add(GeoQueryContext.PROTOTYPE.fromXContext(parser));
             }
         }
         List<QueryContext> queryContextList = new ArrayList<>();
         for (GeoQueryContext queryContext : queryContexts) {
-            int minPrecision = this.precision;
-            if (queryContext.getPrecision() != -1) {
-                minPrecision = Math.min(minPrecision, queryContext.getPrecision());
-            }
+            int minPrecision = Math.min(this.precision, queryContext.getPrecision());
             GeoPoint point = queryContext.getGeoPoint();
             final Collection<String> locations = new HashSet<>();
             String geoHash = GeoHashUtils.stringEncode(point.getLon(), point.getLat(), minPrecision);
diff --git a/core/src/main/java/org/elasticsearch/search/suggest/completion/context/GeoQueryContext.java b/core/src/main/java/org/elasticsearch/search/suggest/completion/context/GeoQueryContext.java
index da9191bf2d..5b406abc1d 100644
--- a/core/src/main/java/org/elasticsearch/search/suggest/completion/context/GeoQueryContext.java
+++ b/core/src/main/java/org/elasticsearch/search/suggest/completion/context/GeoQueryContext.java
@@ -23,14 +23,17 @@ import org.elasticsearch.ElasticsearchParseException;
 import org.elasticsearch.common.ParseField;
 import org.elasticsearch.common.geo.GeoPoint;
 import org.elasticsearch.common.geo.GeoUtils;
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.xcontent.ObjectParser;
-import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.Objects;
 
 import static org.elasticsearch.search.suggest.completion.context.GeoContextMapping.CONTEXT_BOOST;
 import static org.elasticsearch.search.suggest.completion.context.GeoContextMapping.CONTEXT_NEIGHBOURS;
@@ -40,7 +43,10 @@ import static org.elasticsearch.search.suggest.completion.context.GeoContextMapp
 /**
  * Defines the query context for {@link GeoContextMapping}
  */
-public final class GeoQueryContext implements ToXContent {
+public final class GeoQueryContext implements QueryContext {
+    public static final String NAME = "geo";
+    public static final GeoQueryContext PROTOTYPE = new GeoQueryContext(null, 1, 12, Collections.emptyList());
+
     private final GeoPoint geoPoint;
     private final int boost;
     private final int precision;
@@ -81,14 +87,109 @@ public final class GeoQueryContext implements ToXContent {
         return neighbours;
     }
 
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        GeoQueryContext that = (GeoQueryContext) o;
+
+        if (boost != that.boost) return false;
+        if (precision != that.precision) return false;
+        if (geoPoint != null ? !geoPoint.equals(that.geoPoint) : that.geoPoint != null) return false;
+        return neighbours != null ? neighbours.equals(that.neighbours) : that.neighbours == null;
+
+    }
+
+    @Override
+    public int hashCode() {
+        int result = geoPoint != null ? geoPoint.hashCode() : 0;
+        result = 31 * result + boost;
+        result = 31 * result + precision;
+        result = 31 * result + (neighbours != null ? neighbours.hashCode() : 0);
+        return result;
+    }
+
     public static Builder builder() {
         return new Builder();
     }
 
+    @Override
+    public String getWriteableName() {
+        return NAME;
+    }
+
+    private static ObjectParser<GeoQueryContext.Builder, Void> GEO_CONTEXT_PARSER = new ObjectParser<>(NAME, null);
+    static {
+        GEO_CONTEXT_PARSER.declareField((parser, geoQueryContext, geoContextMapping) -> geoQueryContext.setGeoPoint(GeoUtils.parseGeoPoint(parser)), new ParseField(CONTEXT_VALUE), ObjectParser.ValueType.OBJECT);
+        GEO_CONTEXT_PARSER.declareInt(GeoQueryContext.Builder::setBoost, new ParseField(CONTEXT_BOOST));
+        // TODO : add string support for precision for GeoUtils.geoHashLevelsForPrecision()
+        GEO_CONTEXT_PARSER.declareInt(GeoQueryContext.Builder::setPrecision, new ParseField(CONTEXT_PRECISION));
+        // TODO : add string array support for precision for GeoUtils.geoHashLevelsForPrecision()
+        GEO_CONTEXT_PARSER.declareIntArray(GeoQueryContext.Builder::setNeighbours, new ParseField(CONTEXT_NEIGHBOURS));
+        GEO_CONTEXT_PARSER.declareDouble(GeoQueryContext.Builder::setLat, new ParseField("lat"));
+        GEO_CONTEXT_PARSER.declareDouble(GeoQueryContext.Builder::setLon, new ParseField("lon"));
+    }
+
+    @Override
+    public GeoQueryContext fromXContext(XContentParser parser) throws IOException {
+        XContentParser.Token token = parser.currentToken();
+        GeoQueryContext.Builder builder = new Builder();
+        if (token == XContentParser.Token.START_OBJECT) {
+            GEO_CONTEXT_PARSER.parse(parser, builder);
+        } else if (token == XContentParser.Token.VALUE_STRING) {
+            builder.setGeoPoint(GeoPoint.fromGeohash(parser.text()));
+        } else {
+            throw new ElasticsearchParseException("geo context must be an object or string");
+        }
+        return builder.build();
+    }
+
+    @Override
+    public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
+        builder.startObject();
+        builder.startObject(CONTEXT_VALUE);
+        builder.field("lat", geoPoint.getLat());
+        builder.field("lon", geoPoint.getLon());
+        builder.endObject();
+        builder.field(CONTEXT_BOOST, boost);
+        builder.field(CONTEXT_NEIGHBOURS, neighbours);
+        builder.field(CONTEXT_PRECISION, precision);
+        builder.endObject();
+        return builder;
+    }
+
+    @Override
+    public void writeTo(StreamOutput out) throws IOException {
+        out.writeGeoPoint(geoPoint);
+        out.writeVInt(boost);
+        out.writeInt(precision);
+        out.writeVInt(neighbours.size());
+        for (Integer neighbour : neighbours) {
+            out.writeVInt(neighbour);
+        }
+    }
+
+    @Override
+    public QueryContext readFrom(StreamInput in) throws IOException {
+        Builder builder = new Builder();
+        builder.geoPoint = in.readGeoPoint();
+        builder.boost = in.readVInt();
+        builder.precision = in.readInt();
+        int nNeighbour = in.readVInt();
+        if (nNeighbour != 0) {
+            builder.neighbours = new ArrayList<>(nNeighbour);
+            for (int i = 0; i < nNeighbour; i++) {
+                builder.neighbours.add(in.readVInt());
+            }
+        }
+        return builder.build();
+    }
+
     public static class Builder {
         private GeoPoint geoPoint;
         private int boost = 1;
-        private int precision = -1;
+        private int precision = 12;
         private List<Integer> neighbours = Collections.emptyList();
 
         public Builder() {
@@ -99,6 +200,9 @@ public final class GeoQueryContext implements ToXContent {
          * Defaults to 1
          */
         public Builder setBoost(int boost) {
+            if (boost <= 0) {
+                throw new IllegalArgumentException("boost must be greater than 0");
+            }
             this.boost = boost;
             return this;
         }
@@ -108,6 +212,9 @@ public final class GeoQueryContext implements ToXContent {
          * Defaults to using index-time precision level
          */
         public Builder setPrecision(int precision) {
+            if (precision < 1 || precision > 12) {
+                throw new IllegalArgumentException("precision must be between 1 and 12");
+            }
             this.precision = precision;
             return this;
         }
@@ -117,6 +224,11 @@ public final class GeoQueryContext implements ToXContent {
          * Defaults to only considering neighbours at the index-time precision level
          */
         public Builder setNeighbours(List<Integer> neighbours) {
+            for (int neighbour : neighbours) {
+                if (neighbour < 1 || neighbour > 12) {
+                    throw new IllegalArgumentException("neighbour value must be between 1 and 12");
+                }
+            }
             this.neighbours = neighbours;
             return this;
         }
@@ -126,6 +238,7 @@ public final class GeoQueryContext implements ToXContent {
          * This is a required field
          */
         public Builder setGeoPoint(GeoPoint geoPoint) {
+            Objects.requireNonNull(geoPoint, "geoPoint must not be null");
             this.geoPoint = geoPoint;
             return this;
         }
@@ -144,50 +257,10 @@ public final class GeoQueryContext implements ToXContent {
             if (geoPoint == null) {
                 if (Double.isNaN(lat) == false && Double.isNaN(lon) == false) {
                     geoPoint = new GeoPoint(lat, lon);
-                } else {
-                    throw new IllegalArgumentException("no geohash or geo point provided");
                 }
             }
+            Objects.requireNonNull(geoPoint, "geoPoint must not be null");
             return new GeoQueryContext(geoPoint, boost, precision, neighbours);
         }
     }
-
-    private static ObjectParser<GeoQueryContext.Builder, Void> GEO_CONTEXT_PARSER = new ObjectParser<>("geo", null);
-    static {
-        GEO_CONTEXT_PARSER.declareField((parser, geoQueryContext, geoContextMapping) -> geoQueryContext.setGeoPoint(GeoUtils.parseGeoPoint(parser)), new ParseField("context"), ObjectParser.ValueType.OBJECT);
-        GEO_CONTEXT_PARSER.declareInt(GeoQueryContext.Builder::setBoost, new ParseField("boost"));
-        // TODO : add string support for precision for GeoUtils.geoHashLevelsForPrecision()
-        GEO_CONTEXT_PARSER.declareInt(GeoQueryContext.Builder::setPrecision, new ParseField("precision"));
-        // TODO : add string array support for precision for GeoUtils.geoHashLevelsForPrecision()
-        GEO_CONTEXT_PARSER.declareIntArray(GeoQueryContext.Builder::setNeighbours, new ParseField("neighbours"));
-        GEO_CONTEXT_PARSER.declareDouble(GeoQueryContext.Builder::setLat, new ParseField("lat"));
-        GEO_CONTEXT_PARSER.declareDouble(GeoQueryContext.Builder::setLon, new ParseField("lon"));
-    }
-
-    public static GeoQueryContext parse(XContentParser parser) throws IOException {
-        XContentParser.Token token = parser.currentToken();
-        GeoQueryContext.Builder builder = new Builder();
-        if (token == XContentParser.Token.START_OBJECT) {
-            GEO_CONTEXT_PARSER.parse(parser, builder);
-        } else if (token == XContentParser.Token.VALUE_STRING) {
-            builder.setGeoPoint(GeoPoint.fromGeohash(parser.text()));
-        } else {
-            throw new ElasticsearchParseException("geo context must be an object or string");
-        }
-        return builder.build();
-    }
-
-    @Override
-    public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
-        builder.startObject();
-        builder.startObject(CONTEXT_VALUE);
-        builder.field("lat", geoPoint.getLat());
-        builder.field("lon", geoPoint.getLon());
-        builder.endObject();
-        builder.field(CONTEXT_BOOST, boost);
-        builder.field(CONTEXT_NEIGHBOURS, neighbours);
-        builder.field(CONTEXT_PRECISION, precision);
-        builder.endObject();
-        return builder;
-    }
 }
diff --git a/core/src/main/java/org/elasticsearch/search/suggest/completion/context/QueryContext.java b/core/src/main/java/org/elasticsearch/search/suggest/completion/context/QueryContext.java
new file mode 100644
index 0000000000..ccfd4a8d3d
--- /dev/null
+++ b/core/src/main/java/org/elasticsearch/search/suggest/completion/context/QueryContext.java
@@ -0,0 +1,34 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you 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.elasticsearch.search.suggest.completion.context;
+
+import org.elasticsearch.common.io.stream.NamedWriteable;
+import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.XContentParser;
+
+import java.io.IOException;
+
+/**
+ * Interface for serializing/de-serializing completion query context
+ */
+public interface QueryContext extends ToXContent, NamedWriteable<QueryContext> {
+
+    QueryContext fromXContext(XContentParser parser) throws IOException;
+}