* Removed `script.default_lang` setting and made `painless` the hardcoded default script language.

** The default script language is now maintained in `Script` class.
* Added `script.legacy.default_lang` setting that controls the default language for scripts that are stored inside documents (for example percolator queries).  This defaults to groovy.
** Added `QueryParseContext#getDefaultScriptLanguage()` that manages the default scripting language. Returns always `painless`, unless loading query/search request in legacy mode then the returns what is configured in `script.legacy.default_lang` setting.
** In the aggregation parsing code added `ParserContext` that also holds the default scripting language like `QueryParseContext`. Most parser don't have access to `QueryParseContext`. This is for scripts in aggregations.
* The `lang` script field is always serialized (toXContent).

Closes #20122

3 files changed, 29 insertions, 24 deletions

diff --git a/core/src/main/java/org/elasticsearch/search/aggregations/bucket/range/RangeParser.java b/core/src/main/java/org/elasticsearch/search/aggregations/bucket/range/RangeParser.java
index 6ebd413d2d..c8cb2c7671 100644
--- a/core/src/main/java/org/elasticsearch/search/aggregations/bucket/range/RangeParser.java
+++ b/core/src/main/java/org/elasticsearch/search/aggregations/bucket/range/RangeParser.java
@@ -24,6 +24,7 @@ import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.common.xcontent.XContentParser.Token;
 import org.elasticsearch.search.aggregations.bucket.range.RangeAggregator.Range;
 import org.elasticsearch.search.aggregations.support.AbstractValuesSourceParser.NumericValuesSourceParser;
+import org.elasticsearch.search.aggregations.support.XContentParseContext;
 import org.elasticsearch.search.aggregations.support.ValueType;
 import org.elasticsearch.search.aggregations.support.ValuesSourceType;
 
@@ -65,20 +66,21 @@ public class RangeParser extends NumericValuesSourceParser {
     }
 
     @Override
-    protected boolean token(String aggregationName, String currentFieldName, Token token, XContentParser parser,
-            ParseFieldMatcher parseFieldMatcher, Map<ParseField, Object> otherOptions) throws IOException {
+    protected boolean token(String aggregationName, String currentFieldName, Token token,
+                            XContentParseContext context, Map<ParseField, Object> otherOptions) throws IOException {
+        XContentParser parser = context.getParser();
         if (token == XContentParser.Token.START_ARRAY) {
-            if (parseFieldMatcher.match(currentFieldName, RangeAggregator.RANGES_FIELD)) {
+            if (context.matchField(currentFieldName, RangeAggregator.RANGES_FIELD)) {
                 List<Range> ranges = new ArrayList<>();
                 while ((token = parser.nextToken()) != XContentParser.Token.END_ARRAY) {
-                    Range range = parseRange(parser, parseFieldMatcher);
+                    Range range = parseRange(parser, context.getParseFieldMatcher());
                     ranges.add(range);
                 }
                 otherOptions.put(RangeAggregator.RANGES_FIELD, ranges);
                 return true;
             }
         } else if (token == XContentParser.Token.VALUE_BOOLEAN) {
-            if (parseFieldMatcher.match(currentFieldName, RangeAggregator.KEYED_FIELD)) {
+            if (context.matchField(currentFieldName, RangeAggregator.KEYED_FIELD)) {
                 boolean keyed = parser.booleanValue();
                 otherOptions.put(RangeAggregator.KEYED_FIELD, keyed);
                 return true;
diff --git a/core/src/main/java/org/elasticsearch/search/aggregations/bucket/range/geodistance/GeoDistanceParser.java b/core/src/main/java/org/elasticsearch/search/aggregations/bucket/range/geodistance/GeoDistanceParser.java
index 16cb909ea0..677731d64e 100644
--- a/core/src/main/java/org/elasticsearch/search/aggregations/bucket/range/geodistance/GeoDistanceParser.java
+++ b/core/src/main/java/org/elasticsearch/search/aggregations/bucket/range/geodistance/GeoDistanceParser.java
@@ -19,7 +19,6 @@
 package org.elasticsearch.search.aggregations.bucket.range.geodistance;
 
 import org.elasticsearch.common.ParseField;
-import org.elasticsearch.common.ParseFieldMatcher;
 import org.elasticsearch.common.geo.GeoDistance;
 import org.elasticsearch.common.geo.GeoPoint;
 import org.elasticsearch.common.io.stream.StreamInput;
@@ -30,6 +29,7 @@ import org.elasticsearch.common.xcontent.XContentParser.Token;
 import org.elasticsearch.search.aggregations.bucket.range.RangeAggregator;
 import org.elasticsearch.search.aggregations.support.AbstractValuesSourceParser.GeoPointValuesSourceParser;
 import org.elasticsearch.search.aggregations.support.GeoPointParser;
+import org.elasticsearch.search.aggregations.support.XContentParseContext;
 import org.elasticsearch.search.aggregations.support.ValueType;
 import org.elasticsearch.search.aggregations.support.ValuesSourceType;
 
@@ -110,28 +110,29 @@ public class GeoDistanceParser extends GeoPointValuesSourceParser {
     }
 
     @Override
-    protected boolean token(String aggregationName, String currentFieldName, Token token, XContentParser parser,
-            ParseFieldMatcher parseFieldMatcher, Map<ParseField, Object> otherOptions) throws IOException {
-        if (geoPointParser.token(aggregationName, currentFieldName, token, parser, parseFieldMatcher, otherOptions)) {
+    protected boolean token(String aggregationName, String currentFieldName, Token token,
+                            XContentParseContext context, Map<ParseField, Object> otherOptions) throws IOException {
+        XContentParser parser = context.getParser();
+        if (geoPointParser.token(aggregationName, currentFieldName, token, parser, context.getParseFieldMatcher(), otherOptions)) {
             return true;
         } else if (token == XContentParser.Token.VALUE_STRING) {
-            if (parseFieldMatcher.match(currentFieldName, UNIT_FIELD)) {
+            if (context.matchField(currentFieldName, UNIT_FIELD)) {
                 DistanceUnit unit = DistanceUnit.fromString(parser.text());
                 otherOptions.put(UNIT_FIELD, unit);
                 return true;
-            } else if (parseFieldMatcher.match(currentFieldName, DISTANCE_TYPE_FIELD)) {
+            } else if (context.matchField(currentFieldName, DISTANCE_TYPE_FIELD)) {
                 GeoDistance distanceType = GeoDistance.fromString(parser.text());
                 otherOptions.put(DISTANCE_TYPE_FIELD, distanceType);
                 return true;
             }
         } else if (token == XContentParser.Token.VALUE_BOOLEAN) {
-            if (parseFieldMatcher.match(currentFieldName, RangeAggregator.KEYED_FIELD)) {
+            if (context.matchField(currentFieldName, RangeAggregator.KEYED_FIELD)) {
                 boolean keyed = parser.booleanValue();
                 otherOptions.put(RangeAggregator.KEYED_FIELD, keyed);
                 return true;
             }
         } else if (token == XContentParser.Token.START_ARRAY) {
-            if (parseFieldMatcher.match(currentFieldName, RangeAggregator.RANGES_FIELD)) {
+            if (context.matchField(currentFieldName, RangeAggregator.RANGES_FIELD)) {
                 List<Range> ranges = new ArrayList<>();
                 while ((token = parser.nextToken()) != XContentParser.Token.END_ARRAY) {
                     String fromAsStr = null;
@@ -144,17 +145,17 @@ public class GeoDistanceParser extends GeoPointValuesSourceParser {
                         if (token == XContentParser.Token.FIELD_NAME) {
                             toOrFromOrKey = parser.currentName();
                         } else if (token == XContentParser.Token.VALUE_NUMBER) {
-                            if (parseFieldMatcher.match(toOrFromOrKey, Range.FROM_FIELD)) {
+                            if (context.matchField(toOrFromOrKey, Range.FROM_FIELD)) {
                                 from = parser.doubleValue();
-                            } else if (parseFieldMatcher.match(toOrFromOrKey, Range.TO_FIELD)) {
+                            } else if (context.matchField(toOrFromOrKey, Range.TO_FIELD)) {
                                 to = parser.doubleValue();
                             }
                         } else if (token == XContentParser.Token.VALUE_STRING) {
-                            if (parseFieldMatcher.match(toOrFromOrKey, Range.KEY_FIELD)) {
+                            if (context.matchField(toOrFromOrKey, Range.KEY_FIELD)) {
                                 key = parser.text();
-                            } else if (parseFieldMatcher.match(toOrFromOrKey, Range.FROM_FIELD)) {
+                            } else if (context.matchField(toOrFromOrKey, Range.FROM_FIELD)) {
                                 fromAsStr = parser.text();
-                            } else if (parseFieldMatcher.match(toOrFromOrKey, Range.TO_FIELD)) {
+                            } else if (context.matchField(toOrFromOrKey, Range.TO_FIELD)) {
                                 toAsStr = parser.text();
                             }
                         }
diff --git a/core/src/main/java/org/elasticsearch/search/aggregations/bucket/range/ip/IpRangeParser.java b/core/src/main/java/org/elasticsearch/search/aggregations/bucket/range/ip/IpRangeParser.java
index 8445fb2d45..5d95f0dd49 100644
--- a/core/src/main/java/org/elasticsearch/search/aggregations/bucket/range/ip/IpRangeParser.java
+++ b/core/src/main/java/org/elasticsearch/search/aggregations/bucket/range/ip/IpRangeParser.java
@@ -31,6 +31,7 @@ import org.elasticsearch.common.xcontent.XContentParser.Token;
 import org.elasticsearch.search.aggregations.support.AbstractValuesSourceParser.BytesValuesSourceParser;
 import org.elasticsearch.search.aggregations.bucket.range.RangeAggregator;
 import org.elasticsearch.search.aggregations.bucket.range.ip.IpRangeAggregationBuilder.Range;
+import org.elasticsearch.search.aggregations.support.XContentParseContext;
 import org.elasticsearch.search.aggregations.support.ValueType;
 import org.elasticsearch.search.aggregations.support.ValuesSource;
 import org.elasticsearch.search.aggregations.support.ValuesSourceAggregationBuilder;
@@ -102,21 +103,22 @@ public class IpRangeParser extends BytesValuesSourceParser {
 
     @Override
     protected boolean token(String aggregationName, String currentFieldName,
-            Token token, XContentParser parser,
-            ParseFieldMatcher parseFieldMatcher,
-            Map<ParseField, Object> otherOptions) throws IOException {
-        if (parseFieldMatcher.match(currentFieldName, RangeAggregator.RANGES_FIELD)) {
+                            Token token,
+                            XContentParseContext context,
+                            Map<ParseField, Object> otherOptions) throws IOException {
+        XContentParser parser = context.getParser();
+        if (context.matchField(currentFieldName, RangeAggregator.RANGES_FIELD)) {
             if (parser.currentToken() != Token.START_ARRAY) {
                 throw new ParsingException(parser.getTokenLocation(), "[ranges] must be passed as an array, but got a " + token);
             }
             List<Range> ranges = new ArrayList<>();
             while ((token = parser.nextToken()) != XContentParser.Token.END_ARRAY) {
-                Range range = parseRange(parser, parseFieldMatcher);
+                Range range = parseRange(parser, context.getParseFieldMatcher());
                 ranges.add(range);
             }
             otherOptions.put(RangeAggregator.RANGES_FIELD, ranges);
             return true;
-        } else if (parseFieldMatcher.match(parser.currentName(), RangeAggregator.KEYED_FIELD)) {
+        } else if (context.matchField(parser.currentName(), RangeAggregator.KEYED_FIELD)) {
             otherOptions.put(RangeAggregator.KEYED_FIELD, parser.booleanValue());
             return true;
         }