[7.x] Update Painless Fields API design to use mapped types (#78950) (#…

…79201)

This change updates the Painless fields API to use mapped types instead of Java types. For this initial 
release we only support unsigned long field.

As we now intend to do conversions solely on the field classes themselves, converters and field values 
have been removed. Instead of using field values potentially as source fallback we will now rely on 
whatever class is passed into the script to support the field method. In the future, this method will 
need to check if a field exists on doc and if not, then do source fallback itself once that feature is 
supported.

The path to retrieve a field is also different. Instead of using script doc values we now have our own 
way to retrieve the fields with a getScriptField method added to LeafDocLookup. This allows us less 
restrictive design space to generate the field type based the type in the leaf doc lookup; however, this 
will still require additional information that we need to plumb through for certain field types. Once we 
support all the field types this makes it easier to deprecate and remove script doc values.

modules/lang-painless/src/main/resources/org/elasticsearch/painless/org.elasticsearch.script.fields.txt

@@ -9,19 +9,13 @@
 # The whitelist for the fields api
 
 # API
-class org.elasticsearch.script.field.Field {
-  org.elasticsearch.script.field.Converter BigInteger @augmented[augmented_canonical_class_name="org.elasticsearch.script.field.BigIntegerField"]
-  org.elasticsearch.script.field.Converter Long @augmented[augmented_canonical_class_name="org.elasticsearch.script.field.LongField"]
+class org.elasticsearch.script.field.Field @dynamic_type {
   String getName()
   boolean isEmpty()
+  int size()
   List getValues()
   def getValue(def)
-  double getDouble(double)
-  long getLong(long)
-  org.elasticsearch.script.field.Field as(org.elasticsearch.script.field.Converter)
-}
-
-class org.elasticsearch.script.field.Converter {
+  def getValue(int, def)
 }
 
 class org.elasticsearch.script.DocBasedScript {

modules/lang-painless/src/yamlRestTest/resources/rest-api-spec/test/painless/100_terms_agg.yml

@@ -66,24 +66,6 @@ setup:
   - is_false: aggregations.str_terms.buckets.1.key_as_string
   - match: { aggregations.str_terms.buckets.1.doc_count: 1 }
 
----
-"String Value Script with doc notation (fields api)":
-
-  - do:
-      search:
-        rest_total_hits_as_int: true
-        body: { "size" : 0, "aggs" : { "str_terms" : { "terms" : { "field" : "str", "script": { "source": "return field('str').getValue('') + \"1\""} } } } }
-
-  - match: { hits.total: 3 }
-
-  - length: { aggregations.str_terms.buckets: 2 }
-  - match: { aggregations.str_terms.buckets.0.key: "abc1" }
-  - is_false: aggregations.str_terms.buckets.0.key_as_string
-  - match: { aggregations.str_terms.buckets.0.doc_count: 2 }
-  - match: { aggregations.str_terms.buckets.1.key: "bcd1" }
-  - is_false: aggregations.str_terms.buckets.1.key_as_string
-  - match: { aggregations.str_terms.buckets.1.doc_count: 1 }
-
 ---
 "Long Value Script with doc notation":
 
@@ -102,24 +84,6 @@ setup:
   - is_false: aggregations.long_terms.buckets.1.key_as_string
   - match: { aggregations.long_terms.buckets.1.doc_count: 1 }
 
----
-"Long Value Script with doc notation (fields api)":
-
-  - do:
-      search:
-        rest_total_hits_as_int: true
-        body: { "size" : 0, "aggs" : { "long_terms" : { "terms" : { "field" : "number", "script": { "source": "return field('number').getValue(0L) + 1"} } } } }
-
-  - match: { hits.total: 3 }
-
-  - length: { aggregations.long_terms.buckets: 2 }
-  - match: { aggregations.long_terms.buckets.0.key: 2.0 }
-  - is_false: aggregations.long_terms.buckets.0.key_as_string
-  - match: { aggregations.long_terms.buckets.0.doc_count: 2 }
-  - match: { aggregations.long_terms.buckets.1.key: 3.0 }
-  - is_false: aggregations.long_terms.buckets.1.key_as_string
-  - match: { aggregations.long_terms.buckets.1.doc_count: 1 }
-
 ---
 "Double Value Script with doc notation":
 
@@ -138,24 +102,6 @@ setup:
   - is_false: aggregations.double_terms.buckets.1.key_as_string
   - match: { aggregations.double_terms.buckets.1.doc_count: 1 }
 
----
-"Double Value Script with doc notation (fields api)":
-
-  - do:
-      search:
-        rest_total_hits_as_int: true
-        body: { "size" : 0, "aggs" : { "double_terms" : { "terms" : { "field" : "double", "script": { "source": "return field('double').getValue(0.0) + 1"} } } } }
-
-  - match: { hits.total: 3 }
-
-  - length: { aggregations.double_terms.buckets: 2 }
-  - match: { aggregations.double_terms.buckets.0.key: 2.0 }
-  - is_false: aggregations.double_terms.buckets.0.key_as_string
-  - match: { aggregations.double_terms.buckets.0.doc_count: 2 }
-  - match: { aggregations.double_terms.buckets.1.key: 3.0 }
-  - is_false: aggregations.double_terms.buckets.1.key_as_string
-  - match: { aggregations.double_terms.buckets.1.doc_count: 1 }
-
 ---
 "Bucket script with keys":
 

modules/lang-painless/src/yamlRestTest/resources/rest-api-spec/test/painless/130_metric_agg.yml

@@ -61,25 +61,3 @@ setup:
   - match: { hits.total: 3 }
   - match: { aggregations.total.value: 4.0 }
 
----
-"Scripted Metric Agg Total (fields api)":
-
-  - do:
-      search:
-        rest_total_hits_as_int: true
-        body: {
-          "size": 0,
-          "aggs": {
-            "total": {
-              "scripted_metric": {
-                "init_script": "state.transactions = []",
-                "map_script": "state.transactions.add(field('double').getValue(0.0))",
-                "combine_script": "double total = 0.0; for (t in state.transactions) { total += t } return total",
-                "reduce_script": "double total = 0; for (a in states) { total += a } return total"
-              }
-            }
-          }
-        }
-
-  - match: { hits.total: 3 }
-  - match: { aggregations.total.value: 4.0 }

modules/lang-painless/src/yamlRestTest/resources/rest-api-spec/test/painless/20_scriptfield.yml

@@ -44,21 +44,6 @@ setup:
 
     - match: { hits.hits.0.fields.bar.0: "aaabbb"}
 
----
-"Scripted Field (fields api)":
-  - do:
-      search:
-        rest_total_hits_as_int: true
-        body:
-          script_fields:
-            bar:
-              script:
-                source: "field('foo').getValue('') + params.x;"
-                params:
-                  x: "bbb"
-
-  - match: { hits.hits.0.fields.bar.0: "aaabbb"}
-
 ---
 "Scripted Field Doing Compare":
     - do:
@@ -88,35 +73,6 @@ setup:
 
     - match: { hits.hits.0.fields.bar.0: false}
 
----
-"Scripted Field Doing Compare (fields api)":
-  - do:
-      search:
-        rest_total_hits_as_int: true
-        body:
-          script_fields:
-            bar:
-              script:
-                source: "boolean compare(Supplier s, def v) {return s.get() == v;}
-                                     compare(() -> { return field('foo').getValue('') }, params.x);"
-                params:
-                  x: "aaa"
-
-  - match: { hits.hits.0.fields.bar.0: true}
-  - do:
-      search:
-        rest_total_hits_as_int: true
-        body:
-          script_fields:
-            bar:
-              script:
-                source: "boolean compare(Supplier s, def v) {return s.get() == v;}
-                                     compare(() -> { return doc['foo'].value }, params.x);"
-                params:
-                  x: "bbb"
-
-  - match: { hits.hits.0.fields.bar.0: false}
-
 ---
 "Scripted Field with a null safe dereference (non-null)":
     - do:
@@ -160,19 +116,6 @@ setup:
 
     - match: { hits.hits.0.fields.bar.0: 7}
 
----
-"Access a date (fields api)":
-  - do:
-      search:
-        rest_total_hits_as_int: true
-        body:
-          script_fields:
-            bar:
-              script:
-                source: "field('date').getValue(new Date()).dayOfWeekEnum.value"
-
-  - match: { hits.hits.0.fields.bar.0: 7}
-
 ---
 "Access many dates":
     - do:
@@ -191,24 +134,6 @@ setup:
 
     - match: { hits.hits.0.fields.bar.0: "7 3 3"}
 
----
-"Access many dates (fields api)":
-  - do:
-      search:
-        rest_total_hits_as_int: true
-        body:
-          script_fields:
-            bar:
-              script:
-                source: >
-                  StringBuilder b = new StringBuilder();
-                  for (def date : field('dates').getValues()) {
-                    b.append(" ").append(date.getDayOfWeekEnum().value);
-                  }
-                  return b.toString().trim()
-
-  - match: { hits.hits.0.fields.bar.0: "7 3 3"}
-
 ---
 "Scripted Field with script error":
     - do: