WL#16345: DOM support for JSON Modify and JSON Merge functions

1. JSON_DOM support for JSON Modify and JSON Merge functions
2. Multi arg expression support for JSON MERGE functions and MODIFY
   functions

Bug#36531320 - CREATE TABLE AS SELECT JSON_COL FROM TABLE produces wrong results
if JSON column has NULL values

Change-Id: I9e7c770acf1032861f0931890ef37bc289fc6fa2

Author: Amith Nagarajappa

sql-common/json_dom.cc

@@ -105,7 +105,6 @@ static Json_dom *json_binary_to_dom_template(const json_binary::Value &v);
 
 using Sorted_index_array = Prealloced_array<size_t, 16>;
 
-#ifdef MYSQL_SERVER
 /**
   Auto-wrap a dom in an array if it is not already an array. Delete
   the dom if there is a memory allocation failure.
@@ -138,7 +137,6 @@ Json_dom_ptr merge_doms(Json_dom_ptr left, Json_dom_ptr right) {
 
   return left_array;
 }
-#endif  // ifdef MYSQL_SERVER
 
 void *Json_dom::operator new(size_t size, const std::nothrow_t &) noexcept {
   /*
@@ -824,7 +822,6 @@ bool Json_object::add_alias(const std::string &key, Json_dom_ptr value) {
   return false;
 }
 
-#ifdef MYSQL_SERVER
 bool Json_object::consume(Json_object_ptr other) {
   for (auto &other_member : other->m_map) {
     auto &key = other_member.first;
@@ -848,7 +845,6 @@ bool Json_object::consume(Json_object_ptr other) {
 
   return false;
 }
-#endif  // ifdef MYSQL_SERVER
 
 template <typename Key>
 static Json_dom *json_object_get(const Json_dom *object [[maybe_unused]],

sql-common/json_path.cc

@@ -771,3 +771,33 @@ static bool is_ecmascript_identifier(const std::string_view &name) {
 
   return true;
 }
+
+bool clone_without_autowrapping(const Json_path *source_path,
+                                Json_path_clone *target_path, Json_wrapper *doc,
+                                PSI_memory_key key) {
+  Json_wrapper_vector hits(key);
+  target_path->clear();
+  for (const Json_path_leg *path_leg : *source_path) {
+    if (path_leg->is_autowrap()) {
+      /*
+         We have a partial path of the form
+         pathExpression[0]
+         So see if pathExpression identifies a non-array value.
+      */
+      hits.clear();
+      if (doc->seek(*target_path, target_path->leg_count(), &hits, false, true))
+        return true; /* purecov: inspected */
+      if (!hits.empty() && hits[0].type() != enum_json_type::J_ARRAY) {
+        /*
+          pathExpression identifies a non-array value.
+          We satisfy the conditions of the rule above.
+          So we can throw away the [0] leg.
+        */
+        continue;
+      }
+    }
+    // The rule above is NOT satisfied. So add the leg.
+    if (target_path->append(path_leg)) return true; /* purecov: inspected */
+  }
+  return false;
+}

sql-common/json_path.h

@@ -44,6 +44,7 @@
 #include "prealloced_array.h"  // Prealloced_array
 
 class String;
+class Json_wrapper;
 
 /** The type of a Json_path_leg. */
 enum enum_json_path_leg_type {
@@ -494,4 +495,26 @@ bool parse_path(size_t path_length, const char *path_expression,
 */
 bool parse_path(const String &path_value, bool forbid_wildcards,
                 Json_path *json_path);
+
+/**
+  Clone a source path to a target path, stripping out legs which are made
+  redundant by the auto-wrapping rule from the WL#7909 spec and further
+  extended in the WL#9831 spec:
+
+  "If an array cell path leg or an array range path leg is evaluated against a
+  non-array value, the result of the evaluation is the same as if the non-array
+  value had been wrapped in a single-element array."
+
+  @see Json_path_leg::is_autowrap
+
+  @param[in]      source_path The original path.
+  @param[in,out]  target_path The clone to be filled in.
+  @param[in]      doc The document to seek through.
+  @param[in]      key Instrumented memory key
+  @returns True if an error occurred. False otherwise.
+*/
+bool clone_without_autowrapping(const Json_path *source_path,
+                                Json_path_clone *target_path, Json_wrapper *doc,
+                                PSI_memory_key key);
+
 #endif /* SQL_JSON_PATH_INCLUDED */

sql/item_json_func.cc

@@ -2080,58 +2080,6 @@ bool Item_func_json_array_insert::val_json(Json_wrapper *wr) {
   return false;
 }
 
-/**
-  Clone a source path to a target path, stripping out legs which are made
-  redundant by the auto-wrapping rule from the WL#7909 spec and further
-  extended in the WL#9831 spec:
-
-  "If an array cell path leg or an array range path leg is evaluated against a
-  non-array value, the result of the evaluation is the same as if the non-array
-  value had been wrapped in a single-element array."
-
-  @see Json_path_leg::is_autowrap
-
-  @param[in]      source_path The original path.
-  @param[in,out]  target_path The clone to be filled in.
-  @param[in]      doc The document to seek through.
-
-  @returns True if an error occurred. False otherwise.
-*/
-static bool clone_without_autowrapping(const Json_path *source_path,
-                                       Json_path_clone *target_path,
-                                       Json_wrapper *doc) {
-  Json_wrapper_vector hits(key_memory_JSON);
-
-  target_path->clear();
-  for (const Json_path_leg *path_leg : *source_path) {
-    if (path_leg->is_autowrap()) {
-      /*
-         We have a partial path of the form
-
-         pathExpression[0]
-
-         So see if pathExpression identifies a non-array value.
-      */
-      hits.clear();
-      if (doc->seek(*target_path, target_path->leg_count(), &hits, false, true))
-        return true; /* purecov: inspected */
-
-      if (!hits.empty() && hits[0].type() != enum_json_type::J_ARRAY) {
-        /*
-          pathExpression identifies a non-array value.
-          We satisfy the conditions of the rule above.
-          So we can throw away the [0] leg.
-        */
-        continue;
-      }
-    }
-    // The rule above is NOT satisfied. So add the leg.
-    if (target_path->append(path_leg)) return true; /* purecov: inspected */
-  }
-
-  return false;
-}
-
 void Item_json_func::mark_for_partial_update(const Field_json *field) {
   assert(supports_partial_update(field));
   m_partial_update_column = field;
@@ -2231,7 +2179,8 @@ bool Item_func_json_set_replace::val_json(Json_wrapper *wr) {
       if (current_path == nullptr) goto return_null;
 
       // Clone the path, stripping off redundant auto-wrapping.
-      if (clone_without_autowrapping(current_path, &m_path, &docw)) {
+      if (clone_without_autowrapping(current_path, &m_path, &docw,
+                                     key_memory_JSON)) {
         return error_json();
       }
 
@@ -2895,7 +2844,7 @@ bool Item_func_json_remove::val_json(Json_wrapper *wr) {
   Json_path_clone path(key_memory_JSON);
   for (uint path_idx = 0; path_idx < path_count; ++path_idx) {
     if (clone_without_autowrapping(m_path_cache.get_path(path_idx + 1), &path,
-                                   &wrapper))
+                                   &wrapper, key_memory_JSON))
       return error_json(); /* purecov: inspected */
 
     // Cannot remove the root of the document.