1 files changed, 325 insertions, 0 deletions

diff --git a/sql/item_jsonfunc.cc b/sql/item_jsonfunc.cc
index 960a6e9ccc8..2f43f907c8b 100644
--- a/sql/item_jsonfunc.cc
+++ b/sql/item_jsonfunc.cc
@@ -2152,6 +2152,331 @@ null_return:
 }
 
 
+static int copy_value_patch(String *str, json_engine_t *je)
+{
+  int first_key= 1;
+
+  if (je->value_type != JSON_VALUE_OBJECT)
+  {
+    const uchar *beg, *end;
+
+    beg= je->value_begin;
+
+    if (!json_value_scalar(je))
+    {
+      if (json_skip_level(je))
+        return 1;
+      end= je->s.c_str;
+    }
+    else
+      end= je->value_end;
+
+    if (append_simple(str, beg, end-beg))
+      return 1;
+
+    return 0;
+  }
+  /* JSON_VALUE_OBJECT */
+
+  if (str->append("{", 1))
+    return 1;
+  while (json_scan_next(je) == 0 && je->state != JST_OBJ_END)
+  {
+    const uchar *key_start;
+    /* Loop through the Json_1 keys and compare with the Json_2 keys. */
+    DBUG_ASSERT(je->state == JST_KEY);
+    key_start= je->s.c_str;
+
+    if (json_read_value(je))
+      return 1;
+
+    if (je->value_type == JSON_VALUE_NULL)
+      continue;
+
+    if (!first_key)
+    {
+      if (str->append(", ", 2))
+        return 3;
+    }
+    else
+      first_key= 0;
+
+    if (str->append("\"", 1) ||
+        append_simple(str, key_start, je->value_begin - key_start) ||
+        copy_value_patch(str, je))
+      return 1;
+  }
+  if (str->append("}", 1))
+    return 1;
+
+  return 0;
+}
+
+
+static int do_merge_patch(String *str, json_engine_t *je1, json_engine_t *je2,
+                          bool *empty_result)
+{
+  if (json_read_value(je1) || json_read_value(je2))
+    return 1;
+
+  if (je1->value_type == JSON_VALUE_OBJECT &&
+      je2->value_type == JSON_VALUE_OBJECT)
+  {
+    json_engine_t sav_je1= *je1;
+    json_engine_t sav_je2= *je2;
+
+    int first_key= 1;
+    json_string_t key_name;
+    size_t sav_len;
+    bool mrg_empty;
+  
+    *empty_result= FALSE;
+    json_string_set_cs(&key_name, je1->s.cs);
+
+    if (str->append("{", 1))
+      return 3;
+    while (json_scan_next(je1) == 0 &&
+           je1->state != JST_OBJ_END)
+    {
+      const uchar *key_start, *key_end;
+      /* Loop through the Json_1 keys and compare with the Json_2 keys. */
+      DBUG_ASSERT(je1->state == JST_KEY);
+      key_start= je1->s.c_str;
+      do
+      {
+        key_end= je1->s.c_str;
+      } while (json_read_keyname_chr(je1) == 0);
+
+      if (je1->s.error)
+        return 1;
+
+      sav_len= str->length();
+
+      if (!first_key)
+      {
+        if (str->append(", ", 2))
+          return 3;
+        *je2= sav_je2;
+      }
+
+      if (str->append("\"", 1) ||
+          append_simple(str, key_start, key_end - key_start) ||
+          str->append("\":", 2))
+        return 3;
+
+      while (json_scan_next(je2) == 0 &&
+          je2->state != JST_OBJ_END)
+      {
+        int ires;
+        DBUG_ASSERT(je2->state == JST_KEY);
+        json_string_set_str(&key_name, key_start, key_end);
+        if (!json_key_matches(je2, &key_name))
+        {
+          if (je2->s.error || json_skip_key(je2))
+            return 2;
+          continue;
+        }
+
+        /* Json_2 has same key as Json_1. Merge them. */
+        if ((ires= do_merge_patch(str, je1, je2, &mrg_empty)))
+          return ires;
+
+        if (mrg_empty)
+          str->length(sav_len);
+        else
+          first_key= 0;
+
+        goto merged_j1;
+      }
+
+      if (je2->s.error)
+        return 2;
+
+      key_start= je1->s.c_str;
+      /* Just append the Json_1 key value. */
+      if (json_skip_key(je1))
+        return 1;
+      if (append_simple(str, key_start, je1->s.c_str - key_start))
+        return 3;
+      first_key= 0;
+
+merged_j1:
+      continue;
+    }
+
+    *je2= sav_je2;
+    /*
+      Now loop through the Json_2 keys.
+      Skip if there is same key in Json_1
+    */
+    while (json_scan_next(je2) == 0 &&
+           je2->state != JST_OBJ_END)
+    {
+      const uchar *key_start, *key_end;
+      DBUG_ASSERT(je2->state == JST_KEY);
+      key_start= je2->s.c_str;
+      do
+      {
+        key_end= je2->s.c_str;
+      } while (json_read_keyname_chr(je2) == 0);
+
+      if (je2->s.error)
+        return 1;
+
+      *je1= sav_je1;
+      while (json_scan_next(je1) == 0 &&
+             je1->state != JST_OBJ_END)
+      {
+        DBUG_ASSERT(je1->state == JST_KEY);
+        json_string_set_str(&key_name, key_start, key_end);
+        if (!json_key_matches(je1, &key_name))
+        {
+          if (je1->s.error || json_skip_key(je1))
+            return 2;
+          continue;
+        }
+        if (json_skip_key(je2) ||
+            json_skip_level(je1))
+          return 1;
+        goto continue_j2;
+      }
+
+      if (je1->s.error)
+        return 2;
+
+
+      sav_len= str->length();
+
+      if (!first_key && str->append(", ", 2))
+        return 3;
+
+      if (str->append("\"", 1) ||
+          append_simple(str, key_start, key_end - key_start) ||
+          str->append("\":", 2))
+        return 3;
+
+      if (json_read_value(je2))
+        return 1;
+
+      if (je2->value_type == JSON_VALUE_NULL)
+        str->length(sav_len);
+      else
+      {
+        if (copy_value_patch(str, je2))
+          return 1;
+        first_key= 0;
+      }
+
+continue_j2:
+      continue;
+    }
+
+    if (str->append("}", 1))
+      return 3;
+  }
+  else
+  {
+    if (!json_value_scalar(je1) && json_skip_level(je1))
+      return 1;
+
+    *empty_result= je2->value_type == JSON_VALUE_NULL;
+    if (!(*empty_result) && copy_value_patch(str, je2))
+      return 1;
+  }
+
+  return 0;
+}
+
+
+String *Item_func_json_merge_patch::val_str(String *str)
+{
+  DBUG_ASSERT(fixed == 1);
+  json_engine_t je1, je2;
+  String *js1= args[0]->val_json(&tmp_js1), *js2=NULL;
+  uint n_arg;
+  bool empty_result, merge_to_null;
+
+  merge_to_null= args[0]->null_value;
+
+  for (n_arg=1; n_arg < arg_count; n_arg++)
+  {
+    js2= args[n_arg]->val_json(&tmp_js2);
+    if (args[n_arg]->null_value)
+    {
+      merge_to_null= true;
+      goto cont_point;
+    }
+
+    json_scan_start(&je2, js2->charset(),(const uchar *) js2->ptr(),
+                    (const uchar *) js2->ptr() + js2->length());
+
+    if (merge_to_null)
+    {
+      if (json_read_value(&je2))
+        goto error_return;
+      if (je2.value_type == JSON_VALUE_OBJECT)
+      {
+        merge_to_null= true;
+        goto cont_point;
+      }
+      merge_to_null= false;
+      str->set(js2->ptr(), js2->length(), js2->charset());
+      goto cont_point;
+    }
+
+    str->set_charset(js1->charset());
+    str->length(0);
+
+
+    json_scan_start(&je1, js1->charset(),(const uchar *) js1->ptr(),
+                    (const uchar *) js1->ptr() + js1->length());
+
+    if (do_merge_patch(str, &je1, &je2, &empty_result))
+      goto error_return;
+
+    if (empty_result)
+      str->append("null");
+
+cont_point:
+    {
+      /* Swap str and js1. */
+      if (str == &tmp_js1)
+      {
+        str= js1;
+        js1= &tmp_js1;
+      }
+      else
+      {
+        js1= str;
+        str= &tmp_js1;
+      }
+    }
+  }
+
+  if (merge_to_null)
+    goto null_return;
+
+  json_scan_start(&je1, js1->charset(),(const uchar *) js1->ptr(),
+                  (const uchar *) js1->ptr() + js1->length());
+  str->length(0);
+  str->set_charset(js1->charset());
+  if (json_nice(&je1, str, Item_func_json_format::LOOSE))
+    goto error_return;
+
+  null_value= 0;
+  return str;
+
+error_return:
+  if (je1.s.error)
+    report_json_error(js1, &je1, 0);
+  if (je2.s.error)
+    report_json_error(js2, &je2, n_arg);
+null_return:
+  null_value= 1;
+  return NULL;
+}
+
+
 bool Item_func_json_length::fix_length_and_dec()
 {
   if (arg_count > 1)