MDEV-19888 Add abstract class Item_json_func

2 files changed, 123 insertions, 73 deletions

diff --git a/sql/item_jsonfunc.cc b/sql/item_jsonfunc.cc
index a90e7fb3a1a..14bffc998e3 100644
--- a/sql/item_jsonfunc.cc
+++ b/sql/item_jsonfunc.cc
@@ -439,7 +439,17 @@ bool Item_func_json_value::fix_length_and_dec()
 {
   collation.set(args[0]->collation);
   max_length= args[0]->max_length;
-  path.set_constant_flag(args[1]->const_item());
+  set_constant_flag(args[1]->const_item());
+  maybe_null= 1;
+  return FALSE;
+}
+
+
+bool Item_func_json_query::fix_length_and_dec()
+{
+  collation.set(args[0]->collation);
+  max_length= args[0]->max_length;
+  set_constant_flag(args[1]->const_item());
   maybe_null= 1;
   return FALSE;
 }
@@ -449,115 +459,100 @@ bool Item_func_json_value::fix_length_and_dec()
   Returns NULL, not an error if the found value
   is not a scalar.
 */
-String *Item_func_json_value::val_str(String *str)
+bool Json_path_extractor::extract(String *str, Item *item_js, Item *item_jp,
+                                  CHARSET_INFO *cs)
 {
-  json_engine_t je;
-  String *js= args[0]->val_json(&tmp_js);
+  String *js= item_js->val_json(&tmp_js);
   int error= 0;
   uint array_counters[JSON_DEPTH_LIMIT];
 
-  if (!path.parsed)
+  if (!parsed)
   {
-    String *s_p= args[1]->val_str(&tmp_path);
+    String *s_p= item_jp->val_str(&tmp_path);
     if (s_p &&
-        json_path_setup(&path.p, s_p->charset(), (const uchar *) s_p->ptr(),
+        json_path_setup(&p, s_p->charset(), (const uchar *) s_p->ptr(),
                         (const uchar *) s_p->ptr() + s_p->length()))
-      goto err_return;
-    path.parsed= path.constant;
+      return true;
+    parsed= constant;
   }
 
-  if ((null_value= args[0]->null_value || args[1]->null_value))
-    return NULL;
-
-  json_scan_start(&je, js->charset(),(const uchar *) js->ptr(),
-                  (const uchar *) js->ptr() + js->length());
+  if (item_js->null_value || item_jp->null_value)
+    return true;
 
+  Json_engine_scan je(*js);
   str->length(0);
-  str->set_charset(collation.collation);
+  str->set_charset(cs);
 
-  path.cur_step= path.p.steps;
+  cur_step= p.steps;
 continue_search:
-  if (json_find_path(&je, &path.p, &path.cur_step, array_counters))
-  {
-    if (je.s.error)
-      goto err_return;
-
-    null_value= 1;
-    return 0;
-  }
+  if (json_find_path(&je, &p, &cur_step, array_counters))
+    return true;
 
   if (json_read_value(&je))
-    goto err_return;
+    return true;
 
   if (unlikely(check_and_get_value(&je, str, &error)))
   {
     if (error)
-      goto err_return;
+      return true;
     goto continue_search;
   }
 
-  return str;
-
-err_return:
-  null_value= 1;
-  return 0;
+  return false;
 }
 
 
-bool Item_func_json_value::check_and_get_value(json_engine_t *je, String *res,
-                                               int *error)
+bool Json_engine_scan::check_and_get_value_scalar(String *res, int *error)
 {
   CHARSET_INFO *json_cs;
   const uchar *js;
   uint js_len;
 
-  if (!json_value_scalar(je))
+  if (!json_value_scalar(this))
   {
     /* We only look for scalar values! */
-    if (json_skip_level(je) || json_scan_next(je))
+    if (json_skip_level(this) || json_scan_next(this))
       *error= 1;
     return true;
   }
 
-  if (je->value_type == JSON_VALUE_TRUE ||
-      je->value_type == JSON_VALUE_FALSE)
+  if (value_type == JSON_VALUE_TRUE ||
+      value_type == JSON_VALUE_FALSE)
   {
     json_cs= &my_charset_utf8mb4_bin;
-    js= (const uchar *) ((je->value_type == JSON_VALUE_TRUE) ? "1" : "0");
+    js= (const uchar *) ((value_type == JSON_VALUE_TRUE) ? "1" : "0");
     js_len= 1;
   }
   else
   {
-    json_cs= je->s.cs;
-    js= je->value;
-    js_len= je->value_len;
+    json_cs= s.cs;
+    js= value;
+    js_len= value_len;
   }
 
 
-  return st_append_json(res, json_cs, js, js_len); 
+  return st_append_json(res, json_cs, js, js_len);
 }
 
 
-bool Item_func_json_query::check_and_get_value(json_engine_t *je, String *res,
-                                               int *error)
+bool Json_engine_scan::check_and_get_value_complex(String *res, int *error)
 {
-  const uchar *value;
-  if (json_value_scalar(je))
+  if (json_value_scalar(this))
   {
     /* We skip scalar values. */
-    if (json_scan_next(je))
+    if (json_scan_next(this))
       *error= 1;
     return true;
   }
 
-  value= je->value;
-  if (json_skip_level(je))
+  const uchar *tmp_value= value;
+  if (json_skip_level(this))
   {
     *error= 1;
     return true;
   }
 
-  res->set((const char *) je->value, (uint32)(je->s.c_str - value), je->s.cs);
+  res->set((const char *) value, (uint32)(s.c_str - tmp_value), s.cs);
   return false;
 }
 
diff --git a/sql/item_jsonfunc.h b/sql/item_jsonfunc.h
index e9b77502e80..a9e6f39b5c8 100644
--- a/sql/item_jsonfunc.h
+++ b/sql/item_jsonfunc.h
@@ -40,6 +40,33 @@ public:
 };
 
 
+class Json_engine_scan: public json_engine_t
+{
+public:
+  Json_engine_scan(CHARSET_INFO *i_cs, const uchar *str, const uchar *end)
+  {
+    json_scan_start(this, i_cs, str, end);
+  }
+  Json_engine_scan(const String &str)
+   :Json_engine_scan(str.charset(), (const uchar *) str.ptr(),
+                                    (const uchar *) str.end())
+  { }
+  bool check_and_get_value_scalar(String *res, int *error);
+  bool check_and_get_value_complex(String *res, int *error);
+};
+
+
+class Json_path_extractor: public json_path_with_flags
+{
+protected:
+  String tmp_js, tmp_path;
+  virtual ~Json_path_extractor() { }
+  virtual bool check_and_get_value(Json_engine_scan *je,
+                                   String *to, int *error)=0;
+  bool extract(String *to, Item *js, Item *jp, CHARSET_INFO *cs);
+};
+
+
 class Item_func_json_valid: public Item_bool_func
 {
 protected:
@@ -78,32 +105,65 @@ public:
 };
 
 
-class Item_func_json_value: public Item_str_func
+class Item_json_func: public Item_str_func
+{
+public:
+  Item_json_func(THD *thd)
+   :Item_str_func(thd) { }
+  Item_json_func(THD *thd, Item *a)
+   :Item_str_func(thd, a) { }
+  Item_json_func(THD *thd, Item *a, Item *b)
+   :Item_str_func(thd, a, b) { }
+  Item_json_func(THD *thd, List<Item> &list)
+   :Item_str_func(thd, list) { }
+  bool is_json_type() { return true; }
+};
+
+
+class Item_func_json_value: public Item_str_func,
+                            public Json_path_extractor
 {
-protected:
-  json_path_with_flags path;
-  String tmp_js, tmp_path;
 
 public:
   Item_func_json_value(THD *thd, Item *js, Item *i_path):
     Item_str_func(thd, js, i_path) {}
   const char *func_name() const { return "json_value"; }
   bool fix_length_and_dec();
-  String *val_str(String *);
-  virtual bool check_and_get_value(json_engine_t *je, String *res, int *error);
+  String *val_str(String *to)
+  {
+    null_value= Json_path_extractor::extract(to, args[0], args[1],
+                                             collation.collation);
+    return null_value ? NULL : to;
+  }
+  bool check_and_get_value(Json_engine_scan *je,
+                           String *res, int *error) override
+  {
+    return je->check_and_get_value_scalar(res, error);
+  }
   Item *get_copy(THD *thd)
   { return get_item_copy<Item_func_json_value>(thd, this); }
 };
 
 
-class Item_func_json_query: public Item_func_json_value
+class Item_func_json_query: public Item_json_func,
+                            public Json_path_extractor
 {
 public:
   Item_func_json_query(THD *thd, Item *js, Item *i_path):
-    Item_func_json_value(thd, js, i_path) {}
-  bool is_json_type() { return true; }
+    Item_json_func(thd, js, i_path) {}
   const char *func_name() const { return "json_query"; }
-  bool check_and_get_value(json_engine_t *je, String *res, int *error);
+  bool fix_length_and_dec();
+  String *val_str(String *to)
+  {
+    null_value= Json_path_extractor::extract(to, args[0], args[1],
+                                             collation.collation);
+    return null_value ? NULL : to;
+  }
+  bool check_and_get_value(Json_engine_scan *je,
+                           String *res, int *error) override
+  {
+    return je->check_and_get_value_complex(res, error);
+  }
   Item *get_copy(THD *thd)
   { return get_item_copy<Item_func_json_query>(thd, this); }
 };
@@ -139,18 +199,17 @@ public:
 };
 
 
-class Item_json_str_multipath: public Item_str_func
+class Item_json_str_multipath: public Item_json_func
 {
 protected:
   json_path_with_flags *paths;
   String *tmp_paths;
 public:
   Item_json_str_multipath(THD *thd, List<Item> &list):
-    Item_str_func(thd, list), tmp_paths(0) {}
+    Item_json_func(thd, list), tmp_paths(0) {}
   bool fix_fields(THD *thd, Item **ref);
   void cleanup();
   virtual uint get_n_paths() const = 0;
-  bool is_json_type() { return true; }
 };
 
 
@@ -217,18 +276,17 @@ public:
 };
 
 
-class Item_func_json_array: public Item_str_func
+class Item_func_json_array: public Item_json_func
 {
 protected:
   String tmp_val;
   ulong result_limit;
 public:
   Item_func_json_array(THD *thd):
-    Item_str_func(thd) {}
+    Item_json_func(thd) {}
   Item_func_json_array(THD *thd, List<Item> &list):
-    Item_str_func(thd, list) {}
+    Item_json_func(thd, list) {}
   String *val_str(String *);
-  bool is_json_type() { return true; }
   bool fix_length_and_dec();
   const char *func_name() const { return "json_array"; }
   Item *get_copy(THD *thd)
@@ -273,7 +331,6 @@ public:
   Item_func_json_object(THD *thd, List<Item> &list):
     Item_func_json_array(thd, list) {}
   String *val_str(String *);
-  bool is_json_type() { return true; }
   const char *func_name() const { return "json_object"; }
   Item *get_copy(THD *thd)
   { return get_item_copy<Item_func_json_object>(thd, this); }
@@ -288,7 +345,6 @@ public:
   Item_func_json_merge(THD *thd, List<Item> &list):
     Item_func_json_array(thd, list) {}
   String *val_str(String *);
-  bool is_json_type() { return true; }
   const char *func_name() const { return "json_merge_preserve"; }
   Item *get_copy(THD *thd)
   { return get_item_copy<Item_func_json_merge>(thd, this); }
@@ -439,7 +495,7 @@ public:
 };
 
 
-class Item_func_json_format: public Item_str_func
+class Item_func_json_format: public Item_json_func
 {
 public:
   enum formats
@@ -454,15 +510,14 @@ protected:
   String tmp_js;
 public:
   Item_func_json_format(THD *thd, Item *js, formats format):
-    Item_str_func(thd, js), fmt(format) {}
+    Item_json_func(thd, js), fmt(format) {}
   Item_func_json_format(THD *thd, List<Item> &list):
-    Item_str_func(thd, list), fmt(DETAILED) {}
+    Item_json_func(thd, list), fmt(DETAILED) {}
 
   const char *func_name() const;
   bool fix_length_and_dec();
   String *val_str(String *str);
   String *val_json(String *str);
-  bool is_json_type() { return true; }
   Item *get_copy(THD *thd)
   { return get_item_copy<Item_func_json_format>(thd, this); }
 };