MDEV-9143 JSON_xxx functions.

        The rest of mysql/json functions implemented.
        CAST AS JSON implemented.

1 files changed, 971 insertions, 14 deletions

diff --git a/sql/item_jsonfunc.cc b/sql/item_jsonfunc.cc
index 80713710927..4fa2f02bedc 100644
--- a/sql/item_jsonfunc.cc
+++ b/sql/item_jsonfunc.cc
@@ -48,6 +48,45 @@ static bool eq_ascii_string(const CHARSET_INFO *cs,
 }
 
 
+static bool append_simple(String *s, const char *a, uint a_len)
+{
+  if (!s->realloc_with_extra_if_needed(s->length() + a_len))
+  {
+    s->q_append(a, a_len);
+    return FALSE;
+  }
+
+  return TRUE;
+}
+
+
+static inline bool append_simple(String *s, const uchar *a, uint a_len)
+{
+  return append_simple(s, (const char *) a, a_len);
+}
+
+
+/*
+  Appends JSON string to the String object taking charsets in
+  consideration.
+static int st_append_json(String *s,
+             CHARSET_INFO *json_cs, const uchar *js, uint js_len)
+{
+  int str_len= js_len * s->charset()->mbmaxlen;
+
+  if (!s->reserve(str_len, 1024) &&
+      (str_len= json_unescape(json_cs, js, js + js_len,
+         s->charset(), (uchar *) s->end(), (uchar *) s->end() + str_len)) > 0)
+  {
+    s->length(s->length() + str_len);
+    return 0;
+  }
+
+  return js_len;
+}
+*/
+
+
 /*
   Appends arbitrary String to the JSON string taking charsets in
   consideration.
@@ -278,6 +317,50 @@ String *Item_func_json_quote::val_str(String *str)
 }
 
 
+void Item_func_json_unquote::fix_length_and_dec()
+{
+  collation.set(&my_charset_utf8_general_ci);
+  max_length= args[0]->max_length;
+}
+
+
+String *Item_func_json_unquote::val_str(String *str)
+{
+  String *js= args[0]->val_str(&tmp_s);
+  json_engine_t je;
+  int c_len;
+
+  if ((null_value= args[0]->null_value))
+    return NULL;
+
+  json_scan_start(&je, js->charset(),(const uchar *) js->ptr(),
+                  (const uchar *) js->ptr() + js->length());
+
+  if (json_read_value(&je))
+    goto error;
+
+  if (je.value_type != JSON_VALUE_STRING)
+    return js;
+
+  str->length(0);
+  str->set_charset(&my_charset_utf8_general_ci);
+
+  if (str->realloc_with_extra_if_needed(je.value_len) ||
+      (c_len= json_unescape(js->charset(),
+        je.value, je.value + je.value_len,
+        &my_charset_utf8_general_ci,
+        (uchar *) str->ptr(), (uchar *) (str->ptr() + je.value_len))) < 0)
+    goto error;
+
+  str->length(c_len);
+  return str;
+
+error:
+  null_value= 1;
+  return 0;
+}
+
+
 static int alloc_tmp_paths(THD *thd, uint n_paths,
                            json_path_with_flags **paths,String **tmp_paths)
 {
@@ -642,6 +725,27 @@ void Item_func_json_contains_path::cleanup()
 }
 
 
+static int parse_one_or_all(Item *ooa_arg,
+                            bool *ooa_parsed, bool ooa_constant, bool *mode_one)
+{
+  if (!*ooa_parsed)
+  {
+    char buff[20];
+    String *res, tmp(buff, sizeof(buff), &my_charset_bin);
+    res= ooa_arg->val_str(&tmp);
+    *mode_one=eq_ascii_string(res->charset(), "one",
+                             res->ptr(), res->length());
+    if (!*mode_one)
+    {
+      if (!eq_ascii_string(res->charset(), "all", res->ptr(), res->length()))
+        return TRUE;
+    }
+    *ooa_parsed= ooa_constant;
+  }
+  return FALSE;
+}
+
+
 longlong Item_func_json_contains_path::val_int()
 {
   String *js= args[0]->val_str(&tmp_js);
@@ -652,20 +756,8 @@ longlong Item_func_json_contains_path::val_int()
   if ((null_value= args[0]->null_value))
     return 0;
 
-  if (!ooa_parsed)
-  {
-    char buff[20];
-    String *res, tmp(buff, sizeof(buff), &my_charset_bin);
-    res= args[1]->val_str(&tmp);
-    mode_one=eq_ascii_string(res->charset(), "one",
-                             res->ptr(), res->length());
-    if (!mode_one)
-    {
-      if (!eq_ascii_string(res->charset(), "all", res->ptr(), res->length()))
-        goto error;
-    }
-    ooa_parsed= ooa_constant;
-  }
+  if (parse_one_or_all(args[1], &ooa_parsed, ooa_constant, &mode_one))
+    goto error;
 
   result= !mode_one;
   for (n_arg=2; n_arg < arg_count; n_arg++)
@@ -742,6 +834,9 @@ static int append_json_value(String *str, Item *item, String *tmp_val)
     String *sv= item->val_str(tmp_val);
     if (item->null_value)
       goto append_null;
+    if (item->is_json_type())
+      return str->append(sv->ptr(), sv->length());
+
     if (item->result_type() == STRING_RESULT)
     {
       return str->append("\"", 1) ||
@@ -915,6 +1010,117 @@ error:
 }
 
 
+String *Item_func_json_array_insert::val_str(String *str)
+{
+  json_engine_t je;
+  String *js= args[0]->val_str(&tmp_js);
+  uint n_arg, n_path;
+
+  DBUG_ASSERT(fixed == 1);
+
+  if ((null_value= args[0]->null_value))
+    return 0;
+
+  for (n_arg=1, n_path=0; n_arg < arg_count; n_arg+=2, n_path++)
+  {
+    uint array_counters[JSON_DEPTH_LIMIT];
+    json_path_with_flags *c_path= paths + n_path;
+    const char *item_pos;
+    uint n_item;
+
+    if (!c_path->parsed)
+    {
+      String *s_p= args[n_arg]->val_str(tmp_paths+n_path);
+      if (s_p &&
+          (json_path_setup(&c_path->p,s_p->charset(),(const uchar *) s_p->ptr(),
+                           (const uchar *) s_p->ptr() + s_p->length()) ||
+           c_path->p.last_step - 1 > c_path->p.steps ||
+           c_path->p.last_step->type != JSON_PATH_ARRAY))
+        goto error;
+      c_path->parsed= c_path->constant;
+      c_path->p.last_step--;
+    }
+    if (args[n_arg]->null_value)
+      goto null_return;
+
+    json_scan_start(&je, js->charset(),(const uchar *) js->ptr(),
+                    (const uchar *) js->ptr() + js->length());
+
+    c_path->cur_step= c_path->p.steps;
+
+    if (json_find_path(&je, &c_path->p, &c_path->cur_step, array_counters))
+    {
+      if (je.s.error)
+        goto error;
+
+      /* Can't find the array to insert. */
+      goto null_return;
+    }
+
+    if (json_read_value(&je))
+      goto error;
+
+    if (je.value_type != JSON_VALUE_ARRAY)
+    {
+      /* Must be an array. */
+      goto null_return;
+    }
+
+    item_pos= 0;
+    n_item= 0;
+
+    while (json_scan_next(&je) == 0 &&
+           je.state != JST_ARRAY_END && item_pos == 0)
+    {
+      switch (je.state)
+      {
+      case JST_VALUE:
+        if (n_item == c_path->p.last_step[1].n_item)
+        {
+          item_pos= (const char *) je.s.c_str;
+          break;
+        }
+        n_item++;
+        break;
+      case JST_OBJ_START:
+      case JST_ARRAY_START:
+        if (json_skip_level(&je))
+          break;
+        break;
+      default:
+        break;
+      }
+    }
+
+    str->length(0);
+    str->set_charset(js->charset());
+    if (!item_pos)
+      item_pos= (const char *) (je.s.c_str - je.sav_c_len);
+
+    if (append_simple(str, js->ptr(), item_pos - js->ptr()) ||
+        ((je.state == JST_ARRAY_END) ?
+           (n_item > 0  && str->append(", ", 2)) : str->append(" ", 1)) ||
+        append_json_value(str, args[n_arg+1], &tmp_val) ||
+        (je.state != JST_ARRAY_END && str->append(",", 1)) ||
+        append_simple(str, item_pos, js->end() - item_pos))
+      goto error; /* Out of memory. */
+
+    {
+      String *tmp_str= str;
+      str= &tmp_js;
+      js= tmp_str;
+    }
+  }
+
+  return js;
+
+null_return:
+error:
+  null_value= 1;
+  return 0;
+}
+
+
 String *Item_func_json_object::val_str(String *str)
 {
   DBUG_ASSERT(fixed == 1);
@@ -1107,3 +1313,754 @@ error:
 }
 
 
+void Item_func_json_insert::fix_length_and_dec()
+{
+  uint n_arg;
+  ulonglong char_length;
+
+  collation.set(args[0]->collation);
+  char_length= args[0]->max_char_length();
+
+  for (n_arg= 1; n_arg < arg_count; n_arg+= 2)
+  {
+    paths[n_arg-1].set_constant_flag(args[n_arg]->const_item());
+    char_length+= args[n_arg+1]->max_char_length() + 4;
+  }
+
+  fix_char_length_ulonglong(char_length);
+}
+
+
+String *Item_func_json_insert::val_str(String *str)
+{
+  json_engine_t je;
+  String *js= args[0]->val_str(&tmp_js);
+  uint n_arg, n_path;
+  json_string_t key_name;
+
+  DBUG_ASSERT(fixed == 1);
+
+  if ((null_value= args[0]->null_value))
+    return 0;
+
+  str->set_charset(js->charset());
+  json_string_set_cs(&key_name, js->charset());
+
+  for (n_arg=1, n_path=0; n_arg < arg_count; n_arg+=2, n_path++)
+  {
+    uint array_counters[JSON_DEPTH_LIMIT];
+    json_path_with_flags *c_path= paths + n_path;
+    const char *v_to;
+    const json_path_step_t *lp;
+
+    if (!c_path->parsed)
+    {
+      String *s_p= args[n_arg]->val_str(tmp_paths+n_path);
+      if (s_p)
+      {
+        if (json_path_setup(&c_path->p,s_p->charset(),
+                            (const uchar *) s_p->ptr(),
+                            (const uchar *) s_p->ptr() + s_p->length()))
+          goto error;
+
+        /* We search to the last step. */
+        c_path->p.last_step--;
+      }
+      c_path->parsed= c_path->constant;
+    }
+    if (args[n_arg]->null_value)
+    {
+      null_value= 1;
+      return 0;
+    }
+
+    json_scan_start(&je, js->charset(),(const uchar *) js->ptr(),
+                    (const uchar *) js->ptr() + js->length());
+
+    c_path->cur_step= c_path->p.steps;
+
+    if (c_path->p.last_step >= c_path->p.steps &&
+        json_find_path(&je, &c_path->p, &c_path->cur_step, array_counters))
+    {
+      if (je.s.error)
+        goto error;
+    }
+
+    if (json_read_value(&je))
+      goto error;
+
+    lp= c_path->p.last_step+1;
+    if (lp->type == JSON_PATH_ARRAY)
+    {
+      uint n_item= 0;
+
+      if (je.value_type != JSON_VALUE_ARRAY)
+      {
+        const uchar *v_from= je.value_begin;
+        if (!mode_insert)
+          continue;
+
+        str->length(0);
+        /* Wrap the value as an array. */
+        if (append_simple(str, js->ptr(), (const char *) v_from - js->ptr()) ||
+            str->append("[", 1))
+          goto error; /* Out of memory. */
+
+        if (je.value_type == JSON_VALUE_OBJECT)
+        {
+          if (json_skip_level(&je))
+            goto error;
+        }
+
+        if (append_simple(str, v_from, je.s.c_str - v_from) ||
+            str->append(", ", 2) ||
+            append_json_value(str, args[n_arg+1], &tmp_val) ||
+            str->append("]", 1) ||
+            append_simple(str, je.s.c_str, js->end()-(const char *) je.s.c_str))
+          goto error; /* Out of memory. */
+
+        goto continue_point;
+      }
+
+      while (json_scan_next(&je) == 0 && je.state != JST_ARRAY_END)
+      {
+        switch (je.state)
+        {
+        case JST_VALUE:
+          if (n_item == lp->n_item)
+            goto v_found;
+          n_item++;
+          if (json_skip_array_item(&je))
+            goto error;
+          break;
+        default:
+          break;
+        }
+      }
+
+      if (je.s.error)
+        goto error;
+
+      if (!mode_insert)
+        continue;
+
+      v_to= (const char *) (je.s.c_str - je.sav_c_len);
+      str->length(0);
+      if (append_simple(str, js->ptr(), v_to - js->ptr()) ||
+          str->append(", ", 2) ||
+          append_json_value(str, args[n_arg+1], &tmp_val) ||
+          append_simple(str, v_to, js->end() - v_to))
+        goto error; /* Out of memory. */
+    }
+    else /*JSON_PATH_KEY*/
+    {
+      if (je.value_type != JSON_VALUE_OBJECT)
+        continue;
+
+      while (json_scan_next(&je) == 0 && je.state != JST_OBJ_END)
+      {
+        switch (je.state)
+        {
+        case JST_KEY:
+          json_string_set_str(&key_name, lp->key, lp->key_end);
+          if (json_key_matches(&je, &key_name))
+            goto v_found;
+          if (json_skip_key(&je))
+            goto error;
+          break;
+        default:
+          break;
+        }
+      }
+
+      if (je.s.error)
+        goto error;
+
+      if (!mode_insert)
+        continue;
+
+      v_to= (const char *) (je.s.c_str - je.sav_c_len);
+      str->length(0);
+      if (append_simple(str, js->ptr(), v_to - js->ptr()) ||
+          str->append(", \"", 3) ||
+          append_simple(str, lp->key, lp->key_end - lp->key) ||
+          str->append("\":", 2) ||
+          append_json_value(str, args[n_arg+1], &tmp_val) ||
+          append_simple(str, v_to, js->end() - v_to))
+        goto error; /* Out of memory. */
+    }
+
+    goto continue_point;
+
+v_found:
+
+    if (!mode_replace)
+      continue;
+
+    if (json_read_value(&je))
+      goto error;
+
+    v_to= (const char *) je.value_begin;
+    str->length(0);
+    if (!json_value_scalar(&je))
+    {
+      if (json_skip_level(&je))
+        goto error;
+    }
+
+    if (append_simple(str, js->ptr(), v_to - js->ptr()) ||
+        append_json_value(str, args[n_arg+1], &tmp_val) ||
+        append_simple(str, je.s.c_str, js->end()-(const char *) je.s.c_str))
+      goto error; /* Out of memory. */
+continue_point:
+    {
+      String *tmp= str;
+      str= &tmp_js;
+      js= tmp;
+    }
+  }
+
+  return js;
+
+error:
+  null_value= 1;
+  return 0;
+}
+
+
+void Item_func_json_remove::fix_length_and_dec()
+{
+  collation.set(args[0]->collation);
+  max_length= args[0]->max_length;
+
+  mark_constant_paths(paths, args+1, arg_count-1);
+}
+
+
+String *Item_func_json_remove::val_str(String *str)
+{
+  json_engine_t je;
+  String *js= args[0]->val_str(&tmp_js);
+  uint n_arg, n_path;
+  json_string_t key_name;
+
+  DBUG_ASSERT(fixed == 1);
+
+  if (args[0]->null_value)
+    goto null_return;
+
+  str->set_charset(js->charset());
+  json_string_set_cs(&key_name, js->charset());
+
+  for (n_arg=1, n_path=0; n_arg < arg_count; n_arg+=2, n_path++)
+  {
+    uint array_counters[JSON_DEPTH_LIMIT];
+    json_path_with_flags *c_path= paths + n_path;
+    const char *rem_start, *rem_end;
+    const json_path_step_t *lp;
+    uint n_item= 0;
+
+    if (!c_path->parsed)
+    {
+      String *s_p= args[n_arg]->val_str(tmp_paths+n_path);
+      if (s_p)
+      {
+        if (json_path_setup(&c_path->p,s_p->charset(),
+                            (const uchar *) s_p->ptr(),
+                            (const uchar *) s_p->ptr() + s_p->length()))
+          goto error;
+
+        /* We search to the last step. */
+        c_path->p.last_step--;
+        if (c_path->p.last_step < c_path->p.steps)
+          goto null_return;
+      }
+      c_path->parsed= c_path->constant;
+    }
+    if (args[n_arg]->null_value)
+    {
+      null_value= 1;
+      return 0;
+    }
+
+    json_scan_start(&je, js->charset(),(const uchar *) js->ptr(),
+                    (const uchar *) js->ptr() + js->length());
+
+    c_path->cur_step= c_path->p.steps;
+
+    if (json_find_path(&je, &c_path->p, &c_path->cur_step, array_counters))
+    {
+      if (je.s.error)
+        goto error;
+    }
+
+    if (json_read_value(&je))
+      goto error;
+
+    lp= c_path->p.last_step+1;
+    if (lp->type == JSON_PATH_ARRAY)
+    {
+      if (je.value_type != JSON_VALUE_ARRAY)
+        continue;
+
+      while (json_scan_next(&je) == 0 && je.state != JST_ARRAY_END)
+      {
+        switch (je.state)
+        {
+        case JST_VALUE:
+          if (n_item == lp->n_item)
+          {
+            rem_start= (const char *) (je.s.c_str -
+                         (n_item ? je.sav_c_len : 0));
+            goto v_found;
+          }
+          n_item++;
+          if (json_skip_array_item(&je))
+            goto error;
+          break;
+        default:
+          break;
+        }
+      }
+
+      if (je.s.error)
+        goto error;
+
+      continue;
+    }
+    else /*JSON_PATH_KEY*/
+    {
+      if (je.value_type != JSON_VALUE_OBJECT)
+        continue;
+
+      while (json_scan_next(&je) == 0 && je.state != JST_OBJ_END)
+      {
+        switch (je.state)
+        {
+        case JST_KEY:
+          if (n_item == 0)
+            rem_start= (const char *) (je.s.c_str - je.sav_c_len);
+          json_string_set_str(&key_name, lp->key, lp->key_end);
+          if (json_key_matches(&je, &key_name))
+          {
+            goto v_found;
+          }
+
+          if (json_skip_key(&je))
+            goto error;
+
+          rem_start= (const char *) je.s.c_str;
+          n_item++;
+          break;
+        default:
+          break;
+        }
+      }
+
+      if (je.s.error)
+        goto error;
+
+      continue;
+    }
+
+v_found:
+
+    if (json_skip_key(&je) || json_scan_next(&je))
+      goto error;
+
+    rem_end= (je.state == JST_VALUE) ? 
+      (const char *) je.s.c_str : (const char *) (je.s.c_str - je.sav_c_len);
+
+    str->length(0);
+
+    if (append_simple(str, js->ptr(), rem_start - js->ptr()) ||
+        append_simple(str, rem_end, js->end() - rem_end))
+          goto error; /* Out of memory. */
+
+    {
+      String *tmp= str;
+      str= &tmp_js;
+      js= tmp;
+    }
+  }
+
+  return js;
+
+null_return:
+error:
+  null_value= 1;
+  return 0;
+}
+
+
+void Item_func_json_keys::fix_length_and_dec()
+{
+  collation.set(args[0]->collation);
+  max_length= args[0]->max_length;
+  if (arg_count > 1)
+    path.set_constant_flag(args[1]->const_item());
+}
+
+
+String *Item_func_json_keys::val_str(String *str)
+{
+  json_engine_t je;
+  String *js= args[0]->val_str(&tmp_js);
+  uint n_keys= 0;
+  uint array_counters[JSON_DEPTH_LIMIT];
+
+  if ((args[0]->null_value))
+    goto null_return;
+
+  json_scan_start(&je, js->charset(),(const uchar *) js->ptr(),
+                  (const uchar *) js->ptr() + js->length());
+
+  if (arg_count < 2)
+    goto skip_search;
+
+  if (!path.parsed)
+  {
+    String *s_p= args[1]->val_str(&tmp_path);
+    if (s_p &&
+        json_path_setup(&path.p, s_p->charset(), (const uchar *) s_p->ptr(),
+                        (const uchar *) s_p->ptr() + s_p->length()))
+      goto err_return;
+    path.parsed= path.constant;
+  }
+
+  if (args[1]->null_value)
+    goto null_return;
+
+  path.cur_step= path.p.steps;
+
+  if (json_find_path(&je, &path.p, &path.cur_step, array_counters))
+  {
+    if (je.s.error)
+      goto err_return;
+
+    goto null_return;
+  }
+
+skip_search:
+  if (json_read_value(&je))
+    goto err_return;
+
+  if (je.value_type != JSON_VALUE_OBJECT)
+    goto null_return;
+  
+  str->length(0);
+  if (str->append("[", 1))
+    goto err_return; /* Out of memory. */
+  /* Parse the OBJECT collecting the keys. */
+  while (json_scan_next(&je) == 0 && je.state != JST_OBJ_END)
+  {
+    const uchar *key_start, *key_end;
+
+    switch (je.state)
+    {
+    case JST_KEY:
+      key_start= je.s.c_str;
+      while (json_read_keyname_chr(&je) == 0)
+      {
+        key_end= je.s.c_str;
+      }
+      if (je.s.error ||
+          (n_keys > 0 && str->append(", ", 2)) ||
+          str->append("\"", 1) ||
+          append_simple(str, key_start, key_end - key_start) ||
+          str->append("\"", 1))
+        goto err_return;
+      n_keys++;
+      break;
+    case JST_OBJ_START:
+    case JST_ARRAY_START:
+      if (json_skip_level(&je))
+        break;
+      break;
+    default:
+      break;
+    }
+  }
+
+  if (je.s.error || str->append("]", 1))
+    goto err_return;
+
+  null_value= 0;
+  return str;
+
+null_return:
+err_return:
+  null_value= 1;
+  return 0;
+}
+
+
+bool Item_func_json_search::fix_fields(THD *thd, Item **ref)
+{
+  if (Item_json_str_multipath::fix_fields(thd, ref))
+    return TRUE;
+
+  if (arg_count < 4)
+    return FALSE;
+
+  return fix_escape_item(thd, args[3], &tmp_js, true,
+                         args[0]->collation.collation, &escape);
+}
+
+
+static const uint SQR_MAX_BLOB_WIDTH= sqrt(MAX_BLOB_WIDTH);
+
+void Item_func_json_search::fix_length_and_dec()
+{
+  collation.set(args[0]->collation);
+
+  /*
+    It's rather difficult to estimate the length of the result.
+    I belive arglen^2 is the reasonable upper limit.
+  */
+  if (args[0]->max_length > SQR_MAX_BLOB_WIDTH)
+    max_length= MAX_BLOB_WIDTH;
+  else
+  {
+    max_length= args[0]->max_length;
+    max_length*= max_length;
+  }
+
+  ooa_constant= args[1]->const_item();
+  ooa_parsed= FALSE;
+
+  if (arg_count > 4)
+    mark_constant_paths(paths, args+4, arg_count-4);
+}
+
+
+int Item_func_json_search::compare_json_value_wild(json_engine_t *je,
+                                                   const String *cmp_str)
+{
+  return my_wildcmp(collation.collation,
+      (const char *) je->value, (const char *) (je->value + je->value_len),
+      cmp_str->ptr(), cmp_str->end(), escape, wild_one, wild_many) ? 0 : 1;
+}
+
+
+static int append_json_path(String *str, const json_path_t *p)
+{
+  const json_path_step_t *c;
+
+  if (str->append("\"$", 2))
+    return TRUE;
+
+  for (c= p->steps+1; c <= p->last_step; c++)
+  {
+    if (c->type == JSON_PATH_KEY)
+    {
+      if (str->append(".", 1) ||
+          append_simple(str, c->key, c->key_end-c->key))
+        return TRUE;
+    }
+    else /*JSON_PATH_ARRAY*/
+    {
+
+      if (str->append("[", 1) ||
+          str->append_ulonglong(c->n_item) ||
+          str->append("]", 1))
+        return TRUE;
+    }
+  }
+
+  return str->append("\"", 1);
+}
+
+
+static int json_path_compare(const json_path_t *a, const json_path_t *b)
+{
+  uint i, a_len= a->last_step - a->steps, b_len= b->last_step - b->steps;
+
+  if (a_len > b_len)
+    return -2;
+
+  for (i=0; i <= a_len; i++)
+  {
+    const json_path_step_t *sa= a->steps + i;
+    const json_path_step_t *sb= b->steps + i;
+
+    if (sa->type != sb->type)
+      return -1;
+    
+    if (sa->type == JSON_PATH_ARRAY)
+    {
+      if (!sa->wild && sa->n_item != sb->n_item)
+        return -1;
+    }
+    else /* JSON_PATH_KEY */
+    {
+      if (!sa->wild &&
+          (sa->key_end - sa->key != sb->key_end - sb->key ||
+           memcmp(sa->key, sb->key, sa->key_end - sa->key) != 0))
+        return -1;
+    }
+  }
+
+  return b_len > a_len;
+}
+
+
+static bool path_ok(const json_path_with_flags *paths_list, int n_paths,
+                    const json_path_t *p)
+{
+  for (; n_paths > 0; n_paths--, paths_list++)
+  {
+    if (json_path_compare(&paths_list->p, p) >= 0)
+      return TRUE;
+  }
+  return FALSE;
+}
+
+
+String *Item_func_json_search::val_str(String *str)
+{
+  String *js= args[0]->val_str(&tmp_js);
+  String *s_str= args[2]->val_str(&tmp_js);
+  json_engine_t je;
+  json_path_t p, sav_path;
+  uint n_arg;
+
+  if (args[0]->null_value || args[2]->null_value)
+    goto null_return;
+
+  if (parse_one_or_all(args[1], &ooa_parsed, ooa_constant, &mode_one))
+    goto error;
+
+  if (args[1]->null_value)
+    goto null_return;
+
+  n_path_found= 0;
+  str->set_charset(js->charset());
+  str->length(0);
+
+  for (n_arg=4; n_arg < arg_count; n_arg++)
+  {
+    json_path_with_flags *c_path= paths + n_arg - 4;
+    if (!c_path->parsed)
+    {
+      String *s_p= args[n_arg]->val_str(tmp_paths + (n_arg-1));
+      if (s_p &&
+          json_path_setup(&c_path->p,s_p->charset(),(const uchar *) s_p->ptr(),
+                          (const uchar *) s_p->ptr() + s_p->length()))
+        goto error;
+      c_path->parsed= c_path->constant;
+    }
+  }
+
+  json_scan_start(&je, js->charset(),(const uchar *) js->ptr(),
+                  (const uchar *) js->ptr() + js->length());
+
+  p.last_step= p.steps;
+  p.steps[0].wild= 0;
+  p.steps[0].type= JSON_PATH_ARRAY;
+  p.steps[0].n_item= 0;
+
+  do
+  {
+    switch (je.state)
+    {
+    case JST_KEY:
+      p.last_step->key= je.s.c_str;
+      while (json_read_keyname_chr(&je) == 0)
+        p.last_step->key_end= je.s.c_str;
+      if (je.s.error)
+        goto error;
+      /* Now we have je.state == JST_VALUE, so let's handle it. */
+
+    case JST_VALUE:
+      if (json_read_value(&je))
+        goto error;
+      if (json_value_scalar(&je))
+      {
+        if ((arg_count < 5 || path_ok(paths, n_arg - 4, &p)) &&
+            compare_json_value_wild(&je, s_str) != 0)
+        {
+          ++n_path_found;
+          if (n_path_found == 1)
+          {
+            sav_path= p;
+            sav_path.last_step= sav_path.steps + (p.last_step - p.steps);
+          }
+          else
+          {
+            if (n_path_found == 2)
+            {
+              if (str->append("[", 1) ||
+                  append_json_path(str, &sav_path))
+                goto error;
+            }
+            if (str->append(", ", 2) || append_json_path(str, &p))
+              goto error;
+          }
+
+          if (mode_one)
+            goto end;
+        }
+        if (p.last_step->type == JSON_PATH_ARRAY)
+          p.last_step->n_item++;
+
+      }
+      else
+      {
+        p.last_step++;
+        if (je.value_type == JSON_VALUE_ARRAY)
+        {
+          p.last_step->type= JSON_PATH_ARRAY;
+          p.last_step->n_item= 0;
+        }
+        else /*JSON_VALUE_OBJECT*/
+          p.last_step->type= JSON_PATH_KEY;
+      }
+
+      break;
+    case JST_OBJ_END:
+    case JST_ARRAY_END:
+      p.last_step--;
+      if (p.last_step->type == JSON_PATH_ARRAY)
+        p.last_step->n_item++;
+      break;
+    default:
+      break;
+    }
+  } while (json_scan_next(&je) == 0);
+
+  if (je.s.error)
+    goto error;
+
+end:
+  if (n_path_found == 0)
+    goto null_return;
+  if (n_path_found == 1)
+  {
+    if (append_json_path(str, &sav_path))
+      goto error;
+  }
+  else
+  {
+    if (str->append("]", 1))
+      goto error;
+  }
+
+  return str;
+
+
+null_return:
+error:
+  /* TODO: launch error messages. */
+  null_value= 1;
+  return 0;
+}
+
+
+void Item_json_typecast::fix_length_and_dec()
+{
+  maybe_null= args[0]->maybe_null;
+  max_length= args[0]->max_length;
+}
+
+