object of type 'Item_string' in sql/json_schema.cc
Analysis: make_string_literal() returns pointer of type
Item_basic_constant which is converted to pointer of type Item_string. Now,
Item_string is base class of Item_basic_constant, so the error about
downcasting.
Fix: using constructor of Item_string type directly instead of
downcasting would be more appropriate.
always return 1
Analysis: Implementation used double to store value. longlong is better
choice
Fix: Use longlong for multiple_of and the value to store it and num_flag to
check for decimals.
Analysis: multipleOf must be strictly greater then 0. However the
implementation only disallowed values strcitly less than 0
Fix: check if value is less than or equal to 0 instead of less than 0 and
return true.
Also fixed the incorrect return value for some other keywords.
Analysis: Current implementation does not check the number of elements in
the enum array and whether they are unique or not.
Fix: Add a counter that counts number of elements and before inserting the
element in the enum hash check whether it exists.
Implementation:
Implementation is made according to json schema validation draft 2020
JSON schema basically has same structure as that of json object, consisting
of key-value pairs. So it can be parsed in the same manner as
any json object.
However, none of the keywords are mandatory, so making guess about the
json value type based only on the keywords would be incorrect.
Hence we need separate objects denoting each keyword.
So during create_object_and_handle_keyword() we create appropriate objects
based on the keywords and validate each of them individually on the json
document by calling respective validate() function if the type matches.
If any of them fails, return false, else return true.
