Tracking: Support the full JSON Path language

[b41sh]

JSON path has already implemented the basic elements accessors and comparison predicates filter expression, in order to support the full JSON Path language, the following tasks need to be done further.

• Variables:
  • [ ] Variables
• Modes:
  • [ ] lax
  • [ ] strict
• Item methods:
  • [ ] type()
  • [ ] size()
  • [ ] double()
  • [ ] ceiling()
  • [ ] floor()
  • [ ] abs()
  • [ ] datetime()
  • [ ] keyvalue()
• Arithmetic expressions
  • [ ] Unary + or -
  • [ ] Binary +, -, *, /, %
• Filter expression
  • [x] exists path predicate
  • [ ] like_regex predicate
  • [ ] starts with predicate
  • [ ] is unknown predicate

The syntax and functionality of JSON Path should be implemented in accordance with the SQL:2016 (ISO/IEC 9075:2016) standard. Here are some references:

• SQL Technical Reports — Part 6: SQL support for JavaScript Object Notation (JSON)
• PostgreSQL Jsonpath in examples and roadmap
• Gentle Guide to JSONPATH in PostgreSQL