Process data by ‘jsondata.JSONPointer’

The module jsondata.JSONPointer provides for the most important operators for the assembly and evaluation of JSON pointers in accordance to RFC6901.

Basic types of provided basic operations are:

• Pointer Arithmetics: Manipulates and calculates the pointer itself. Thus the comparison is related to the resulting contained set. Where the shorter matching pointer path contains more elements, than the longer, which itself is contained in the matching shorter path.
• Pointed Value Evaluation: Fetches values from JSON documents. Thus the comparison is related to the resulting values pointed to by the pointer path.
• Calculations with Pointed Values: Applies common arithmetics on to evaluated values and numeric parts of pointers.

Syntax Elements

The current release provides the following operators for the class ‘JSONPointer’.

Pointer comparison:

ops := '>' | '<' | '>=' | '<=' | '==' | '!='

Pointer calculation and assignment operations:

ops := '=' | '+' | '+='

Pointed value evaluation operators:

ops := '()'

Examples

Examples for the provided basic calculations are:

Arithmetics

• Pointer Arithmetics:

  import jsondata.JSONPointer
  
  a = JSONPointer("/a/b/c")
  b = JSONPointer("/x/y")
  c = JSONPointer("/a/b/c/2/x/y/v")
  d = JSONPointer("/a/b/c/2/x/y")
  e = JSONPointer("/a/b/c/2/x")
  
  # loop with increment
  for i in range(0,4):
     print str(a + i + b) + " > " + str(c) + " = " + str(a + i + b > c )
  
  print
  print str(a + 2 + b) + " > " + str(d) + " = " + str(a + 2 + b > d )
  
  print
  print str(a + 2 + b) + " > " + str(e) + " = " + str(a + 2 + b > e )
  

  prints the results:

  /a/b/c/0/x/y > /a/b/c/2/x/y/v = False
  /a/b/c/1/x/y > /a/b/c/2/x/y/v = False
  /a/b/c/2/x/y > /a/b/c/2/x/y/v = True
  /a/b/c/3/x/y > /a/b/c/2/x/y/v = False
  
  /a/b/c/2/x/y > /a/b/c/2/x/y = False
  
  /a/b/c/2/x/y > /a/b/c/2/x = False
  

  Where the shorter matching pointer path contains more elements, than the longer, which itself is contained in the matching shorter path.

Evaluation

• Pointed Value Evaluation:

  import jsondata.JSONPointer
  
  jdata = { 'a': { 'b': { 'c': 2, 'd': 3 } } }
  
  a = JSONPointer("/a/b/c")
  b = JSONPointer("/x/y")
  c = JSONPointer("/2/x/y/v")
  d = JSONPointer("/a/b/d")
  
  print a(jdata) + b
  print JSONPointer(a(jdata)) + d(jdata)
  print JSONPointer(a(jdata)) + JSONPointer(d(jdata))
  print c
  print a(jdata) + b > c
  

  prints the results:

  /2/x/y
  /2/3
  /2/3
  /2/x/y/v
  True
  

Calculation

• Calculations with Pointed Values:

  import jsondata.JSONPointer
  
  jdata = { 'a': { 'b': { 'c': 2, 'd': 3 } } }
  
  a = JSONPointer("/a/b/c")
  b = JSONPointer("/x/y")
  c = JSONPointer("/2/x/y/v")
  d = JSONPointer("/a/b/d")
  
  print a(jdata) + d(jdata)
  print JSONPointer(a(jdata) + d(jdata))
  

  prints the results:

  5
  /5