CODEWITHSUNDEEP
python-3.xparsingquery-stringpyparsing
Droid
Droid

Reputation: 1362

string parsing a complex logical operators in pyparsing

i am trying parse logical operators, query string see below

code!=720 AND first_name=abc OR last_name=def AND status_code=OK

and get the parsed string as a binary tree. For the above expression the expected parsed expression should look like

[[['code', '!=', '720'], 'AND', ['first_name', '=', 'abc']], 'OR', [['last_name', '=', 'def'], 'AND', ['status_code', '=', 'OK']]]

i tried to do this code but i do not get the desired output

operator = pp.Regex(">=|<=|!=|>|<|=").setName("operator")
number = pp.Regex(r'[+-]?\w+(:?\.\w*)?(:?[eE][+-]?\w+)?')
word = pp.Word(pp.alphas, pp.alphanums + "_-*(1234567890 ,)")
term = word | number
condition = pp.Group(term + operator + term)


expr = pp.operatorPrecedence(condition,
         [('NOT', 1, pp.opAssoc.RIGHT,),
          ('AND', 2, pp.opAssoc.LEFT,),
          ('OR', 2, pp.opAssoc.LEFT,)])

example 

query_string = 'code!=720 AND first_name=abc OR last_name=def AND status_code=OK'
print(expr.parseString(query_string)[0])

and output is wrong

 [['code', '!=', '720'], 'AND', ['first_name', '=', 'abc OR last_name']]

can you help me write the correct condition?

Upvotes: 5

Views: 1718

Answers (1)

PaulMcG
PaulMcG

Reputation: 63762

All comments above incorporated in this code:

import pyparsing as pp

operator = pp.oneOf(">= <= != > < =").setName("operator")
number = pp.pyparsing_common.number()
# there is no space character in this pp.Word expression
word = pp.Word(pp.alphas, pp.alphanums + "_-*(1234567890,)")
term = word | number | pp.quotedString
condition = pp.Group(term + operator + term)


expr = pp.operatorPrecedence(condition,
         [('NOT', 1, pp.opAssoc.RIGHT,),
          ('AND', 2, pp.opAssoc.LEFT,),
          ('OR', 2, pp.opAssoc.LEFT,)])

query_string = 'code!=720 AND first_name=abc OR last_name=def AND status_code=OK'
print(expr.parseString(query_string, parseAll=True)[0])

which gives this output:

[[['code', '!=', 720], 'AND', ['first_name', '=', 'abc']], 'OR', [['last_name', '=', 'def'], 'AND', ['status_code', '=', 'OK']]]

Upvotes: 6

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