Help parsin numbers

[Anonymous]

Good morning,
I'm trying to parse numbers, both in decimal and hexadecimal format, and I need to return their radix.
My problem is that the ParseResults objects passed to my parseAction does nto have the attribute hex or dec as i specify.
Here is my code:

def processParsedNum(results):
    '''
    Process a ParsingResults objects resulting from parsing a number
    @param results: the object containing all the parsed tokens
    @return a stringified version of the parsed number
    '''
    #Process value
    val = results.value
    radix = 10
    rawValue = results.value
    #Process radix
    strValue = None
    if results.dec:
        strValue = val.dec
    elif results.hex:
        strValue = "0x" + val.hex
        results = 16
    #Process prefix
    if results.prefix:
        strValue = results.prefix + strValue
    results = strValue
    results = radix
    results = rawValue
    return results

#Decimal numbers
SYMBOL = oneOf('+ -')
NUM_INT = Word(nums)
NUM_FLOAT = Combine(NUM_INT + Literal(".") + NUM_INT, adjacent=True)
NUM_EXPONENTIAL = Combine(Or() + \
                          oneOf("E e") + \
                          Optional(SYMBOL) + \
                          NUM_INT, \
                          adjacent=True)
NUM_DEC = Or()
NUM_DEC.setResultsName('dec')

#HEXADECIMAL number may have either the prefix . or the h,H suffixes
NUM_HEX = Or([Suppress(Literal(".")) + Word(nums+"ABCDEF"+"abcdef"), \
              Word(nums+"ABCDEF"+"abcdef") + Suppress(oneOf("H h"))])
NUM_HEX.setResultsName('hex')

NUM = Optional(SYMBOL).setResultsName('prefix') + \
      Or().setResultsName('value')
NUM
NUM.setParseAction(processParsedNum)

I don't know what i'm doing wrong (of course i'm doing something), but i guess there should be a way of navigating through the parsed elements and it sub-elements.

Thanks in advance.

Cheers!

[Paul McGuire]

Sorry to not see your post earlier. The problem is in the somewhat misleading function name "setResultsName". This method does not just set the return name, but returns a copy of the original expression. The reason for this is that a single expression might occur several times in a larger parser, with different results names associated with it.

In your parser, the solution is to simply assign the value returned by setResultsName back to the expression itself:

NUM_DEC = NUM_DEC.setResultsName('dec')
NUM_HEX = NUM_HEX.setResultsName('hex')

There is a shortened form of setResultsName which is useful when building up a larger expression from smaller ones.

NUM_DEC = NUM_DEC('dec')
NUM_HEX = NUM_HEX('hex')

Otherwise, your pyparsing parser code looks fine. With these changes, I was able to get your parser working with test strings "100", ".100", and "100h".  You have a few remaining minor bugs in your parse action, here is a working version:

def processParsedNum(results):
    '''
    Process a ParsingResults objects resulting from parsing a number
    @param results: the object containing all the parsed tokens 
    @return a stringified version of the parsed number
    '''
    #Process value
    val = results.value
    radix = 10
    rawValue = results.value
    #Process radix
    strValue = None
    if results.dec:
        strValue = results.dec
    elif results.hex:
        strValue = "0x" + results.hex
        radix = 16
    #Process prefix
    if results.prefix:
        strValue = results.prefix + strValue
    results['value'] = strValue
    results['radix'] = radix
    results['rawValue'] = rawValue
    return results

Sorry for the delay, good luck in your parsing endeavors!
- Paul McGuire