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- # rangeCheck.py
- #
- # A sample program showing how parse actions can convert parsed
- # strings into a data type or object, and to validate the parsed value.
- #
- # Updated to use new addCondition method and expr() copy.
- #
- # Copyright 2011,2015 Paul T. McGuire
- #
- from pyparsing import Word, nums, Suppress, Optional
- from datetime import datetime
- def ranged_value(expr, minval=None, maxval=None):
- # have to specify at least one range boundary
- if minval is None and maxval is None:
- raise ValueError("minval or maxval must be specified")
- # set range testing function and error message depending on
- # whether either or both min and max values are given
- inRangeCondition = {
- (True, False) : lambda s,l,t : t[0] <= maxval,
- (False, True) : lambda s,l,t : minval <= t[0],
- (False, False) : lambda s,l,t : minval <= t[0] <= maxval,
- }[minval is None, maxval is None]
- outOfRangeMessage = {
- (True, False) : "value is greater than %s" % maxval,
- (False, True) : "value is less than %s" % minval,
- (False, False) : "value is not in the range ({0} to {1})".format(minval,maxval),
- }[minval is None, maxval is None]
- return expr().addCondition(inRangeCondition, message=outOfRangeMessage)
- # define the expressions for a date of the form YYYY/MM/DD or YYYY/MM (assumes YYYY/MM/01)
- integer = Word(nums).setName("integer")
- integer.setParseAction(lambda t:int(t[0]))
- month = ranged_value(integer, 1, 12)
- day = ranged_value(integer, 1, 31)
- year = ranged_value(integer, 2000, None)
- SLASH = Suppress('/')
- dateExpr = year("year") + SLASH + month("month") + Optional(SLASH + day("day"))
- dateExpr.setName("date")
- # convert date fields to datetime (also validates dates as truly valid dates)
- dateExpr.setParseAction(lambda t: datetime(t.year, t.month, t.day or 1).date())
- # add range checking on dates
- mindate = datetime(2002,1,1).date()
- maxdate = datetime.now().date()
- dateExpr = ranged_value(dateExpr, mindate, maxdate)
- dateExpr.runTests("""
- 2011/5/8
- 2001/1/1
- 2004/2/29
- 2004/2
- 1999/12/31""")
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