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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, Opt
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 ({} to {})".format(minval, maxval),
}[minval is None, maxval is None]
return expr().add_condition(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).set_name("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") + Opt(SLASH + day("day"))
dateExpr.set_name("date")
# convert date fields to datetime (also validates dates as truly valid dates)
dateExpr.set_parse_action(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.run_tests(
"""
2011/5/8
2001/1/1
2004/2/29
2004/2
1999/12/31"""
)
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