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| author | Paul McGuire <ptmcg@austin.rr.com> | 2014-10-11 05:11:47 +0000 |
|---|---|---|
| committer | Paul McGuire <ptmcg@austin.rr.com> | 2014-10-11 05:11:47 +0000 |
| commit | 169c544d9eef11444648714530df1050a40b4d9b (patch) | |
| tree | a92d1f91004eecc97cfcf81c1d9f0c9968d3057f /src/examples/rangeCheck.py | |
| parent | b6bb2dfea7d97d013c4b69bd3b44d40daa45d792 (diff) | |
| download | pyparsing-git-169c544d9eef11444648714530df1050a40b4d9b.tar.gz | |
Minor mods to released examples
Diffstat (limited to 'src/examples/rangeCheck.py')
| -rw-r--r-- | src/examples/rangeCheck.py | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/src/examples/rangeCheck.py b/src/examples/rangeCheck.py new file mode 100644 index 0000000..35c9ef3 --- /dev/null +++ b/src/examples/rangeCheck.py @@ -0,0 +1,76 @@ +# 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.
+#
+# Copyright 2011, Paul T. McGuire
+#
+
+from pyparsing import Word, nums, Suppress, ParseException, empty, Optional
+from datetime import datetime
+
+def rangeCheck(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
+ inRangeFn = {
+ (True, False) : lambda x : x <= maxval,
+ (False, True) : lambda x : minval <= x,
+ (False, False) : lambda x : minval <= x <= maxval,
+ }[minval is None, maxval is None]
+ outOfRangeMessage = {
+ (True, False) : "value %%s is greater than %s" % maxval,
+ (False, True) : "value %%s is less than %s" % minval,
+ (False, False) : "value %%s is not in the range (%s to %s)" % (minval,maxval),
+ }[minval is None, maxval is None]
+
+ # define the actual range checking parse action
+ def rangeCheckParseAction(string, loc, tokens):
+ parsedval = tokens[0]
+ if not inRangeFn(parsedval):
+ raise ParseException(string, loc, outOfRangeMessage % parsedval)
+
+ return rangeCheckParseAction
+
+# 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 = integer.copy().addParseAction(rangeCheck(1,12))
+day = integer.copy().addParseAction(rangeCheck(1,31))
+year = integer.copy().addParseAction(rangeCheck(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.addParseAction(rangeCheck(mindate, maxdate))
+
+
+tests = """
+ 2011/5/8
+ 2001/1/1
+ 2004/2/29
+ 2004/2/30
+ 2004/2
+ """.splitlines()
+for t in tests:
+ t = t.strip()
+ if not t: continue
+ print(t)
+ try:
+ print(dateExpr.parseString(t)[0])
+ except Exception as e:
+ print(str(e))
+ print()
+
+
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