1 files changed, 84 insertions, 0 deletions
diff --git a/examples/datetime_parse_actions.py b/examples/datetime_parse_actions.py
new file mode 100644
index 0000000..ff38656
--- /dev/null
+++ b/examples/datetime_parse_actions.py
@@ -0,0 +1,84 @@
+# parseActions.py
+#
+#   A sample program a parser to match a date string of the form "YYYY/MM/DD",
+# and return it as a datetime, or raise an exception if not a valid date.
+#
+# Copyright 2012, Paul T. McGuire
+#
+from datetime import datetime
+import pyparsing as pp
+from pyparsing import pyparsing_common as ppc
+
+# define an integer string, and a parse action to convert it
+# to an integer at parse time
+integer = pp.Word(pp.nums).set_name("integer")
+
+
+def convert_to_int(tokens):
+    # no need to test for validity - we can't get here
+    # unless tokens[0] contains all numeric digits
+    return int(tokens[0])
+
+
+integer.set_parse_action(convert_to_int)
+# or can be written as one line as
+# integer = Word(nums).set_parse_action(lambda t: int(t[0]))
+
+# define a pattern for a year/month/day date
+date_expr = integer("year") + "/" + integer("month") + "/" + integer("day")
+date_expr.ignore(pp.python_style_comment)
+
+
+def convert_to_datetime(s, loc, tokens):
+    try:
+        # note that the year, month, and day fields were already
+        # converted to ints from strings by the parse action defined
+        # on the integer expression above
+        return datetime(tokens.year, tokens.month, tokens.day).date()
+    except Exception as ve:
+        errmsg = "'%s/%s/%s' is not a valid date, %s" % (
+            tokens.year,
+            tokens.month,
+            tokens.day,
+            ve,
+        )
+        raise pp.ParseException(s, loc, errmsg)
+
+
+date_expr.set_parse_action(convert_to_datetime)
+
+
+date_expr.run_tests(
+    """\
+    2000/1/1
+
+    # invalid month
+    2000/13/1
+
+    # 1900 was not a leap year
+    1900/2/29
+
+    # but 2000 was
+    2000/2/29
+    """
+)
+
+
+# if dates conform to ISO8601, use definitions in pyparsing_common
+date_expr = ppc.iso8601_date.set_parse_action(ppc.convert_to_date())
+date_expr.ignore(pp.python_style_comment)
+
+date_expr.run_tests(
+    """\
+    2000-01-01
+
+    # invalid month
+    2000-13-01
+
+    # 1900 was not a leap year
+    1900-02-29
+
+    # but 2000 was
+    2000-02-29
+    """
+)