# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1496700125 -7200
# Node ID 7023d88d726051bae98f61b9d72199f383553a7f
# Parent  c6bcb246a972e19b147f92fedac0d3ded074ccf5
Removed context details from selectors, converting datetime values to
enumerators only when needed to provide the necessary result resolution.

diff -r c6bcb246a972 -r 7023d88d7260 tests/qualifiers.py
--- a/tests/qualifiers.py	Mon Jun 05 18:42:20 2017 +0200
+++ b/tests/qualifiers.py	Tue Jun 06 00:02:05 2017 +0200
@@ -3,7 +3,7 @@
 """
 Test qualifiers for recurring events.
 
-Copyright (C) 2014, 2015 Paul Boddie <paul@boddie.org.uk>
+Copyright (C) 2014, 2015, 2017 Paul Boddie <paul@boddie.org.uk>
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -772,4 +772,36 @@
 print l[-1] == (1998, 3, 30, 9, 0, 0), (1998, 3, 30, 9, 0, 0), l[-1]
 print
 
+qualifiers = get_qualifiers(["FREQ=MONTHLY", "BYMONTHDAY=5", "FREQ=HOURLY", "INTERVAL=12"])
+
+l = order_qualifiers(qualifiers)
+show(l)
+dt = (2017, 6, 13)
+l = get_datetime_structure(dt)
+show(l)
+l = combine_datetime_with_qualifiers(dt, qualifiers)
+show(l)
+
+s = get_selector(dt, qualifiers)
+l = s.materialise(dt, (2019, 1, 1))
+print len(l) == 36
+print l[0] == (2017, 7, 5, 0), (2017, 7, 5, 0), l[0]
+print l[-1] == (2018, 12, 5, 12), (2018, 12, 5, 12), l[-1]
+
+qualifiers = get_qualifiers(["FREQ=DAILY", "BYMONTH=1"])
+
+l = order_qualifiers(qualifiers)
+show(l)
+dt = (2017, 6, 13)
+l = get_datetime_structure(dt)
+show(l)
+l = combine_datetime_with_qualifiers(dt, qualifiers)
+show(l)
+
+s = get_selector(dt, qualifiers)
+l = s.materialise(dt, (2019, 1, 1))
+print len(l) == 31
+print l[0] == (2018, 1, 1), (2018, 1, 1), l[0]
+print l[-1] == (2018, 1, 31), (2018, 1, 31), l[-1]
+
 # vim: tabstop=4 expandtab shiftwidth=4
diff -r c6bcb246a972 -r 7023d88d7260 vRecurrence.py
--- a/vRecurrence.py	Mon Jun 05 18:42:20 2017 +0200
+++ b/vRecurrence.py	Tue Jun 06 00:02:05 2017 +0200
@@ -84,11 +84,20 @@
     "BYSECOND"
     )
 
+# Levels defining days.
+
+daylevels = [2, 3, 4, 5]
+
 # Map from levels to lengths of datetime tuples.
 
 lengths = [1, 2, 3, 3, 3, 3, 4, 5, 6]
 positions = [l-1 for l in lengths]
 
+# Define the lowest values at each resolution (years, months, days... hours,
+# minutes, seconds).
+
+firstvalues = [0, 1, 1, 1, 1, 1, 0, 0, 0]
+
 # Map from qualifiers to interval units. Here, weeks are defined as 7 days.
 
 units = {"WEEKLY" : 7}
@@ -245,6 +254,22 @@
     """
     Combine 'datetime' with 'qualifiers' to produce a structure for recurrence
     production.
+
+    Initial datetime values appearing at broader resolutions than any qualifiers
+    are ignored, since their details will be used when materialising the
+    results.
+
+    Qualifiers are accumulated in order to define a selection. Datetime values
+    occurring between qualifiers or at the same resolution as qualifiers are
+    ignored.
+
+    Any remaining datetime values are introduced as enumerators, provided that
+    they do not conflict with qualifiers. For example, specific day values
+    conflict with day selectors and weekly qualifiers.
+
+    The purpose of the remaining datetime values is to define a result within
+    a period selected by the most precise qualifier. For example, the selection
+    of a day and month in a year recurrence.
     """
 
     iter_dt = iter(get_datetime_structure(datetime))
@@ -254,51 +279,34 @@
 
     from_dt = get_next(iter_dt)
     from_q = get_next(iter_q)
-
     have_q = False
 
-    # The initial context for any qualifiers is taken from the first datetime
-    # value, which should be the year.
-
-    context = []
-    context.append(from_dt.args["values"][0])
-
     # Consume from both lists, merging entries.
 
     while from_dt and from_q:
         _level = from_dt.level
         level = from_q.level
 
-        # Datetime value at wider resolution. Use the datetime value to expand
-        # the context within which qualifiers will operate.
+        # Datetime value at wider resolution.
 
         if _level < level:
             from_dt = get_next(iter_dt)
-            context.append(from_dt.args["values"][0])
 
         # Qualifier at wider or same resolution as datetime value.
 
         else:
-            # Without any previous qualifier, introduce a special qualifier to
-            # provide context for this qualifier.
-
             if not have_q:
-                add_initial_qualifier(from_q, level, context, l)
+                add_initial_qualifier(from_q, level, l)
                 have_q = True
 
-            # Associate the datetime context with the qualifier and add it to
-            # the combined list.
+            # Add the qualifier to the combined list.
 
-            from_q.context = tuple(context)
             l.append(from_q)
 
-            # Datetime value at same resolution. Expand the context using the
-            # value.
+            # Datetime value at same resolution.
 
             if _level == level:
                 from_dt = get_next(iter_dt)
-                if from_dt:
-                    context.append(from_dt.args["values"][0])
 
             # Get the next qualifier.
 
@@ -307,20 +315,23 @@
     # Complete the list by adding remaining datetime enumerators.
 
     while from_dt:
-        l.append(from_dt)
+
+        # Ignore datetime values that conflict with day-level qualifiers.
+
+        if not l or from_dt.level != freq["DAILY"] or l[-1].level not in daylevels:
+            l.append(from_dt)
+
         from_dt = get_next(iter_dt)
 
     # Complete the list by adding remaining qualifiers.
 
     while from_q:
         if not have_q:
-            add_initial_qualifier(from_q, level, context, l)
+            add_initial_qualifier(from_q, level, l)
             have_q = True
 
-        # Associate the datetime context with the qualifier and add it to the
-        # combined list.
+        # Add the qualifier to the combined list.
 
-        from_q.context = tuple(context)
         l.append(from_q)
 
         # Get the next qualifier.
@@ -329,17 +340,16 @@
 
     return l
 
-def add_initial_qualifier(from_q, level, context, l):
+def add_initial_qualifier(from_q, level, l):
 
     """
     Take the first qualifier 'from_q' at the given resolution 'level', using it
-    to create an initial qualifier providing appropriate context, using the
-    given 'context', adding it to the combined list 'l' if required.
+    to create an initial qualifier, adding it to the combined list 'l' if
+    required.
     """
 
     if isinstance(from_q, Enum) and level > 0:
         repeat = Pattern(level - 1, {"interval" : 1}, None)
-        repeat.context = tuple(context[:level])
         l.append(repeat)
 
 # Datetime arithmetic.
@@ -446,7 +456,7 @@
 
     "A generic selector."
 
-    def __init__(self, level, args, qualifier, selecting=None):
+    def __init__(self, level, args, qualifier, selecting=None, first=False):
 
         """
         Initialise at the given 'level' a selector employing the given 'args'
@@ -460,17 +470,14 @@
         self.args = args
         self.qualifier = qualifier
         self.selecting = selecting
-
-        # Define an empty context to be overridden.
-
-        self.context = ()
+        self.first = first
 
         # Define the index of values from datetimes involved with this selector.
 
         self.pos = positions[level]
 
     def __repr__(self):
-        return "%s(%r, %r, %r, %r)" % (self.__class__.__name__, self.level, self.args, self.qualifier, self.context)
+        return "%s(%r, %r, %r, %r)" % (self.__class__.__name__, self.level, self.args, self.qualifier, self.first)
 
     def materialise(self, start, end, count=None, setpos=None, inclusive=False):
 
@@ -487,7 +494,7 @@
         start = to_tuple(start)
         end = to_tuple(end)
         counter = count and [0, count]
-        results = self.materialise_items(self.context, start, end, counter, setpos, inclusive)
+        results = self.materialise_items(start, start, end, counter, setpos, inclusive)
         results.sort()
         return results[:count]
 
@@ -560,10 +567,6 @@
         starting at the end of the search period, if present in the results.
         """
 
-        # Obtain the pattern context's value at the appropriate level.
-
-        first = scale(self.context[self.pos], self.pos)
-
         # Define the step between result periods.
 
         interval = self.args.get("interval", 1) * units.get(self.qualifier, 1)
@@ -574,12 +577,19 @@
         unit_interval = units.get(self.qualifier, 1)
         unit_step = scale(unit_interval, self.pos)
 
-        # Combine supplied context details with the pattern context. This should
-        # provide additional resolution information that may be missing from the
-        # supplied context. For example, the outer selector may indicate a month
-        # context, but this selector may need day information.
+        # Employ the context as the current period if this is the first
+        # qualifier in the selection chain.
+
+        if self.first:
+            current = context[:self.pos+1]
 
-        current = combine(context, first)
+        # Otherwise, obtain the first value at this resolution within the
+        # context period.
+
+        else:
+            first = scale(firstvalues[self.level], self.pos)
+            current = combine(context[:self.pos], first)
+
         results = []
 
         # Obtain periods before the end (and also at the end if inclusive),
@@ -702,7 +712,7 @@
         step = scale(1, self.pos)
         results = []
         for value in self.args["values"]:
-            current = combine(context, scale(value, self.pos))
+            current = combine(context[:self.pos], scale(value, self.pos))
             next = update(current, step)
 
             # To support setpos, only current and next bound the search, not
@@ -782,6 +792,7 @@
     """
 
     current = selectors[0]
+    current.first = True
     for selector in selectors[1:]:
         current.selecting = selector
         current = selector