# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1512684696 -3600
# Node ID f3b89d7e3e2a38982eb2c56805b0abe69ec29caf
# Parent  28fe0ad38cd487845c6bd5ae04e9117dccfe9a45
Consolidate resolution-related information into a single table.

diff -r 28fe0ad38cd4 -r f3b89d7e3e2a vRecurrence.py
--- a/vRecurrence.py	Mon Dec 04 23:47:37 2017 +0100
+++ b/vRecurrence.py	Thu Dec 07 23:11:36 2017 +0100
@@ -58,19 +58,37 @@
 import operator
 
 # Frequency levels, specified by FREQ in iCalendar.
+# Enumeration levels, employed by BY... qualifiers.
+# Labels, employed in string representations of selectors.
+# Datetime tuple lengths.
+# The first/lowest values at each resolution.
+# Parent resolutions, employed for repetition at a lower resolution than selected.
 
-freq_levels = (
-    "YEARLY",
-    "MONTHLY",
-    "WEEKLY",
-    None,       # yearday has no equivalent frequency
-    None,       # monthday has no equivalent frequency
-    "DAILY",
-    "HOURLY",
-    "MINUTELY",
-    "SECONDLY"
+resolutions = (
+    # Frequency  # Enumeration  # Label      # Length  # First  # Parent
+    ("YEARLY",   None,          "YEARS",     1,        0,       None),  # nothing beyond years
+    ("MONTHLY",  "BYMONTH",     "MONTHS",    2,        1,       0),     # months -> years
+    ("WEEKLY",   "BYWEEKNO",    "WEEKS",     3,        1,       1),     # weeks -> months
+    (None,       "BYYEARDAY",   "YEARDAYS",  3,        1,       0),     # yeardays -> years
+    (None,       "BYMONTHDAY",  "MONTHDAYS", 3,        1,       1),     # monthdays -> months
+    ("DAILY",    "BYDAY",       "DAYS",      3,        1,       2),     # weekdays -> weeks
+    ("HOURLY",   "BYHOUR",      "HOURS",     4,        0,       5),     # hours -> days
+    ("MINUTELY", "BYMINUTE",    "MINUTES",   5,        0,       6),     # minutes -> hours
+    ("SECONDLY", "BYSECOND",    "SECONDS",   6,        0,       7),     # seconds -> minutes
     )
 
+freq_levels        = map(lambda x: x[0], resolutions)
+enum_levels        = map(lambda x: x[1], resolutions)
+level_labels       = map(lambda x: x[2], resolutions)
+lengths            = map(lambda x: x[3], resolutions)
+positions          = map(lambda x: x[3] - 1, resolutions)
+firstvalues        = map(lambda x: x[4], resolutions)
+enum_parent_levels = map(lambda x: x[5], resolutions)
+
+# Add labels corresponding to negative indexes.
+
+level_labels += ("COUNT", "DTSTART")
+
 # Symbols corresponding to resolution levels.
 
 YEARS, MONTHS, WEEKS, DAYS, HOURS, MINUTES, SECONDS = 0, 1, 2, 5, 6, 7, 8
@@ -83,56 +101,9 @@
 
 COUNT, DTSTART, BYSETPOS = -2, -1, None
 
-level_labels = (
-    "YEARS", "MONTHS", "WEEKS", "YEARDAYS", "MONTHDAYS", "DAYS", "HOURS",
-    "MINUTES", "SECONDS",
-
-    # Negative indexes.
-
-    "COUNT", "DTSTART"
-    )
-
-# Enumeration levels, employed by BY... qualifiers.
-
-enum_levels = (
-    None,
-    "BYMONTH",
-    "BYWEEKNO",
-    "BYYEARDAY",
-    "BYMONTHDAY",
-    "BYDAY",
-    "BYHOUR",
-    "BYMINUTE",
-    "BYSECOND"
-    )
-
-# Map levels to parent levels.
-
-enum_parent_levels = (
-    None,       # nothing beyond years
-    0,          # months -> years
-    1,          # weeks -> months
-    0,          # yeardays -> years
-    1,          # monthdays -> months
-    2,          # weekdays -> weeks
-    5,          # hours -> days
-    6,          # minutes -> hours
-    7           # seconds -> minutes
-    )
-
 # 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]
+daylevels = map(lambda t: t[0], filter(lambda t: t[1] == 3, enumerate(lengths)))
 
 # Map from qualifiers to interval multiples. Here, weeks are defined as 7 days.