From 1b633959b1153b40ff8fcddd8430e0c6b0e9574b Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Thu, 8 Jun 2017 23:37:05 +0000
Subject: improve API documentation and testing

Oh, so that's why I hadn't released this project earlier...
---
 lib/msgthr.rb | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 73 insertions(+), 9 deletions(-)

(limited to 'lib/msgthr.rb')

diff --git a/lib/msgthr.rb b/lib/msgthr.rb
index f8b5896..ea63731 100644
--- a/lib/msgthr.rb
+++ b/lib/msgthr.rb
@@ -2,6 +2,18 @@
 # License: GPL-2.0+ <https://www.gnu.org/licenses/gpl-2.0.txt>
 
 # Non-recursive, container-agnostic message threading.
+#
+# Usage is typically:
+#
+# * use Msgthr.new to create a new object
+# * use Msgthr#add! for every message you have
+# * use Msgthr#thread! to perform threading operations
+# * optionally, use Msgthr#order! to sort messages
+# * use Msgthr#walk_thread to iterate through the threaded tree
+#
+# See https://80x24.org/msgthr/README for more info
+# You may email us publically at mailto:msgthr-public@80x24.org
+# Archives are at https://80x24.org/msgthr-public/
 class Msgthr
 
   # an Array of root (parent-less) messages, only populated after
@@ -20,20 +32,68 @@ class Msgthr
     @id_table.clear
   end
 
-  # Threads the message
-  # This does not sort
+  # Performs threading on the messages and returns the rootset
+  # (set of message containers without parents).
+  #
+  # Call this after all #add operations are complete.
+  # This does not sort, use #order! if sorting is necessary.
   def thread!
     ret = @rootset
     @id_table.each_value { |cont| ret << cont if cont.parent.nil? }.clear
     ret
   end
 
+  # Performs an in-place sort on messages after thread!
+  # This is optional and intended to be called this only after #thread!
+  #
+  # This takes a block which yields an array of Msgthr::Container
+  # objects for sorting.
+  #
+  # To sort by unique +mid+ identifiers for each container:
+  #
+  #   msgthr.order! { |ary| ary.sort_by!(&:mid) }
+  #
+  # If your opaque message pointer contains a +time+ accessor which gives
+  # a Time object:
+  #
+  #   msgthr.order! do |ary|
+  #     ary.sort_by! do |cont| # Msgthr::Container
+  #       cur = cont.topmost
+  #       cur ? cur.msg.time : Time.at(0)
+  #     end
+  #   end
+  #
+  # Note, using Msgthr::Container#topmost is NOT necessary when accessing
+  # Msgthr::Container#mid, as any known missing messages (ghosts)
+  # will still have a +mid+.  However, Msgthr::Container#topmost is
+  # necessary if accessing Msgthr::Container#msg.
   def order!
     yield @rootset
-    @rootset.each { |cont| cont.order! { |children| yield(children) } }
+    @rootset.each do |cont|
+      # this calls Msgthr::Container#order!, which is non-recursive
+      cont.order! { |children| yield(children) }
+    end
   end
 
-  # non-recursively walk a thread
+  # non-recursively walk a set of messages after #thread!
+  # (and optionally, #order!)
+  #
+  # This takes a block and yields 3 elements to it: +|level, container, index|+
+  # for each message container.
+  #
+  # * +level+ is the current depth within the walk (non-negative Integer)
+  # * +container+ is the Msgthr::Container object
+  # * +index+ is the offset of the container within its level (starting at 0)
+  #
+  # To display the subject of each message with indentation,
+  # assuming your +msg+ pointer has a +subject+ field:
+  #
+  #   msgthr.walk_thread do |level, container, index|
+  #     msg = container.msg
+  #     subject = msg ? msg.subject : "[missing: <#{container.mid}>]"
+  #     indent = '  ' * level
+  #     printf("#{indent} % 3d. %s\n", index, subject)
+  #   end
   def walk_thread
     i = -1
     q = @rootset.map { |cont| [ 0, cont, i += 1 ] }
@@ -49,20 +109,24 @@ class Msgthr
   # Adds a message to prepare a Msgthr object for threading.
   #
   # * +mid+ is a unique identifier for the message in a given thread.
+  #   It is typically a String or Integer, but may be anything usable
+  #   as a Hash key in Ruby.
   #
-  # * +refs+ should be an Array of unique identifiers.  For mail and
-  #   news messages, this is usually the parsed result of the
-  #   "References:" header.  Order should be oldest to newest
+  # * +refs+ should be an Array of unique identifiers belonging
+  #   to ancestors of the current message.
+  #   For mail and news messages, this is usually the parsed result
+  #   of the "References:" header.  Order should be oldest to newest
   #   in terms of ancestry, with the last element being the
   #   immediate parent of the given message.
   #
-  #   This is +nil+ for messages with no parent.
+  #   This is +nil+ for messages with no parent (root messages).
   #
   # * +msg+ is an opaque object which typically contains a
   #   Mail or Tmail object for handling mail.
   #
   # If +mid+ is a String, it is recommended to freeze the string before
-  # calling this method to avoid wasting memory on hash keys.
+  # calling this method to avoid wasting memory on hash keys.  Likewise
+  # is true for any String objects in +refs+.
   def add(mid, refs, msg)
     cur = @id_table[mid] ||= Msgthr::Container.new(mid)
     cur.msg = msg
-- 
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