1 ## Herein lies all the code responsible for threading messages. It's
2 ## basically an online version of the JWZ threading algorithm:
3 ## http://www.jwz.org/doc/threading.html
5 ## I didn't implement it for efficiency, but thanks to our search
6 ## engine backend, it's typically not applied to very many messages at
9 ## At the top level, we have a ThreadSet, which represents a set of
10 ## threads, e.g. a message folder or an inbox. Each ThreadSet contains
11 ## zero or more Threads. A Thread represents all the message related
12 ## to a particular subject. Each Thread has one or more Containers. A
13 ## Container is a recursive structure that holds the message tree as
14 ## determined by the references: and in-reply-to: headers. Each
15 ## Container holds zero or one messages. In the case of zero messages,
16 ## it means we've seen a reference to the message but haven't (yet)
17 ## seen the message itself.
19 ## A Thread can have multiple top-level Containers if we decide to
20 ## group them together independent of tree structure, typically if
21 ## (e.g. due to someone using a primitive MUA) the messages have the
22 ## same subject but we don't have evidence from in-reply-to: or
23 ## references: headers. In this case Thread#each can optionally yield
24 ## a faked root object tying them all together into one tree
32 attr_reader :containers
34 ## ah, the joys of a multithreaded application with a class called
35 ## "Thread". i keep instantiating the wrong one...
36 raise "wrong Thread class, buddy!" if block_given?
44 def empty?; @containers.empty?; end
45 def empty!; @containers.clear; end
46 def drop c; @containers.delete(c) or raise "bad drop"; end
50 f.puts "=== start thread #{self} with #{@containers.length} trees ==="
51 @containers.each { |c| c.dump_recursive f }
52 f.puts "=== end thread ==="
55 ## yields each message, its depth, and its parent. the message yield
56 ## parameter can be a Message object, or :fake_root, or nil (no
57 ## message found but the presence of one deduced from other
59 def each fake_root=false
61 root = @containers.find_all { |c| c.message && !Message.subj_is_reply?(c.message.subj) }.argmin { |c| c.date }
65 root.first_useful_descendant.each_with_stuff do |c, d, par|
66 yield c.message, d, (par ? par.message : nil)
68 elsif @containers.length > 1 && fake_root
70 yield :fake_root, 0, nil
73 @containers.each do |cont|
75 fud = cont.first_useful_descendant
76 fud.each_with_stuff do |c, d, par|
77 ## special case here: if we're an empty root that's already
78 ## been joined by a fake root, don't emit
79 yield c.message, d + adj, (par ? par.message : nil) unless
80 fake_root && c.message.nil? && root.nil? && c == fud
85 def first; each { |m, *o| return m if m }; nil; end
86 def dirty?; any? { |m, *o| m && m.dirty? }; end
87 def date; map { |m, *o| m.date if m }.compact.max; end
89 with_snippets = select { |m, *o| m && m.snippet && !m.snippet.empty? }
90 first_unread, * = with_snippets.select { |m, *o| m.has_label?(:unread) }.sort_by { |m, *o| m.date }.first
91 return first_unread.snippet if first_unread
92 last_read, * = with_snippets.sort_by { |m, *o| m.date }.last
93 return last_read.snippet if last_read
96 def authors; map { |m, *o| m.from if m }.compact.uniq; end
98 def apply_label t; each { |m, *o| m && m.add_label(t) }; end
99 def remove_label t; each { |m, *o| m && m.remove_label(t) }; end
101 def toggle_label label
111 def set_labels l; each { |m, *o| m && m.labels = l }; end
113 def has_label? t; any? { |m, *o| m && m.has_label?(t) }; end
114 def save index; each { |m, *o| m && m.save(index) }; end
116 def direct_participants
117 map { |m, *o| [m.from] + m.to if m }.flatten.compact.uniq
121 map { |m, *o| [m.from] + m.to + m.cc + m.bcc if m }.flatten.compact.uniq
124 def size; map { |m, *o| m ? 1 : 0 }.sum; end
125 def subj; argfind { |m, *o| m && m.subj }; end
127 map { |m, *o| m && m.labels }.flatten.compact.uniq.sort_by { |t| t.to_s }
130 each { |m, *o| m && m.labels = l.clone }
134 inject(nil) do |a, b|
141 b.date > a.date ? b : a
147 "<thread containing: #{@containers.join ', '}>"
150 def prune_dangling_container_trees!
151 @containers.delete_if { |c| c.dangling? }
155 ## recursive structure used internally to represent message trees as
156 ## described by reply-to: and references: headers.
158 ## the 'id' field is the same as the message id. but the message might
159 ## be empty, in the case that we represent a message that was referenced
160 ## by another message (as an ancestor) but never received.
162 attr_accessor :message, :parent, :children, :id, :thread
165 raise "non-String #{id.inspect}" unless id.is_a? String
167 @message, @parent, @thread = nil, nil, nil
171 def each_with_stuff parent=nil
172 yield self, 0, parent
173 @children.each do |c|
174 c.each_with_stuff(self) { |cc, d, par| yield cc, d + 1, par }
179 if @children.any? { |c| !c.empty? }
181 elsif @children.any? { |c| !c.dangling? }
192 @parent && @parent.descendant_of?(o)
196 def == o; Container === o && id == o.id; end
198 def empty?; @message.nil?; end
199 def root?; @parent.nil?; end
200 def root; root? ? self : @parent.root; end
202 ## skip over any containers which are empty and have only one child. we use
203 ## this make the threaded display a little nicer, and only stick in the
204 ## "missing message" line when it's graphically necessary, i.e. when the
205 ## missing message has more than one descendent.
206 def first_useful_descendant
207 if empty? && @children.size == 1
208 @children.first.first_useful_descendant
216 @children.argfind { |c| c.find_attr attr }
221 def subj; find_attr :subj; end
222 def date; find_attr :date; end
224 def is_reply?; subj && Message.subject_is_reply?(subj); end
228 (@parent.nil? ? nil : "parent=#{@parent.id}"),
229 (@children.empty? ? nil : "children=#{@children.map { |c| c.id }.inspect}"),
230 ].compact.join(" ") + ">"
233 def dump_recursive f=$stdout, indent=0, root=true, parent=nil
234 raise "inconsistency" unless parent.nil? || parent.children.include?(self)
239 line = #"[#{useful? ? 'U' : ' '}] " +
241 "[#{thread}] #{@message.subj} " ##{@message.refs.inspect} / #{@message.replytos.inspect}"
246 f.puts "#{id} #{line}"#[0 .. (105 - indent)]
248 @children.each { |c| c.dump_recursive f, indent, false, self }
252 ## A set of threads, so a forest. Is integrated with the index and
253 ## builds thread structures by reading messages from it.
255 ## If 'thread_by_subj' is true, puts messages with the same subject in
256 ## one thread, even if they don't reference each other. This is
257 ## helpful for crappy MUAs that don't set In-reply-to: or References:
258 ## headers, but means that messages may be threaded unnecessarily.
260 attr_reader :num_messages
261 bool_reader :thread_by_subj
263 def initialize index, thread_by_subj=true
266 ## map from message ids to container objects
267 @messages = SavingHash.new { |id| Container.new id }
268 ## map from subject strings or (or root message ids) to thread objects
269 @threads = SavingHash.new { Thread.new }
270 @thread_by_subj = thread_by_subj
273 def thread_for_id mid; (c = @messages[mid]) && c.root.thread end
274 def contains_id? id; @messages.member?(id) && !@messages[id].empty? end
275 def thread_for m; thread_for_id m.id end
276 def contains? m; contains_id? m.id end
278 def threads; prune_empty_threads.values end
279 def size; prune_empty_threads.size end
283 @threads.each do |s, t|
284 f.puts "**********************"
285 f.puts "** for subject #{s} **"
286 f.puts "**********************"
291 ## link two containers
292 def link p, c, overwrite=false
293 if p == c || p.descendant_of?(c) || c.descendant_of?(p) # would create a loop
294 # puts "*** linking parent #{p} and child #{c} would create a loop"
298 if c.parent.nil? || overwrite
306 def remove_container c
307 c.parent.children.delete c if c.parent # remove from tree
308 thread = c.root.thread # find containing thread
310 thread.prune_dangling_container_trees!
314 private :remove_container
316 def prune_empty_threads; @threads.delete_if { |k, t| t.empty? } end
317 private :prune_empty_threads
319 ## remove a single message id. not used anywhere, afaik.
321 return unless(c = @messages[mid])
325 def remove_thread_containing_id mid
326 c = @messages[mid] or return
328 @threads.delete_if { |key, thread| t == thread }
331 ## load in (at most) num number of threads from the index
332 def load_n_threads num, opts={}
333 @index.each_id_by_date opts do |mid, builder|
335 next if contains_id? mid
338 load_thread_for_message m, :skip_killed => opts[:skip_killed], :load_deleted => opts[:load_deleted], :load_spam => opts[:load_spam]
339 yield size if block_given?
343 ## loads in all messages needed to thread m
344 ## may do nothing if m's thread is killed
345 def load_thread_for_message m, opts={}
346 good = @index.each_message_in_thread_for m, opts do |mid, builder|
347 next if contains_id? mid
348 add_message builder.call
350 add_message m if good
353 ## merges in a pre-loaded thread
355 raise "duplicate" if @threads.values.member? t
356 t.each { |m, *o| add_message m }
360 m.refs.any? { |ref_id| @messages.member? ref_id }
363 ## the heart of the threading code
364 def add_message message
365 el = @messages[message.id]
366 return if el.message # we've seen it before
371 ## link via references:
373 message.refs.each do |ref_id|
374 ref = @messages[ref_id]
375 link prev, ref if prev
378 link prev, el, true if prev
380 ## link via in-reply-to:
381 message.replytos.each do |ref_id|
382 ref = @messages[ref_id]
384 break # only do the first one
389 ## new root. need to drop old one and put this one in its place
390 if root != oldroot && oldroot.thread
391 oldroot.thread.drop oldroot
397 Message.normalize_subj root.subj
402 ## check to see if the subject is still the same (in the case
403 ## that we first added a child message with a different
406 unless @threads[key] == root.thread
409 @threads[key] << root
410 root.thread = @threads[key]
412 @threads[key] = root.thread
416 thread = @threads[key]