1 files changed, 79 insertions, 4 deletions

diff --git a/lib/Data/MultiValued/RangeContainer.pm b/lib/Data/MultiValued/RangeContainer.pm
index e9b1b62..0bfe8cd 100644
--- a/lib/Data/MultiValued/RangeContainer.pm
+++ b/lib/Data/MultiValued/RangeContainer.pm
@@ -5,6 +5,27 @@ use MooseX::Types::Moose qw(Num Str Any Undef ArrayRef);
 use MooseX::Types::Structured qw(Dict);
 use Data::MultiValued::Exceptions;
 
+# ABSTRACT: container for ranged values
+
+=head1 DESCRIPTION
+
+Please don't use this module directly, use L<Data::MultiValued::Ranges>.
+
+This module implements the storage for ranged data. It's similar to
+L<Array::IntSpan>, but simpler (and slower).
+
+A range is defined by a pair of numbers, C<from> and C<to>, and it
+contains C<< Num $x : $min <= $x < $max >>. C<undef> is treated as
+"inf" (negative infinity if used as C<from> or C<at>, positive
+infinity if used as C<to>).
+
+The internal representation of a range is a hash with three keys,
+C<from> C<to> C<value>.
+
+=head1 METHODS
+
+=cut
+
 has _storage => (
     is => 'rw',
     isa => ArrayRef[
@@ -18,6 +39,16 @@ has _storage => (
     default => sub { [ ]  },
 );
 
+=head2 C<get>
+
+  my $value = $obj->get({ at => $point });
+
+Retrieves the range that includes the given point. Throws a
+L<Data::MultiValued::Exceptions::RangeNotFound> exception if no range
+includes the point.
+
+=cut
+
 sub get {
     my ($self,$args) = @_;
 
@@ -45,6 +76,8 @@ sub _cmp {
     return $a <=> $b;
 }
 
+# a binary search would be a good idea.
+
 sub _get_slot_at {
     my ($self,$at) = @_;
 
@@ -56,6 +89,10 @@ sub _get_slot_at {
     return;
 }
 
+# this is quite probably uselessly slow: we don't really need all of
+# @before and @after, we just need to know if they're not empty; also,
+# a binary search would be a good idea.
+
 sub _partition_slots {
     my ($self,$from,$to) = @_;
 
@@ -80,7 +117,18 @@ sub _partition_slots {
     return \@before,\@overlap,\@after;
 }
 
-sub set_or_create {
+=head2 C<get_or_create>
+
+  $obj->get_or_create({ from => $min, to => $max });
+
+Retrieves the range that has the given extremes. If no such range
+exists, creates a new range, splicing any existing overlapping range,
+and returns it. Throws L<Data::MultiValued::Exceptions::BadRange> if
+C<< $min > $max >>.
+
+=cut
+
+sub get_or_create {
     my ($self,$args) = @_;
 
     my $from = $args->{from};
@@ -103,6 +151,19 @@ sub set_or_create {
     return $range;
 }
 
+=head2 C<clear>
+
+  $obj->clear({ from => $min, to => $max });
+
+Removes the range that has the given extremes. If no such range
+exists, splices any existing overlapping range so that C<<
+$obj->get({at => $point }) >> for any C<< $min <= $point < $max >>
+will die.
+
+Throws L<Data::MultiValued::Exceptions::BadRange> if C<< $min > $max >>.
+
+=cut
+
 sub clear {
     my ($self,$args) = @_;
 
@@ -133,10 +194,16 @@ sub _clear_slot {
     $self->_splice_slot($from,$to);
 }
 
+# Most of the splicing mechanics is here. Given a range and something
+# to put in it, do "the right thing"
+
 sub _splice_slot {
     my ($self,$from,$to,$new) = @_;
 
-    if (!@{$self->_storage}) { # empty
+    # if !$new, it's like C<splice> without a replacement list: we
+    # just delete the range
+
+    if (!@{$self->_storage}) { # empty, just store
         push @{$self->_storage},$new if $new;
         return $new;
     }
@@ -144,27 +211,33 @@ sub _splice_slot {
     my ($before,$overlap,$after) = $self->_partition_slots($from,$to);
 
     if (!@$before && !@$overlap) {
+        # nothing before, nothing overlapping: put $new at the beginning
         unshift @{$self->_storage},$new if $new;
         return $new;
     }
     if (!@$after && !@$overlap) {
+        # nothing after, nothing overlapping: put $new at the end
         push @{$self->_storage},$new if $new;
         return $new;
     }
 
-    # by costruction, the first and the last may have to be split, all
-    # others must be removed
+    # ok, we have to insert in the middle of things, and maybe we have
+    # to trim existing ranges
+
     my $first_to_replace;
     my $how_many = @$overlap;
 
     my @replacement = $new ? ($new) : ();
 
     if ($how_many > 0) { # we have to splice
+        # by costruction, the first and the last may have to be split, all
+        # others must be removed
         $first_to_replace = $overlap->[0];
         my $last_to_replace = $overlap->[-1];
         my $first = $self->_storage->[$first_to_replace];
         my $last = $self->_storage->[$last_to_replace];
 
+        # does the first overlapping range need trimming?
         if (_cmp($first->{from},$from,0,0)<0
             && _cmp($first->{to},$from,1,0)>=0) {
             unshift @replacement, {
@@ -173,6 +246,7 @@ sub _splice_slot {
                 value => $first->{value},
             }
         }
+        # does the last overlapping range need trimming?
         if (_cmp($last->{from},$to,0,1)<=0
             && _cmp($last->{to},$to,1,1)>0) {
             push @replacement, {
@@ -183,6 +257,7 @@ sub _splice_slot {
         }
     }
     else {
+        # no overlaps, just insert between @before and @after
         $first_to_replace = $before->[-1]+1;
     }