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# Author: Chao-Kuei Hung
# For more info, including license, please see doc/index.html
package BST;
# Binary Search Tree
use strict;
use Carp;
use vars qw(@ISA);
@ISA = qw(Collection);
use Collection;
use TreeNode;
sub new {
my ($class, %opts) = @_;
$class = ref($class) if ref($class);
my ($t) = delete $opts{-type};
croak "'BST' code does not know how to process '$t' data\n"
unless $t eq 'sortable';
my ($self) = $class->SUPER::new(%opts);
my ($init_data) = (delete $opts{-init_data} or []);
my ($operation) = (delete $opts{-operation} or []);
my ($dummy) = TreeNode->new($self, undef, -status=>"hidden");
$self->{rootparent} = $dummy;
my ($v);
foreach $v (@$init_data) {
# -node_opts is taken care of in insert()
$self->insert($v);
$self->cget(-canvas)->set_mark(1);
}
while (@$operation) {
my ($op) = shift @$operation;
my ($data) = shift @$operation;
if ($op eq 'remove') {
# $data->{area} = 0 unless defined $data->{area};
# $data->{name} = '?' unless defined $data->{name};
$self->remove($data);
} elsif ($op eq 'insert') {
$self->insert($data);
} elsif ($op eq 'rot_cw') {
$self->rotate_cw($data);
} elsif ($op eq 'rot_ccw') {
$self->rotate_ccw($data);
} else {
carp "unknown operation '$op' ignored\n";
}
$self->cget(-canvas)->set_mark(1);
}
return $self;
}
sub root {
# my ($self, $nv) = @_;
my ($self, $nv) = @_; die if defined $nv;
return $self->{rootparent}->child(0);
}
sub search {
my ($self) = shift @_;
return $self->root()->search(@_);
}
sub insert {
my ($self, $sk_cont, %opts) = @_;
# $sk_cont is search key, should have the same structure as -content=>...
die "insertion works only for binary trees"
unless $self->cget(-ary) == 2;
my ($parent, $rank, $r, $c, $nn);
if (ref $self->root()) {
$parent = $self->search($sk_cont, -to_leaf=>1);
$rank = $self->cget(-compare)->(
$sk_cont, $parent->cget(-content)
);
# skewed!! bad!! please check the case when compare returns 0
$rank = $rank <= 0 ? 0 : 1;
} else {
$parent = $self->{rootparent};
$rank = 0;
}
%opts = ( %{ $self->cget(-node_opts) }, %opts );
$nn = TreeNode->new($parent, $rank, -content=>$sk_cont, %opts);
# as always, the host should take care of prepending %opts with -node_opts
$nn->configure(-status=>"focus");
$self->cget(-canvas)->set_mark(0);
$nn->configure(-status=>"done");
return $nn;
}
sub hide {
my ($self, $node) = @_;
# $node->configure(-status=>"discard");
$node->configure(-status=>"hidden");
$node->moveto(0,-0.5);
}
sub remove {
my ($self, $node) = @_;
die "removal works only for binary trees"
unless $self->cget(-ary) == 2;
if (not UNIVERSAL::isa($node, "TreeNode")) {
$node = $self->search($node);
if (not ref $node) {
carp "can't find node for removal\n";
return undef;
}
}
$node->configure(-status=>"focus");
$self->cget(-canvas)->set_mark(0);
my ($p, $r, $n) = ($node->parent(), $node->rank(), 0);
++$n if ref $node->child(0);
++$n if ref $node->child(1);
if ($n == 2) {
my ($subst) = $node->child(0)->findmax();
my ($subst_status) = $subst->cget(-status);
$self->remove($subst);
$p->set_child($r, $subst);
$subst->set_child(0, $node->child(0));
$subst->set_child(1, $node->child(1));
$subst->configure(-status=>$subst_status);
# $self->cget(-canvas)->set_mark(0);
} elsif ($n == 1) {
my ($i) = ref $node->child(0) ? 0 : 1;
$p->adopt_subtree($r, $node->child($i));
} else { # $n == 0
$p->set_child($r, undef);
}
$self->hide($node);
$self->cget(-canvas)->set_mark(0);
return $node;
}
sub rotate_cw {
my ($self, $pivot) = @_;
die "removal works only for binary trees"
unless $self->cget(-ary) == 2;
if (not UNIVERSAL::isa($pivot, "TreeNode")) {
$pivot = $self->search($pivot);
if (not ref $pivot) {
carp "can't find node for rotation\n";
return;
}
}
$pivot->rotate_cw();
}
sub rotate_ccw {
my ($self, $pivot) = @_;
die "removal works only for binary trees"
unless $self->cget(-ary) == 2;
if (not UNIVERSAL::isa($pivot, "TreeNode")) {
$pivot = $self->search($pivot);
if (not ref $pivot) {
carp "can't find node for rotation\n";
return;
}
}
$pivot->rotate_ccw();
}
$::Config->{BST} = {
-ary => 2,
};
if ($0 =~ /BST.pm$/) {
# being tested as a stand-alone program, so run test code.
require "utilalgo";
my ($mw, $ctrl, $can);
$mw = MainWindow->new(-title=>"main_test");
$can->{main} = gen_can($mw, undef, -elevation=>1, -maxlevel=>2);
$ctrl = gen_ctrl($mw, $can);
my ($tr) = BST->new(-canvas=>$can->{main}, %{ do "data/countries.gr" });
# $can->{main}->set_mark(1);
$ctrl->configure(-recorder=>0);
# If the canvas refuses to show any change, remember to verify that:
# - set_mark() was called at least once
# - -recorder is set to zero before entering MainLoop
# Failing to do either of the above will result in a mysterious bug
# that takes days to figure out !@#$%
Tk::MainLoop();
}
1;
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