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#!/usr/bin/perl
use strict;
use warnings;
package Language::TECO::Buffer;
sub new {
my $class = shift;
my $initial_buffer = shift;
$initial_buffer = '' unless defined $initial_buffer;
return bless { buffer => $initial_buffer, pointer => 0 }, $class;
}
sub set {
my $self = shift;
my $pointer = shift;
die 'Pointer off page' if $pointer < 0 || $pointer > length $self->{buffer};
$self->{pointer} = $pointer;
}
sub offset {
my $self = shift;
$self->set($self->{pointer} + shift);
}
sub insert {
my $self = shift;
my $text = shift;
substr($self->{buffer}, $self->{pointer}, 0) = $text;
$self->offset(length $text);
}
sub delete {
my $self = shift;
my $length = shift;
if ($length < 0) {
$length = -$length;
$self->offset(-$length);
}
die "Pointer off page"
if $self->{pointer} + $length > length $self->{buffer};
substr($self->{buffer}, $self->{pointer}, $length) = '';
}
sub endpos { length shift->{buffer} }
sub curpos { shift->{pointer} }
sub print {
my $self = shift;
my ($start, $end) = @_;
print substr $self->{buffer}, $start, $end - $start;
}
1;
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