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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 curpos { shift->{pointer} }
sub endpos { length shift->{buffer} }
sub buffer {
my $self = shift;
my ($start, $end) = @_;
$start = 0 unless defined $start;
$end = $self->endpos unless defined $end;
return substr $self->{buffer}, $start, $end - $start;
}
sub set {
my $self = shift;
my $pointer = shift;
die 'Pointer off page' if $pointer < 0 || $pointer > $self->endpos;
$self->{pointer} = $pointer;
return;
}
sub offset {
my $self = shift;
$self->set($self->{pointer} + shift);
return;
}
sub insert {
my $self = shift;
my $text = shift;
substr($self->{buffer}, $self->curpos, 0) = $text;
$self->offset(length $text);
return;
}
sub delete {
my $self = shift;
my $length;
if (@_ > 1) {
my $pos = shift;
$self->set($pos);
$length = shift() - $pos;
}
else {
$length = shift;
}
if ($length < 0) {
$length = -$length;
$self->offset(-$length);
}
die "Pointer off page"
if $self->curpos + $length > $self->endpos;
substr($self->{buffer}, $self->curpos, $length) = '';
return;
}
sub get_line_offset {
my $self = shift;
my $num = shift;
if ($num > 0) {
pos $self->{buffer} = $self->curpos;
$self->{buffer} =~ /(?:.*(?:\n|$)){0,$num}/g;
return ($-[0], $+[0]) if wantarray;
return $+[0];
}
else {
$num = -$num;
my $rev = reverse $self->buffer;
my $len = $self->endpos;
pos $rev = $len - $self->curpos;
$rev =~ /.*?(?:\n.*?){0,$num}(?=\n|$)/g;
return ($len - $+[0], $len - $-[0]) if wantarray;
return $len - $+[0];
}
}
1;
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