mirror of https://github.com/BOINC/boinc.git
427 lines
13 KiB
Perl
427 lines
13 KiB
Perl
# Text::Aligner - Align text in columns
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package Text::Aligner;
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use strict;
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use warnings;
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BEGIN {
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use Exporter ();
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use vars qw ($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS);
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$VERSION = 0.03;
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@ISA = qw (Exporter);
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#Give a hoot don't pollute, do not export more than needed by default
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@EXPORT = qw ();
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@EXPORT_OK = qw ( align);
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%EXPORT_TAGS = ();
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}
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# this is a non-method, and currently the only user interface
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sub align ($@) {
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my $ali = Text::Aligner->new( shift);
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$ali->alloc( map ref eq 'SCALAR' ? $$_ : $_, @_);
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if ( defined wantarray ) {
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my @just = map $ali->justify( ref eq 'SCALAR' ? $$_ : $_), @_;
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return @just if wantarray;
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return join "\n", @just, '';
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} else {
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for ( @_ ) {
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$_ = $ali->justify( $_) for ref eq 'SCALAR' ? $$_ : $_; # one-shot
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}
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}
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}
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### class Text::Aligner
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sub _new { # internal creator
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my $class = shift;
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my ( $width, $pos) = @_; # both method-or-coderef (this is very general)
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bless {
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width => $width,
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pos => $pos,
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left => Text::Aligner::MaxKeeper->new,
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right => Text::Aligner::MaxKeeper->new,
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}, $class;
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}
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# create an aligner
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sub new {
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my ( $class, $spec) = @_;
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$spec ||= 0; # left alignment is default
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my $al;
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if ( !ref( $spec) and $spec =~ s/^auto/num/ ) {
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$al = Text::Aligner::Auto->_new( $spec);
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} else {
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$al = $class->_new( _compile_alispec( $spec));
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}
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$al;
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}
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# return left and right field widths for an object
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sub _measure0 {
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my $al = shift;
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my $obj = shift;
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$obj = '' unless defined $obj;
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my ( $w, $p);
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if ( ref $obj ) {
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( $w, $p) = ( $obj->$al->{ width}->(), $obj->$al->{ pos}->() );
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} else {
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( $w, $p) = ( $al->{ width}->( $obj), $al->{ pos}->( $obj) );
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}
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$_ ||= 0 for $w, $p;
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( $p, $w - $p);
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}
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# return left and right field widths for an object
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sub _measure {
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my $al = shift;
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my $obj = shift;
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$obj = '' unless defined $obj;
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my ( $wmeth, $pmeth) = @{ $al}{ qw( width pos)};
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my $w = ref $wmeth ? $wmeth->( $obj) : $obj->$wmeth;
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my $p = ref $pmeth ? $pmeth->( $obj) : $obj->$pmeth;
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$_ ||= 0 for $w, $p;
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( $p, $w - $p);
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}
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# return left and rigth maxima, or nothing if the aligner is empty
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sub _status {
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my @lr = ( $_[ 0]->{ left}->max, $_[ 0]->{ right}->max);
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# $l and $r should be both defined or undefined, unless the
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# MaxKeeper memory is corrupted by forgetting unremembered things.
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return unless defined( $lr[ 0]) and defined( $lr[ 1]);
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@lr;
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}
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# remember alignment requirements
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sub alloc {
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my $al = shift;
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for ( @_ ) {
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# $_ ||= ''; print "allocing '$_'\n";
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my ( $l, $r) = $al->_measure( $_);
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$al->{ left}->remember( $l); # space needed left of pos
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$al->{ right}->remember( $r); # ...and right of pos
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}
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$al;
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}
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# release alignment requirement. it disturbs an aligner deeply to forget
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# things it hasn't remembered. the effects may be delayed.
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sub _forget {
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my $al = shift;
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for ( map defined() ? $_ : '', @_ ) {
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# print "forgetting '$_'\n";
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my ( $l, $r) = $al->_measure( $_);
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$al->{ left}->forget( $l);
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$al->{ right}->forget( $r);
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}
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$al;
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}
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# justify a string. a string is aligned within the aligner's field, and
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# filled with blanks or cut to size, as appropriate. a string that has
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# been allocated will never be trimmed (that is the point of allocation).
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# if the aligner is empty it returns the string unaltered.
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sub justify {
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my $al = shift;
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my $str = shift;
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# print "justifying '$str'\n";
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$str .= ''; # stringify (objects, numbers, undef)
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my ( $l_pad, $r_pad) = $al->_padding( $str);
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substr( $str, 0, -$l_pad) = '' if $l_pad < 0; # trim if negative
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substr( $str, $r_pad) = '' if $r_pad < 0; # ... both ends
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join $str, ' ' x $l_pad, ' ' x $r_pad; # pad if positive
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}
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# return two numbers that indicate how many blanks are needed on each side
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# of a string to justify it. Negative values mean trim that many characters.
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# an empty aligner returns ( 0, 0), so doesn't change anything.
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sub _padding {
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my $al = shift;
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my $str = shift;
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my ( $this_l, $this_r) = $al->_measure( $str);
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my ( $l_pad, $r_pad) = ( 0, 0);
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if ( $al->_status ) {
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( $l_pad, $r_pad) = $al->_status;
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$l_pad -= $this_l;
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$r_pad -= $this_r;
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}
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( $l_pad, $r_pad);
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}
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# _compile_alispec() returns positioners according to specification. In
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# effect, it is is the interpreter for alignment specifications.
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sub _compile_alispec { # it's a dirty job...
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my $width = sub { length shift }; # this is always so for string aligners
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my $pos; # the positioner we actually compile
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local $_ = shift || ''; # alignment specification
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if ( ref() eq 'Regexp' ) {
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my $regex = $_; # lexical copy!
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$pos = sub {
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local $_ = shift;
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m/$regex/ ? $-[ 0] : length; # assume match after string
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};
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} else {
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s/^left/0/;
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s/^center/0.5/;
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s/^right/1/;
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if ( _is_number( $_) ) {
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my $proportion = $_; # use lexical copy
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$pos = sub { int( $proportion*length shift) };
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} elsif ( $_ =~ /^(?:num|point)(?:\((.*))?/ ) {
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my $point = defined $1 ? $1 : '';
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$point =~ s/\)$//; # ignore trailing paren, if present
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length $point or $point = '.';
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$pos = sub { index( shift() . $point, $point) }
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} else {
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$pos = sub { 0 };
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}
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}
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( $width, $pos);
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}
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# decide if a string is a number. (see perlfaq4). This needs to become
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# more flexible for auto-alignment
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sub _is_number { defined( $_[ 0]) and $_[ 0] =~ /^-?\d+\.?\d*$/ }
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package Text::Aligner::Auto;
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# Combined numeric and left alignment. Numbers are aligned numerically,
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# other strings are left-aligned. The resulting columns are interleaved
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# flush left and filled on the right if necessary.
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sub _new { # only called by Text::Aligner->new()
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my $class = shift;
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my $numspec = shift; # currently ignored
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bless {
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num => Text::Aligner->new( 'num'), # align numbers among themselves
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other => Text::Aligner->new, # left-align anything else
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}, $class;
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}
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sub alloc {
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my $aa = shift;
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my @num = grep _is_number( $_), @_;
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my @other = grep !_is_number( $_), @_;
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$aa->{ num}->alloc( @num);
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$aa->{ other}->alloc( @other);
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$aa;
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}
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sub _forget {
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my $aa = shift;
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$aa->{ num}->_forget( grep _is_number( $_), @_);
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$aa->{ other}->_forget( grep !_is_number( $_), @_);
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$aa;
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}
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# justify as required
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sub justify {
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my ( $aa, $str) = @_;
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# align according to type
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$str = $aa->{ _is_number( $str) ? 'num' : 'other'}->justify( $str);
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my $combi = Text::Aligner->new; # left-justify pre-aligned string
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# initialise to size of partial aligners. (don't initialise from
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# empty aligner)
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$combi->alloc( $aa->{ num}->justify( '')) if $aa->{ num}->_status;
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$combi->alloc( $aa->{ other}->justify( '')) if $aa->{ other}->_status;
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$combi->justify( $str);
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}
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# for convenience
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BEGIN { # import _is_number()
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*_is_number = \ &Text::Aligner::_is_number;
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}
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package Text::Aligner::MaxKeeper;
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# Keep the maximum of a dynamic set of numbers. Optimized for the case of
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# a relatively small range of numbers that may occur repeatedly.
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sub new {
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bless {
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max => undef,
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seen => {},
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}, shift;
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}
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sub max { $_[ 0]->{ max} }
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sub remember {
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my ( $mk, $val) = @_;
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_to_max( $mk->{ max}, $val);
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$mk->{ seen}->{ $val}++;
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$mk;
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}
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sub forget {
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my ( $mk, $val) = @_;
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if ( exists $mk->{ seen}->{ $val} ) {
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my $seen = $mk->{ seen};
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unless ( --$seen->{ $val} ) {
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delete $seen->{ $val};
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if ( $mk->{ max} == $val ) {
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# lost the maximum, recalculate
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undef $mk->{ max};
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_to_max( $mk->{ max}, keys %$seen);
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}
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}
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}
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$mk;
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}
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sub _to_max {
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my $var = \ shift;
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defined $_ and ( not defined $$var or $$var < $_) and $$var = $_ for @_;
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$$var;
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}
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########################################### main pod documentation begin ##
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=head1 NAME
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Text::Aligner
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=head1 SYNOPSIS
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use Text::Aligner qw( align);
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# Print the words "just a test!" right-justified each on a line:
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my @lines = align( 'right', qw( just a test!);
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print "$_\n" for @lines;
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=head1 DESCRIPTION
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Text::Aligner exports a single function, align(), which is
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used to justify strings to various alignment styles. The
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alignment specification is the first argument, followed by
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any number of scalars which are subject to alignment.
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The operation depends on context. In list context, a list of
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the justified scalars is returned. In scalar context, the
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justified arguments are joined into a single string with newlines
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appended. The original arguments remain unchanged. In void
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context, in-place justification is attempted. In this case, all
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arguments must be lvalues.
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Align() also does one level of scalar dereferencing. That is,
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whenever one of the arguments is a scalar reference, the scalar
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pointed to is aligned instead. Other references are simply stringified.
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An undefined argument is interpreted as an empty string without
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complaint.
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=head1 ALIGNMENT
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The first argument of the align() function is an alignment style, a
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single scalar.
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It can be one of the strings "left", "right", "center", "num", "point",
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or "auto", or a regular expression (qr/.../), or a coderef.
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A default style of "left" is assumed for every other value, including
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"" and undef.
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"left", "right" and "center" have the obvious meanings. These can
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also be given as numbers 0, 1, and 0.5 respectively. (Other numbers
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are also possible, but probably not very useful).
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"num", and its synonym "point", specify that the decimal points be
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aligned (assumed on the right, unless present). Arbitrary (non-numeric)
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strings are also aligned in this manner, so they end up one column left
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of the (possibly assumed) decimal point, flush right with any integers.
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For the occasional string like "inf", or "-" for missing values, this
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may be the right place. A string-only column ends up right-aligned
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(unless there are points present).
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The "auto" style seperates numeric strings (that are composed of
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"-", ".", and digits in the usual manner) and aligns them numerically.
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Other strings are left aligned with the number that sticks out
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farthest to the left. This gives left alignment for string-only
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columns and numeric alignment for columns of numbers. In mixed
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columns, strings are reasonably placed to serve as column headings
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or intermediate titles.
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With "num" (and "point") it is possible to specify another character
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for the decimal point in the form "num(,)". In fact, you can specify
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any string after a leading "(", and the closing ")" is optional.
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"point(=>)" could be used to align certain pieces of Perl code. This
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option is currently not available with "auto" alignment (because
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recognition of numbers is Anglo-centric).
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If a regular expression is specified, the points are aligned where
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the first match of the regex starts. A match is assumed immediately
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after the string if it doesn't match.
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A regular expression is a powerful way of alignment specification. It
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can replace most others easily, except center alignment and, of course,
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the double action of "auto".
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=head1 POSITIONERS
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For entirely self-defined forms of alignment, a coderef, also known
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as a positioner, can be given instead of an alignment style. This
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code will be called once or more times with the string to be aligned
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as its argument. It must return two numbers, a width and a position,
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that describe how to align a string with other strings.
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The width should normally be the length of the string. The position
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defines a point relative to the beginning of the string, which is
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aligned with the positions given for other strings.
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A zero position for all strings results in left alignment, positioning
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to the end of the string results in right alignment, and returning
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half the length gives center alignment. "num" alignment is realized
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by marking the position of the decimal point.
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Note that the position you return is a relative measure. Adding a
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constant value to all positions results in no change in alignment.
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It doesn't have to point inside the string (as in right alignment,
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where it points one character past the end of the string).
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The first return value of a positioner should almost always be the
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length of the given string. It may be useful to ly about the string
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length if the string contains escape sequences that occupy no place
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on screen.
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=head1 USAGE
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use Text::Aligner qw( align);
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align( $style, $str, ...);
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$style must be given and must be an alignment specification.
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Any number of scalars can follow. An argument that contains a
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scalar reference is dereferenced before it is used. In scalar
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and list context, the aligned strings are returned. In void
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context, the values are aligned in place and must be lvalues.
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=head1 BUGS
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None known as of realease, but...
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=head1 AUTHOR
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Anno Siegel
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CPAN ID: ANNO
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siegel@zrz.tu-berlin.de
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http://www.tu-berlin.de/~siegel
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=head1 COPYRIGHT
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Copyright (c) 2002 Anno Siegel. All rights reserved.
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This program is free software; you can redistribute
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it and/or modify it under the same terms as Perl itself.
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The full text of the license can be found in the
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LICENSE file included with this module.
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=head1 SEE ALSO
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perl(1)
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Text::Table
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=cut
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1; #this line is important and will help the module return a true value
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__END__
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