lib/perl5/5.6.1/msys/Data/Dumper.pm

   1 #
   2 # Data/Dumper.pm
   3 #
   4 # convert perl data structures into perl syntax suitable for both printing
   5 # and eval
   6 #
   7 # Documentation at the __END__
   8 #
   9
  10 package Data::Dumper;
  11
  12 $VERSION = '2.102';
  13
  14 #$| = 1;
  15
  16 require 5.005_64;
  17 require Exporter;
  18 use XSLoader ();
  19 require overload;
  20
  21 use Carp;
  22
  23 @ISA = qw(Exporter);
  24 @EXPORT = qw(Dumper);
  25 @EXPORT_OK = qw(DumperX);
  26
  27 XSLoader::load 'Data::Dumper';
  28
  29 # module vars and their defaults
  30 $Indent = 2 unless defined $Indent;
  31 $Purity = 0 unless defined $Purity;
  32 $Pad = "" unless defined $Pad;
  33 $Varname = "VAR" unless defined $Varname;
  34 $Useqq = 0 unless defined $Useqq;
  35 $Terse = 0 unless defined $Terse;
  36 $Freezer = "" unless defined $Freezer;
  37 $Toaster = "" unless defined $Toaster;
  38 $Deepcopy = 0 unless defined $Deepcopy;
  39 $Quotekeys = 1 unless defined $Quotekeys;
  40 $Bless = "bless" unless defined $Bless;
  41 #$Expdepth = 0 unless defined $Expdepth;
  42 $Maxdepth = 0 unless defined $Maxdepth;
  43
  44 #
  45 # expects an arrayref of values to be dumped.
  46 # can optionally pass an arrayref of names for the values.
  47 # names must have leading $ sign stripped. begin the name with *
  48 # to cause output of arrays and hashes rather than refs.
  49 #
  50 sub new {
  51   my($c, $v, $n) = @_;
  52
  53   croak "Usage:  PACKAGE->new(ARRAYREF, [ARRAYREF])"
  54     unless (defined($v) && (ref($v) eq 'ARRAY'));
  55   $n = [] unless (defined($n) && (ref($v) eq 'ARRAY'));
  56
  57   my($s) = {
  58              level      => 0,           # current recursive depth
  59              indent     => $Indent,     # various styles of indenting
  60              pad        => $Pad,        # all lines prefixed by this string
  61              xpad       => "",          # padding-per-level
  62              apad       => "",          # added padding for hash keys n such
  63              sep        => "",          # list separator
  64              seen       => {},          # local (nested) refs (id => [name, val])
  65              todump     => $v,          # values to dump []
  66              names      => $n,          # optional names for values []
  67              varname    => $Varname,    # prefix to use for tagging nameless ones
  68              purity     => $Purity,     # degree to which output is evalable
  69              useqq      => $Useqq,      # use "" for strings (backslashitis ensues)
  70              terse      => $Terse,      # avoid name output (where feasible)
  71              freezer    => $Freezer,    # name of Freezer method for objects
  72              toaster    => $Toaster,    # name of method to revive objects
  73              deepcopy   => $Deepcopy,   # dont cross-ref, except to stop recursion
  74              quotekeys  => $Quotekeys,  # quote hash keys
  75              'bless'    => $Bless,      # keyword to use for "bless"
  76 #            expdepth   => $Expdepth,   # cutoff depth for explicit dumping
  77              maxdepth   => $Maxdepth,   # depth beyond which we give up
  78            };
  79
  80   if ($Indent > 0) {
  81     $s->{xpad} = "  ";
  82     $s->{sep} = "\n";
  83   }
  84   return bless($s, $c);
  85 }
  86
  87 #
  88 # add-to or query the table of already seen references
  89 #
  90 sub Seen {
  91   my($s, $g) = @_;
  92   if (defined($g) && (ref($g) eq 'HASH'))  {
  93     my($k, $v, $id);
  94     while (($k, $v) = each %$g) {
  95       if (defined $v and ref $v) {
  96         ($id) = (overload::StrVal($v) =~ /\((.*)\)$/);
  97         if ($k =~ /^[*](.*)$/) {
  98           $k = (ref $v eq 'ARRAY') ? ( "\\\@" . $1 ) :
  99                (ref $v eq 'HASH')  ? ( "\\\%" . $1 ) :
 100                (ref $v eq 'CODE')  ? ( "\\\&" . $1 ) :
 101                                      (   "\$" . $1 ) ;
 102         }
 103         elsif ($k !~ /^\$/) {
 104           $k = "\$" . $k;
 105         }
 106         $s->{seen}{$id} = [$k, $v];
 107       }
 108       else {
 109         carp "Only refs supported, ignoring non-ref item \$$k";
 110       }
 111     }
 112     return $s;
 113   }
 114   else {
 115     return map { @$_ } values %{$s->{seen}};
 116   }
 117 }
 118
 119 #
 120 # set or query the values to be dumped
 121 #
 122 sub Values {
 123   my($s, $v) = @_;
 124   if (defined($v) && (ref($v) eq 'ARRAY'))  {
 125     $s->{todump} = [@$v];        # make a copy
 126     return $s;
 127   }
 128   else {
 129     return @{$s->{todump}};
 130   }
 131 }
 132
 133 #
 134 # set or query the names of the values to be dumped
 135 #
 136 sub Names {
 137   my($s, $n) = @_;
 138   if (defined($n) && (ref($n) eq 'ARRAY'))  {
 139     $s->{names} = [@$n];         # make a copy
 140     return $s;
 141   }
 142   else {
 143     return @{$s->{names}};
 144   }
 145 }
 146
 147 sub DESTROY {}
 148
 149 sub Dump {
 150     return &Dumpxs
 151         unless $Data::Dumper::Useqq || (ref($_[0]) && $_[0]->{useqq});
 152     return &Dumpperl;
 153 }
 154
 155 #
 156 # dump the refs in the current dumper object.
 157 # expects same args as new() if called via package name.
 158 #
 159 sub Dumpperl {
 160   my($s) = shift;
 161   my(@out, $val, $name);
 162   my($i) = 0;
 163   local(@post);
 164
 165   $s = $s->new(@_) unless ref $s;
 166
 167   for $val (@{$s->{todump}}) {
 168     my $out = "";
 169     @post = ();
 170     $name = $s->{names}[$i++];
 171     if (defined $name) {
 172       if ($name =~ /^[*](.*)$/) {
 173         if (defined $val) {
 174           $name = (ref $val eq 'ARRAY') ? ( "\@" . $1 ) :
 175                   (ref $val eq 'HASH')  ? ( "\%" . $1 ) :
 176                   (ref $val eq 'CODE')  ? ( "\*" . $1 ) :
 177                                           ( "\$" . $1 ) ;
 178         }
 179         else {
 180           $name = "\$" . $1;
 181         }
 182       }
 183       elsif ($name !~ /^\$/) {
 184         $name = "\$" . $name;
 185       }
 186     }
 187     else {
 188       $name = "\$" . $s->{varname} . $i;
 189     }
 190
 191     my $valstr;
 192     {
 193       local($s->{apad}) = $s->{apad};
 194       $s->{apad} .= ' ' x (length($name) + 3) if $s->{indent} >= 2;
 195       $valstr = $s->_dump($val, $name);
 196     }
 197
 198     $valstr = "$name = " . $valstr . ';' if @post or !$s->{terse};
 199     $out .= $s->{pad} . $valstr . $s->{sep};
 200     $out .= $s->{pad} . join(';' . $s->{sep} . $s->{pad}, @post)
 201       . ';' . $s->{sep} if @post;
 202
 203     push @out, $out;
 204   }
 205   return wantarray ? @out : join('', @out);
 206 }
 207
 208 #
 209 # twist, toil and turn;
 210 # and recurse, of course.
 211 #
 212 sub _dump {
 213   my($s, $val, $name) = @_;
 214   my($sname);
 215   my($out, $realpack, $realtype, $type, $ipad, $id, $blesspad);
 216
 217   $type = ref $val;
 218   $out = "";
 219
 220   if ($type) {
 221
 222     # prep it, if it looks like an object
 223     if (my $freezer = $s->{freezer}) {
 224       $val->$freezer() if UNIVERSAL::can($val, $freezer);
 225     }
 226
 227     ($realpack, $realtype, $id) =
 228       (overload::StrVal($val) =~ /^(?:(.*)\=)?([^=]*)\(([^\(]*)\)$/);
 229
 230     # if it has a name, we need to either look it up, or keep a tab
 231     # on it so we know when we hit it later
 232     if (defined($name) and length($name)) {
 233       # keep a tab on it so that we dont fall into recursive pit
 234       if (exists $s->{seen}{$id}) {
 235 #       if ($s->{expdepth} < $s->{level}) {
 236           if ($s->{purity} and $s->{level} > 0) {
 237             $out = ($realtype eq 'HASH')  ? '{}' :
 238               ($realtype eq 'ARRAY') ? '[]' :
 239                 'do{my $o}' ;
 240             push @post, $name . " = " . $s->{seen}{$id}[0];
 241           }
 242           else {
 243             $out = $s->{seen}{$id}[0];
 244             if ($name =~ /^([\@\%])/) {
 245               my $start = $1;
 246               if ($out =~ /^\\$start/) {
 247                 $out = substr($out, 1);
 248               }
 249               else {
 250                 $out = $start . '{' . $out . '}';
 251               }
 252             }
 253           }
 254           return $out;
 255 #        }
 256       }
 257       else {
 258         # store our name
 259         $s->{seen}{$id} = [ (($name =~ /^[@%]/)     ? ('\\' . $name ) :
 260                              ($realtype eq 'CODE' and
 261                               $name =~ /^[*](.*)$/) ? ('\\&' . $1 )   :
 262                              $name          ),
 263                             $val ];
 264       }
 265     }
 266
 267     if ($realpack and $realpack eq 'Regexp') {
 268         $out = "$val";
 269         $out =~ s,/,\\/,g;
 270         return "qr/$out/";
 271     }
 272
 273     # If purity is not set and maxdepth is set, then check depth:
 274     # if we have reached maximum depth, return the string
 275     # representation of the thing we are currently examining
 276     # at this depth (i.e., 'Foo=ARRAY(0xdeadbeef)').
 277     if (!$s->{purity}
 278         and $s->{maxdepth} > 0
 279         and $s->{level} >= $s->{maxdepth})
 280     {
 281       return qq['$val'];
 282     }
 283
 284     # we have a blessed ref
 285     if ($realpack) {
 286       $out = $s->{'bless'} . '( ';
 287       $blesspad = $s->{apad};
 288       $s->{apad} .= '       ' if ($s->{indent} >= 2);
 289     }
 290
 291     $s->{level}++;
 292     $ipad = $s->{xpad} x $s->{level};
 293
 294     if ($realtype eq 'SCALAR' || $realtype eq 'REF') {
 295       if ($realpack) {
 296         $out .= 'do{\\(my $o = ' . $s->_dump($$val, "\${$name}") . ')}';
 297       }
 298       else {
 299         $out .= '\\' . $s->_dump($$val, "\${$name}");
 300       }
 301     }
 302     elsif ($realtype eq 'GLOB') {
 303         $out .= '\\' . $s->_dump($$val, "*{$name}");
 304     }
 305     elsif ($realtype eq 'ARRAY') {
 306       my($v, $pad, $mname);
 307       my($i) = 0;
 308       $out .= ($name =~ /^\@/) ? '(' : '[';
 309       $pad = $s->{sep} . $s->{pad} . $s->{apad};
 310       ($name =~ /^\@(.*)$/) ? ($mname = "\$" . $1) :
 311         # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
 312         ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
 313           ($mname = $name . '->');
 314       $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
 315       for $v (@$val) {
 316         $sname = $mname . '[' . $i . ']';
 317         $out .= $pad . $ipad . '#' . $i if $s->{indent} >= 3;
 318         $out .= $pad . $ipad . $s->_dump($v, $sname);
 319         $out .= "," if $i++ < $#$val;
 320       }
 321       $out .= $pad . ($s->{xpad} x ($s->{level} - 1)) if $i;
 322       $out .= ($name =~ /^\@/) ? ')' : ']';
 323     }
 324     elsif ($realtype eq 'HASH') {
 325       my($k, $v, $pad, $lpad, $mname);
 326       $out .= ($name =~ /^\%/) ? '(' : '{';
 327       $pad = $s->{sep} . $s->{pad} . $s->{apad};
 328       $lpad = $s->{apad};
 329       ($name =~ /^\%(.*)$/) ? ($mname = "\$" . $1) :
 330         # omit -> if $foo->[0]->{bar}, but not ${$foo->[0]}->{bar}
 331         ($name =~ /^\\?[\%\@\*\$][^{].*[]}]$/) ? ($mname = $name) :
 332           ($mname = $name . '->');
 333       $mname .= '->' if $mname =~ /^\*.+\{[A-Z]+\}$/;
 334       while (($k, $v) = each %$val) {
 335         my $nk = $s->_dump($k, "");
 336         $nk = $1 if !$s->{quotekeys} and $nk =~ /^[\"\']([A-Za-z_]\w*)[\"\']$/;
 337         $sname = $mname . '{' . $nk . '}';
 338         $out .= $pad . $ipad . $nk . " => ";
 339
 340         # temporarily alter apad
 341         $s->{apad} .= (" " x (length($nk) + 4)) if $s->{indent} >= 2;
 342         $out .= $s->_dump($val->{$k}, $sname) . ",";
 343         $s->{apad} = $lpad if $s->{indent} >= 2;
 344       }
 345       if (substr($out, -1) eq ',') {
 346         chop $out;
 347         $out .= $pad . ($s->{xpad} x ($s->{level} - 1));
 348       }
 349       $out .= ($name =~ /^\%/) ? ')' : '}';
 350     }
 351     elsif ($realtype eq 'CODE') {
 352       $out .= 'sub { "DUMMY" }';
 353       carp "Encountered CODE ref, using dummy placeholder" if $s->{purity};
 354     }
 355     else {
 356       croak "Can\'t handle $realtype type.";
 357     }
 358
 359     if ($realpack) { # we have a blessed ref
 360       $out .= ', \'' . $realpack . '\'' . ' )';
 361       $out .= '->' . $s->{toaster} . '()'  if $s->{toaster} ne '';
 362       $s->{apad} = $blesspad;
 363     }
 364     $s->{level}--;
 365
 366   }
 367   else {                                 # simple scalar
 368
 369     my $ref = \$_[1];
 370     # first, catalog the scalar
 371     if ($name ne '') {
 372       ($id) = ("$ref" =~ /\(([^\(]*)\)$/);
 373       if (exists $s->{seen}{$id}) {
 374         if ($s->{seen}{$id}[2]) {
 375           $out = $s->{seen}{$id}[0];
 376           #warn "[<$out]\n";
 377           return "\${$out}";
 378         }
 379       }
 380       else {
 381         #warn "[>\\$name]\n";
 382         $s->{seen}{$id} = ["\\$name", $ref];
 383       }
 384     }
 385     if (ref($ref) eq 'GLOB' or "$ref" =~ /=GLOB\([^()]+\)$/) {  # glob
 386       my $name = substr($val, 1);
 387       if ($name =~ /^[A-Za-z_][\w:]*$/) {
 388         $name =~ s/^main::/::/;
 389         $sname = $name;
 390       }
 391       else {
 392         $sname = $s->_dump($name, "");
 393         $sname = '{' . $sname . '}';
 394       }
 395       if ($s->{purity}) {
 396         my $k;
 397         local ($s->{level}) = 0;
 398         for $k (qw(SCALAR ARRAY HASH)) {
 399           my $gval = *$val{$k};
 400           next unless defined $gval;
 401           next if $k eq "SCALAR" && ! defined $$gval;  # always there
 402
 403           # _dump can push into @post, so we hold our place using $postlen
 404           my $postlen = scalar @post;
 405           $post[$postlen] = "\*$sname = ";
 406           local ($s->{apad}) = " " x length($post[$postlen]) if $s->{indent} >= 2;
 407           $post[$postlen] .= $s->_dump($gval, "\*$sname\{$k\}");
 408         }
 409       }
 410       $out .= '*' . $sname;
 411     }
 412     elsif (!defined($val)) {
 413       $out .= "undef";
 414     }
 415     elsif ($val =~ /^(?:0|-?[1-9]\d{0,8})$/) { # safe decimal number
 416       $out .= $val;
 417     }
 418     else {                               # string
 419       if ($s->{useqq}) {
 420         $out .= qquote($val, $s->{useqq});
 421       }
 422       else {
 423         $val =~ s/([\\\'])/\\$1/g;
 424         $out .= '\'' . $val .  '\'';
 425       }
 426     }
 427   }
 428   if ($id) {
 429     # if we made it this far, $id was added to seen list at current
 430     # level, so remove it to get deep copies
 431     if ($s->{deepcopy}) {
 432       delete($s->{seen}{$id});
 433     }
 434     elsif ($name) {
 435       $s->{seen}{$id}[2] = 1;
 436     }
 437   }
 438   return $out;
 439 }
 440
 441 #
 442 # non-OO style of earlier version
 443 #
 444 sub Dumper {
 445   return Data::Dumper->Dump([@_]);
 446 }
 447
 448 # compat stub
 449 sub DumperX {
 450   return Data::Dumper->Dumpxs([@_], []);
 451 }
 452
 453 sub Dumpf { return Data::Dumper->Dump(@_) }
 454
 455 sub Dumpp { print Data::Dumper->Dump(@_) }
 456
 457 #
 458 # reset the "seen" cache
 459 #
 460 sub Reset {
 461   my($s) = shift;
 462   $s->{seen} = {};
 463   return $s;
 464 }
 465
 466 sub Indent {
 467   my($s, $v) = @_;
 468   if (defined($v)) {
 469     if ($v == 0) {
 470       $s->{xpad} = "";
 471       $s->{sep} = "";
 472     }
 473     else {
 474       $s->{xpad} = "  ";
 475       $s->{sep} = "\n";
 476     }
 477     $s->{indent} = $v;
 478     return $s;
 479   }
 480   else {
 481     return $s->{indent};
 482   }
 483 }
 484
 485 sub Pad {
 486   my($s, $v) = @_;
 487   defined($v) ? (($s->{pad} = $v), return $s) : $s->{pad};
 488 }
 489
 490 sub Varname {
 491   my($s, $v) = @_;
 492   defined($v) ? (($s->{varname} = $v), return $s) : $s->{varname};
 493 }
 494
 495 sub Purity {
 496   my($s, $v) = @_;
 497   defined($v) ? (($s->{purity} = $v), return $s) : $s->{purity};
 498 }
 499
 500 sub Useqq {
 501   my($s, $v) = @_;
 502   defined($v) ? (($s->{useqq} = $v), return $s) : $s->{useqq};
 503 }
 504
 505 sub Terse {
 506   my($s, $v) = @_;
 507   defined($v) ? (($s->{terse} = $v), return $s) : $s->{terse};
 508 }
 509
 510 sub Freezer {
 511   my($s, $v) = @_;
 512   defined($v) ? (($s->{freezer} = $v), return $s) : $s->{freezer};
 513 }
 514
 515 sub Toaster {
 516   my($s, $v) = @_;
 517   defined($v) ? (($s->{toaster} = $v), return $s) : $s->{toaster};
 518 }
 519
 520 sub Deepcopy {
 521   my($s, $v) = @_;
 522   defined($v) ? (($s->{deepcopy} = $v), return $s) : $s->{deepcopy};
 523 }
 524
 525 sub Quotekeys {
 526   my($s, $v) = @_;
 527   defined($v) ? (($s->{quotekeys} = $v), return $s) : $s->{quotekeys};
 528 }
 529
 530 sub Bless {
 531   my($s, $v) = @_;
 532   defined($v) ? (($s->{'bless'} = $v), return $s) : $s->{'bless'};
 533 }
 534
 535 sub Maxdepth {
 536   my($s, $v) = @_;
 537   defined($v) ? (($s->{'maxdepth'} = $v), return $s) : $s->{'maxdepth'};
 538 }
 539
 540
 541 # used by qquote below
 542 my %esc = (
 543     "\a" => "\\a",
 544     "\b" => "\\b",
 545     "\t" => "\\t",
 546     "\n" => "\\n",
 547     "\f" => "\\f",
 548     "\r" => "\\r",
 549     "\e" => "\\e",
 550 );
 551
 552 # put a string value in double quotes
 553 sub qquote {
 554   local($_) = shift;
 555   s/([\\\"\@\$])/\\$1/g;
 556   return qq("$_") unless
 557     /[^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~]/;  # fast exit
 558
 559   my $high = shift || "";
 560   s/([\a\b\t\n\f\r\e])/$esc{$1}/g;
 561
 562   if (ord('^')==94)  { # ascii
 563     # no need for 3 digits in escape for these
 564     s/([\0-\037])(?!\d)/'\\'.sprintf('%o',ord($1))/eg;
 565     s/([\0-\037\177])/'\\'.sprintf('%03o',ord($1))/eg;
 566     # all but last branch below not supported --BEHAVIOR SUBJECT TO CHANGE--
 567     if ($high eq "iso8859") {
 568       s/([\200-\240])/'\\'.sprintf('%o',ord($1))/eg;
 569     } elsif ($high eq "utf8") {
 570 #     use utf8;
 571 #     $str =~ s/([^\040-\176])/sprintf "\\x{%04x}", ord($1)/ge;
 572     } elsif ($high eq "8bit") {
 573         # leave it as it is
 574     } else {
 575       s/([\200-\377])/'\\'.sprintf('%03o',ord($1))/eg;
 576     }
 577   }
 578   else { # ebcdic
 579       s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])(?!\d)}
 580        {my $v = ord($1); '\\'.sprintf(($v <= 037 ? '%o' : '%03o'), $v)}eg;
 581       s{([^ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~])}
 582        {'\\'.sprintf('%03o',ord($1))}eg;
 583   }
 584
 585   return qq("$_");
 586 }
 587
 588 1;
 589 __END__
 590
 591 =head1 NAME
 592
 593 Data::Dumper - stringified perl data structures, suitable for both printing and C<eval>
 594
 595
 596 =head1 SYNOPSIS
 597
 598     use Data::Dumper;
 599
 600     # simple procedural interface
 601     print Dumper($foo, $bar);
 602
 603     # extended usage with names
 604     print Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
 605
 606     # configuration variables
 607     {
 608       local $Data::Dump::Purity = 1;
 609       eval Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]);
 610     }
 611
 612     # OO usage
 613     $d = Data::Dumper->new([$foo, $bar], [qw(foo *ary)]);
 614        ...
 615     print $d->Dump;
 616        ...
 617     $d->Purity(1)->Terse(1)->Deepcopy(1);
 618     eval $d->Dump;
 619
 620
 621 =head1 DESCRIPTION
 622
 623 Given a list of scalars or reference variables, writes out their contents in
 624 perl syntax. The references can also be objects.  The contents of each
 625 variable is output in a single Perl statement.  Handles self-referential
 626 structures correctly.
 627
 628 The return value can be C<eval>ed to get back an identical copy of the
 629 original reference structure.
 630
 631 Any references that are the same as one of those passed in will be named
 632 C<$VAR>I<n> (where I<n> is a numeric suffix), and other duplicate references
 633 to substructures within C<$VAR>I<n> will be appropriately labeled using arrow
 634 notation.  You can specify names for individual values to be dumped if you
 635 use the C<Dump()> method, or you can change the default C<$VAR> prefix to
 636 something else.  See C<$Data::Dumper::Varname> and C<$Data::Dumper::Terse>
 637 below.
 638
 639 The default output of self-referential structures can be C<eval>ed, but the
 640 nested references to C<$VAR>I<n> will be undefined, since a recursive
 641 structure cannot be constructed using one Perl statement.  You should set the
 642 C<Purity> flag to 1 to get additional statements that will correctly fill in
 643 these references.
 644
 645 In the extended usage form, the references to be dumped can be given
 646 user-specified names.  If a name begins with a C<*>, the output will
 647 describe the dereferenced type of the supplied reference for hashes and
 648 arrays, and coderefs.  Output of names will be avoided where possible if
 649 the C<Terse> flag is set.
 650
 651 In many cases, methods that are used to set the internal state of the
 652 object will return the object itself, so method calls can be conveniently
 653 chained together.
 654
 655 Several styles of output are possible, all controlled by setting
 656 the C<Indent> flag.  See L<Configuration Variables or Methods> below
 657 for details.
 658
 659
 660 =head2 Methods
 661
 662 =over 4
 663
 664 =item I<PACKAGE>->new(I<ARRAYREF [>, I<ARRAYREF]>)
 665
 666 Returns a newly created C<Data::Dumper> object.  The first argument is an
 667 anonymous array of values to be dumped.  The optional second argument is an
 668 anonymous array of names for the values.  The names need not have a leading
 669 C<$> sign, and must be comprised of alphanumeric characters.  You can begin
 670 a name with a C<*> to specify that the dereferenced type must be dumped
 671 instead of the reference itself, for ARRAY and HASH references.
 672
 673 The prefix specified by C<$Data::Dumper::Varname> will be used with a
 674 numeric suffix if the name for a value is undefined.
 675
 676 Data::Dumper will catalog all references encountered while dumping the
 677 values. Cross-references (in the form of names of substructures in perl
 678 syntax) will be inserted at all possible points, preserving any structural
 679 interdependencies in the original set of values.  Structure traversal is
 680 depth-first,  and proceeds in order from the first supplied value to
 681 the last.
 682
 683 =item I<$OBJ>->Dump  I<or>  I<PACKAGE>->Dump(I<ARRAYREF [>, I<ARRAYREF]>)
 684
 685 Returns the stringified form of the values stored in the object (preserving
 686 the order in which they were supplied to C<new>), subject to the
 687 configuration options below.  In a list context, it returns a list
 688 of strings corresponding to the supplied values.
 689
 690 The second form, for convenience, simply calls the C<new> method on its
 691 arguments before dumping the object immediately.
 692
 693 =item I<$OBJ>->Seen(I<[HASHREF]>)
 694
 695 Queries or adds to the internal table of already encountered references.
 696 You must use C<Reset> to explicitly clear the table if needed.  Such
 697 references are not dumped; instead, their names are inserted wherever they
 698 are encountered subsequently.  This is useful especially for properly
 699 dumping subroutine references.
 700
 701 Expects a anonymous hash of name => value pairs.  Same rules apply for names
 702 as in C<new>.  If no argument is supplied, will return the "seen" list of
 703 name => value pairs, in a list context.  Otherwise, returns the object
 704 itself.
 705
 706 =item I<$OBJ>->Values(I<[ARRAYREF]>)
 707
 708 Queries or replaces the internal array of values that will be dumped.
 709 When called without arguments, returns the values.  Otherwise, returns the
 710 object itself.
 711
 712 =item I<$OBJ>->Names(I<[ARRAYREF]>)
 713
 714 Queries or replaces the internal array of user supplied names for the values
 715 that will be dumped.  When called without arguments, returns the names.
 716 Otherwise, returns the object itself.
 717
 718 =item I<$OBJ>->Reset
 719
 720 Clears the internal table of "seen" references and returns the object
 721 itself.
 722
 723 =back
 724
 725 =head2 Functions
 726
 727 =over 4
 728
 729 =item Dumper(I<LIST>)
 730
 731 Returns the stringified form of the values in the list, subject to the
 732 configuration options below.  The values will be named C<$VAR>I<n> in the
 733 output, where I<n> is a numeric suffix.  Will return a list of strings
 734 in a list context.
 735
 736 =back
 737
 738 =head2 Configuration Variables or Methods
 739
 740 Several configuration variables can be used to control the kind of output
 741 generated when using the procedural interface.  These variables are usually
 742 C<local>ized in a block so that other parts of the code are not affected by
 743 the change.
 744
 745 These variables determine the default state of the object created by calling
 746 the C<new> method, but cannot be used to alter the state of the object
 747 thereafter.  The equivalent method names should be used instead to query
 748 or set the internal state of the object.
 749
 750 The method forms return the object itself when called with arguments,
 751 so that they can be chained together nicely.
 752
 753 =over 4
 754
 755 =item $Data::Dumper::Indent  I<or>  I<$OBJ>->Indent(I<[NEWVAL]>)
 756
 757 Controls the style of indentation.  It can be set to 0, 1, 2 or 3.  Style 0
 758 spews output without any newlines, indentation, or spaces between list
 759 items.  It is the most compact format possible that can still be called
 760 valid perl.  Style 1 outputs a readable form with newlines but no fancy
 761 indentation (each level in the structure is simply indented by a fixed
 762 amount of whitespace).  Style 2 (the default) outputs a very readable form
 763 which takes into account the length of hash keys (so the hash value lines
 764 up).  Style 3 is like style 2, but also annotates the elements of arrays
 765 with their index (but the comment is on its own line, so array output
 766 consumes twice the number of lines).  Style 2 is the default.
 767
 768 =item $Data::Dumper::Purity  I<or>  I<$OBJ>->Purity(I<[NEWVAL]>)
 769
 770 Controls the degree to which the output can be C<eval>ed to recreate the
 771 supplied reference structures.  Setting it to 1 will output additional perl
 772 statements that will correctly recreate nested references.  The default is
 773 0.
 774
 775 =item $Data::Dumper::Pad  I<or>  I<$OBJ>->Pad(I<[NEWVAL]>)
 776
 777 Specifies the string that will be prefixed to every line of the output.
 778 Empty string by default.
 779
 780 =item $Data::Dumper::Varname  I<or>  I<$OBJ>->Varname(I<[NEWVAL]>)
 781
 782 Contains the prefix to use for tagging variable names in the output. The
 783 default is "VAR".
 784
 785 =item $Data::Dumper::Useqq  I<or>  I<$OBJ>->Useqq(I<[NEWVAL]>)
 786
 787 When set, enables the use of double quotes for representing string values.
 788 Whitespace other than space will be represented as C<[\n\t\r]>, "unsafe"
 789 characters will be backslashed, and unprintable characters will be output as
 790 quoted octal integers.  Since setting this variable imposes a performance
 791 penalty, the default is 0.  C<Dump()> will run slower if this flag is set,
 792 since the fast XSUB implementation doesn't support it yet.
 793
 794 =item $Data::Dumper::Terse  I<or>  I<$OBJ>->Terse(I<[NEWVAL]>)
 795
 796 When set, Data::Dumper will emit single, non-self-referential values as
 797 atoms/terms rather than statements.  This means that the C<$VAR>I<n> names
 798 will be avoided where possible, but be advised that such output may not
 799 always be parseable by C<eval>.
 800
 801 =item $Data::Dumper::Freezer  I<or>  $I<OBJ>->Freezer(I<[NEWVAL]>)
 802
 803 Can be set to a method name, or to an empty string to disable the feature.
 804 Data::Dumper will invoke that method via the object before attempting to
 805 stringify it.  This method can alter the contents of the object (if, for
 806 instance, it contains data allocated from C), and even rebless it in a
 807 different package.  The client is responsible for making sure the specified
 808 method can be called via the object, and that the object ends up containing
 809 only perl data types after the method has been called.  Defaults to an empty
 810 string.
 811
 812 =item $Data::Dumper::Toaster  I<or>  $I<OBJ>->Toaster(I<[NEWVAL]>)
 813
 814 Can be set to a method name, or to an empty string to disable the feature.
 815 Data::Dumper will emit a method call for any objects that are to be dumped
 816 using the syntax C<bless(DATA, CLASS)->METHOD()>.  Note that this means that
 817 the method specified will have to perform any modifications required on the
 818 object (like creating new state within it, and/or reblessing it in a
 819 different package) and then return it.  The client is responsible for making
 820 sure the method can be called via the object, and that it returns a valid
 821 object.  Defaults to an empty string.
 822
 823 =item $Data::Dumper::Deepcopy  I<or>  $I<OBJ>->Deepcopy(I<[NEWVAL]>)
 824
 825 Can be set to a boolean value to enable deep copies of structures.
 826 Cross-referencing will then only be done when absolutely essential
 827 (i.e., to break reference cycles).  Default is 0.
 828
 829 =item $Data::Dumper::Quotekeys  I<or>  $I<OBJ>->Quotekeys(I<[NEWVAL]>)
 830
 831 Can be set to a boolean value to control whether hash keys are quoted.
 832 A false value will avoid quoting hash keys when it looks like a simple
 833 string.  Default is 1, which will always enclose hash keys in quotes.
 834
 835 =item $Data::Dumper::Bless  I<or>  $I<OBJ>->Bless(I<[NEWVAL]>)
 836
 837 Can be set to a string that specifies an alternative to the C<bless>
 838 builtin operator used to create objects.  A function with the specified
 839 name should exist, and should accept the same arguments as the builtin.
 840 Default is C<bless>.
 841
 842 =item $Data::Dumper::Maxdepth  I<or>  $I<OBJ>->Maxdepth(I<[NEWVAL]>)
 843
 844 Can be set to a positive integer that specifies the depth beyond which
 845 which we don't venture into a structure.  Has no effect when
 846 C<Data::Dumper::Purity> is set.  (Useful in debugger when we often don't
 847 want to see more than enough).  Default is 0, which means there is
 848 no maximum depth.
 849
 850 =back
 851
 852 =head2 Exports
 853
 854 =over 4
 855
 856 =item Dumper
 857
 858 =back
 859
 860 =head1 EXAMPLES
 861
 862 Run these code snippets to get a quick feel for the behavior of this
 863 module.  When you are through with these examples, you may want to
 864 add or change the various configuration variables described above,
 865 to see their behavior.  (See the testsuite in the Data::Dumper
 866 distribution for more examples.)
 867
 868
 869     use Data::Dumper;
 870
 871     package Foo;
 872     sub new {bless {'a' => 1, 'b' => sub { return "foo" }}, $_[0]};
 873
 874     package Fuz;                       # a weird REF-REF-SCALAR object
 875     sub new {bless \($_ = \ 'fu\'z'), $_[0]};
 876
 877     package main;
 878     $foo = Foo->new;
 879     $fuz = Fuz->new;
 880     $boo = [ 1, [], "abcd", \*foo,
 881              {1 => 'a', 023 => 'b', 0x45 => 'c'},
 882              \\"p\q\'r", $foo, $fuz];
 883
 884     ########
 885     # simple usage
 886     ########
 887
 888     $bar = eval(Dumper($boo));
 889     print($@) if $@;
 890     print Dumper($boo), Dumper($bar);  # pretty print (no array indices)
 891
 892     $Data::Dumper::Terse = 1;          # don't output names where feasible
 893     $Data::Dumper::Indent = 0;         # turn off all pretty print
 894     print Dumper($boo), "\n";
 895
 896     $Data::Dumper::Indent = 1;         # mild pretty print
 897     print Dumper($boo);
 898
 899     $Data::Dumper::Indent = 3;         # pretty print with array indices
 900     print Dumper($boo);
 901
 902     $Data::Dumper::Useqq = 1;          # print strings in double quotes
 903     print Dumper($boo);
 904
 905
 906     ########
 907     # recursive structures
 908     ########
 909
 910     @c = ('c');
 911     $c = \@c;
 912     $b = {};
 913     $a = [1, $b, $c];
 914     $b->{a} = $a;
 915     $b->{b} = $a->[1];
 916     $b->{c} = $a->[2];
 917     print Data::Dumper->Dump([$a,$b,$c], [qw(a b c)]);
 918
 919
 920     $Data::Dumper::Purity = 1;         # fill in the holes for eval
 921     print Data::Dumper->Dump([$a, $b], [qw(*a b)]); # print as @a
 922     print Data::Dumper->Dump([$b, $a], [qw(*b a)]); # print as %b
 923
 924
 925     $Data::Dumper::Deepcopy = 1;       # avoid cross-refs
 926     print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
 927
 928
 929     $Data::Dumper::Purity = 0;         # avoid cross-refs
 930     print Data::Dumper->Dump([$b, $a], [qw(*b a)]);
 931
 932     ########
 933     # deep structures
 934     ########
 935
 936     $a = "pearl";
 937     $b = [ $a ];
 938     $c = { 'b' => $b };
 939     $d = [ $c ];
 940     $e = { 'd' => $d };
 941     $f = { 'e' => $e };
 942     print Data::Dumper->Dump([$f], [qw(f)]);
 943
 944     $Data::Dumper::Maxdepth = 3;       # no deeper than 3 refs down
 945     print Data::Dumper->Dump([$f], [qw(f)]);
 946
 947
 948     ########
 949     # object-oriented usage
 950     ########
 951
 952     $d = Data::Dumper->new([$a,$b], [qw(a b)]);
 953     $d->Seen({'*c' => $c});            # stash a ref without printing it
 954     $d->Indent(3);
 955     print $d->Dump;
 956     $d->Reset->Purity(0);              # empty the seen cache
 957     print join "----\n", $d->Dump;
 958
 959
 960     ########
 961     # persistence
 962     ########
 963
 964     package Foo;
 965     sub new { bless { state => 'awake' }, shift }
 966     sub Freeze {
 967         my $s = shift;
 968         print STDERR "preparing to sleep\n";
 969         $s->{state} = 'asleep';
 970         return bless $s, 'Foo::ZZZ';
 971     }
 972
 973     package Foo::ZZZ;
 974     sub Thaw {
 975         my $s = shift;
 976         print STDERR "waking up\n";
 977         $s->{state} = 'awake';
 978         return bless $s, 'Foo';
 979     }
 980
 981     package Foo;
 982     use Data::Dumper;
 983     $a = Foo->new;
 984     $b = Data::Dumper->new([$a], ['c']);
 985     $b->Freezer('Freeze');
 986     $b->Toaster('Thaw');
 987     $c = $b->Dump;
 988     print $c;
 989     $d = eval $c;
 990     print Data::Dumper->Dump([$d], ['d']);
 991
 992
 993     ########
 994     # symbol substitution (useful for recreating CODE refs)
 995     ########
 996
 997     sub foo { print "foo speaking\n" }
 998     *other = \&foo;
 999     $bar = [ \&other ];
1000     $d = Data::Dumper->new([\&other,$bar],['*other','bar']);
1001     $d->Seen({ '*foo' => \&foo });
1002     print $d->Dump;
1003
1004
1005 =head1 BUGS
1006
1007 Due to limitations of Perl subroutine call semantics, you cannot pass an
1008 array or hash.  Prepend it with a C<\> to pass its reference instead.  This
1009 will be remedied in time, with the arrival of prototypes in later versions
1010 of Perl.  For now, you need to use the extended usage form, and prepend the
1011 name with a C<*> to output it as a hash or array.
1012
1013 C<Data::Dumper> cheats with CODE references.  If a code reference is
1014 encountered in the structure being processed, an anonymous subroutine that
1015 contains the string '"DUMMY"' will be inserted in its place, and a warning
1016 will be printed if C<Purity> is set.  You can C<eval> the result, but bear
1017 in mind that the anonymous sub that gets created is just a placeholder.
1018 Someday, perl will have a switch to cache-on-demand the string
1019 representation of a compiled piece of code, I hope.  If you have prior
1020 knowledge of all the code refs that your data structures are likely
1021 to have, you can use the C<Seen> method to pre-seed the internal reference
1022 table and make the dumped output point to them, instead.  See L<EXAMPLES>
1023 above.
1024
1025 The C<Useqq> flag makes Dump() run slower, since the XSUB implementation
1026 does not support it.
1027
1028 SCALAR objects have the weirdest looking C<bless> workaround.
1029
1030
1031 =head1 AUTHOR
1032
1033 Gurusamy Sarathy        gsar@activestate.com
1034
1035 Copyright (c) 1996-98 Gurusamy Sarathy. All rights reserved.
1036 This program is free software; you can redistribute it and/or
1037 modify it under the same terms as Perl itself.
1038
1039
1040 =head1 VERSION
1041
1042 Version 2.11   (unreleased)
1043
1044 =head1 SEE ALSO
1045
1046 perl(1)
1047
1048 =cut