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[p5sagit/p5-mst-13.2.git] / ext / B / B / Concise.pm

package B::Concise;
# Copyright (C) 2000-2003 Stephen McCamant. All rights reserved.
# This program is free software; you can redistribute and/or modify it
# under the same terms as Perl itself.

use strict;
use warnings;

use Exporter ();

our $VERSION   = "0.55";
our @ISA       = qw(Exporter);
our @EXPORT_OK = qw(set_style set_style_standard add_callback
		    concise_cv concise_main);

use B qw(class ppname main_start main_root main_cv cstring svref_2object
	 SVf_IOK SVf_NOK SVf_POK SVf_IVisUV OPf_KIDS);

my %style = 
  ("terse" =>
   ["(?(#label =>\n)?)(*(    )*)#class (#addr) #name (?([#targ])?) "
    . "#svclass~(?((#svaddr))?)~#svval~(?(label \"#coplabel\")?)\n",
    "(*(    )*)goto #class (#addr)\n",
    "#class pp_#name"],
   "concise" =>
   ["#hyphseq2 (*(   (x( ;)x))*)<#classsym> "
    . "#exname#arg(?([#targarglife])?)~#flags(?(/#private)?)(x(;~->#next)x)\n",
    "  (*(    )*)     goto #seq\n",
    "(?(<#seq>)?)#exname#arg(?([#targarglife])?)"],
   "linenoise" =>
   ["(x(;(*( )*))x)#noise#arg(?([#targarg])?)(x( ;\n)x)",
    "gt_#seq ",
    "(?(#seq)?)#noise#arg(?([#targarg])?)"],
   "debug" =>
   ["#class (#addr)\n\top_next\t\t#nextaddr\n\top_sibling\t#sibaddr\n\t"
    . "op_ppaddr\tPL_ppaddr[OP_#NAME]\n\top_type\t\t#typenum\n\top_seq\t\t"
    . "#seqnum\n\top_flags\t#flagval\n\top_private\t#privval\n"
    . "(?(\top_first\t#firstaddr\n)?)(?(\top_last\t\t#lastaddr\n)?)"
    . "(?(\top_sv\t\t#svaddr\n)?)",
    "    GOTO #addr\n",
    "#addr"],
   "env" => [$ENV{B_CONCISE_FORMAT}, $ENV{B_CONCISE_GOTO_FORMAT},
	     $ENV{B_CONCISE_TREE_FORMAT}],
  );

my($format, $gotofmt, $treefmt);
my $curcv;
my $cop_seq_base;
my @callbacks;

sub set_style {
    ($format, $gotofmt, $treefmt) = @_;
}

sub set_style_standard {
    my($name) = @_;
    set_style(@{$style{$name}});
}

sub add_callback {
    push @callbacks, @_;
}

sub concise_cv {
    my ($order, $cvref) = @_;
    my $cv = svref_2object($cvref);
    $curcv = $cv;
    sequence($cv->START);
    if ($order eq "exec") {
	walk_exec($cv->START);
    } elsif ($order eq "basic") {
	walk_topdown($cv->ROOT, sub { $_[0]->concise($_[1]) }, 0);
    } else {
	print tree($cv->ROOT, 0)
    }
}

sub concise_main {
    my($order) = @_;
    sequence(main_start);
    $curcv = main_cv;
    if ($order eq "exec") {
	return if class(main_start) eq "NULL";
	walk_exec(main_start);
    } elsif ($order eq "tree") {
	return if class(main_root) eq "NULL";
	print tree(main_root, 0);
    } elsif ($order eq "basic") {
	return if class(main_root) eq "NULL";
	walk_topdown(main_root,
		     sub { $_[0]->concise($_[1]) }, 0);
    }
}

my $start_sym = "\e(0"; # "\cN" sometimes also works
my $end_sym   = "\e(B"; # "\cO" respectively

my @tree_decorations = 
  (["  ", "--", "+-", "|-", "| ", "`-", "-", 1],
   [" ", "-", "+", "+", "|", "`", "", 0],
   ["  ", map("$start_sym$_$end_sym", "qq", "wq", "tq", "x ", "mq", "q"), 1],
   [" ", map("$start_sym$_$end_sym", "q", "w", "t", "x", "m"), "", 0],
  );
my $tree_style = 0;

my $base = 36;
my $big_endian = 1;

my $order = "basic";

set_style_standard("concise");

sub compile {
    my @options = grep(/^-/, @_);
    my @args = grep(!/^-/, @_);
    my $do_main = 0;
    for my $o (@options) {
	if ($o eq "-basic") {
	    $order = "basic";
	} elsif ($o eq "-exec") {
	    $order = "exec";
	} elsif ($o eq "-tree") {
	    $order = "tree";
	} elsif ($o eq "-compact") {
	    $tree_style |= 1;
	} elsif ($o eq "-loose") {
	    $tree_style &= ~1;
	} elsif ($o eq "-vt") {
	    $tree_style |= 2;
	} elsif ($o eq "-ascii") {
	    $tree_style &= ~2;
	} elsif ($o eq "-main") {
	    $do_main = 1;
	} elsif ($o =~ /^-base(\d+)$/) {
	    $base = $1;
	} elsif ($o eq "-bigendian") {
	    $big_endian = 1;
	} elsif ($o eq "-littleendian") {
	    $big_endian = 0;
	} elsif (exists $style{substr($o, 1)}) {
	    set_style(@{$style{substr($o, 1)}});
	} else {
	    warn "Option $o unrecognized";
	}
    }
    return sub {
	if (@args) {
	    for my $objname (@args) {
		$objname = "main::" . $objname unless $objname =~ /::/;
		print "$objname:\n";
		eval "concise_cv(\$order, \\&$objname)";
		die "concise_cv($order, \\&$objname) failed: $@" if $@;
	    }
	}
	if (!@args or $do_main) {
	    print "main program:\n" if $do_main;
	    concise_main($order);
	}
    }
}

my %labels;
my $lastnext;

my %opclass = ('OP' => "0", 'UNOP' => "1", 'BINOP' => "2", 'LOGOP' => "|",
	       'LISTOP' => "@", 'PMOP' => "/", 'SVOP' => "\$", 'GVOP' => "*",
	       'PVOP' => '"', 'LOOP' => "{", 'COP' => ";", 'PADOP' => "#");

no warnings 'qw'; # "Possible attempt to put comments..."
my @linenoise =
  qw'#  () sc (  @? 1  $* gv *{ m$ m@ m% m? p/ *$ $  $# & a& pt \\ s\\ rf bl
     `  *? <> ?? ?/ r/ c/ // qr s/ /c y/ =  @= C  sC Cp sp df un BM po +1 +I
     -1 -I 1+ I+ 1- I- ** *  i* /  i/ %$ i% x  +  i+ -  i- .  "  << >> <  i<
     >  i> <= i, >= i. == i= != i! <? i? s< s> s, s. s= s! s? b& b^ b| -0 -i
     !  ~  a2 si cs rd sr e^ lg sq in %x %o ab le ss ve ix ri sf FL od ch cy
     uf lf uc lc qm @  [f [  @[ eh vl ky dl ex %  ${ @{ uk pk st jn )  )[ a@
     a% sl +] -] [- [+ so rv GS GW MS MW .. f. .f && || ^^ ?: &= |= -> s{ s}
     v} ca wa di rs ;; ;  ;d }{ {  }  {} f{ it {l l} rt }l }n }r dm }g }e ^o
     ^c ^| ^# um bm t~ u~ ~d DB db ^s se ^g ^r {w }w pf pr ^O ^K ^R ^W ^d ^v
     ^e ^t ^k t. fc ic fl .s .p .b .c .l .a .h g1 s1 g2 s2 ?. l? -R -W -X -r
     -w -x -e -o -O -z -s -M -A -C -S -c -b -f -d -p -l -u -g -k -t -T -B cd
     co cr u. cm ut r. l@ s@ r@ mD uD oD rD tD sD wD cD f$ w$ p$ sh e$ k$ g3
     g4 s4 g5 s5 T@ C@ L@ G@ A@ S@ Hg Hc Hr Hw Mg Mc Ms Mr Sg Sc So rq do {e
     e} {t t} g6 G6 6e g7 G7 7e g8 G8 8e g9 G9 9e 6s 7s 8s 9s 6E 7E 8E 9E Pn
     Pu GP SP EP Gn Gg GG SG EG g0 c$ lk t$ ;s n> // /= CO';

my $chars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

sub op_flags {
    my($x) = @_;
    my(@v);
    push @v, "v" if ($x & 3) == 1;
    push @v, "s" if ($x & 3) == 2;
    push @v, "l" if ($x & 3) == 3;
    push @v, "K" if $x & 4;
    push @v, "P" if $x & 8;
    push @v, "R" if $x & 16;
    push @v, "M" if $x & 32;
    push @v, "S" if $x & 64;
    push @v, "*" if $x & 128;
    return join("", @v);
}

sub base_n {
    my $x = shift;
    return "-" . base_n(-$x) if $x < 0;
    my $str = "";
    do { $str .= substr($chars, $x % $base, 1) } while $x = int($x / $base);
    $str = reverse $str if $big_endian;
    return $str;
}

my %sequence_num;
my $seq_max = 1;

sub seq {
    my($op) = @_;
    return "-" if not exists $sequence_num{$$op};
    return base_n($sequence_num{$$op});
}

sub walk_topdown {
    my($op, $sub, $level) = @_;
    $sub->($op, $level);
    if ($op->flags & OPf_KIDS) {
	for (my $kid = $op->first; $$kid; $kid = $kid->sibling) {
	    walk_topdown($kid, $sub, $level + 1);
	}
    }
    if (class($op) eq "PMOP" and $op->pmreplroot and $ {$op->pmreplroot}
	and $op->pmreplroot->isa("B::OP")) {
	walk_topdown($op->pmreplroot, $sub, $level + 1);
    }
}

sub walklines {
    my($ar, $level) = @_;
    for my $l (@$ar) {
	if (ref($l) eq "ARRAY") {
	    walklines($l, $level + 1);
	} else {
	    $l->concise($level);
	}
    }
}

sub walk_exec {
    my($top, $level) = @_;
    my %opsseen;
    my @lines;
    my @todo = ([$top, \@lines]);
    while (@todo and my($op, $targ) = @{shift @todo}) {
	for (; $$op; $op = $op->next) {
	    last if $opsseen{$$op}++;
	    push @$targ, $op;
	    my $name = $op->name;
	    if (class($op) eq "LOGOP") {
		my $ar = [];
		push @$targ, $ar;
		push @todo, [$op->other, $ar];
	    } elsif ($name eq "subst" and $ {$op->pmreplstart}) {
		my $ar = [];
		push @$targ, $ar;
		push @todo, [$op->pmreplstart, $ar];
	    } elsif ($name =~ /^enter(loop|iter)$/) {
		$labels{$op->nextop->seq} = "NEXT";
		$labels{$op->lastop->seq} = "LAST";
		$labels{$op->redoop->seq} = "REDO";		
	    }
	}
    }
    walklines(\@lines, 0);
}

# The structure of this routine is purposely modeled after op.c's peep()
sub sequence {
    my($op) = @_;
    my $oldop = 0;
    return if class($op) eq "NULL" or exists $sequence_num{$$op};
    for (; $$op; $op = $op->next) {
	last if exists $sequence_num{$$op};
	my $name = $op->name;
	if ($name =~ /^(null|scalar|lineseq|scope)$/) {
	    next if $oldop and $ {$op->next};
	} else {
	    $sequence_num{$$op} = $seq_max++;
	    if (class($op) eq "LOGOP") {
		my $other = $op->other;
		$other = $other->next while $other->name eq "null";
		sequence($other);
	    } elsif (class($op) eq "LOOP") {
		my $redoop = $op->redoop;
		$redoop = $redoop->next while $redoop->name eq "null";
		sequence($redoop);
		my $nextop = $op->nextop;
		$nextop = $nextop->next while $nextop->name eq "null";
		sequence($nextop);
		my $lastop = $op->lastop;
		$lastop = $lastop->next while $lastop->name eq "null";
		sequence($lastop);
	    } elsif ($name eq "subst" and $ {$op->pmreplstart}) {
		my $replstart = $op->pmreplstart;
		$replstart = $replstart->next while $replstart->name eq "null";
		sequence($replstart);
	    }
	}
	$oldop = $op;
    }
}

sub fmt_line {
    my($hr, $fmt, $level) = @_;
    my $text = $fmt;
    $text =~ s/\(\?\(([^\#]*?)\#(\w+)([^\#]*?)\)\?\)/
      $hr->{$2} ? $1.$hr->{$2}.$3 : ""/eg;
    $text =~ s/\(x\((.*?);(.*?)\)x\)/$order eq "exec" ? $1 : $2/egs;
    $text =~ s/\(\*\(([^;]*?)\)\*\)/$1 x $level/egs;
    $text =~ s/\(\*\((.*?);(.*?)\)\*\)/$1 x ($level - 1) . $2 x ($level>0)/egs;
    $text =~ s/#([a-zA-Z]+)(\d+)/sprintf("%-$2s", $hr->{$1})/eg;
    $text =~ s/#([a-zA-Z]+)/$hr->{$1}/eg;
    $text =~ s/[ \t]*~+[ \t]*/ /g;
    return $text;
}

my %priv;
$priv{$_}{128} = "LVINTRO"
  for ("pos", "substr", "vec", "threadsv", "gvsv", "rv2sv", "rv2hv", "rv2gv",
       "rv2av", "rv2arylen", "aelem", "helem", "aslice", "hslice", "padsv",
       "padav", "padhv");
$priv{$_}{64} = "REFC" for ("leave", "leavesub", "leavesublv", "leavewrite");
$priv{"aassign"}{64} = "COMMON";
$priv{"sassign"}{64} = "BKWARD";
$priv{$_}{64} = "RTIME" for ("match", "subst", "substcont");
@{$priv{"trans"}}{1,2,4,8,16,64} = ("<UTF", ">UTF", "IDENT", "SQUASH", "DEL",
				    "COMPL", "GROWS");
$priv{"repeat"}{64} = "DOLIST";
$priv{"leaveloop"}{64} = "CONT";
@{$priv{$_}}{32,64,96} = ("DREFAV", "DREFHV", "DREFSV")
  for ("entersub", map("rv2${_}v", "a", "s", "h", "g"), "aelem", "helem");
$priv{"entersub"}{16} = "DBG";
$priv{"entersub"}{32} = "TARG";
@{$priv{$_}}{4,8,128} = ("INARGS","AMPER","NO()") for ("entersub", "rv2cv");
$priv{"gv"}{32} = "EARLYCV";
$priv{"aelem"}{16} = $priv{"helem"}{16} = "LVDEFER";
$priv{$_}{16} = "OURINTR" for ("gvsv", "rv2sv", "rv2av", "rv2hv", "r2gv");
$priv{$_}{16} = "TARGMY"
  for (map(($_,"s$_"),"chop", "chomp"),
       map(($_,"i_$_"), "postinc", "postdec", "multiply", "divide", "modulo",
	   "add", "subtract", "negate"), "pow", "concat", "stringify",
       "left_shift", "right_shift", "bit_and", "bit_xor", "bit_or",
       "complement", "atan2", "sin", "cos", "rand", "exp", "log", "sqrt",
       "int", "hex", "oct", "abs", "length", "index", "rindex", "sprintf",
       "ord", "chr", "crypt", "quotemeta", "join", "push", "unshift", "flock",
       "chdir", "chown", "chroot", "unlink", "chmod", "utime", "rename",
       "link", "symlink", "mkdir", "rmdir", "wait", "waitpid", "system",
       "exec", "kill", "getppid", "getpgrp", "setpgrp", "getpriority",
       "setpriority", "time", "sleep");
@{$priv{"const"}}{8,16,32,64,128} = ("STRICT","ENTERED", '$[', "BARE", "WARN");
$priv{"flip"}{64} = $priv{"flop"}{64} = "LINENUM";
$priv{"list"}{64} = "GUESSED";
$priv{"delete"}{64} = "SLICE";
$priv{"exists"}{64} = "SUB";
$priv{$_}{64} = "LOCALE"
  for ("sort", "prtf", "sprintf", "slt", "sle", "seq", "sne", "sgt", "sge",
       "scmp", "lc", "uc", "lcfirst", "ucfirst");
@{$priv{"sort"}}{1,2,4} = ("NUM", "INT", "REV");
$priv{"threadsv"}{64} = "SVREFd";
@{$priv{$_}}{16,32,64,128} = ("INBIN","INCR","OUTBIN","OUTCR")
  for ("open", "backtick");
$priv{"exit"}{128} = "VMS";

sub private_flags {
    my($name, $x) = @_;
    my @s;
    for my $flag (128, 96, 64, 32, 16, 8, 4, 2, 1) {
	if ($priv{$name}{$flag} and $x & $flag and $x >= $flag) {
	    $x -= $flag;
	    push @s, $priv{$name}{$flag};
	}
    }
    push @s, $x if $x;
    return join(",", @s);
}

sub concise_sv {
    my($sv, $hr) = @_;
    $hr->{svclass} = class($sv);
    $hr->{svclass} = "UV"
      if $hr->{svclass} eq "IV" and $sv->FLAGS & SVf_IVisUV;
    $hr->{svaddr} = sprintf("%#x", $$sv);
    if ($hr->{svclass} eq "GV") {
	my $gv = $sv;
	my $stash = $gv->STASH->NAME;
	if ($stash eq "main") {
	    $stash = "";
	} else {
	    $stash = $stash . "::";
	}
	$hr->{svval} = "*$stash" . $gv->SAFENAME;
	return "*$stash" . $gv->SAFENAME;
    } else {
	while (class($sv) eq "RV") {
	    $hr->{svval} .= "\\";
	    $sv = $sv->RV;
	}
	if (class($sv) eq "SPECIAL") {
	    $hr->{svval} .= ["Null", "sv_undef", "sv_yes", "sv_no"]->[$$sv];
	} elsif ($sv->FLAGS & SVf_NOK) {
	    $hr->{svval} .= $sv->NV;
	} elsif ($sv->FLAGS & SVf_IOK) {
	    $hr->{svval} .= $sv->int_value;
	} elsif ($sv->FLAGS & SVf_POK) {
	    $hr->{svval} .= cstring($sv->PV);
	} elsif (class($sv) eq "HV") {
	    $hr->{svval} .= 'HASH';
	}
	return $hr->{svclass} . " " .  $hr->{svval};
    }
}

sub concise_op {
    my ($op, $level, $format) = @_;
    my %h;
    $h{exname} = $h{name} = $op->name;
    $h{NAME} = uc $h{name};
    $h{class} = class($op);
    $h{extarg} = $h{targ} = $op->targ;
    $h{extarg} = "" unless $h{extarg};
    if ($h{name} eq "null" and $h{targ}) {
	$h{exname} = "ex-" . substr(ppname($h{targ}), 3);
	$h{extarg} = "";
    } elsif ($h{targ}) {
	my $padname = (($curcv->PADLIST->ARRAY)[0]->ARRAY)[$h{targ}];
	if (defined $padname and class($padname) ne "SPECIAL") {
	    $h{targarg}  = $padname->PVX;
	    my $intro = $padname->NVX - $cop_seq_base;
	    my $finish = int($padname->IVX) - $cop_seq_base;
	    $finish = "end" if $finish == 999999999 - $cop_seq_base;
	    $h{targarglife} = "$h{targarg}:$intro,$finish";
	} else {
	    $h{targarglife} = $h{targarg} = "t" . $h{targ};
	}
    }
    $h{arg} = "";
    $h{svclass} = $h{svaddr} = $h{svval} = "";
    if ($h{class} eq "PMOP") {
	my $precomp = $op->precomp;
	if (defined $precomp) {
	    $precomp = cstring($precomp); # Escape literal control sequences
 	    $precomp = "/$precomp/";
	} else {
	    $precomp = "";
	}
	my $pmreplroot = $op->pmreplroot;
	my $pmreplstart;
	if ($pmreplroot && $$pmreplroot && $pmreplroot->isa("B::GV")) {
	    # with C<@stash_array = split(/pat/, str);>,
	    #  *stash_array is stored in pmreplroot.
	    $h{arg} = "($precomp => \@" . $pmreplroot->NAME . ")";
	} elsif ($ {$op->pmreplstart}) {
	    undef $lastnext;
	    $pmreplstart = "replstart->" . seq($op->pmreplstart);
	    $h{arg} = "(" . join(" ", $precomp, $pmreplstart) . ")";
	} else {
	    $h{arg} = "($precomp)";
	}
    } elsif ($h{class} eq "PVOP" and $h{name} ne "trans") {
	$h{arg} = '("' . $op->pv . '")';
	$h{svval} = '"' . $op->pv . '"';
    } elsif ($h{class} eq "COP") {
	my $label = $op->label;
	$h{coplabel} = $label;
	$label = $label ? "$label: " : "";
	my $loc = $op->file;
	$loc =~ s[.*/][];
	$loc .= ":" . $op->line;
	my($stash, $cseq) = ($op->stash->NAME, $op->cop_seq - $cop_seq_base);
	my $arybase = $op->arybase;
	$arybase = $arybase ? ' $[=' . $arybase : "";
	$h{arg} = "($label$stash $cseq $loc$arybase)";
    } elsif ($h{class} eq "LOOP") {
	$h{arg} = "(next->" . seq($op->nextop) . " last->" . seq($op->lastop)
	  . " redo->" . seq($op->redoop) . ")";
    } elsif ($h{class} eq "LOGOP") {
	undef $lastnext;
	$h{arg} = "(other->" . seq($op->other) . ")";
    } elsif ($h{class} eq "SVOP") {
	if (! ${$op->sv}) {
	    my $sv = (($curcv->PADLIST->ARRAY)[1]->ARRAY)[$op->targ];
	    $h{arg} = "[" . concise_sv($sv, \%h) . "]";
	    $h{targarglife} = $h{targarg} = "";
	} else {
	    $h{arg} = "(" . concise_sv($op->sv, \%h) . ")";
	}
    } elsif ($h{class} eq "PADOP") {
	my $sv = (($curcv->PADLIST->ARRAY)[1]->ARRAY)[$op->padix];
	$h{arg} = "[" . concise_sv($sv, \%h) . "]";
    }
    $h{seq} = $h{hyphseq} = seq($op);
    $h{seq} = "" if $h{seq} eq "-";
    $h{seqnum} = $op->seq;
    $h{next} = $op->next;
    $h{next} = (class($h{next}) eq "NULL") ? "(end)" : seq($h{next});
    $h{nextaddr} = sprintf("%#x", $ {$op->next});
    $h{sibaddr} = sprintf("%#x", $ {$op->sibling});
    $h{firstaddr} = sprintf("%#x", $ {$op->first}) if $op->can("first");
    $h{lastaddr} = sprintf("%#x", $ {$op->last}) if $op->can("last");

    $h{classsym} = $opclass{$h{class}};
    $h{flagval} = $op->flags;
    $h{flags} = op_flags($op->flags);
    $h{privval} = $op->private;
    $h{private} = private_flags($h{name}, $op->private);
    $h{addr} = sprintf("%#x", $$op);
    $h{label} = $labels{$op->seq};
    $h{typenum} = $op->type;
    $h{noise} = $linenoise[$op->type];
    $_->(\%h, $op, \$format, \$level) for @callbacks;
    return fmt_line(\%h, $format, $level);
}

sub B::OP::concise {
    my($op, $level) = @_;
    if ($order eq "exec" and $lastnext and $$lastnext != $$op) {
	my $h = {"seq" => seq($lastnext), "class" => class($lastnext),
		 "addr" => sprintf("%#x", $$lastnext)};
	print fmt_line($h, $gotofmt, $level+1);
    }
    $lastnext = $op->next;
    print concise_op($op, $level, $format);
}

# B::OP::terse (see Terse.pm) now just calls this
sub b_terse {
    my($op, $level) = @_;

    # This isn't necessarily right, but there's no easy way to get
    # from an OP to the right CV. This is a limitation of the
    # ->terse() interface style, and there isn't much to do about
    # it. In particular, we can die in concise_op if the main pad
    # isn't long enough, or has the wrong kind of entries, compared to
    # the pad a sub was compiled with. The fix for that would be to
    # make a backwards compatible "terse" format that never even
    # looked at the pad, just like the old B::Terse. I don't think
    # that's worth the effort, though.
    $curcv = main_cv unless $curcv;

    if ($order eq "exec" and $lastnext and $$lastnext != $$op) {
	my $h = {"seq" => seq($lastnext), "class" => class($lastnext),
		 "addr" => sprintf("%#x", $$lastnext)};
	print fmt_line($h, $style{"terse"}[1], $level+1);
    }
    $lastnext = $op->next;
    print concise_op($op, $level, $style{"terse"}[0]);
}

sub tree {
    my $op = shift;
    my $level = shift;
    my $style = $tree_decorations[$tree_style];
    my($space, $single, $kids, $kid, $nokid, $last, $lead, $size) = @$style;
    my $name = concise_op($op, $level, $treefmt);
    if (not $op->flags & OPf_KIDS) {
	return $name . "\n";
    }
    my @lines;
    for (my $kid = $op->first; $$kid; $kid = $kid->sibling) {
	push @lines, tree($kid, $level+1);
    }
    my $i;
    for ($i = $#lines; substr($lines[$i], 0, 1) eq " "; $i--) {
	$lines[$i] = $space . $lines[$i];
    }
    if ($i > 0) {
	$lines[$i] = $last . $lines[$i];
	while ($i-- > 1) {
	    if (substr($lines[$i], 0, 1) eq " ") {
		$lines[$i] = $nokid . $lines[$i];
	    } else {
		$lines[$i] = $kid . $lines[$i];		
	    }
	}
	$lines[$i] = $kids . $lines[$i];
    } else {
	$lines[0] = $single . $lines[0];
    }
    return("$name$lead" . shift @lines,
           map(" " x (length($name)+$size) . $_, @lines));
}

# *** Warning: fragile kludge ahead ***
# Because the B::* modules run in the same interpreter as the code
# they're compiling, their presence tends to distort the view we have
# of the code we're looking at. In particular, perl gives sequence
# numbers to both OPs in general and COPs in particular. If the
# program we're looking at were run on its own, these numbers would
# start at 1. Because all of B::Concise and all the modules it uses
# are compiled first, though, by the time we get to the user's program
# the sequence numbers are alreay at pretty high numbers, which would
# be distracting if you're trying to tell OPs apart. Therefore we'd
# like to subtract an offset from all the sequence numbers we display,
# to restore the simpler view of the world. The trick is to know what
# that offset will be, when we're still compiling B::Concise!  If we
# hardcoded a value, it would have to change every time B::Concise or
# other modules we use do. To help a little, what we do here is
# compile a little code at the end of the module, and compute the base
# sequence number for the user's program as being a small offset
# later, so all we have to worry about are changes in the offset.
# (Note that we now only play this game with COP sequence numbers. OP
# sequence numbers aren't used to refer to OPs from a distance, and
# they don't have much significance, so we just generate our own
# sequence numbers which are easier to control. This way we also don't
# stand in the way of a possible future removal of OP sequence
# numbers).

# When you say "perl -MO=Concise -e '$a'", the output should look like:

# 4  <@> leave[t1] vKP/REFC ->(end)
# 1     <0> enter ->2
 #^ smallest OP sequence number should be 1
# 2     <;> nextstate(main 1 -e:1) v ->3
 #                         ^ smallest COP sequence number should be 1
# -     <1> ex-rv2sv vK/1 ->4
# 3        <$> gvsv(*a) s ->4

# If the second of the marked numbers there isn't 1, it means you need
# to update the corresponding magic number in the next line.
# Remember, this needs to stay the last things in the module.

# Why is this different for MacOS?  Does it matter?
my $cop_seq_mnum = $^O eq 'MacOS' ? 10 : 9;
$cop_seq_base = svref_2object(eval 'sub{0;}')->START->cop_seq + $cop_seq_mnum;

1;

__END__

=head1 NAME

B::Concise - Walk Perl syntax tree, printing concise info about ops

=head1 SYNOPSIS

    perl -MO=Concise[,OPTIONS] foo.pl

    use B::Concise qw(set_style add_callback);

=head1 DESCRIPTION

This compiler backend prints the internal OPs of a Perl program's syntax
tree in one of several space-efficient text formats suitable for debugging
the inner workings of perl or other compiler backends. It can print OPs in
the order they appear in the OP tree, in the order they will execute, or
in a text approximation to their tree structure, and the format of the
information displyed is customizable. Its function is similar to that of
perl's B<-Dx> debugging flag or the B<B::Terse> module, but it is more
sophisticated and flexible.

=head1 EXAMPLE

Here's is a short example of output, using the default formatting
conventions :

    % perl -MO=Concise -e '$a = $b + 42'
    8  <@> leave[t1] vKP/REFC ->(end)
    1     <0> enter ->2
    2     <;> nextstate(main 1 -e:1) v ->3
    7     <2> sassign vKS/2 ->8
    5        <2> add[t1] sK/2 ->6
    -           <1> ex-rv2sv sK/1 ->4
    3              <$> gvsv(*b) s ->4
    4           <$> const(IV 42) s ->5
    -        <1> ex-rv2sv sKRM*/1 ->7
    6           <$> gvsv(*a) s ->7

Each line corresponds to an operator. Null ops appear as C<ex-opname>,
where I<opname> is the op that has been optimized away by perl.

The number on the first row indicates the op's sequence number. It's
given in base 36 by default.

The symbol between angle brackets indicates the op's type : for example,
<2> is a BINOP, <@> a LISTOP, etc. (see L</"OP class abbreviations">).

The opname may be followed by op-specific information in parentheses
(e.g. C<gvsv(*b)>), and by targ information in brackets (e.g.
C<leave[t1]>).

Next come the op flags. The common flags are listed below
(L</"OP flags abbreviations">). The private flags follow, separated
by a slash. For example, C<vKP/REFC> means that the leave op has
public flags OPf_WANT_VOID, OPf_KIDS, and OPf_PARENS, and the private
flag OPpREFCOUNTED.

Finally an arrow points to the sequence number of the next op.

=head1 OPTIONS

Arguments that don't start with a hyphen are taken to be the names of
subroutines to print the OPs of; if no such functions are specified, the
main body of the program (outside any subroutines, and not including use'd
or require'd files) is printed.

=over 4

=item B<-basic>

Print OPs in the order they appear in the OP tree (a preorder
traversal, starting at the root). The indentation of each OP shows its
level in the tree.  This mode is the default, so the flag is included
simply for completeness.

=item B<-exec>

Print OPs in the order they would normally execute (for the majority
of constructs this is a postorder traversal of the tree, ending at the
root). In most cases the OP that usually follows a given OP will
appear directly below it; alternate paths are shown by indentation. In
cases like loops when control jumps out of a linear path, a 'goto'
line is generated.

=item B<-tree>

Print OPs in a text approximation of a tree, with the root of the tree
at the left and 'left-to-right' order of children transformed into
'top-to-bottom'. Because this mode grows both to the right and down,
it isn't suitable for large programs (unless you have a very wide
terminal).

=item B<-compact>

Use a tree format in which the minimum amount of space is used for the
lines connecting nodes (one character in most cases). This squeezes out
a few precious columns of screen real estate.

=item B<-loose>

Use a tree format that uses longer edges to separate OP nodes. This format
tends to look better than the compact one, especially in ASCII, and is
the default.

=item B<-vt>

Use tree connecting characters drawn from the VT100 line-drawing set.
This looks better if your terminal supports it.

=item B<-ascii>

Draw the tree with standard ASCII characters like C<+> and C<|>. These don't
look as clean as the VT100 characters, but they'll work with almost any
terminal (or the horizontal scrolling mode of less(1)) and are suitable
for text documentation or email. This is the default.

=item B<-main>

Include the main program in the output, even if subroutines were also
specified.

=item B<-base>I<n>

Print OP sequence numbers in base I<n>. If I<n> is greater than 10, the
digit for 11 will be 'a', and so on. If I<n> is greater than 36, the digit
for 37 will be 'A', and so on until 62. Values greater than 62 are not
currently supported. The default is 36.

=item B<-bigendian>

Print sequence numbers with the most significant digit first. This is the
usual convention for Arabic numerals, and the default.

=item B<-littleendian>

Print seqence numbers with the least significant digit first.

=item B<-concise>

Use the author's favorite set of formatting conventions. This is the
default, of course.

=item B<-terse>

Use formatting conventions that emulate the ouput of B<B::Terse>. The
basic mode is almost indistinguishable from the real B<B::Terse>, and the
exec mode looks very similar, but is in a more logical order and lacks
curly brackets. B<B::Terse> doesn't have a tree mode, so the tree mode
is only vaguely reminiscient of B<B::Terse>.

=item B<-linenoise>

Use formatting conventions in which the name of each OP, rather than being
written out in full, is represented by a one- or two-character abbreviation.
This is mainly a joke.

=item B<-debug>

Use formatting conventions reminiscient of B<B::Debug>; these aren't
very concise at all.

=item B<-env>

Use formatting conventions read from the environment variables
C<B_CONCISE_FORMAT>, C<B_CONCISE_GOTO_FORMAT>, and C<B_CONCISE_TREE_FORMAT>.

=back

=head1 FORMATTING SPECIFICATIONS

For each general style ('concise', 'terse', 'linenoise', etc.) there are
three specifications: one of how OPs should appear in the basic or exec
modes, one of how 'goto' lines should appear (these occur in the exec
mode only), and one of how nodes should appear in tree mode. Each has the
same format, described below. Any text that doesn't match a special
pattern is copied verbatim.

=over 4

=item B<(x(>I<exec_text>B<;>I<basic_text>B<)x)>

Generates I<exec_text> in exec mode, or I<basic_text> in basic mode.

=item B<(*(>I<text>B<)*)>

Generates one copy of I<text> for each indentation level.

=item B<(*(>I<text1>B<;>I<text2>B<)*)>

Generates one fewer copies of I<text1> than the indentation level, followed
by one copy of I<text2> if the indentation level is more than 0.

=item B<(?(>I<text1>B<#>I<var>I<Text2>B<)?)>

If the value of I<var> is true (not empty or zero), generates the
value of I<var> surrounded by I<text1> and I<Text2>, otherwise
nothing.

=item B<#>I<var>

Generates the value of the variable I<var>.

=item B<#>I<var>I<N>

Generates the value of I<var>, left jutified to fill I<N> spaces.

=item B<~>

Any number of tildes and surrounding whitespace will be collapsed to
a single space.

=back

The following variables are recognized:

=over 4

=item B<#addr>

The address of the OP, in hexidecimal.

=item B<#arg>

The OP-specific information of the OP (such as the SV for an SVOP, the
non-local exit pointers for a LOOP, etc.) enclosed in paretheses.

=item B<#class>

The B-determined class of the OP, in all caps.

=item B<#classsym>

A single symbol abbreviating the class of the OP.

=item B<#coplabel>

The label of the statement or block the OP is the start of, if any.

=item B<#exname>

The name of the OP, or 'ex-foo' if the OP is a null that used to be a foo.

=item B<#extarg>

The target of the OP, or nothing for a nulled OP.

=item B<#firstaddr>

The address of the OP's first child, in hexidecimal.

=item B<#flags>

The OP's flags, abbreviated as a series of symbols.

=item B<#flagval>

The numeric value of the OP's flags.

=item B<#hyphseq>

The sequence number of the OP, or a hyphen if it doesn't have one.

=item B<#label>

'NEXT', 'LAST', or 'REDO' if the OP is a target of one of those in exec
mode, or empty otherwise.

=item B<#lastaddr>

The address of the OP's last child, in hexidecimal.

=item B<#name>

The OP's name.

=item B<#NAME>

The OP's name, in all caps.

=item B<#next>

The sequence number of the OP's next OP.

=item B<#nextaddr>

The address of the OP's next OP, in hexidecimal.

=item B<#noise>

A one- or two-character abbreviation for the OP's name.

=item B<#private>

The OP's private flags, rendered with abbreviated names if possible.

=item B<#privval>

The numeric value of the OP's private flags.

=item B<#seq>

The sequence number of the OP. Note that this is now a sequence number
generated by B::Concise, rather than the real op_seq value (for which
see B<#seqnum>).

=item B<#seqnum>

The real sequence number of the OP, as a regular number and not adjusted
to be relative to the start of the real program. (This will generally be
a fairly large number because all of B<B::Concise> is compiled before
your program is).

=item B<#sibaddr>

The address of the OP's next youngest sibling, in hexidecimal.

=item B<#svaddr>

The address of the OP's SV, if it has an SV, in hexidecimal.

=item B<#svclass>

The class of the OP's SV, if it has one, in all caps (e.g., 'IV').

=item B<#svval>

The value of the OP's SV, if it has one, in a short human-readable format.

=item B<#targ>

The numeric value of the OP's targ.

=item B<#targarg>

The name of the variable the OP's targ refers to, if any, otherwise the
letter t followed by the OP's targ in decimal.

=item B<#targarglife>

Same as B<#targarg>, but followed by the COP sequence numbers that delimit
the variable's lifetime (or 'end' for a variable in an open scope) for a
variable.

=item B<#typenum>

The numeric value of the OP's type, in decimal.

=back

=head1 ABBREVIATIONS

=head2 OP flags abbreviations

    v      OPf_WANT_VOID    Want nothing (void context)
    s      OPf_WANT_SCALAR  Want single value (scalar context)
    l      OPf_WANT_LIST    Want list of any length (list context)
    K      OPf_KIDS         There is a firstborn child.
    P      OPf_PARENS       This operator was parenthesized.
                             (Or block needs explicit scope entry.)
    R      OPf_REF          Certified reference.
                             (Return container, not containee).
    M      OPf_MOD          Will modify (lvalue).
    S      OPf_STACKED      Some arg is arriving on the stack.
    *      OPf_SPECIAL      Do something weird for this op (see op.h)

=head2 OP class abbreviations

    0      OP (aka BASEOP)  An OP with no children
    1      UNOP             An OP with one child
    2      BINOP            An OP with two children
    |      LOGOP            A control branch OP
    @      LISTOP           An OP that could have lots of children
    /      PMOP             An OP with a regular expression
    $      SVOP             An OP with an SV
    "      PVOP             An OP with a string
    {      LOOP             An OP that holds pointers for a loop
    ;      COP              An OP that marks the start of a statement
    #      PADOP            An OP with a GV on the pad

=head1 Using B::Concise outside of the O framework

It is possible to extend B<B::Concise> by using it outside of the B<O>
framework and providing new styles and new variables.

    use B::Concise qw(set_style add_callback);
    set_style($format, $gotofmt, $treefmt);
    add_callback
    (
        sub
        {
            my ($h, $op, $level, $format) = @_;
            $h->{variable} = some_func($op);
        }
    );
    B::Concise::compile(@options)->();

You can specify a style by calling the B<set_style> subroutine.  If you
have a new variable in your style, or you want to change the value of an
existing variable, you will need to add a callback to specify the value
for that variable.

This is done by calling B<add_callback> passing references to any
callback subroutines.  The subroutines are called in the same order as
they are added.  Each subroutine is passed four parameters.  These are a
reference to a hash, the keys of which are the names of the variables
and the values of which are their values, the op, the level and the
format.

To define your own variables, simply add them to the hash, or change
existing values if you need to.  The level and format are passed in as
references to scalars, but it is unlikely that they will need to be
changed or even used.

To switch back to one of the standard styles like C<concise> or
C<terse>, use C<set_style_standard>.

To see the output, call the subroutine returned by B<compile> in the
same way that B<O> does.

=head1 AUTHOR

Stephen McCamant, E<lt>smcc@CSUA.Berkeley.EDUE<gt>.

=cut