--- /dev/null
+package B::Concise;
+# Copyright (C) 2000, 2001 Stephen McCamant. All rights reserved.
+# This program is free software; you can redistribute and/or modify it
+# under the same terms as Perl itself.
+
+our $VERSION = "0.50";
+use strict;
+use B qw(class ppname main_start main_root main_cv cstring svref_2object
+ SVf_IOK SVf_NOK SVf_POK OPf_KIDS);
+
+my %style =
+ ("terse" =>
+ ["(?(#label =>\n)?)(*( )*)#class (#addr) pp_#name "
+ . "(?([#targ])?) #svclass~(?((#svaddr))?)~#svval\n",
+ "(*( )*)goto #class (#addr)\n",
+ "#class pp_#name"],
+ "concise" =>
+ ["#hyphseq2 (*( (x( ;)x))*)<#classsym> "
+ . "#exname#arg(?([#targarglife])?)~#flags(?(/#private)?)(x(;~->#next)x)\n",
+ " (*( )*) goto #seq\n",
+ "(?(<#seq>)?)#exname#arg(?([#targarglife])?)"],
+ "linenoise" =>
+ ["(x(;(*( )*))x)#noise#arg(?([#targarg])?)(x( ;\n)x)",
+ "gt_#seq ",
+ "(?(#seq)?)#noise#arg(?([#targarg])?)"],
+ "debug" =>
+ ["#class (#addr)\n\top_next\t\t#nextaddr\n\top_sibling\t#sibaddr\n\t"
+ . "op_ppaddr\tPL_ppaddr[OP_#NAME]\n\top_type\t\t#typenum\n\top_seq\t\t"
+ . "#seqnum\n\top_flags\t#flagval\n\top_private\t#privval\n"
+ . "(?(\top_first\t#firstaddr\n)?)(?(\top_last\t\t#lastaddr\n)?)"
+ . "(?(\top_sv\t\t#svaddr\n)?)",
+ " GOTO #addr\n",
+ "#addr"],
+ "env" => [$ENV{B_CONCISE_FORMAT}, $ENV{B_CONCISE_GOTO_FORMAT},
+ $ENV{B_CONCISE_TREE_FORMAT}],
+ );
+
+my($format, $gotofmt, $treefmt);
+my $curcv;
+my($seq_base, $cop_seq_base);
+
+sub concise_cv {
+ my ($order, $cvref) = @_;
+ my $cv = svref_2object($cvref);
+ $curcv = $cv;
+ if ($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)
+ }
+}
+
+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";
+
+sub compile {
+ my @options = grep(/^-/, @_);
+ my @args = grep(!/^-/, @_);
+ my $do_main = 0;
+ ($format, $gotofmt, $treefmt) = @{$style{"concise"}};
+ 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)}) {
+ ($format, $gotofmt, $treefmt) = @{$style{substr($o, 1)}};
+ } else {
+ warn "Option $o unrecognized";
+ }
+ }
+ if (@args) {
+ return sub {
+ for my $objname (@args) {
+ $objname = "main::" . $objname unless $objname =~ /::/;
+ eval "concise_cv(\$order, \\&$objname)";
+ die "concise_cv($order, \\&$objname) failed: $@" if $@;
+ }
+ }
+ }
+ if (!@args or $do_main) {
+ if ($order eq "exec") {
+ return sub { return if class(main_start) eq "NULL";
+ $curcv = main_cv;
+ walk_exec(main_start) }
+ } elsif ($order eq "tree") {
+ return sub { return if class(main_root) eq "NULL";
+ $curcv = main_cv;
+ print tree(main_root, 0) }
+ } elsif ($order eq "basic") {
+ return sub { return if class(main_root) eq "NULL";
+ $curcv = main_cv;
+ walk_topdown(main_root,
+ sub { $_[0]->concise($_[1]) }, 0); }
+ }
+ }
+}
+
+my %labels;
+my $lastnext;
+
+my %opclass = ('OP' => "0", 'UNOP' => "1", 'BINOP' => "2", 'LOGOP' => "|",
+ 'LISTOP' => "@", 'PMOP' => "/", 'SVOP' => "\$", 'GVOP' => "*",
+ 'PVOP' => '"', 'LOOP' => "{", 'COP' => ";");
+
+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>';
+
+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;
+}
+
+sub seq { return $_[0]->seq ? base_n($_[0]->seq - $seq_base) : "-" }
+
+sub walk_topdown {
+ my($op, $sub, $level) = @_;
+ $sub->($op, $level);
+ if ($op->flags & OPf_KIDS) {
+ for (my $kid = $op->first; $$kid; $kid = $kid->sibling) {
+ walk_topdown($kid, $sub, $level + 1);
+ }
+ }
+ if (class($op) eq "PMOP" and $ {$op->pmreplroot}) {
+ walk_topdown($op->pmreplroot, $sub, $level + 1);
+ }
+}
+
+sub walklines {
+ my($ar, $level) = @_;
+ for my $l (@$ar) {
+ if (ref($l) eq "ARRAY") {
+ walklines($l, $level + 1);
+ } else {
+ $l->concise($level);
+ }
+ }
+}
+
+sub walk_exec {
+ my($top, $level) = @_;
+ my %opsseen;
+ my @lines;
+ my @todo = ([$top, \@lines]);
+ while (@todo and my($op, $targ) = @{shift @todo}) {
+ for (; $$op; $op = $op->next) {
+ last if $opsseen{$$op}++;
+ push @$targ, $op;
+ my $name = $op->name;
+ if ($name
+ =~ /^(or|and|(map|grep)while|entertry|range|cond_expr)$/) {
+ 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);
+}
+
+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";
+$priv{"aassign"}{32} = "PHASH";
+$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} = "INBIN" for ("open", "backtick");
+$priv{$_}{32} = "INCR" for ("open", "backtick");
+$priv{$_}{64} = "OUTBIN" for ("open", "backtick");
+$priv{$_}{128} = "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 $x;
+ return join(",", @s);
+}
+
+sub concise_op {
+ my ($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->PV;
+ 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;
+ $precomp = defined($precomp) ? "/$precomp/" : "";
+ my $pmreplstart;
+ if ($ {$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;
+ $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") {
+ my $sv = $op->sv;
+ $h{svclass} = class($sv);
+ $h{svaddr} = sprintf("%#x", $$sv);
+ if ($h{svclass} eq "GV") {
+ my $gv = $sv;
+ my $stash = $gv->STASH->NAME;
+ if ($stash eq "main") {
+ $stash = "";
+ } else {
+ $stash = $stash . "::";
+ }
+ $h{arg} = "(*$stash" . $gv->NAME . ")";
+ $h{svval} = "*$stash" . $gv->NAME;
+ } else {
+ while (class($sv) eq "RV") {
+ $h{svval} .= "\\";
+ $sv = $sv->RV;
+ }
+ if (class($sv) eq "SPECIAL") {
+ $h{svval} = ["Null", "sv_undef", "sv_yes", "sv_no"]->[$$sv];
+ } elsif ($sv->FLAGS & SVf_NOK) {
+ $h{svval} = $sv->NV;
+ } elsif ($sv->FLAGS & SVf_IOK) {
+ $h{svval} = $sv->IV;
+ } elsif ($sv->FLAGS & SVf_POK) {
+ $h{svval} = cstring($sv->PV);
+ }
+ $h{arg} = "($h{svclass} $h{svval})";
+ }
+ }
+ $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", $$op);
+ $h{label} = $labels{$op->seq};
+ $h{typenum} = $op->type;
+ $h{noise} = $linenoise[$op->type];
+ return fmt_line(\%h, $format, $level);
+}
+
+sub B::OP::concise {
+ my($op, $level) = @_;
+ if ($order eq "exec" and $lastnext and $$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);
+}
+
+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) . $_, @lines));
+}
+
+# This is a bit of a hack; the 2 and 15 were determined empirically.
+# These need to stay the last things in the module.
+$cop_seq_base = svref_2object(eval 'sub{0;}')->START->cop_seq + 2;
+$seq_base = svref_2object(eval 'sub{}')->START->seq + 15;
+
+1;
+
+__END__
+
+=head1 NAME
+
+B::Concise - Walk Perl syntax tree, printing concise info about ops
+
+=head1 SYNOPSIS
+
+ perl -MO=Concise[,OPTIONS] foo.pl
+
+=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 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<#classym>
+
+A single symbol abbreviating the class of the OP.
+
+=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<#hyphenseq>
+
+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>
+
+The 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.
+
+=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
+
+=head1 AUTHOR
+
+Stephen McCamant, C<smcc@CSUA.Berkeley.EDU>
+
+=cut