[perl5.git] / lib / DB.pm

#
# Documentation is at the __END__
#

package DB;

# "private" globals

my ($running, $ready, $deep, $usrctxt, $evalarg, 
    @stack, @saved, @skippkg, @clients);
my $preeval = {};
my $posteval = {};
my $ineval = {};

####
#
# Globals - must be defined at startup so that clients can refer to 
# them right after a C<require DB;>
#
####

BEGIN {

  # these are hardcoded in perl source (some are magical)

  $DB::sub = '';        # name of current subroutine
  %DB::sub = ();        # "filename:fromline-toline" for every known sub
  $DB::single = 0;      # single-step flag (set it to 1 to enable stops in BEGIN/use)
  $DB::signal = 0;      # signal flag (will cause a stop at the next line)
  $DB::trace = 0;       # are we tracing through subroutine calls?
  @DB::args = ();       # arguments of current subroutine or @ARGV array
  @DB::dbline = ();     # list of lines in currently loaded file
  %DB::dbline = ();     # actions in current file (keyed by line number)
  @DB::ret = ();        # return value of last sub executed in list context
  $DB::ret = '';        # return value of last sub executed in scalar context

  # other "public" globals  

  $DB::package = '';    # current package space
  $DB::filename = '';   # current filename
  $DB::subname = '';    # currently executing sub (fullly qualified name)
  $DB::lineno = '';     # current line number

  $DB::VERSION = $DB::VERSION = '1.02';

  # initialize private globals to avoid warnings

  $running = 1;         # are we running, or are we stopped?
  @stack = (0);
  @clients = ();
  $deep = 100;
  $ready = 0;
  @saved = ();
  @skippkg = ();
  $usrctxt = '';
  $evalarg = '';
}

####
# entry point for all subroutine calls
#
sub sub {
  push(@stack, $DB::single);
  $DB::single &= 1;
  $DB::single |= 4 if $#stack == $deep;
  if ($DB::sub eq 'DESTROY' or substr($DB::sub, -9) eq '::DESTROY' or not defined wantarray) {
    &$DB::sub;
    $DB::single |= pop(@stack);
    $DB::ret = undef;
  }
  elsif (wantarray) {
    @DB::ret = &$DB::sub;
    $DB::single |= pop(@stack);
    @DB::ret;
  }
  else {
    $DB::ret = &$DB::sub;
    $DB::single |= pop(@stack);
    $DB::ret;
  }
}

####
# this is called by perl for every statement
#
sub DB {
  return unless $ready;
  &save;
  ($DB::package, $DB::filename, $DB::lineno) = caller;

  return if @skippkg and grep { $_ eq $DB::package } @skippkg;

  $usrctxt = "package $DB::package;";		# this won't let them modify, alas
  local(*DB::dbline) = "::_<$DB::filename";

  # we need to check for pseudofiles on Mac OS (these are files
  # not attached to a filename, but instead stored in Dev:Pseudo)
  # since this is done late, $DB::filename will be "wrong" after
  # skippkg
  if ($^O eq 'MacOS' && $#DB::dbline < 0) {
    $DB::filename = 'Dev:Pseudo';
    *DB::dbline = "::_<$DB::filename";
  }

  my ($stop, $action);
  if (($stop,$action) = split(/\0/,$DB::dbline{$DB::lineno})) {
    if ($stop eq '1') {
      $DB::signal |= 1;
    }
    else {
      $stop = 0 unless $stop;			# avoid un_init warning
      $evalarg = "\$DB::signal |= do { $stop; }"; &eval;
      $DB::dbline{$DB::lineno} =~ s/;9($|\0)/$1/;    # clear any temp breakpt
    }
  }
  if ($DB::single || $DB::trace || $DB::signal) {
    $DB::subname = ($DB::sub =~ /\'|::/) ? $DB::sub : "${DB::package}::$DB::sub"; #';
    DB->loadfile($DB::filename, $DB::lineno);
  }
  $evalarg = $action, &eval if $action;
  if ($DB::single || $DB::signal) {
    _outputall($#stack . " levels deep in subroutine calls.\n") if $DB::single & 4;
    $DB::single = 0;
    $DB::signal = 0;
    $running = 0;
    
    &eval if ($evalarg = DB->prestop);
    my $c;
    for $c (@clients) {
      # perform any client-specific prestop actions
      &eval if ($evalarg = $c->cprestop);
      
      # Now sit in an event loop until something sets $running
      do {
	$c->idle;                     # call client event loop; must not block
	if ($running == 2) {          # client wants something eval-ed
	  &eval if ($evalarg = $c->evalcode);
	  $running = 0;
	}
      } until $running;
      
      # perform any client-specific poststop actions
      &eval if ($evalarg = $c->cpoststop);
    }
    &eval if ($evalarg = DB->poststop);
  }
  ($@, $!, $,, $/, $\, $^W) = @saved;
  ();
}
  
####
# this takes its argument via $evalarg to preserve current @_
#    
sub eval {
  ($@, $!, $,, $/, $\, $^W) = @saved;
  eval "$usrctxt $evalarg; &DB::save";
  _outputall($@) if $@;
}

###############################################################################
#         no compile-time subroutine call allowed before this point           #
###############################################################################

use strict;                # this can run only after DB() and sub() are defined

sub save {
  @saved = ($@, $!, $,, $/, $\, $^W);
  $, = ""; $/ = "\n"; $\ = ""; $^W = 0;
}

sub catch {
  for (@clients) { $_->awaken; }
  $DB::signal = 1;
  $ready = 1;
}

####
#
# Client callable (read inheritable) methods defined after this point
#
####

sub register {
  my $s = shift;
  $s = _clientname($s) if ref($s);
  push @clients, $s;
}

sub done {
  my $s = shift;
  $s = _clientname($s) if ref($s);
  @clients = grep {$_ ne $s} @clients;
  $s->cleanup;
#  $running = 3 unless @clients;
  exit(0) unless @clients;
}

sub _clientname {
  my $name = shift;
  "$name" =~ /^(.+)=[A-Z]+\(.+\)$/;
  return $1;
}

sub next {
  my $s = shift;
  $DB::single = 2;
  $running = 1;
}

sub step {
  my $s = shift;
  $DB::single = 1;
  $running = 1;
}

sub cont {
  my $s = shift;
  my $i = shift;
  $s->set_tbreak($i) if $i;
  for ($i = 0; $i <= $#stack;) {
	$stack[$i++] &= ~1;
  }
  $DB::single = 0;
  $running = 1;
}

####
# XXX caller must experimentally determine $i (since it depends
# on how many client call frames are between this call and the DB call).
# Such is life.
#
sub ret {
  my $s = shift;
  my $i = shift;      # how many levels to get to DB sub
  $i = 0 unless defined $i;
  $stack[$#stack-$i] |= 1;
  $DB::single = 0;
  $running = 1;
}

####
# XXX caller must experimentally determine $start (since it depends
# on how many client call frames are between this call and the DB call).
# Such is life.
#
sub backtrace {
  my $self = shift;
  my $start = shift;
  my($p,$f,$l,$s,$h,$w,$e,$r,$a, @a, @ret,$i);
  $start = 1 unless $start;
  for ($i = $start; ($p,$f,$l,$s,$h,$w,$e,$r) = caller($i); $i++) {
    @a = @DB::args;
    for (@a) {
      s/'/\\'/g;
      s/([^\0]*)/'$1'/ unless /^-?[\d.]+$/;
      s/([\200-\377])/sprintf("M-%c",ord($1)&0177)/eg;
      s/([\0-\37\177])/sprintf("^%c",ord($1)^64)/eg;
    }
    $w = $w ? '@ = ' : '$ = ';
    $a = $h ? '(' . join(', ', @a) . ')' : '';
    $e =~ s/\n\s*\;\s*\Z// if $e;
    $e =~ s/[\\\']/\\$1/g if $e;
    if ($r) {
      $s = "require '$e'";
    } elsif (defined $r) {
      $s = "eval '$e'";
    } elsif ($s eq '(eval)') {
      $s = "eval {...}";
    }
    $f = "file `$f'" unless $f eq '-e';
    push @ret, "$w&$s$a from $f line $l";
    last if $DB::signal;
  }
  return @ret;
}

sub _outputall {
  my $c;
  for $c (@clients) {
    $c->output(@_);
  }
}

sub trace_toggle {
  my $s = shift;
  $DB::trace = !$DB::trace;
}


####
# without args: returns all defined subroutine names
# with subname args: returns a listref [file, start, end]
#
sub subs {
  my $s = shift;
  if (@_) {
    my(@ret) = ();
    while (@_) {
      my $name = shift;
      push @ret, [$DB::sub{$name} =~ /^(.*)\:(\d+)-(\d+)$/] 
	if exists $DB::sub{$name};
    }
    return @ret;
  }
  return keys %DB::sub;
}

####
# first argument is a filename whose subs will be returned
# if a filename is not supplied, all subs in the current
# filename are returned.
#
sub filesubs {
  my $s = shift;
  my $fname = shift;
  $fname = $DB::filename unless $fname;
  return grep { $DB::sub{$_} =~ /^$fname/ } keys %DB::sub;
}

####
# returns a list of all filenames that DB knows about
#
sub files {
  my $s = shift;
  my(@f) = grep(m|^_<|, keys %main::);
  return map { substr($_,2) } @f;
}

####
# returns reference to an array holding the lines in currently
# loaded file
#
sub lines {
  my $s = shift;
  return \@DB::dbline;
}

####
# loadfile($file, $line)
#
sub loadfile {
  my $s = shift;
  my($file, $line) = @_;
  if (!defined $main::{'_<' . $file}) {
    my $try;
    if (($try) = grep(m|^_<.*$file|, keys %main::)) {  
      $file = substr($try,2);
    }
  }
  if (defined($main::{'_<' . $file})) {
    my $c;
#    _outputall("Loading file $file..");
    *DB::dbline = "::_<$file";
    $DB::filename = $file;
    for $c (@clients) {
#      print "2 ", $file, '|', $line, "\n";
      $c->showfile($file, $line);
    }
    return $file;
  }
  return undef;
}

sub lineevents {
  my $s = shift;
  my $fname = shift;
  my(%ret) = ();
  my $i;
  $fname = $DB::filename unless $fname;
  local(*DB::dbline) = "::_<$fname";
  for ($i = 1; $i <= $#DB::dbline; $i++) {
    $ret{$i} = [$DB::dbline[$i], split(/\0/, $DB::dbline{$i})] 
      if defined $DB::dbline{$i};
  }
  return %ret;
}

sub set_break {
  my $s = shift;
  my $i = shift;
  my $cond = shift;
  $i ||= $DB::lineno;
  $cond ||= '1';
  $i = _find_subline($i) if ($i =~ /\D/);
  $s->output("Subroutine not found.\n") unless $i;
  if ($i) {
    if ($DB::dbline[$i] == 0) {
      $s->output("Line $i not breakable.\n");
    }
    else {
      $DB::dbline{$i} =~ s/^[^\0]*/$cond/;
    }
  }
}

sub set_tbreak {
  my $s = shift;
  my $i = shift;
  $i = _find_subline($i) if ($i =~ /\D/);
  $s->output("Subroutine not found.\n") unless $i;
  if ($i) {
    if ($DB::dbline[$i] == 0) {
      $s->output("Line $i not breakable.\n");
    }
    else {
      $DB::dbline{$i} =~ s/($|\0)/;9$1/; # add one-time-only b.p.
    }
  }
}

sub _find_subline {
  my $name = shift;
  $name =~ s/\'/::/;
  $name = "${DB::package}\:\:" . $name if $name !~ /::/;
  $name = "main" . $name if substr($name,0,2) eq "::";
  my($fname, $from, $to) = ($DB::sub{$name} =~ /^(.*):(\d+)-(\d+)$/);
  if ($from) {
    local *DB::dbline = "::_<$fname";
    ++$from while $DB::dbline[$from] == 0 && $from < $to;
    return $from;
  }
  return undef;
}

sub clr_breaks {
  my $s = shift;
  my $i;
  if (@_) {
    while (@_) {
      $i = shift;
      $i = _find_subline($i) if ($i =~ /\D/);
      $s->output("Subroutine not found.\n") unless $i;
      if (defined $DB::dbline{$i}) {
        $DB::dbline{$i} =~ s/^[^\0]+//;
        if ($DB::dbline{$i} =~ s/^\0?$//) {
          delete $DB::dbline{$i};
        }
      }
    }
  }
  else {
    for ($i = 1; $i <= $#DB::dbline ; $i++) {
      if (defined $DB::dbline{$i}) {
        $DB::dbline{$i} =~ s/^[^\0]+//;
        if ($DB::dbline{$i} =~ s/^\0?$//) {
          delete $DB::dbline{$i};
        }
      }
    }
  }
}

sub set_action {
  my $s = shift;
  my $i = shift;
  my $act = shift;
  $i = _find_subline($i) if ($i =~ /\D/);
  $s->output("Subroutine not found.\n") unless $i;
  if ($i) {
    if ($DB::dbline[$i] == 0) {
      $s->output("Line $i not actionable.\n");
    }
    else {
      $DB::dbline{$i} =~ s/\0[^\0]*//;
      $DB::dbline{$i} .= "\0" . $act;
    }
  }
}

sub clr_actions {
  my $s = shift;
  my $i;
  if (@_) {
    while (@_) {
      my $i = shift;
      $i = _find_subline($i) if ($i =~ /\D/);
      $s->output("Subroutine not found.\n") unless $i;
      if ($i && $DB::dbline[$i] != 0) {
	$DB::dbline{$i} =~ s/\0[^\0]*//;
	delete $DB::dbline{$i} if $DB::dbline{$i} =~ s/^\0?$//;
      }
    }
  }
  else {
    for ($i = 1; $i <= $#DB::dbline ; $i++) {
      if (defined $DB::dbline{$i}) {
	$DB::dbline{$i} =~ s/\0[^\0]*//;
	delete $DB::dbline{$i} if $DB::dbline{$i} =~ s/^\0?$//;
      }
    }
  }
}

sub prestop {
  my ($client, $val) = @_;
  return defined($val) ? $preeval->{$client} = $val : $preeval->{$client};
}

sub poststop {
  my ($client, $val) = @_;
  return defined($val) ? $posteval->{$client} = $val : $posteval->{$client};
}

#
# "pure virtual" methods
#

# client-specific pre/post-stop actions.
sub cprestop {}
sub cpoststop {}

# client complete startup
sub awaken {}

sub skippkg {
  my $s = shift;
  push @skippkg, @_ if @_;
}

sub evalcode {
  my ($client, $val) = @_;
  if (defined $val) {
    $running = 2;    # hand over to DB() to evaluate in its context
    $ineval->{$client} = $val;
  }
  return $ineval->{$client};
}

sub ready {
  my $s = shift;
  return $ready = 1;
}

# stubs
    
sub init {}
sub stop {}
sub idle {}
sub cleanup {}
sub output {}

#
# client init
#
for (@clients) { $_->init }

$SIG{'INT'} = \&DB::catch;

# disable this if stepping through END blocks is desired
# (looks scary and deconstructivist with Swat)
END { $ready = 0 }

1;
__END__

=head1 NAME

DB - programmatic interface to the Perl debugging API

=head1 SYNOPSIS

    package CLIENT;
    use DB;
    @ISA = qw(DB);

    # these (inherited) methods can be called by the client

    CLIENT->register()      # register a client package name
    CLIENT->done()          # de-register from the debugging API
    CLIENT->skippkg('hide::hide')  # ask DB not to stop in this package
    CLIENT->cont([WHERE])       # run some more (until BREAK or another breakpt)
    CLIENT->step()              # single step
    CLIENT->next()              # step over
    CLIENT->ret()               # return from current subroutine
    CLIENT->backtrace()         # return the call stack description
    CLIENT->ready()             # call when client setup is done
    CLIENT->trace_toggle()      # toggle subroutine call trace mode
    CLIENT->subs([SUBS])        # return subroutine information
    CLIENT->files()             # return list of all files known to DB
    CLIENT->lines()             # return lines in currently loaded file
    CLIENT->loadfile(FILE,LINE) # load a file and let other clients know
    CLIENT->lineevents()        # return info on lines with actions
    CLIENT->set_break([WHERE],[COND])
    CLIENT->set_tbreak([WHERE])
    CLIENT->clr_breaks([LIST])
    CLIENT->set_action(WHERE,ACTION)
    CLIENT->clr_actions([LIST])
    CLIENT->evalcode(STRING)  # eval STRING in executing code's context
    CLIENT->prestop([STRING]) # execute in code context before stopping
    CLIENT->poststop([STRING])# execute in code context before resuming

    # These methods will be called at the appropriate times.
    # Stub versions provided do nothing.
    # None of these can block.

    CLIENT->init()          # called when debug API inits itself
    CLIENT->stop(FILE,LINE) # when execution stops
    CLIENT->idle()          # while stopped (can be a client event loop)
    CLIENT->cleanup()       # just before exit
    CLIENT->output(LIST)    # called to print any output that API must show

=head1 DESCRIPTION

Perl debug information is frequently required not just by debuggers,
but also by modules that need some "special" information to do their
job properly, like profilers.

This module abstracts and provides all of the hooks into Perl internal
debugging functionality, so that various implementations of Perl debuggers
(or packages that want to simply get at the "privileged" debugging data)
can all benefit from the development of this common code.  Currently used
by Swat, the perl/Tk GUI debugger.

Note that multiple "front-ends" can latch into this debugging API
simultaneously.  This is intended to facilitate things like
debugging with a command line and GUI at the same time, debugging 
debuggers etc.  [Sounds nice, but this needs some serious support -- GSAR]

In particular, this API does B<not> provide the following functions:

=over 4

=item *

data display

=item *

command processing

=item *

command alias management

=item *

user interface (tty or graphical)

=back

These are intended to be services performed by the clients of this API.

This module attempts to be squeaky clean w.r.t C<use strict;> and when
warnings are enabled.


=head2 Global Variables

The following "public" global names can be read by clients of this API.
Beware that these should be considered "readonly".

=over 8

=item  $DB::sub

Name of current executing subroutine.

=item  %DB::sub

The keys of this hash are the names of all the known subroutines.  Each value
is an encoded string that has the sprintf(3) format 
C<("%s:%d-%d", filename, fromline, toline)>.

=item  $DB::single

Single-step flag.  Will be true if the API will stop at the next statement.

=item  $DB::signal

Signal flag. Will be set to a true value if a signal was caught.  Clients may
check for this flag to abort time-consuming operations.

=item  $DB::trace

This flag is set to true if the API is tracing through subroutine calls.

=item  @DB::args

Contains the arguments of current subroutine, or the C<@ARGV> array if in the 
toplevel context.

=item  @DB::dbline

List of lines in currently loaded file.

=item  %DB::dbline

Actions in current file (keys are line numbers).  The values are strings that
have the sprintf(3) format C<("%s\000%s", breakcondition, actioncode)>. 

=item  $DB::package

Package namespace of currently executing code.

=item  $DB::filename

Currently loaded filename.

=item  $DB::subname

Fully qualified name of currently executing subroutine.

=item  $DB::lineno

Line number that will be executed next.

=back

=head2 API Methods

The following are methods in the DB base class.  A client must
access these methods by inheritance (*not* by calling them directly),
since the API keeps track of clients through the inheritance
mechanism.

=over 8

=item CLIENT->register()

register a client object/package

=item CLIENT->evalcode(STRING)

eval STRING in executing code context

=item CLIENT->skippkg('D::hide')

ask DB not to stop in these packages

=item CLIENT->run()

run some more (until a breakpt is reached)

=item CLIENT->step()

single step

=item CLIENT->next()

step over

=item CLIENT->done()

de-register from the debugging API

=back

=head2 Client Callback Methods

The following "virtual" methods can be defined by the client.  They will
be called by the API at appropriate points.  Note that unless specified
otherwise, the debug API only defines empty, non-functional default versions
of these methods.

=over 8

=item CLIENT->init()

Called after debug API inits itself.

=item CLIENT->prestop([STRING])

Usually inherited from DB package.  If no arguments are passed,
returns the prestop action string.

=item CLIENT->stop()

Called when execution stops (w/ args file, line).

=item CLIENT->idle()

Called while stopped (can be a client event loop).

=item CLIENT->poststop([STRING])

Usually inherited from DB package.  If no arguments are passed,
returns the poststop action string.

=item CLIENT->evalcode(STRING)

Usually inherited from DB package.  Ask for a STRING to be C<eval>-ed
in executing code context.

=item CLIENT->cleanup()

Called just before exit.

=item CLIENT->output(LIST)

Called when API must show a message (warnings, errors etc.).


=back


=head1 BUGS

The interface defined by this module is missing some of the later additions
to perl's debugging functionality.  As such, this interface should be considered
highly experimental and subject to change.

=head1 AUTHOR

Gurusamy Sarathy	gsar@activestate.com

This code heavily adapted from an early version of perl5db.pl attributable
to Larry Wall and the Perl Porters.

=cut
Commit	Line	Data
43d8869b GS	1	#
	2	# Documentation is at the __END__
	3	#
	4
	5	package DB;
	6
	7	# "private" globals
	8
	9	my ($running, $ready, $deep, $usrctxt, $evalarg,
	10	@stack, @saved, @skippkg, @clients);
	11	my $preeval = {};
	12	my $posteval = {};
	13	my $ineval = {};
	14
	15	####
	16	#
	17	# Globals - must be defined at startup so that clients can refer to
	18	# them right after a C<require DB;>
	19	#
	20	####
	21
	22	BEGIN {
	23
	24	# these are hardcoded in perl source (some are magical)
	25
	26	$DB::sub = ''; # name of current subroutine
	27	%DB::sub = (); # "filename:fromline-toline" for every known sub
	28	$DB::single = 0; # single-step flag (set it to 1 to enable stops in BEGIN/use)
	29	$DB::signal = 0; # signal flag (will cause a stop at the next line)
	30	$DB::trace = 0; # are we tracing through subroutine calls?
	31	@DB::args = (); # arguments of current subroutine or @ARGV array
	32	@DB::dbline = (); # list of lines in currently loaded file
	33	%DB::dbline = (); # actions in current file (keyed by line number)
	34	@DB::ret = (); # return value of last sub executed in list context
	35	$DB::ret = ''; # return value of last sub executed in scalar context
	36
	37	# other "public" globals
	38
	39	$DB::package = ''; # current package space
	40	$DB::filename = ''; # current filename
	41	$DB::subname = ''; # currently executing sub (fullly qualified name)
	42	$DB::lineno = ''; # current line number
	43
af048c18	44	$DB::VERSION = $DB::VERSION = '1.02';
43d8869b GS	45
	46	# initialize private globals to avoid warnings
	47
	48	$running = 1; # are we running, or are we stopped?
	49	@stack = (0);
	50	@clients = ();
	51	$deep = 100;
	52	$ready = 0;
	53	@saved = ();
	54	@skippkg = ();
	55	$usrctxt = '';
	56	$evalarg = '';
	57	}
	58
	59	####
	60	# entry point for all subroutine calls
	61	#
	62	sub sub {
	63	push(@stack, $DB::single);
	64	$DB::single &= 1;
	65	$DB::single \|= 4 if $#stack == $deep;
1e006cbb	66	if ($DB::sub eq 'DESTROY' or substr($DB::sub, -9) eq '::DESTROY' or not defined wantarray) {
43d8869b GS	67	&$DB::sub;
	68	$DB::single \|= pop(@stack);
	69	$DB::ret = undef;
	70	}
	71	elsif (wantarray) {
	72	@DB::ret = &$DB::sub;
	73	$DB::single \|= pop(@stack);
	74	@DB::ret;
	75	}
	76	else {
	77	$DB::ret = &$DB::sub;
	78	$DB::single \|= pop(@stack);
	79	$DB::ret;
	80	}
	81	}
	82
	83	####
	84	# this is called by perl for every statement
	85	#
	86	sub DB {
	87	return unless $ready;
	88	&save;
	89	($DB::package, $DB::filename, $DB::lineno) = caller;
	90
	91	return if @skippkg and grep { $_ eq $DB::package } @skippkg;
	92
	93	$usrctxt = "package $DB::package;"; # this won't let them modify, alas
	94	local(*DB::dbline) = "::_<$DB::filename";
aa057b67 CN	95
	96	# we need to check for pseudofiles on Mac OS (these are files
	97	# not attached to a filename, but instead stored in Dev:Pseudo)
	98	# since this is done late, $DB::filename will be "wrong" after
	99	# skippkg
	100	if ($^O eq 'MacOS' && $#DB::dbline < 0) {
	101	$DB::filename = 'Dev:Pseudo';
	102	*DB::dbline = "::_<$DB::filename";
	103	}
	104
43d8869b GS	105	my ($stop, $action);
	106	if (($stop,$action) = split(/\0/,$DB::dbline{$DB::lineno})) {
	107	if ($stop eq '1') {
	108	$DB::signal \|= 1;
	109	}
	110	else {
	111	$stop = 0 unless $stop; # avoid un_init warning
	112	$evalarg = "\$DB::signal \|= do { $stop; }"; &eval;
	113	$DB::dbline{$DB::lineno} =~ s/;9($\|\0)/$1/; # clear any temp breakpt
	114	}
	115	}
	116	if ($DB::single \|\| $DB::trace \|\| $DB::signal) {
	117	$DB::subname = ($DB::sub =~ /\'\|::/) ? $DB::sub : "${DB::package}::$DB::sub"; #';
	118	DB->loadfile($DB::filename, $DB::lineno);
	119	}
	120	$evalarg = $action, &eval if $action;
	121	if ($DB::single \|\| $DB::signal) {
	122	_outputall($#stack . " levels deep in subroutine calls.\n") if $DB::single & 4;
	123	$DB::single = 0;
	124	$DB::signal = 0;
	125	$running = 0;
	126
	127	&eval if ($evalarg = DB->prestop);
	128	my $c;
	129	for $c (@clients) {
	130	# perform any client-specific prestop actions
	131	&eval if ($evalarg = $c->cprestop);
	132
	133	# Now sit in an event loop until something sets $running
	134	do {
	135	$c->idle; # call client event loop; must not block
	136	if ($running == 2) { # client wants something eval-ed
	137	&eval if ($evalarg = $c->evalcode);
	138	$running = 0;
	139	}
	140	} until $running;
	141
	142	# perform any client-specific poststop actions
	143	&eval if ($evalarg = $c->cpoststop);
	144	}
	145	&eval if ($evalarg = DB->poststop);
	146	}
	147	($@, $!, $,, $/, $\, $^W) = @saved;
	148	();
	149	}
	150
	151	####
	152	# this takes its argument via $evalarg to preserve current @_
	153	#
	154	sub eval {
	155	($@, $!, $,, $/, $\, $^W) = @saved;
	156	eval "$usrctxt $evalarg; &DB::save";
	157	_outputall($@) if $@;
	158	}
	159
	160	###############################################################################
	161	# no compile-time subroutine call allowed before this point #
	162	###############################################################################
	163
	164	use strict; # this can run only after DB() and sub() are defined
	165
	166	sub save {
	167	@saved = ($@, $!, $,, $/, $\, $^W);
	168	$, = ""; $/ = "\n"; $\ = ""; $^W = 0;
169	}
170
171	sub catch {
172	for (@clients) { $_->awaken; }
173	$DB::signal = 1;
174	$ready = 1;
175	}
176
177	####
178	#
179	# Client callable (read inheritable) methods defined after this point
180	#
181	####
182
183	sub register {
184	my $s = shift;
185	$s = _clientname($s) if ref($s);
186	push @clients, $s;
187	}
188
189	sub done {
190	my $s = shift;
191	$s = _clientname($s) if ref($s);
192	@clients = grep {$_ ne $s} @clients;
193	$s->cleanup;
194	# $running = 3 unless @clients;
195	exit(0) unless @clients;
196	}
197
198	sub _clientname {
199	my $name = shift;
200	"$name" =~ /^(.+)=[A-Z]+\(.+\)$/;
201	return $1;
202	}
203
204	sub next {
205	my $s = shift;
206	$DB::single = 2;
207	$running = 1;
208	}
209
210	sub step {
211	my $s = shift;
212	$DB::single = 1;
213	$running = 1;
214	}
215
216	sub cont {
217	my $s = shift;
218	my $i = shift;
219	$s->set_tbreak($i) if $i;
220	for ($i = 0; $i <= $#stack;) {
221	$stack[$i++] &= ~1;
222	}
223	$DB::single = 0;
224	$running = 1;
225	}
226
227	####
228	# XXX caller must experimentally determine $i (since it depends
229	# on how many client call frames are between this call and the DB call).
230	# Such is life.
231	#
232	sub ret {
233	my $s = shift;
234	my $i = shift; # how many levels to get to DB sub
235	$i = 0 unless defined $i;
236	$stack[$#stack-$i] \|= 1;
237	$DB::single = 0;
238	$running = 1;
239	}
240
241	####
242	# XXX caller must experimentally determine $start (since it depends
243	# on how many client call frames are between this call and the DB call).
244	# Such is life.
245	#
246	sub backtrace {
247	my $self = shift;
248	my $start = shift;
249	my($p,$f,$l,$s,$h,$w,$e,$r,$a, @a, @ret,$i);
250	$start = 1 unless $start;
251	for ($i = $start; ($p,$f,$l,$s,$h,$w,$e,$r) = caller($i); $i++) {
252	@a = @DB::args;
253	for (@a) {
254	s/'/\\'/g;
255	s/([^\0]*)/'$1'/ unless /^-?[\d.]+$/;
256	s/([\200-\377])/sprintf("M-%c",ord($1)&0177)/eg;
257	s/([\0-\37\177])/sprintf("^%c",ord($1)^64)/eg;
258	}
259	$w = $w ? '@ = ' : '$ = ';
260	$a = $h ? '(' . join(', ', @a) . ')' : '';
261	$e =~ s/\n\s\;\s\Z// if $e;
262	$e =~ s/[\\\']/\\$1/g if $e;
263	if ($r) {
264	$s = "require '$e'";
265	} elsif (defined $r) {
266	$s = "eval '$e'";
267	} elsif ($s eq '(eval)') {
268	$s = "eval {...}";
269	}
270	$f = "file `$f'" unless $f eq '-e';
271	push @ret, "$w&$s$a from $f line $l";
272	last if $DB::signal;
273	}
274	return @ret;
275	}
276
277	sub _outputall {
278	my $c;
279	for $c (@clients) {
280	$c->output(@_);
281	}
282	}
283
284	sub trace_toggle {
285	my $s = shift;
286	$DB::trace = !$DB::trace;
287	}
288
289
290	####
291	# without args: returns all defined subroutine names
292	# with subname args: returns a listref [file, start, end]
293	#
294	sub subs {
295	my $s = shift;
296	if (@_) {
297	my(@ret) = ();
298	while (@_) {
299	my $name = shift;
300	push @ret, [$DB::sub{$name} =~ /^(.*)\:(\d+)-(\d+)$/]
301	if exists $DB::sub{$name};
302	}
303	return @ret;
304	}
305	return keys %DB::sub;
306	}
307
308	####
309	# first argument is a filename whose subs will be returned
310	# if a filename is not supplied, all subs in the current
311	# filename are returned.
312	#
313	sub filesubs {
314	my $s = shift;
315	my $fname = shift;
316	$fname = $DB::filename unless $fname;
317	return grep { $DB::sub{$_} =~ /^$fname/ } keys %DB::sub;
318	}
319
320	####
321	# returns a list of all filenames that DB knows about
322	#
323	sub files {
324	my $s = shift;
325	my(@f) = grep(m\|^_<\|, keys %main::);
326	return map { substr($_,2) } @f;
327	}
328
329	####
330	# returns reference to an array holding the lines in currently
331	# loaded file
332	#
333	sub lines {
334	my $s = shift;
335	return \@DB::dbline;
336	}
337
338	####
339	# loadfile($file, $line)
340	#
341	sub loadfile {
342	my $s = shift;
343	my($file, $line) = @_;
344	if (!defined $main::{'_<' . $file}) {
345	my $try;
346	if (($try) = grep(m\|^_<.*$file\|, keys %main::)) {
347	$file = substr($try,2);
348	}
349	}
350	if (defined($main::{'_<' . $file})) {
351	my $c;
352	# _outputall("Loading file $file..");
353	*DB::dbline = "::_<$file";
354	$DB::filename = $file;
355	for $c (@clients) {
356	# print "2 ", $file, '\|', $line, "\n";
357	$c->showfile($file, $line);
358	}
359	return $file;
360	}
361	return undef;
362	}
363
364	sub lineevents {
365	my $s = shift;
366	my $fname = shift;
367	my(%ret) = ();
368	my $i;
369	$fname = $DB::filename unless $fname;
370	local(*DB::dbline) = "::_<$fname";
371	for ($i = 1; $i <= $#DB::dbline; $i++) {
372	$ret{$i} = [$DB::dbline[$i], split(/\0/, $DB::dbline{$i})]
373	if defined $DB::dbline{$i};
374	}
375	return %ret;
376	}
377
378	sub set_break {
379	my $s = shift;
380	my $i = shift;
381	my $cond = shift;
382	$i \|\|= $DB::lineno;
383	$cond \|\|= '1';
384	$i = _find_subline($i) if ($i =~ /\D/);
385	$s->output("Subroutine not found.\n") unless $i;
386	if ($i) {
387	if ($DB::dbline[$i] == 0) {
388	$s->output("Line $i not breakable.\n");
389	}
390	else {
391	$DB::dbline{$i} =~ s/^[^\0]*/$cond/;
392	}
393	}
394	}
395
396	sub set_tbreak {
397	my $s = shift;
398	my $i = shift;
399	$i = _find_subline($i) if ($i =~ /\D/);
400	$s->output("Subroutine not found.\n") unless $i;
401	if ($i) {
402	if ($DB::dbline[$i] == 0) {
403	$s->output("Line $i not breakable.\n");
404	}
405	else {
406	$DB::dbline{$i} =~ s/($\|\0)/;9$1/; # add one-time-only b.p.
407	}
408	}
409	}
410
411	sub _find_subline {
412	my $name = shift;
413	$name =~ s/\'/::/;
414	$name = "${DB::package}\:\:" . $name if $name !~ /::/;
415	$name = "main" . $name if substr($name,0,2) eq "::";
416	my($fname, $from, $to) = ($DB::sub{$name} =~ /^(.*):(\d+)-(\d+)$/);
417	if ($from) {
c95f170b	418	local *DB::dbline = "::_<$fname";
43d8869b GS	419	++$from while $DB::dbline[$from] == 0 && $from < $to;
	420	return $from;
	421	}
	422	return undef;
	423	}
	424
	425	sub clr_breaks {
	426	my $s = shift;
	427	my $i;
	428	if (@_) {
	429	while (@_) {
	430	$i = shift;
	431	$i = _find_subline($i) if ($i =~ /\D/);
	432	$s->output("Subroutine not found.\n") unless $i;
	433	if (defined $DB::dbline{$i}) {
	434	$DB::dbline{$i} =~ s/^[^\0]+//;
	435	if ($DB::dbline{$i} =~ s/^\0?$//) {
	436	delete $DB::dbline{$i};
	437	}
	438	}
	439	}
	440	}
	441	else {
	442	for ($i = 1; $i <= $#DB::dbline ; $i++) {
	443	if (defined $DB::dbline{$i}) {
	444	$DB::dbline{$i} =~ s/^[^\0]+//;
	445	if ($DB::dbline{$i} =~ s/^\0?$//) {
	446	delete $DB::dbline{$i};
	447	}
	448	}
	449	}
	450	}
	451	}
	452
	453	sub set_action {
	454	my $s = shift;
	455	my $i = shift;
	456	my $act = shift;
	457	$i = _find_subline($i) if ($i =~ /\D/);
	458	$s->output("Subroutine not found.\n") unless $i;
	459	if ($i) {
	460	if ($DB::dbline[$i] == 0) {
	461	$s->output("Line $i not actionable.\n");
	462	}
	463	else {
	464	$DB::dbline{$i} =~ s/\0[^\0]*//;
	465	$DB::dbline{$i} .= "\0" . $act;
	466	}
	467	}
	468	}
	469
	470	sub clr_actions {
	471	my $s = shift;
	472	my $i;
	473	if (@_) {
	474	while (@_) {
	475	my $i = shift;
	476	$i = _find_subline($i) if ($i =~ /\D/);
	477	$s->output("Subroutine not found.\n") unless $i;
	478	if ($i && $DB::dbline[$i] != 0) {
	479	$DB::dbline{$i} =~ s/\0[^\0]*//;
	480	delete $DB::dbline{$i} if $DB::dbline{$i} =~ s/^\0?$//;
	481	}
	482	}
483	}
484	else {
485	for ($i = 1; $i <= $#DB::dbline ; $i++) {
486	if (defined $DB::dbline{$i}) {
487	$DB::dbline{$i} =~ s/\0[^\0]*//;
488	delete $DB::dbline{$i} if $DB::dbline{$i} =~ s/^\0?$//;
489	}
490	}
491	}
492	}
493
494	sub prestop {
495	my ($client, $val) = @_;
496	return defined($val) ? $preeval->{$client} = $val : $preeval->{$client};
497	}
498
499	sub poststop {
500	my ($client, $val) = @_;
501	return defined($val) ? $posteval->{$client} = $val : $posteval->{$client};
502	}
503
504	#
505	# "pure virtual" methods
506	#
507
508	# client-specific pre/post-stop actions.
509	sub cprestop {}
510	sub cpoststop {}
511
512	# client complete startup
513	sub awaken {}
514
515	sub skippkg {
516	my $s = shift;
517	push @skippkg, @_ if @_;
518	}
519
520	sub evalcode {
521	my ($client, $val) = @_;
522	if (defined $val) {
523	$running = 2; # hand over to DB() to evaluate in its context
524	$ineval->{$client} = $val;
525	}
526	return $ineval->{$client};
527	}
528
529	sub ready {
530	my $s = shift;
531	return $ready = 1;
532	}
533
534	# stubs
535
536	sub init {}
537	sub stop {}
538	sub idle {}
539	sub cleanup {}
540	sub output {}
541
542	#
543	# client init
544	#
545	for (@clients) { $_->init }
546
547	$SIG{'INT'} = \&DB::catch;
548
549	# disable this if stepping through END blocks is desired
550	# (looks scary and deconstructivist with Swat)
551	END { $ready = 0 }
552
553	1;
554	__END__
555
556	=head1 NAME
557
538c5554	558	DB - programmatic interface to the Perl debugging API
43d8869b GS	559
	560	=head1 SYNOPSIS
	561
	562	package CLIENT;
	563	use DB;
	564	@ISA = qw(DB);
3cb6de81	565
43d8869b	566	# these (inherited) methods can be called by the client
3cb6de81	567
43d8869b GS	568	CLIENT->register() # register a client package name
	569	CLIENT->done() # de-register from the debugging API
	570	CLIENT->skippkg('hide::hide') # ask DB not to stop in this package
	571	CLIENT->cont([WHERE]) # run some more (until BREAK or another breakpt)
	572	CLIENT->step() # single step
	573	CLIENT->next() # step over
	574	CLIENT->ret() # return from current subroutine
	575	CLIENT->backtrace() # return the call stack description
	576	CLIENT->ready() # call when client setup is done
	577	CLIENT->trace_toggle() # toggle subroutine call trace mode
	578	CLIENT->subs([SUBS]) # return subroutine information
	579	CLIENT->files() # return list of all files known to DB
	580	CLIENT->lines() # return lines in currently loaded file
	581	CLIENT->loadfile(FILE,LINE) # load a file and let other clients know
	582	CLIENT->lineevents() # return info on lines with actions
	583	CLIENT->set_break([WHERE],[COND])
	584	CLIENT->set_tbreak([WHERE])
	585	CLIENT->clr_breaks([LIST])
	586	CLIENT->set_action(WHERE,ACTION)
	587	CLIENT->clr_actions([LIST])
	588	CLIENT->evalcode(STRING) # eval STRING in executing code's context
	589	CLIENT->prestop([STRING]) # execute in code context before stopping
	590	CLIENT->poststop([STRING])# execute in code context before resuming
	591
	592	# These methods will be called at the appropriate times.
	593	# Stub versions provided do nothing.
	594	# None of these can block.
3cb6de81	595
43d8869b GS	596	CLIENT->init() # called when debug API inits itself
	597	CLIENT->stop(FILE,LINE) # when execution stops
	598	CLIENT->idle() # while stopped (can be a client event loop)
	599	CLIENT->cleanup() # just before exit
	600	CLIENT->output(LIST) # called to print any output that API must show
	601
	602	=head1 DESCRIPTION
	603
	604	Perl debug information is frequently required not just by debuggers,
	605	but also by modules that need some "special" information to do their
	606	job properly, like profilers.
	607
	608	This module abstracts and provides all of the hooks into Perl internal
	609	debugging functionality, so that various implementations of Perl debuggers
	610	(or packages that want to simply get at the "privileged" debugging data)
	611	can all benefit from the development of this common code. Currently used
	612	by Swat, the perl/Tk GUI debugger.
	613
	614	Note that multiple "front-ends" can latch into this debugging API
	615	simultaneously. This is intended to facilitate things like
	616	debugging with a command line and GUI at the same time, debugging
	617	debuggers etc. [Sounds nice, but this needs some serious support -- GSAR]
	618
	619	In particular, this API does B<not> provide the following functions:
	620
	621	=over 4
	622
	623	=item *
	624
	625	data display
	626
	627	=item *
	628
	629	command processing
	630
	631	=item *
	632
	633	command alias management
	634
	635	=item *
	636
	637	user interface (tty or graphical)
	638
	639	=back
	640
	641	These are intended to be services performed by the clients of this API.
	642
	643	This module attempts to be squeaky clean w.r.t C<use strict;> and when
	644	warnings are enabled.
	645
	646
	647	=head2 Global Variables
	648
	649	The following "public" global names can be read by clients of this API.
	650	Beware that these should be considered "readonly".
	651
	652	=over 8
	653
	654	=item $DB::sub
	655
	656	Name of current executing subroutine.
	657
	658	=item %DB::sub
	659
660	The keys of this hash are the names of all the known subroutines. Each value
661	is an encoded string that has the sprintf(3) format
662	C<("%s:%d-%d", filename, fromline, toline)>.
663
664	=item $DB::single
665
666	Single-step flag. Will be true if the API will stop at the next statement.
667
668	=item $DB::signal
669
670	Signal flag. Will be set to a true value if a signal was caught. Clients may
671	check for this flag to abort time-consuming operations.
672
673	=item $DB::trace
674
675	This flag is set to true if the API is tracing through subroutine calls.
676
677	=item @DB::args
678
679	Contains the arguments of current subroutine, or the C<@ARGV> array if in the
680	toplevel context.
681
682	=item @DB::dbline
683
684	List of lines in currently loaded file.
685
686	=item %DB::dbline
687
688	Actions in current file (keys are line numbers). The values are strings that
689	have the sprintf(3) format C<("%s\000%s", breakcondition, actioncode)>.
690
691	=item $DB::package
692
693	Package namespace of currently executing code.
694
695	=item $DB::filename
696
697	Currently loaded filename.
698
699	=item $DB::subname
700
701	Fully qualified name of currently executing subroutine.
702
703	=item $DB::lineno
704
705	Line number that will be executed next.
706
707	=back
708
709	=head2 API Methods
710
711	The following are methods in the DB base class. A client must
712	access these methods by inheritance (not by calling them directly),
713	since the API keeps track of clients through the inheritance
714	mechanism.
715
716	=over 8
717
718	=item CLIENT->register()
719
720	register a client object/package
721
722	=item CLIENT->evalcode(STRING)
723
724	eval STRING in executing code context
725
726	=item CLIENT->skippkg('D::hide')
727
728	ask DB not to stop in these packages
729
730	=item CLIENT->run()
731
732	run some more (until a breakpt is reached)
733
734	=item CLIENT->step()
735
736	single step
737
738	=item CLIENT->next()
739
740	step over
741
742	=item CLIENT->done()
743
744	de-register from the debugging API
745
746	=back
747
748	=head2 Client Callback Methods
749
750	The following "virtual" methods can be defined by the client. They will
751	be called by the API at appropriate points. Note that unless specified
752	otherwise, the debug API only defines empty, non-functional default versions
753	of these methods.
754
755	=over 8
756
757	=item CLIENT->init()
758
759	Called after debug API inits itself.
760
761	=item CLIENT->prestop([STRING])
762
763	Usually inherited from DB package. If no arguments are passed,
764	returns the prestop action string.
765
766	=item CLIENT->stop()
767
768	Called when execution stops (w/ args file, line).
769
770	=item CLIENT->idle()
771
772	Called while stopped (can be a client event loop).
773
774	=item CLIENT->poststop([STRING])
775
776	Usually inherited from DB package. If no arguments are passed,
777	returns the poststop action string.
778
779	=item CLIENT->evalcode(STRING)
780
781	Usually inherited from DB package. Ask for a STRING to be C<eval>-ed
782	in executing code context.
783
784	=item CLIENT->cleanup()
785
786	Called just before exit.
787
788	=item CLIENT->output(LIST)
789
790	Called when API must show a message (warnings, errors etc.).
791
792
793	=back
794
795
796	=head1 BUGS
797
798	The interface defined by this module is missing some of the later additions
799	to perl's debugging functionality. As such, this interface should be considered
800	highly experimental and subject to change.
801
802	=head1 AUTHOR
803
6e238990	804	Gurusamy Sarathy gsar@activestate.com
43d8869b GS	805
	806	This code heavily adapted from an early version of perl5db.pl attributable
	807	to Larry Wall and the Perl Porters.
	808
	809	=cut