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our $XS_VERSION = $VERSION;
$VERSION = eval $VERSION;

=pod

=head1 NAME

B::Debugger - optree debugger

=head1 SYNOPSIS

  perl -MB::Debugger programm.pl
  B::Debugger 0.01 - optree debugger. h for help
  op 0 enter
  > n
  op 1 nextstate
  > h
  Usage:
  n [n] next op                       l [n|x-y]     list ops
  c [n] continue (until)              d|Debug       op
  b <n> break at op                   o|Concise     op
  s     step into kids                f|Flags       op
  sib   step to next sibling          x|eval expr
  u [n] up                            [sahpicg]v<n> n-th global var: sv1,
  g <n> goto                          pad <n>       n-th pad variable (my)
  h     help
  q     quit debugger, execute        exit           quit with no execution
  op 0 enter
  > b 5
  breakpoint 5 added
  > b const
  breakpoint const added
  > n
  op 2 pushmark
  > l
  -  <0> enter ->-
  -  <;> nextstate(main 111 test.pl:5) v:{ ->-
  -  <0> pushmark sM ->-  > c
  > q
  quit
  executing...

=head1 DESCRIPTION

  Start an optree inspector before the runtime execution begins, similar
  to the perl debugger, but only at the internal optree level, not the
  source level. Kind of interactive B::Concise.

  The ops are numbered and in basic (=parsed) order, starting from 0.
  Breakpoints can be defined as number or by opname.

=head1 OPTIONS

None yet.

Planned:

  -exec      switch to exec order
  -root      start at main_root, not main_start
  -check     hook into CHECK block (Default, at B)
  -unit      hook into UNITCHECK block (after B)
  -init      hook into INIT block (before B)
  -begin     hook into BEGIN block (before compilation)
  -d         debug, be verbose in the internal recursion steps

=head1 COMMANDS

  n [n]   goto the next op, or step the next n ops
  s       step into kid if not next
  sib     step to next sibling
  u [n]   go one or n steps back or up
  g <n>   goto op 0-opmax
  c [n]   continue. Optionally until op n
  l [n|x-y] list n ops or from x to y.
  x <x>   eval perl expression
  f       list B::Flags op
  o/C     list B::Concise op
  d/D     list B::Debug op
  [sahpicg]v<n> inspect n-th global variable. eg. sv1
  h       help
  q       quit debugger, start execution
  exit    quit perl, no execution

=head1 SEE ALSO

Use L<Od> to step through the compiler with the perl debugger.
It delays the C<CHECK> block for the B::backend.

=head1 TODO

How to manage direct opidx access?

  Such as: Concise 10, list 5-10, up, sib
  Do a first sweep in desired basic or exec order recording the ops?

set curcv in Concise

Commandline options

exit

de-recursify and simplify the loop, cont is broken.

=head1 BUGS

Plenty. This is alpha and for interested compiler developers only.

l =>
  coderef CODE(0x1553f40) has no START (set curcv in Concise)

cont, goto broken

=head1 AUTHOR

Reini Urban C<rurban@cpan.org>

=cut

use Devel::Hook;
use B qw(main_start main_root class main_cv);
use B::Utils; # qw(carp croak);