Perl 5 version 26.3 documentation

B::Op_private

NAME

B::Op_private - OP op_private flag definitions

SYNOPSIS

  1.     use B::Op_private;
  3.     # flag details for bit 7 of OP_AELEM's op_private:
  4.     my $name  = $B::Op_private::bits{aelem}{7}; # OPpLVAL_INTRO
  5.     my $value = $B::Op_private::defines{$name}; # 128
  6.     my $label = $B::Op_private::labels{$name};  # LVINTRO
  8.     # the bit field at bits 5..6 of OP_AELEM's op_private:
  9.     my $bf  = $B::Op_private::bits{aelem}{6};
  10.     my $mask = $bf->{bitmask}; # etc

DESCRIPTION

This module provides four global hashes:

  1.     %B::Op_private::bits
  2.     %B::Op_private::defines
  3.     %B::Op_private::labels
  4.     %B::Op_private::ops_using

which contain information about the per-op meanings of the bits in the op_private field.

%bits

This is indexed by op name and then bit number (0..7). For single bit flags, it returns the name of the define (if any) for that bit:

  1.    $B::Op_private::bits{aelem}{7} eq 'OPpLVAL_INTRO';

For bit fields, it returns a hash ref containing details about the field. The same reference will be returned for all bit positions that make up the bit field; so for example these both return the same hash ref:

  1.     $bitfield = $B::Op_private::bits{aelem}{5};
  2.     $bitfield = $B::Op_private::bits{aelem}{6};

The general format of this hash ref is

  1.     {
  2.         # The bit range and mask; these are always present.
  3.         bitmin        => 5,
  4.         bitmax        => 6,
  5.         bitmask       => 0x60,
  7.         # (The remaining keys are optional)
  9.         # The names of any defines that were requested:
  10.         mask_def      => 'OPpFOO_MASK',
  11.         baseshift_def => 'OPpFOO_SHIFT',
  12.         bitcount_def  => 'OPpFOO_BITS',
  14.         # If present, Concise etc will display the value with a 'FOO='
  15.         # prefix. If it equals '-', then Concise will treat the bit
  16.         # field as raw bits and not try to interpret it.
  17.         label         => 'FOO',
  19.         # If present, specifies the names of some defines and the
  20.         # display labels that are used to assign meaning to particu-
  21.         # lar integer values within the bit field; e.g. 3 is dis-
  22.         # played as 'C'.
  23.         enum          => [ qw(
  24.                              1   OPpFOO_A  A
  25.                              2   OPpFOO_B  B
  26.                              3   OPpFOO_C  C
  27.                          )],
  29.     };

%defines

This gives the value of every OPp define, e.g.

  1.     $B::Op_private::defines{OPpLVAL_INTRO} == 128;

%labels

This gives the short display label for each define, as used by B::Concise and perl -Dx , e.g.

  1.     $B::Op_private::labels{OPpLVAL_INTRO} eq 'LVINTRO';

If the label equals '-', then Concise will treat the bit as a raw bit and not try to display it symbolically.

%ops_using

For each define, this gives a reference to an array of op names that use the flag.

  1.     @ops_using_lvintro = @{ $B::Op_private::ops_using{OPp_LVAL_INTRO} };