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  0   !ˆl–äY>” TÊ:”ýÆ™¸'”Å£Â„Lÿ_‹uÐb&=LV[(ÁÇ 7å    !# Copyright (C) 1997-2020 Free Software Foundation, Inc.

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2, or (at your option)
# any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

package Automake::DisjConditions;

use 5.006;
use strict;
use Carp;
use Automake::Condition qw/TRUE FALSE/;

=head1 NAME

Automake::DisjConditions - record a disjunction of Conditions

=head1 SYNOPSIS

  use Automake::Condition;
  use Automake::DisjConditions;

  # Create a Condition to represent "COND1 and not COND2".
  my $cond = new Automake::Condition "COND1_TRUE", "COND2_FALSE";
  # Create a Condition to represent "not COND3".
  my $other = new Automake::Condition "COND3_FALSE";

  # Create a DisjConditions to represent
  #   "(COND1 and not COND2) or (not COND3)"
  my $set = new Automake::DisjConditions $cond, $other;

  # Return the list of Conditions involved in $set.
  my @conds = $set->conds;

  # Return one of the Condition involved in $set.
  my $cond = $set->one_cond;

  # Return true iff $set is always true (i.e. its subconditions
  # cover all cases).
  if ($set->true) { ... }

  # Return false iff $set is always false (i.e. is empty, or contains
  # only false conditions).
  if ($set->false) { ... }

  # Return a string representing the DisjConditions.
  #   "COND1_TRUE COND2_FALSE | COND3_FALSE"
  my $str = $set->string;

  # Return a human readable string representing the DisjConditions.
  #   "(COND1 and !COND2) or (!COND3)"
  my $str = $set->human;

  # Merge (OR) several DisjConditions.
  my $all = $set->merge($set2, $set3, ...)

  # Invert a DisjConditions, i.e., create a new DisjConditions
  # that complements $set.
  my $inv = $set->invert;

  # Multiply two DisjConditions.
  my $prod = $set1->multiply ($set2);

  # Return the subconditions of a DisjConditions with respect to
  # a Condition.  See the description for a real example.
  my $subconds = $set->sub_conditions ($cond);

  # Check whether a new definition in condition $cond would be
  # ambiguous w.r.t. existing definitions in $set.
  ($msg, $ambig_cond) = $set->ambiguous_p ($what, $cond);

=head1 DESCRIPTION

A C<DisjConditions> is a disjunction of C<Condition>s.  In Automake
they are used to represent the conditions into which Makefile
variables and Makefile rules are defined.

If the variable C<VAR> is defined as

  if COND1
    if COND2
      VAR = value1
    endif
  endif
  if !COND3
    if COND4
      VAR = value2
    endif
  endif

then it will be associated a C<DisjConditions> created with
the following statement.

  new Automake::DisjConditions
    (new Automake::Condition ("COND1_TRUE", "COND2_TRUE"),
     new Automake::Condition ("COND3_FALSE", "COND4_TRUE"));

As you can see, a C<DisjConditions> is made from a list of
C<Condition>s.  Since C<DisjConditions> is a disjunction, and
C<Condition> is a conjunction, the above can be read as
follows.

  (COND1 and COND2) or ((not COND3) and COND4)

That's indeed the condition in which C<VAR> has a value.

Like C<Condition> objects, a C<DisjConditions> object is unique
with respect to its conditions.  Two C<DisjConditions> objects created
for the same set of conditions will have the same address.  This makes
it easy to compare C<DisjConditions>s: just compare the references.

=head2 Methods

=over 4

=item C<$set = new Automake::DisjConditions [@conds]>

Create a C<DisjConditions> object from the list of C<Condition>
objects passed in arguments.

If the C<@conds> list is empty, the C<DisjConditions> is assumed to be
false.

As explained previously,