{- # -*- Mode: perl -*-

 use File::Basename;

 my $debug_resolvedepends = $ENV{BUILDFILE_DEBUG_DEPENDS};
 my $debug_rules = $ENV{BUILDFILE_DEBUG_RULES};

 # A cache of objects for which a recipe has already been generated
 my %cache;

 # collectdepends, expanddepends and reducedepends work together to make
 # sure there are no duplicate or weak dependencies and that they are in
 # the right order.  This is used to sort the list of libraries  that a
 # build depends on.
 sub extensionlesslib {
     my @result = map { $_ =~ /(\.a)?$/; $` } @_;
     return @result if wantarray;
     return $result[0];
 }

 # collectdepends dives into the tree of dependencies and returns
 # a list of all the non-weak ones.
 sub collectdepends {
     return () unless @_;

     my $thing = shift;
     my $extensionlessthing = extensionlesslib($thing);
     my @listsofar = @_;    # to check if we're looping
     my @list = @{$unified_info{depends}->{$thing} //
                      $unified_info{depends}->{$extensionlessthing}};
     my @newlist = ();

     print STDERR "DEBUG[collectdepends] $thing > ", join(' ', @listsofar), "\n"
         if $debug_resolvedepends;
     foreach my $item (@list) {
         my $extensionlessitem = extensionlesslib($item);
         # It's time to break off when the dependency list starts looping
         next if grep { extensionlesslib($_) eq $extensionlessitem } @listsofar;
         # Don't add anything here if the dependency is weak
         next if defined $unified_info{attributes}->{depends}->{$thing}->{$item}->{'weak'};
         my @resolved = collectdepends($item, @listsofar, $item);
         push @newlist, $item, @resolved;
     }
     print STDERR "DEBUG[collectdepends] $thing < ", join(' ', @newlist), "\n"
         if $debug_resolvedepends;
     @newlist;
 }

 # expanddepends goes through a list of stuff, checks if they have any
 # dependencies, and adds them at the end of the current position if
 # they aren't already present later on.
 sub expanddepends {
     my @after = ( @_ );
     print STDERR "DEBUG[expanddepends]> ", join(' ', @after), "\n"
         if $debug_resolvedepends;
     my @before = ();
     while (@after) {
         my $item = shift @after;
         print STDERR "DEBUG[expanddepends]\\  ", join(' ', @before), "\n"
             if $debug_resolvedepends;
         print STDERR "DEBUG[expanddepends] - ", $item, "\n"
             if $debug_resolvedepends;
         my @middle = (
             $item,
             map {
                 my $x = $_;
                 my $extlessx = extensionlesslib($x);
                 if (grep { $extlessx eq extensionlesslib($_) } @before
                     and
                     !grep { $extlessx eq extensionlesslib($_) } @after) {
                     print STDERR "DEBUG[expanddepends] + ", $x, "\n"
                         if $debug_resolvedepends;
                     ( $x )
                 } else {
                     print STDERR "DEBUG[expanddepends] ! ", $x, "\n"
                         if $debug_resolvedepends;
                     ()
                 }
             } @{$unified_info{depends}->{$item} // []}
         );
         print STDERR "DEBUG[expanddepends] = ", join(' ', @middle), "\n"
             if $debug_resolvedepends;
         print STDERR "DEBUG[expanddepends]/  ", join(' ', @after), "\n"
             if $debug_resolvedepends;
         push @before, @middle;
     }
     print STDERR "DEBUG[expanddepends]< ", join(' ', @before), "\n"
         if $debug_resolvedepends;
     @before;
 }

 # reducedepends looks through a list, and checks if each item is
 # repeated later on.  If it is, the earlier copy is dropped.
 sub reducedepends {
     my @list = @_;
     print STDERR "DEBUG[reducedepends]> ", join(' ', @list), "\n"
         if $debug_resolvedepends;
     my @newlist = ();
     my %replace = ();
     while (@list) {
         my $item = shift @list;
         my $extensionlessitem = extensionlesslib($item);
         if (grep { $extensionlessitem eq extensionlesslib($_) } @list) {
             if ($item ne $extensionlessitem) {
                 # If this instance of the library is explicitly static, we
                 # prefer that to any shared library name, since it must have
                 # been done on purpose.
                 $replace{$extensionlessitem} = $item;
             }
         } else {
             push @newlist, $item;
         }
     }
     @newlist = map { $replace{$_} // $_; } @newlist;
     print STDERR "DEBUG[reducedepends]< ", join(' ', @newlist), "\n"
         if $debug_resolvedepends;
     @newlist;
 }

 # Do it all
 # This takes multiple inputs and combine them into a single list of
 # interdependent things.  The returned value will include all the input.
 # Callers are responsible for taking away the things they are building.
 sub resolvedepends {
     print STDERR "DEBUG[resolvedepends] START (", join(', ', @_), ")\n"
         if $debug_resolvedepends;
     my @all =
         reducedepends(expanddepends(map { ( $_, collectdepends($_) ) } @_));
     print STDERR "DEBUG[resolvedepends] END (", join(', ', @_), ") : ",
         join(',', map { "\n    $_" } @all), "\n"
         if $debug_resolvedepends;
     @all;
 }

 # dogenerate is responsible for producing all the recipes that build
 # generated source files.  It recurses in case a dependency is also a
 # generated source file.
 sub dogenerate {
     my $src = shift;
     return "" if $cache{$src};
     my $obj = shift;
     my $bin = shift;
     my %opts = @_;
     if ($unified_info{generate}->{$src}) {
         die "$src is generated by Configure, should not appear in build file\n"
             if ref $unified_info{generate}->{$src} eq "";
         my $script = $unified_info{generate}->{$src}->[0];
         $OUT .= generatesrc(src => $src,
                             product => $bin,
                             generator => $unified_info{generate}->{$src},
                             generator_incs => $unified_info{includes}->{$script},
                             generator_deps => $unified_info{depends}->{$script},
                             deps => $unified_info{depends}->{$src},
                             incs => [ @{$unified_info{includes}->{$obj}},
                                       @{$unified_info{includes}->{$bin}} ],
                             defs => [ @{$unified_info{defines}->{$obj}},
                                       @{$unified_info{defines}->{$bin}} ],
                             %opts);
         foreach (@{$unified_info{depends}->{$src}}) {
             dogenerate($_, $obj, $bin, %opts);
         }
     }
     $cache{$src} = 1;
 }

 # doobj is responsible for producing all the recipes that build
 # object files as well as dependency files.
 sub doobj {
     my $obj = shift;
     return "" if $cache{$obj};
     my $bin = shift;
     my %opts = @_;
     if (@{$unified_info{sources}->{$obj}}) {
         $OUT .= src2obj(obj => $obj,
                         product => $bin,
                         srcs => $unified_info{sources}->{$obj},
                         deps => $unified_info{depends}->{$obj},
                         incs => [ @{$unified_info{includes}->{$obj}},
                                   @{$unified_info{includes}->{$bin}} ],
                         defs => [ @{$unified_info{defines}->{$obj}},
                                   @{$unified_info{defines}->{$bin}} ],
                         %opts);
         foreach ((@{$unified_info{sources}->{$obj}},
                   @{$unified_info{depends}->{$obj}})) {
             dogenerate($_, $obj, $bin, %opts);
         }
     }
     $cache{$obj} = 1;
 }

 # dolib is responsible for building libraries.  It will call
 # obj2shlib is shared libraries are produced, and obj2lib in all
 # cases.  It also makes sure all object files for the library are
 # built.
 sub dolib {
     my $lib = shift;
     return "" if $cache{$lib};
     unless ($disabled{shared} || $lib =~ /\.a$/) {
         my $obj2shlib = defined &obj2shlib ? \&obj2shlib : \&libobj2shlib;
         $OUT .= $obj2shlib->(lib => $lib,
                              attrs => $unified_info{attributes}->{libraries}->{$lib},
                              objs => $unified_info{shared_sources}->{$lib},
                              deps => [ grep { $_ ne $lib } resolvedepends($lib) ]);
         foreach ((@{$unified_info{shared_sources}->{$lib}},
                   @{$unified_info{sources}->{$lib}})) {
             # If this is somehow a compiled object, take care of it that way
             # Otherwise, it might simply be generated
             if (defined $unified_info{sources}->{$_}) {
                 doobj($_, $lib, intent => "shlib",
                       attrs => $unified_info{attributes}->{libraries}->{$lib});
             } else {
                 dogenerate($_, undef, undef, intent => "lib");
             }
         }
     }
     $OUT .= obj2lib(lib => $lib,
                     attrs => $unified_info{attributes}->{libraries}->{$lib},
                     objs => [ @{$unified_info{sources}->{$lib}} ]);
     foreach (@{$unified_info{sources}->{$lib}}) {
         doobj($_, $lib, intent => "lib",
               attrs => $unified_info{attributes}->{libraries}->{$lib});
     }
     $cache{$lib} = 1;
 }

 # domodule is responsible for building modules.  It will call
 # obj2dso, and also makes sure all object files for the library
 # are built.
 sub domodule {
     my $module = shift;
     return "" if $cache{$module};
     $OUT .= obj2dso(module => $module,
                     attrs => $unified_info{attributes}->{modules}->{$module},
                     objs => $unified_info{sources}->{$module},
                     deps => [ grep { $_ ne $module }
                               resolvedepends($module) ]);
     foreach (@{$unified_info{sources}->{$module}}) {
         # If this is somehow a compiled object, take care of it that way
         # Otherwise, it might simply be generated
         if (defined $unified_info{sources}->{$_}) {
             doobj($_, $module, intent => "dso",
                   attrs => $unified_info{attributes}->{modules}->{$module});
         } else {
             dogenerate($_, undef, $module, intent => "dso");
         }
     }
     $cache{$module} = 1;
 }

 # dobin is responsible for building programs.  It will call obj2bin,
 # and also makes sure all object files for the library are built.
 sub dobin {
     my $bin = shift;
     return "" if $cache{$bin};
     $OUT .= obj2bin(bin => $bin,
                     attrs => $unified_info{attributes}->{programs}->{$bin},
                     objs => [ @{$unified_info{sources}->{$bin}} ],
                     deps => [ grep { $_ ne $bin } resolvedepends($bin) ]);
     foreach (@{$unified_info{sources}->{$bin}}) {
         doobj($_, $bin, intent => "bin",
               attrs => $unified_info{attributes}->{$bin});
     }
     $cache{$bin} = 1;
 }

 # dobin is responsible for building scripts from templates.  It will
 # call in2script.
 sub doscript {
     my $script = shift;
     return "" if $cache{$script};
     $OUT .= in2script(script => $script,
                       attrs => $unified_info{attributes}->{$script},
                       sources => $unified_info{sources}->{$script});
     $cache{$script} = 1;
 }

 sub dodir {
     my $dir = shift;
     return "" if !exists(&generatedir) or $cache{$dir};
     $OUT .= generatedir(dir => $dir,
                         deps => $unified_info{dirinfo}->{$dir}->{deps},
                         %{$unified_info{dirinfo}->{$_}->{products}});
     $cache{$dir} = 1;
 }

 # Start with populating the cache with all the overrides
 %cache = map { $_ => 1 } @{$unified_info{overrides}};

 # Build mandatory generated headers
 foreach (@{$unified_info{depends}->{""}}) { dogenerate($_); }

 # Build all known libraries, modules, programs and scripts.
 # Everything else will be handled as a consequence.
 foreach (@{$unified_info{libraries}}) { dolib($_);    }
 foreach (@{$unified_info{modules}})   { domodule($_); }
 foreach (@{$unified_info{programs}})  { dobin($_);    }
 foreach (@{$unified_info{scripts}})   { doscript($_); }

 foreach (sort keys %{$unified_info{dirinfo}})  { dodir($_); }
-}