Array.pm

# for our tantrums
my class X::TypeCheck { ... };
my class X::TypeCheck::Splice { ... }
my class X::Subscript::Negative { ... };
my class X::NotEnoughDimensions { ... };
my class X::Assignment::ArrayShapeMismatch { ... };

# stub what we need now
my class array is repr('VMArray') { ... };

# An Array is a List that ensures every item added to it is in a Scalar
# container. It also supports push, pop, shift, unshift, splice, BIND-POS,
# and so forth.
my class Array { # declared in BOOTSTRAP
    # class Array is List
    #     has Mu $!descriptor;

    my class ArrayReificationTarget {
        has $!target;
        has $!descriptor;

        method new(\target, Mu \descriptor) {
            nqp::stmts(
              nqp::bindattr((my \rt = nqp::create(self)),
                self,'$!target',target),
              nqp::p6bindattrinvres(rt,
                self,'$!descriptor',descriptor)
            )
        }

        method push(Mu \value) {
            nqp::push($!target,
                nqp::assign(nqp::p6scalarfromdesc($!descriptor), value));
        }
    }

    my class ListReificationTarget {
        has $!target;

        method new(\target) {
            nqp::p6bindattrinvres(nqp::create(self), self, '$!target', target);
        }

        method push(Mu \value) {
            nqp::push($!target,
                nqp::decont(value));
        }
    }

    multi method clone(Array:D:) { [self] }

    method iterator(Array:D:) {

        # something to iterate over in the future
        if nqp::getattr(self,List,'$!todo').DEFINITE {
            class :: does Iterator {
                has int $!i;
                has $!array;
                has $!reified;
                has $!todo;
                has $!descriptor;

                method !SET-SELF(\array) {
                    $!i           = -1;
                    $!array      := array;
                    $!reified    :=
                      nqp::ifnull(
                        nqp::getattr( array,List,'$!reified'),
                        nqp::bindattr(array,List,'$!reified',
                          nqp::create(IterationBuffer))
                      );
                    $!todo       := nqp::getattr(array,List, '$!todo');
                    $!descriptor := nqp::getattr(array,Array,'$!descriptor');
                    self
                }
                method new(\array) { nqp::create(self)!SET-SELF(array) }

                method pull-one() is raw {
                    nqp::ifnull(
                      nqp::atpos($!reified,$!i = nqp::add_i($!i,1)),
                      nqp::islt_i($!i,nqp::elems($!reified))
                        ?? self!found-hole
                        !! $!todo.DEFINITE
                          ?? nqp::islt_i($!i,$!todo.reify-at-least(nqp::add_i($!i,1)))
                            ?? nqp::atpos($!reified,$!i) # cannot be nqp::null
                            !! self!done
                          !! IterationEnd
                    )
                }
                method !found-hole() {
                   nqp::p6bindattrinvres(
                     (my \v := nqp::p6scalarfromdesc($!descriptor)),
                     Scalar,
                     '$!whence',
                     -> { nqp::bindpos($!reified,$!i,v) }
                   )
                }
                method !done() is raw {
                    $!todo := nqp::bindattr($!array,List,'$!todo',Mu);
                    IterationEnd
                }

                method push-until-lazy($target) {
                    if $!todo.DEFINITE {
                        my int $elems = $!todo.reify-until-lazy;
                        nqp::while(   # doesn't sink
                          nqp::islt_i($!i = nqp::add_i($!i,1),$elems),
                          $target.push(nqp::atpos($!reified,$!i))
                        );
                        nqp::if(
                          $!todo.fully-reified,
                          self!done,
                          nqp::stmts(
                            ($!i = nqp::sub_i($elems,1)),
                            Mu
                          )
                        )
                    }
                    else {
                        my int $elems = nqp::elems($!reified);
                        nqp::while(   # doesn't sink
                          nqp::islt_i($!i = nqp::add_i($!i,1),$elems),
                          $target.push(
                            nqp::ifnull(
                              nqp::atpos($!reified,$!i),
                              nqp::p6bindattrinvres(
                                (my \v := nqp::p6scalarfromdesc($!descriptor)),
                                Scalar,
                                '$!whence',
                                -> { nqp::bindpos($!reified,$!i,v) }
                              )
                            )
                          )
                        );
                        IterationEnd
                    }
                }

                method is-lazy() { $!todo.DEFINITE && $!todo.is-lazy }
            }.new(self)
        }

        # everything we need is already there
        elsif nqp::getattr(self,List,'$!reified').DEFINITE {
            Rakudo::Iterator.ReifiedArray(
              self,
              nqp::getattr(self,Array,'$!descriptor')
            )
        }

        # nothing now or in the future to iterate over
        else {
            Rakudo::Iterator.Empty
        }
    }
    method from-iterator(Array:U: Iterator $iter) {
        nqp::if(
          nqp::eqaddr(
            $iter.push-until-lazy(
              my \target := ArrayReificationTarget.new(
                (my \buffer := nqp::create(IterationBuffer)),
                nqp::null
              )
            ),
            IterationEnd
          ),
          nqp::p6bindattrinvres(nqp::create(self),List,'$!reified',buffer),
          nqp::stmts(
            nqp::bindattr((my \result := nqp::create(self)),
              List,'$!reified',buffer),
            nqp::bindattr((my \todo := nqp::create(List::Reifier)),
              List::Reifier,'$!current-iter',$iter),
            nqp::bindattr(todo,
              List::Reifier,'$!reified',buffer),
            nqp::bindattr(todo,
              List::Reifier,'$!reification-target',target),
            nqp::p6bindattrinvres(result,List,'$!todo',todo)
          )
        )
    }

    proto method new(|) {*}
    multi method new(:$shape!) {
        nqp::if(
          nqp::defined($shape),
          set-shape(self,$shape),
          nqp::if(
            Metamodel::EnumHOW.ACCEPTS($shape.HOW),
            set-shape(self,$shape.^elems),
            nqp::create(self)
          )
        )
    }
    multi method new() {
        nqp::create(self)
    }
    multi method new(\values, :$shape!) {
        nqp::if(
          nqp::defined($shape),
          set-shape(self,$shape),
          nqp::if(
            Metamodel::EnumHOW.ACCEPTS($shape.HOW),
            set-shape(self,$shape.^elems),
            nqp::create(self)
          )
        ).STORE(values)
    }
    multi method new(\values) {
        nqp::create(self).STORE(values)
    }
    multi method new(**@values is raw, :$shape!) {
        nqp::if(
          nqp::defined($shape),
          set-shape(self,$shape),
          nqp::if(
            Metamodel::EnumHOW.ACCEPTS($shape.HOW),
            set-shape(self,$shape.^elems),
            nqp::create(self)
          )
        ).STORE(@values)
    }
    multi method new(**@values is raw) {
        nqp::create(self).STORE(@values)
    }

    proto method STORE(|) {*}
    multi method STORE(Array:D: Iterable:D \iterable) {
        nqp::iscont(iterable)
            ?? self!STORE-ONE(iterable)
            !! self!STORE-ITERABLE(iterable)
    }
    multi method STORE(Array:D: Mu \item) {
        self!STORE-ONE(item)
    }
    method !STORE-ITERABLE(\iterable) {
        my \new-storage = nqp::create(IterationBuffer);
        my \iter = iterable.iterator;
        my \target = ArrayReificationTarget.new(new-storage,
            nqp::decont($!descriptor));
        if iter.push-until-lazy(target) =:= IterationEnd {
            nqp::bindattr(self, List, '$!todo', Mu);
        }
        else {
            my \new-todo = nqp::create(List::Reifier);
            nqp::bindattr(new-todo, List::Reifier, '$!reified', new-storage);
            nqp::bindattr(new-todo, List::Reifier, '$!current-iter', iter);
            nqp::bindattr(new-todo, List::Reifier, '$!reification-target', target);
            nqp::bindattr(self, List, '$!todo', new-todo);
        }
        nqp::bindattr(self, List, '$!reified', new-storage);
        self
    }
    method !STORE-ONE(Mu \item) {
        my \new-storage = nqp::create(IterationBuffer);
        nqp::push(new-storage,
            nqp::assign(nqp::p6scalarfromdesc($!descriptor), item));
        nqp::bindattr(self, List, '$!reified', new-storage);
        nqp::bindattr(self, List, '$!todo', Mu);
        self
    }

    method reification-target() {
        ArrayReificationTarget.new(
            nqp::getattr(self, List, '$!reified'),
            nqp::decont($!descriptor))
    }

    multi method Slip(Array:D:) {

       # A Slip-With-Default is a special kind of Slip that also has a
       # descriptor to be able to generate containers for null elements that
       # have type and default information.
        my class Slip-With-Descriptor is Slip {
            has $!descriptor;

            method iterator() {
                Rakudo::Iterator.ReifiedArray(self,$!descriptor)
            }

            method !AT-POS-CONTAINER(Int:D \pos) {
                nqp::p6bindattrinvres(
                  (my $scalar := nqp::p6scalarfromdesc($!descriptor)),
                  Scalar,
                  '$!whence',
                  -> { nqp::bindpos(
                         nqp::getattr(self,List,'$!reified'),pos,$scalar) }
                )
            }

            multi method AT-POS(Int:D \pos) {
                nqp::ifnull(
                  nqp::atpos(nqp::getattr(self,List,'$!reified'),pos),
                  self!AT-POS-CONTAINER(pos)
                )
            }
            method default() { $!descriptor.default }
        }
        BEGIN Slip-With-Descriptor.^set_name("Slip");

        nqp::if(
          nqp::getattr(self,List,'$!todo').DEFINITE,
          # We're not fully reified, and so have internal mutability still.
          # The safe thing to do is to take an iterator of ourself and build
          # the Slip out of that.
          Slip.from-iterator(self.iterator),
          # We're fully reified.  Make a Slip that shares our reified buffer
          # but that will fill in default values for nulls.
          nqp::if(
            nqp::getattr(self,List,'$!reified').DEFINITE,
            nqp::p6bindattrinvres(
              nqp::p6bindattrinvres(
                nqp::create(Slip-With-Descriptor),
                Slip-With-Descriptor,
                '$!descriptor',
                $!descriptor
              ),
              List,
              '$!reified',
              nqp::getattr(self,List,'$!reified')
            ),
            nqp::create(Slip)
          )
        )
    }

    method FLATTENABLE_LIST() {
        nqp::if(
          nqp::getattr(self,List,'$!todo').DEFINITE,
          nqp::stmts(
            nqp::getattr(self,List,'$!todo').reify-all,
            nqp::getattr(self,List,'$!reified')
          ),
          nqp::if(
            (my $reified := nqp::getattr(self,List,'$!reified')).DEFINITE,
            nqp::stmts(
              nqp::if(
                (my int $elems = nqp::elems($reified)),
                nqp::stmts(
                  (my int $i = -1),
                  nqp::while(
                    nqp::islt_i(($i = nqp::add_i($i,1)),$elems),
                    nqp::if(
                      nqp::isnull(nqp::atpos($reified,$i)),
                      nqp::bindpos(
                        $reified,
                        $i,
                        nqp::p6scalarfromdesc($!descriptor)
                      )
                    )
                  )
                )
              ),
              nqp::getattr(self,List,'$!reified')
            ),
            nqp::bindattr(self,List,'$!reified',nqp::create(IterationBuffer))
          )
        )
    }

    multi method flat(Array:U:) { self }
    multi method flat(Array:D:) { Seq.new(self.iterator) }

    multi method List(Array:D: :$view) {
        nqp::if(
          self.is-lazy,                           # can't make a List
          X::Cannot::Lazy.new(:action<List>).throw,

          nqp::if(                                # all reified
            (my $reified := nqp::getattr(self,List,'$!reified')).DEFINITE,
            nqp::if(
              $view,                              # assume no change in array
              nqp::p6bindattrinvres(
                nqp::create(List),List,'$!reified',$reified),
              nqp::stmts(                         # make cow copy
                (my int $elems = nqp::elems($reified)),
                (my $cow := nqp::setelems(nqp::create(IterationBuffer),$elems)),
                (my int $i = -1),
                nqp::while(
                  nqp::islt_i(($i = nqp::add_i($i,1)),$elems),
                  nqp::bindpos($cow,$i,nqp::ifnull(nqp::decont(nqp::atpos($reified,$i)),Nil)),
                ),
                nqp::p6bindattrinvres(nqp::create(List),List,'$!reified',$cow)
              )
            ),
            nqp::create(List)                     # was empty, is empty
          )
        )
    }

    method shape() { (*,) }

    multi method AT-POS(Array:D: int $pos) is raw {
        nqp::if(
          nqp::isge_i($pos,0)
            && nqp::isconcrete(nqp::getattr(self,List,'$!reified')),
          nqp::ifnull(
            nqp::atpos(nqp::getattr(self,List,'$!reified'),$pos),
            self!AT-POS-SLOW($pos)
          ),
          self!AT-POS-SLOW($pos)
        )
    }
    # because this is a very hot path, we copied the code from the int candidate
    multi method AT-POS(Array:D: Int:D $pos) is raw {
        nqp::if(
          nqp::isge_i($pos,0)
            && nqp::isconcrete(nqp::getattr(self,List,'$!reified')),
          nqp::ifnull(
            nqp::atpos(nqp::getattr(self,List,'$!reified'),$pos),
            self!AT-POS-SLOW($pos)
          ),
          self!AT-POS-SLOW($pos)
        )
    }

    # handle any lookup that's not simple
    method !AT-POS-SLOW(\pos) is raw {
        nqp::if(
          nqp::islt_i(pos,0),
          Failure.new(X::OutOfRange.new(
            :what($*INDEX // 'Index'),:got(pos),:range<0..^Inf>)),
          nqp::if(
            nqp::isconcrete(my $reified := nqp::getattr(self,List,'$!reified')),
            nqp::if(
              nqp::islt_i(pos,nqp::elems($reified)),
              self!AT-POS-CONTAINER(pos),        # it's a hole
              nqp::if(                           # too far out, try reifying
                nqp::isconcrete(my $todo := nqp::getattr(self,List,'$!todo')),
                nqp::stmts(
                  $todo.reify-at-least(nqp::add_i(pos,1)),
                  nqp::ifnull(
                    nqp::atpos($reified,pos),    # reified ok
                    self!AT-POS-CONTAINER(pos)   # reifier didn't reach
                  )
                ),
                self!AT-POS-CONTAINER(pos)       # create an outlander
              )
            ),
            # no reified, implies no todo
            nqp::stmts(                          # create reified
              nqp::bindattr(self,List,'$!reified',nqp::create(IterationBuffer)),
              self!AT-POS-CONTAINER(pos)         # create an outlander
            )
          )
        )
    }
    method !AT-POS-CONTAINER(int $pos) is raw {
        nqp::p6bindattrinvres(
          (my $scalar := nqp::p6scalarfromdesc($!descriptor)),
          Scalar,
          '$!whence',
          -> { nqp::bindpos(nqp::getattr(self,List,'$!reified'),$pos,$scalar) }
        )
    }

    multi method ASSIGN-POS(Array:D: int $pos, Mu \assignee) {
        nqp::if(
          nqp::islt_i($pos,0),
          Failure.new(X::OutOfRange.new(
            :what($*INDEX // 'Index'),:got($pos),:range<0..^Inf>)),
          nqp::if(
            (my $reified := nqp::getattr(self,List,'$!reified')).DEFINITE,
            nqp::if(
              nqp::existspos($reified,$pos),
              (nqp::atpos($reified,$pos) = assignee),         # found it!
              nqp::if(
                nqp::islt_i($pos,nqp::elems($reified)),       # it's a hole
                (nqp::bindpos($reified,$pos,
                  nqp::p6scalarfromdesc($!descriptor)) = assignee),
                nqp::if(
                  (my $todo := nqp::getattr(self,List,'$!todo')).DEFINITE,
                  nqp::stmts(                                 # can reify
                    $todo.reify-at-least(nqp::add_i($pos,1)),
                    nqp::if(
                      nqp::existspos($reified,$pos),
                      (nqp::atpos($reified,$pos) = assignee), # reified
                      (nqp::bindpos($reified,$pos,            # outlander
                        nqp::p6scalarfromdesc($!descriptor)) = assignee),
                    )
                  ),
                  (nqp::bindpos($reified,$pos,                # outlander
                    nqp::p6scalarfromdesc($!descriptor)) = assignee)
                )
              )
            ),
            nqp::stmts(                                       # new outlander
              nqp::bindattr(self,List,'$!reified',nqp::create(IterationBuffer)),
              (nqp::bindpos(nqp::getattr(self,List,'$!reified'),$pos,
                nqp::p6scalarfromdesc($!descriptor)) = assignee)
            )
          )
        )
    }
    # because this is a very hot path, we copied the code from the int candidate
    multi method ASSIGN-POS(Array:D: Int:D $pos, Mu \assignee) {
        nqp::if(
          nqp::islt_i($pos,0),
          Failure.new(X::OutOfRange.new(
            :what($*INDEX // 'Index'),:got($pos),:range<0..^Inf>)),
          nqp::if(
            (my $reified := nqp::getattr(self,List,'$!reified')).DEFINITE,
            nqp::if(
              nqp::existspos($reified,$pos),
              (nqp::atpos($reified,$pos) = assignee),         # found it!
              nqp::if(
                nqp::islt_i($pos,nqp::elems($reified)),       # it's a hole
                (nqp::bindpos($reified,$pos,
                  nqp::p6scalarfromdesc($!descriptor)) = assignee),
                nqp::if(
                  (my $todo := nqp::getattr(self,List,'$!todo')).DEFINITE,
                  nqp::stmts(                                 # can reify
                    $todo.reify-at-least(nqp::add_i($pos,1)),
                    nqp::if(
                      nqp::existspos($reified,$pos),
                      (nqp::atpos($reified,$pos) = assignee), # reified
                      (nqp::bindpos($reified,$pos,            # outlander
                        nqp::p6scalarfromdesc($!descriptor)) = assignee),
                    )
                  ),
                  (nqp::bindpos($reified,$pos,                # outlander
                    nqp::p6scalarfromdesc($!descriptor)) = assignee)
                )
              )
            ),
            nqp::stmts(                                       # new outlander
              nqp::bindattr(self,List,'$!reified',nqp::create(IterationBuffer)),
              (nqp::bindpos(nqp::getattr(self,List,'$!reified'),$pos,
                nqp::p6scalarfromdesc($!descriptor)) = assignee)
            )
          )
        )
    }

    multi method BIND-POS(Array:D: int $pos, Mu \bindval) is raw {
        nqp::if(
          nqp::islt_i($pos,0),
          Failure.new(X::OutOfRange.new(
            :what($*INDEX // 'Index'),:got($pos),:range<0..^Inf>)),
          nqp::stmts(
            nqp::if(
              nqp::getattr(self,List,'$!reified').DEFINITE,
              nqp::if(
                (nqp::isge_i(
                  $pos,nqp::elems(nqp::getattr(self,List,'$!reified')))
                    && nqp::getattr(self,List,'$!todo').DEFINITE),
                nqp::getattr(self,List,'$!todo').reify-at-least(
                  nqp::add_i($pos,1)),
              ),
              nqp::bindattr(self,List,'$!reified',nqp::create(IterationBuffer))
            ),
            nqp::bindpos(nqp::getattr(self,List,'$!reified'),$pos,bindval)
          )
        )
    }
    # because this is a very hot path, we copied the code from the int candidate
    multi method BIND-POS(Array:D: Int:D $pos, Mu \bindval) is raw {
        nqp::if(
          nqp::islt_i($pos,0),
          Failure.new(X::OutOfRange.new(
            :what($*INDEX // 'Index'),:got($pos),:range<0..^Inf>)),
          nqp::stmts(
            nqp::if(
              nqp::getattr(self,List,'$!reified').DEFINITE,
              nqp::if(
                (nqp::isge_i(
                  $pos,nqp::elems(nqp::getattr(self,List,'$!reified')))
                    && nqp::getattr(self,List,'$!todo').DEFINITE),
                nqp::getattr(self,List,'$!todo').reify-at-least(
                  nqp::add_i($pos,1)),
              ),
              nqp::bindattr(self,List,'$!reified',nqp::create(IterationBuffer))
            ),
            nqp::bindpos(nqp::getattr(self,List,'$!reified'),$pos,bindval)
          )
        )
    }

    multi method DELETE-POS(Array:D: int $pos) is raw {
        nqp::if(
          nqp::islt_i($pos,0),
          Failure.new(X::OutOfRange.new(
            :what($*INDEX // 'Index'),:got($pos),:range<0..^Inf>)),
          nqp::if(
            (my $reified := nqp::getattr(self,List,'$!reified')).DEFINITE,
            nqp::stmts(
              nqp::if(
                (my $todo := nqp::getattr(self,List,'$!todo')).DEFINITE,
                $todo.reify-at-least(nqp::add_i($pos,1)),
              ),
              nqp::if(
                nqp::isle_i(                               # something to delete
                  $pos,my int $end = nqp::sub_i(nqp::elems($reified),1)),
                nqp::stmts(
                  (my $value := nqp::ifnull(               # save the value
                    nqp::atpos($reified,$pos),
                    self.default
                  )),
                  nqp::bindpos($reified,$pos,nqp::null),   # remove this one
                  nqp::if(
                    nqp::iseq_i($pos,$end) && nqp::not_i(nqp::defined($todo)),
                    nqp::stmts(                            # shorten from end
                      (my int $i = $pos),
                      nqp::while(
                        (nqp::isge_i(($i = nqp::sub_i($i,1)),0)
                          && nqp::not_i(nqp::existspos($reified,$i))),
                        nqp::null
                      ),
                      nqp::setelems($reified,nqp::add_i($i,1))
                    ),
                  ),
                  $value                                   # value, if any
                ),
                self.default                               # outlander
              ),
            ),
            self.default                                 # no elements
          )
        )
    }
    multi method DELETE-POS(Array:D: Int:D $pos) is raw {
        self.DELETE-POS(nqp::unbox_i($pos))
    }

    # MUST have a separate Slip variant to have it slip
    multi method push(Array:D: Slip \value) {
        self.is-lazy
          ?? X::Cannot::Lazy.new(action => 'push to').throw
          !! self!append-list(value)
    }
    multi method push(Array:D: \value) {
        nqp::if(
          self.is-lazy,
          X::Cannot::Lazy.new(action => 'push to').throw,
          nqp::stmts(
            nqp::push(
              nqp::if(
                nqp::getattr(self,List,'$!reified').DEFINITE,
                nqp::getattr(self,List,'$!reified'),
                nqp::bindattr(self,List,'$!reified',
                  nqp::create(IterationBuffer))
              ),
              nqp::assign(nqp::p6scalarfromdesc($!descriptor),value)
            ),
            self
          )
        )
    }
    multi method push(Array:D: **@values is raw) {
        self.is-lazy
          ?? X::Cannot::Lazy.new(action => 'push to').throw
          !! self!append-list(@values)
    }

    multi method append(Array:D: \value) {
        nqp::if(
          self.is-lazy,
          X::Cannot::Lazy.new(action => 'append to').throw,
          nqp::if(
            (nqp::iscont(value) || nqp::not_i(nqp::istype(value, Iterable))),
            nqp::stmts(
              nqp::push(
                nqp::if(
                  nqp::getattr(self,List,'$!reified').DEFINITE,
                  nqp::getattr(self,List,'$!reified'),
                  nqp::bindattr(self,List,'$!reified',
                    nqp::create(IterationBuffer))
                ),
                nqp::assign(nqp::p6scalarfromdesc($!descriptor),value)
              ),
              self
            ),
            self!append-list(value.list)
          )
        )
    }
    multi method append(Array:D: **@values is raw) {
        self.is-lazy
          ?? X::Cannot::Lazy.new(action => 'append to').throw
          !! self!append-list(@values)
    }
    method !append-list(@values) {
        nqp::if(
          nqp::eqaddr(
            @values.iterator.push-until-lazy(
              ArrayReificationTarget.new(
                nqp::if(
                  nqp::getattr(self,List,'$!reified').DEFINITE,
                  nqp::getattr(self,List,'$!reified'),
                  nqp::bindattr(self,List,'$!reified',
                    nqp::create(IterationBuffer))
                ),
                nqp::decont($!descriptor)
              )
            ),
            IterationEnd
          ),
          self,
          X::Cannot::Lazy.new(:action<push>,:what(self.^name)).throw
        )
    }

    multi method unshift(Array:D: Slip \value) {
        self!prepend-list(value)
    }
    multi method unshift(Array:D: \value) {
        nqp::stmts(
          nqp::unshift(
            nqp::if(
              nqp::getattr(self,List,'$!reified').DEFINITE,
              nqp::getattr(self,List,'$!reified'),
              nqp::bindattr(self,List,'$!reified',
                nqp::create(IterationBuffer))
            ),
            nqp::assign(nqp::p6scalarfromdesc($!descriptor),value)
          ),
          self
        )
    }
    multi method unshift(Array:D: **@values is raw) {
        self!prepend-list(@values)
    }
    multi method prepend(Array:D: \value) {
        nqp::if(
          (nqp::iscont(value) || nqp::not_i(nqp::istype(value, Iterable))),
          nqp::stmts(
            nqp::unshift(
              nqp::if(
                nqp::getattr(self,List,'$!reified').DEFINITE,
                nqp::getattr(self,List,'$!reified'),
                nqp::bindattr(self,List,'$!reified',
                  nqp::create(IterationBuffer))
              ),
              nqp::assign(nqp::p6scalarfromdesc($!descriptor),value)
            ),
            self
          ),
          self!prepend-list(value.list)
        )
    }
    multi method prepend(Array:D: **@values is raw) {
        self!prepend-list(@values)
    }
    method !prepend-list(@values) {
        nqp::stmts(
          nqp::if(
            nqp::getattr(self,List,'$!reified').DEFINITE,
            nqp::splice(nqp::getattr(self,List,'$!reified'), # prepend existing
              nqp::stmts(
                @values.iterator.push-all(
                  ArrayReificationTarget.new(
                    (my $containers := nqp::create(IterationBuffer)),
                    nqp::decont($!descriptor)
                  )
                ),
                $containers
              ),
              0,
              0
            ),
            @values.iterator.push-all(        # no list yet, make this it
              ArrayReificationTarget.new(
                nqp::bindattr(self,List,'$!reified',
                  nqp::create(IterationBuffer)),
                nqp::decont($!descriptor)
              )
            )
          ),
          self
        )
    }

    method pop(Array:D:) is raw is nodal {
        nqp::if(
          self.is-lazy,
          Failure.new(X::Cannot::Lazy.new(action => 'pop from')),
          nqp::if(
            (nqp::getattr(self,List,'$!reified').DEFINITE
              && nqp::elems(nqp::getattr(self,List,'$!reified'))),
            nqp::pop(nqp::getattr(self,List,'$!reified')),
            Failure.new(X::Cannot::Empty.new(:action<pop>,:what(self.^name)))
          )
        )
    }

    method shift(Array:D:) is raw is nodal {
        nqp::if(
          nqp::getattr(self,List,'$!reified').DEFINITE
            && nqp::elems(nqp::getattr(self,List,'$!reified')),
          nqp::ifnull(  # handle holes
            nqp::shift(nqp::getattr(self,List,'$!reified')),
            Nil
          ),
          nqp::if(
            (nqp::getattr(self,List,'$!todo').DEFINITE
              && nqp::getattr(self,List,'$!todo').reify-at-least(1)),
            nqp::shift(nqp::getattr(self,List,'$!reified')),
            Failure.new(X::Cannot::Empty.new(:action<shift>,:what(self.^name)))
          )
        )
    }

    my $empty := nqp::create(IterationBuffer); # splicing in without values
    #------ splice() candidates
    multi method splice(Array:D \SELF:) {
        nqp::if(
          nqp::getattr(SELF,List,'$!reified').DEFINITE,
          nqp::stmts(
            (my $result := nqp::create(SELF)),
            nqp::bindattr($result,Array,'$!descriptor',$!descriptor),
            nqp::stmts(       # transplant the internals
              nqp::bindattr($result,List,'$!reified',
                nqp::getattr(SELF,List,'$!reified')),
              nqp::if(
                nqp::getattr(SELF,List,'$!todo').DEFINITE,
                nqp::bindattr($result,List,'$!todo',
                  nqp::getattr(SELF,List,'$!todo')),
              )
            ),
            (SELF = nqp::create(SELF)),  # XXX this preserves $!descriptor ??
            $result
          ),
          nqp::p6bindattrinvres(   # nothing to return, so create new one
            nqp::create(SELF),Array,'$!descriptor',$!descriptor)
        )
    }

    #------ splice(offset) candidates
    multi method splice(Array:D: Whatever $) {
        nqp::p6bindattrinvres(     # nothing to return, so create new one
          nqp::create(self),Array,'$!descriptor',$!descriptor)
    }
    multi method splice(Array:D: Callable:D $offset) {
        self.splice($offset(self.elems))
    }
    multi method splice(Array:D: Int:D $offset) {
        nqp::if(
          $offset,
          nqp::if(
            nqp::islt_i(nqp::unbox_i($offset),0),
            self!splice-offset-fail($offset),
            nqp::if(
              (my $todo := nqp::getattr(self,List,'$!todo')).DEFINITE,
              nqp::if(
                nqp::isge_i(
                  $todo.reify-at-least($offset),nqp::unbox_i($offset)),
                self!splice-offset(nqp::unbox_i($offset)),
                self!splice-offset-fail($offset)
              ),
              nqp::if(
                (nqp::getattr(self,List,'$!reified').DEFINITE
                  && nqp::isge_i(
                    nqp::elems(nqp::getattr(self,List,'$!reified')),
                    nqp::unbox_i($offset))),
                self!splice-offset(nqp::unbox_i($offset)),
                self!splice-offset-fail($offset)
              )
            )
          ),
          self.splice       # offset 0, take the quick route out
        )
    }
    method !splice-offset(int $offset) {
        nqp::stmts(
          (my int $elems = nqp::elems(nqp::getattr(self,List,'$!reified'))),
          (my int $size  = nqp::sub_i($elems,$offset)),
          nqp::bindattr((my $result:= nqp::create(self)),List,'$!reified',
            (my $buffer := nqp::setelems(nqp::create(IterationBuffer),$size))),
          nqp::bindattr($result,Array,'$!descriptor',$!descriptor),
          (my int $i = nqp::sub_i($offset,1)),
          nqp::while(
            nqp::islt_i(($i = nqp::add_i($i,1)),$elems),
            nqp::bindpos($buffer,nqp::sub_i($i,$offset),
              nqp::atpos(nqp::getattr(self,List,'$!reified'),$i))
          ),
          nqp::splice(
            nqp::getattr(self,List,'$!reified'),$empty,$offset,$size),
          $result
        )
    }
    method !splice-offset-fail($got) {
        X::OutOfRange.new(
          :what('Offset argument to splice'), :$got, :range("0..{self.elems}")
        ).throw
    }

    #------ splice(offset,size) candidates
    multi method splice(Array:D: Whatever $, Whatever $) {
        nqp::p6bindattrinvres(     # nothing to return, so create new one
          nqp::create(self),Array,'$!descriptor',$!descriptor)
    }
    multi method splice(Array:D: Whatever $, Int:D $size) {
        self.splice(self.elems,$size)
    }
    multi method splice(Array:D: Whatever $, Callable:D $size) {
        my int $elems = self.elems;
        self.splice($elems,$size(nqp::sub_i($elems,$elems)));
    }
    multi method splice(Array:D: Callable:D $offset, Callable:D $size) {
        nqp::stmts(
          (my int $elems = self.elems),
          (my int $from  = $offset($elems)),
          self.splice($from,$size(nqp::sub_i($elems,$from)))
        )
    }
    multi method splice(Array:D: Callable:D $offset, Whatever $) {
        self.splice($offset(self.elems))
    }
    multi method splice(Array:D: Callable:D $offset, Int:D $size) {
        self.splice($offset(self.elems),$size)
    }
    multi method splice(Array:D: Int:D $offset, Whatever $) {
        self.splice($offset)
    }
    multi method splice(Array:D: Int:D $offset, Callable:D $size) {
        self.splice($offset,$size(self.elems - $offset))
    }
    multi method splice(Array:D: Int:D $offset, Int:D $size) {
        nqp::if(
          nqp::islt_i(nqp::unbox_i($offset),0),
          self!splice-offset-fail($offset),
          nqp::if(
            nqp::islt_i(nqp::unbox_i($size),0),
            self!splice-size-fail($size,$offset),
            nqp::if(
              (my $todo := nqp::getattr(self,List,'$!todo')).DEFINITE,
              nqp::if(
                nqp::isge_i(
                  $todo.reify-at-least(
                    nqp::add_i(nqp::unbox_i($offset),nqp::unbox_i($size))
                  ),nqp::unbox_i($offset)),
                self!splice-offset-size(
                  nqp::unbox_i($offset),nqp::unbox_i($size)),
                self!splice-size-fail($size,$offset)
              ),
              nqp::if(
                nqp::getattr(self,List,'$!reified').DEFINITE,
                nqp::if(
                  nqp::isge_i(
                    nqp::elems(nqp::getattr(self,List,'$!reified')),
                    nqp::unbox_i($offset)),
                  self!splice-offset-size(
                    nqp::unbox_i($offset),nqp::unbox_i($size)),
                  self!splice-size-fail($size,$offset)
                ),
                nqp::if(
                  nqp::iseq_i(nqp::unbox_i($offset),0),
                  nqp::p6bindattrinvres(     # nothing to return, create new
                    nqp::create(self),Array,'$!descriptor',$!descriptor),
                  self!splice-offset-fail($offset)
                )
              )
            )
          )
        )
    }
    method !splice-offset-size(int $offset,int $size) {
        nqp::stmts(
          (my $result := self!splice-save($offset,$size,my int $removed)),
          nqp::splice(
            nqp::getattr(self,List,'$!reified'),$empty,$offset,$removed),
          $result
        )
    }
    method !splice-save(int $offset,int $size, \removed) {
        nqp::stmts(
          (removed = nqp::if(
            nqp::isgt_i(
              nqp::add_i($offset,$size),
              nqp::elems(nqp::getattr(self,List,'$!reified'))
            ),
            nqp::sub_i(nqp::elems(nqp::getattr(self,List,'$!reified')),$offset),
            $size
          )),
          nqp::if(
            removed,
            nqp::stmts(
              nqp::bindattr((my $saved:= nqp::create(self)),List,'$!reified',
                (my $buffer :=
                  nqp::setelems(nqp::create(IterationBuffer),removed))),
              nqp::bindattr($saved,Array,'$!descriptor',$!descriptor),
              (my int $i = -1),
              nqp::while(
                nqp::islt_i(($i = nqp::add_i($i,1)),removed),
                nqp::bindpos($buffer,$i,nqp::atpos(
                  nqp::getattr(self,List,'$!reified'),nqp::add_i($offset,$i)))
              ),
              $saved
            ),
            nqp::p6bindattrinvres(     # effective size = 0, create new one
              nqp::create(self),Array,'$!descriptor',$!descriptor)
          )
        )
    }
    method !splice-size-fail($got,$offset) {
        nqp::if(
          $offset > self.elems,
          self!splice-offset-fail($offset),
          X::OutOfRange.new(
            :what('Size argument to splice'),
            :$got,
            :range("0..^{self.elems - $offset}")
          ).throw
        )
    }
    #------ splice(offset,size,array) candidates

    # we have these 9 multies to avoid infiniloop when incorrect types are
    # given to $offset/$size. Other attempts to resolve this showed 30%+
    # performance decreases
    multi method splice(Array:D: Whatever   $offset, Whatever   $size, **@new) { self.splice($offset, $size, @new) }
    multi method splice(Array:D: Whatever   $offset, Callable:D $size, **@new) { self.splice($offset, $size, @new) }
    multi method splice(Array:D: Whatever   $offset, Int:D      $size, **@new) { self.splice($offset, $size, @new) }
    multi method splice(Array:D: Callable:D $offset, Whatever   $size, **@new) { self.splice($offset, $size, @new) }
    multi method splice(Array:D: Callable:D $offset, Callable:D $size, **@new) { self.splice($offset, $size, @new) }
    multi method splice(Array:D: Callable:D $offset, Int:D      $size, **@new) { self.splice($offset, $size, @new) }
    multi method splice(Array:D: Int:D      $offset, Whatever   $size, **@new) { self.splice($offset, $size, @new) }
    multi method splice(Array:D: Int:D      $offset, Callable:D $size, **@new) { self.splice($offset, $size, @new) }
    multi method splice(Array:D: Int:D      $offset, Int:D      $size, **@new) { self.splice($offset, $size, @new) }

    multi method splice(Array:D: Whatever $, Whatever $, @new) {
        self.splice(self.elems,0,@new)
    }
    multi method splice(Array:D: Whatever $, Int:D $size, @new) {
        self.splice(self.elems,$size,@new)
    }
    multi method splice(Array:D: Whatever $, Callable:D $size, @new) {
        my int $elems = self.elems;
        self.splice($elems,$size(nqp::sub_i($elems,$elems)),@new);
    }
    multi method splice(Array:D: Callable:D $offset, Callable:D $size, @new) {
        nqp::stmts(
          (my int $elems = self.elems),
          (my int $from  = $offset($elems)),
          self.splice($from,$size(nqp::sub_i($elems,$from)),@new)
        )
    }
    multi method splice(Array:D: Callable:D $offset, Whatever $, @new) {
        nqp::stmts(
          (my int $elems = self.elems),
          (my int $from  = $offset($elems)),
          self.splice($from,nqp::sub_i($elems,$from),@new)
        )
    }
    multi method splice(Array:D: Callable:D $offset, Int:D $size, @new) {
        self.splice($offset(self.elems),$size,@new)
    }
    multi method splice(Array:D: Int:D $offset, Whatever $, @new) {
        self.splice($offset,self.elems - $offset,@new)
    }
    multi method splice(Array:D: Int:D $offset, Callable:D $size, @new) {
        self.splice($offset,$size(self.elems - $offset),@new)
    }
    multi method splice(Array:D: Int:D $offset, Int:D $size, @new) {
        nqp::if(
          nqp::islt_i(nqp::unbox_i($offset),0),
          self!splice-offset-fail($offset),
          nqp::if(
            nqp::islt_i(nqp::unbox_i($size),0),
            self!splice-size-fail($size,$offset),
            nqp::if(
              (my $todo := nqp::getattr(self,List,'$!todo')).DEFINITE,
              nqp::if(
                nqp::isge_i(
                  $todo.reify-at-least(
                    nqp::add_i(nqp::unbox_i($offset),nqp::unbox_i($size))
                  ),nqp::unbox_i($offset)),
                self!splice-offset-size-new(
                  nqp::unbox_i($offset),nqp::unbox_i($size),@new),
                self!splice-size-fail($size,$offset)
              ),
              nqp::if(
                nqp::isge_i(
                  nqp::elems(nqp::if(
                    nqp::getattr(self,List,'$!reified').DEFINITE,
                    nqp::getattr(self,List,'$!reified'),
                    nqp::bindattr(self,List,'$!reified',
                      nqp::create(IterationBuffer))
                  )),
                  nqp::unbox_i($offset),
                ),
                self!splice-offset-size-new(
                  nqp::unbox_i($offset),nqp::unbox_i($size),@new),
                self!splice-offset-fail($offset)
              )
            )
          )
        )
    }
    method !splice-offset-size-new(int $offset,int $size,@new) {
        nqp::if(
          nqp::eqaddr(@new.iterator.push-until-lazy(
            (my $new := IterationBuffer.new)),IterationEnd),
          nqp::if(      # reified all values to splice in
            (nqp::isnull($!descriptor) || nqp::eqaddr(self.of,Mu)),
            nqp::stmts( # no typecheck needed
              (my $result := self!splice-save($offset,$size,my int $removed)),
              nqp::splice(
                nqp::getattr(self,List,'$!reified'),$new,$offset,$removed),
              $result
            ),
            nqp::stmts( # typecheck the values first
              (my $expected := self.of),
              (my int $elems = nqp::elems($new)),
              (my int $i = -1),
              nqp::while(
                (nqp::islt_i(($i = nqp::add_i($i,1)),$elems)
                  && nqp::istype(nqp::atpos($new,$i),$expected)),
                nqp::null
              ),
              nqp::if(
                nqp::islt_i($i,$elems),   # exited loop because of wrong type
                X::TypeCheck::Splice.new(
                  :action<splice>,
                  :got(nqp::atpos($new,$i).WHAT),
                  :$expected
                ).throw,
                nqp::stmts(
                  ($result := self!splice-save($offset,$size,$removed)),
                  nqp::splice(
                    nqp::getattr(self,List,'$!reified'),$new,$offset,$removed),
                  $result
                )
              )
            )
          ),
          X::Cannot::Lazy.new(:action('splice in')).throw
        )
    }

    multi method tail(Array:D: $n) {
        nqp::if(
          nqp::getattr(self,List,'$!todo').DEFINITE,
          self.Any::tail($n),
          Seq.new(
            nqp::if(
              (my $reified := nqp::getattr(self,List,'$!reified')).DEFINITE
                && nqp::elems($reified),
              nqp::stmts(
                (my $iterator := Rakudo::Iterator.ReifiedArray(
                  self,
                  nqp::getattr(self,Array,'$!descriptor')
                )),
                nqp::if(
                  nqp::istype($n,Callable)
                    && nqp::isgt_i((my $skip := -($n(0).Int)),0),
                  $iterator.skip-at-least($skip),
                  nqp::unless(
                    nqp::istype($n,Whatever) || $n == Inf,
                    $iterator.skip-at-least(nqp::elems($reified) - $n)
                  )
                ),
                $iterator
              ),
              Rakudo::Iterator.Empty
            )
          )
        )
    }

    # introspection
    method name() {
        nqp::isnull($!descriptor) ?? Nil !! $!descriptor.name
    }
    method of() {
        nqp::isnull($!descriptor) ?? Mu !! $!descriptor.of
    }
    method default() {
        nqp::isnull($!descriptor) ?? Any !! $!descriptor.default
    }
    method dynamic() {
        nqp::isnull($!descriptor) ?? False !! so $!descriptor.dynamic
    }
    multi method perl(Array:D \SELF:) {
        SELF.perlseen('Array', {
             '$' x nqp::iscont(SELF)  # self is always deconted
             ~ '['
             ~ self.map({nqp::decont($_).perl}).join(', ')
             ~ ',' x (self.elems == 1 && nqp::istype(self.AT-POS(0),Iterable))
             ~ ']'
        })
    }
    multi method gist(Array:D:) {
        self.gistseen('Array', { '[' ~ self.map({.gist}).join(' ') ~ ']' } )
    }
    multi method WHICH(Array:D:) { self.Mu::WHICH }

#=============== class Array is closed in src/core/TypedArray.pm ===============

# vim: ft=perl6 expandtab sw=4