1 # This file is part of NIT ( http://www.nitlanguage.org ).
3 # Copyright 2004-2008 Jean Privat <jean@pryen.org>
5 # This file is free software, which comes along with NIT. This software is
6 # distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
7 # without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
8 # PARTICULAR PURPOSE. You can modify it is you want, provided this header
9 # is kept unaltered, and a notification of the changes is added.
10 # You are allowed to redistribute it and sell it, alone or is a part of
13 # Abstract collection classes and services.
15 # TODO specify the behavior on iterators when collections are modified.
16 module abstract_collection
20 # The root of the collection hierarchy.
22 # Collections modelize finite groups of objects, called elements.
24 # The specific behavior and representation of collections is determined
25 # by the subclasses of the hierarchy.
27 # The main service of Collection is to provide a stable `iterator`
28 # method usable to retrieve all the elements of the collection.
30 # Additional services are provided.
31 # For an implementation point of view, Collection provide a basic
32 # implementation of these services using the `iterator` method.
33 # Subclasses often provide a more efficient implementation.
35 # Because of the `iterator` method, Collections instances can use
36 # the `for` control structure:
38 # var x: Collection[U]
45 # that is equivalent with
47 # var x: Collection[U]
51 # var u = i.item # u is a U
55 interface Collection[E
]
56 # Get a new iterator on the collection.
57 fun iterator
: Iterator[E
] is abstract
59 # Is there no item in the collection?
61 # assert [1,2,3].is_empty == false
62 # assert [1..1[.is_empty == true
63 fun is_empty
: Bool do return length
== 0
65 # Number of items in the collection.
67 # assert [10,20,30].length == 3
68 # assert [20..30[.length == 10
72 for i
in self do nb
+= 1
76 # Is `item` in the collection ?
77 # Comparisons are done with ==
79 # assert [1,2,3].has(2) == true
80 # assert [1,2,3].has(9) == false
81 # assert [1..5[.has(2) == true
82 # assert [1..5[.has(9) == false
83 fun has
(item
: E
): Bool
85 for i
in self do if i
== item
then return true
89 # Is the collection contain only `item`?
90 # Comparisons are done with ==
91 # Return true if the collection is empty.
93 # assert [1,1,1].has_only(1) == true
94 # assert [1,2,3].has_only(1) == false
95 # assert [1..1].has_only(1) == true
96 # assert [1..3].has_only(1) == false
97 # assert [3..3[.has_only(1) == true # empty collection
99 # ENSURE `is_empty implies result == true`
100 fun has_only
(item
: E
): Bool
102 for i
in self do if i
!= item
then return false
106 # How many occurrences of `item` are in the collection?
107 # Comparisons are done with ==
109 # assert [10,20,10].count(10) == 2
110 fun count
(item
: E
): Int
113 for i
in self do if i
== item
then nb
+= 1
117 # Return the first item of the collection
119 # assert [1,2,3].first == 1
126 # Is the collection contains all the elements of `other`?
128 # assert [1,1,1].has_all([1]) == true
129 # assert [1,1,1].has_all([1,2]) == false
130 # assert [1,3,4,2].has_all([1..2]) == true
131 # assert [1,3,4,2].has_all([1..5]) == false
132 fun has_all
(other
: Collection[E
]): Bool
134 for x
in other
do if not has
(x
) then return false
139 # Instances of the Iterator class generates a series of elements, one at a time.
140 # They are mainly used with collections.
141 interface Iterator[E
]
144 fun item
: E
is abstract
146 # Jump to the next item.
150 # Is there a current item ?
151 fun is_ok
: Bool is abstract
153 # Iterate over `self`
154 fun iterator
: Iterator[E
] do return self
156 # Post-iteration hook.
158 # Used to inform `self` that the iteration is over.
159 # Specific iterators can use this to free some resources.
161 # Is automatically invoked at the end of `for` structures.
163 # Do nothing by default.
167 # A collection that contains only one item.
169 # Used to pass arguments by reference.
171 # Also used when one want to give asingle element when a full
172 # collection is expected
176 redef fun first
do return item
178 redef fun is_empty
do return false
180 redef fun length
do return 1
182 redef fun has
(an_item
) do return item
== an_item
184 redef fun has_only
(an_item
) do return item
== an_item
186 redef fun count
(an_item
)
188 if item
== an_item
then
195 redef fun iterator
do return new ContainerIterator[E
](self)
198 var item
: E
is writable
201 # This iterator is quite stupid since it is used for only one item.
202 private class ContainerIterator[E
]
204 redef fun item
do return _container
.item
206 redef fun next
do is_ok
= false
208 redef var is_ok
: Bool = true
210 private var container
: Container[E
]
213 # Items can be removed from this collection
214 interface RemovableCollection[E
]
221 # assert a.length == 0
224 fun clear
is abstract
226 # Remove an occucence of `item`
228 # var a = [1,2,3,1,2,3]
230 # assert a == [1,3,1,2,3]
231 fun remove
(item
: E
) is abstract
233 # Remove all occurences of `item`
235 # var a = [1,2,3,1,2,3]
237 # assert a == [1,3,1,3]
238 fun remove_all
(item
: E
) do while has
(item
) do remove
(item
)
241 # Items can be added to these collections.
242 interface SimpleCollection[E
]
243 super RemovableCollection[E
]
245 # Add an item in a collection.
249 # assert a.has(3) == true
250 # assert a.has(10) == false
252 # Ensure col.has(item)
253 fun add
(item
: E
) is abstract
255 # Add each item of `coll`.
258 # assert a.has(4) == true
259 # assert a.has(10) == false
260 fun add_all
(coll
: Collection[E
]) do for i
in coll
do add
(i
)
265 # Set is a collection without duplicates (according to `==`)
267 # var s: Set[String] = new ArraySet[String]
269 # var b = "Hel" + "lo"
272 # assert s.has(b) == true
273 interface Set[E
: Object]
274 super SimpleCollection[E
]
276 redef fun has_only
(item
)
289 redef fun count
(item
)
298 # Synonym of remove since there is only one item
299 redef fun remove_all
(item
) do remove
(item
)
301 # Equality is defined on set and means that each set contains the same elements
304 if not other
isa Set[Object] then return false
305 if other
.length
!= length
then return false
306 return has_all
(other
)
309 # Because of the law between `==` and `hash`, `hash` is redefined to be the sum of the hash of the elements
312 # 23 is a magic number empirically determined to be not so bad.
313 var res
= 23 + length
314 # Note: the order of the elements must not change the hash value.
315 # So, unlike usual hash functions, the accumulator is not combined with itself.
316 for e
in self do res
+= e
.hash
320 # Returns the union of this set with the `other` set
321 fun union
(other
: Set[E
]): Set[E
]
329 # Returns the intersection of this set with the `other` set
330 fun intersection
(other
: Set[E
]): Set[E
]
333 for v
in self do if other
.has
(v
) then nhs
.add
(v
)
337 protected fun new_set
: Set[E
] is abstract
340 # MapRead are abstract associative collections: `key` -> `item`.
341 interface MapRead[K
: Object, V
]
342 # Get the item at `key`
344 # var x = new HashMap[String, Int]
346 # assert x["four"] == 4
347 # # assert x["five"] #=> abort
349 # If the key is not in the map, `provide_default_value` is called (that aborts by default)
350 # See `get_or_null` and `get_or_default` for safe variations.
351 fun [](key
: K
): V
is abstract
353 # Get the item at `key` or null if `key` is not in the map.
355 # var x = new HashMap[String, Int]
357 # assert x.get_or_null("four") == 4
358 # assert x.get_or_null("five") == null
360 # Note: use `has_key` and `[]` if you need the distinction between a key associated with null, and no key.
361 fun get_or_null
(key
: K
): nullable V
363 if has_key
(key
) then return self[key
]
367 # Get the item at `key` or return `default` if not in map
369 # var x = new HashMap[String, Int]
371 # assert x.get_or_default("four", 40) == 4
372 # assert x.get_or_default("five", 50) == 50
374 fun get_or_default
(key
: K
, default
: V
): V
376 if has_key
(key
) then return self[key
]
380 # Alias for `keys.has`
381 fun has_key
(key
: K
): Bool do return self.keys
.has
(key
)
383 # Get a new iterator on the map.
384 fun iterator
: MapIterator[K
, V
] is abstract
386 # Return the point of view of self on the values only.
387 # Note that `self` and `values` are views on the same data;
388 # therefore any modification of one is visible on the other.
390 # var x = new HashMap[String, Int]
392 # assert x.values.has(4) == true
393 # assert x.values.has(5) == false
394 fun values
: Collection[V
] is abstract
396 # Return the point of view of self on the keys only.
397 # Note that `self` and `keys` are views on the same data;
398 # therefore any modification of one is visible on the other.
400 # var x = new HashMap[String, Int]
402 # assert x.keys.has("four") == true
403 # assert x.keys.has("five") == false
404 fun keys
: Collection[K
] is abstract
406 # Is there no item in the collection?
408 # var x = new HashMap[String, Int]
409 # assert x.is_empty == true
411 # assert x.is_empty == false
412 fun is_empty
: Bool is abstract
414 # Number of items in the collection.
416 # var x = new HashMap[String, Int]
417 # assert x.length == 0
419 # assert x.length == 1
421 # assert x.length == 2
422 fun length
: Int is abstract
424 # Called by the underling implementation of `[]` to provide a default value when a `key` has no value
425 # By default the behavior is to abort.
427 # Note: the value is returned *as is*, implementations may want to store the value in the map before returning it
429 protected fun provide_default_value
(key
: K
): V
do abort
432 # Maps are associative collections: `key` -> `item`.
434 # The main operator over maps is [].
436 # var map: Map[String, Int] = new ArrayMap[String, Int]
438 # map["one"] = 1 # Associate 'one' to '1'
439 # map["two"] = 2 # Associate 'two' to '2'
440 # assert map["one"] == 1
441 # assert map["two"] == 2
443 # Instances of maps can be used with the for structure
445 # for key, value in map do
446 # assert (key == "one" and value == 1) or (key == "two" and value == 2)
449 # The keys and values in the map can also be manipulated directly with the `keys` and `values` methods.
451 # assert map.keys.has("one") == true
452 # assert map.keys.has("tree") == false
453 # assert map.values.has(1) == true
454 # assert map.values.has(3) == false
456 interface Map[K
: Object, V
]
459 # Set the `value` at `key`.
461 # Values can then get retrieved with `[]`.
463 # var x = new HashMap[String, Int]
465 # assert x["four"] == 4
467 # If the key was associated with a value, this old value is discarded
468 # and replaced with the new one.
471 # assert x["four"] == 40
472 # assert x.values.has(4) == false
474 fun []=(key
: K
, value
: V
) is abstract
476 # Add each (key,value) of `map` into `self`.
477 # If a same key exists in `map` and `self`, then the value in self is discarded.
479 # It is the analogous of `SimpleCollection::add_all`
481 # var x = new HashMap[String, Int]
484 # var y = new HashMap[String, Int]
488 # assert x["four"] == 40
489 # assert x["five"] == 5
490 # assert x["nine"] == 90
491 fun recover_with
(map
: MapRead[K
, V
])
502 # var x = new HashMap[String, Int]
505 # assert x.keys.has("four") == false
508 fun clear
is abstract
510 redef fun values
: RemovableCollection[V
] is abstract
512 redef fun keys
: RemovableCollection[K
] is abstract
516 interface MapIterator[K
: Object, V
]
519 fun item
: V
is abstract
521 # The key of the current item.
523 fun key
: K
is abstract
525 # Jump to the next item.
529 # Is there a current item ?
530 fun is_ok
: Bool is abstract
532 # Set a new `item` at `key`.
533 #fun item=(item: E) is abstract
535 # Post-iteration hook.
537 # Used to inform `self` that the iteration is over.
538 # Specific iterators can use this to free some resources.
540 # Is automatically invoked at the end of `for` structures.
542 # Do nothing by default.
546 # Iterator on a 'keys' point of view of a map
547 class MapKeysIterator[K
: Object, V
]
549 # The original iterator
550 var original_iterator
: MapIterator[K
, V
]
552 redef fun is_ok
do return self.original_iterator
.is_ok
553 redef fun next
do self.original_iterator
.next
554 redef fun item
do return self.original_iterator
.key
557 # Iterator on a 'values' point of view of a map
558 class MapValuesIterator[K
: Object, V
]
560 # The original iterator
561 var original_iterator
: MapIterator[K
, V
]
563 redef fun is_ok
do return self.original_iterator
.is_ok
564 redef fun next
do self.original_iterator
.next
565 redef fun item
do return self.original_iterator
.item
568 # Sequences are indexed collections.
569 # The first item is 0. The last is `length-1`.
571 # The order is the main caracteristic of sequence
572 # and all concrete implementation of sequences are basically interchangeable.
573 interface SequenceRead[E
]
576 # Get the first item.
577 # Is equivalent with `self[0]`.
580 # assert a.first == 1
582 # REQUIRE `not is_empty`
585 assert not_empty
: not is_empty
589 # Return the index-th element of the sequence.
590 # The first element is 0 and the last is `length-1`
591 # If index is invalid, the program aborts
598 # REQUIRE `index >= 0 and index < length`
599 fun [](index
: Int): E
is abstract
602 # Is equivalent with `self[length-1]`.
607 # REQUIRE `not is_empty`
610 assert not_empty
: not is_empty
611 return self[length-1
]
614 # The index of the first occurrence of `item`.
615 # Return -1 if `item` is not found.
616 # Comparison is done with `==`.
618 # var a = [10,20,30,10,20,30]
619 # assert a.index_of(20) == 1
620 # assert a.index_of(40) == -1
621 fun index_of
(item
: E
): Int do return index_of_from
(item
, 0)
623 # The index of the last occurrence of `item`.
624 # Return -1 if `item` is not found.
625 # Comparison is done with `==`.
627 # var a = [10,20,30,10,20,30]
628 # assert a.last_index_of(20) == 4
629 # assert a.last_index_of(40) == -1
630 fun last_index_of
(item
: E
): Int do return last_index_of_from
(item
, length-1
)
632 # The index of the first occurrence of `item`, starting from pos.
633 # Return -1 if `item` is not found.
634 # Comparison is done with `==`.
636 # var a = [10,20,30,10,20,30]
637 # assert a.index_of_from(20, 3) == 4
638 # assert a.index_of_from(20, 4) == 4
639 # assert a.index_of_from(20, 5) == -1
640 fun index_of_from
(item
: E
, pos
: Int): Int
645 if p
>=pos
and i
.item
== item
then return i
.index
652 # The index of the last occurrence of `item` starting from `pos` and decrementing.
653 # Return -1 if `item` is not found.
654 # Comparison is done with `==`.
656 # var a = [10,20,30,10,20,30]
657 # assert a.last_index_of_from(20, 2) == 1
658 # assert a.last_index_of_from(20, 1) == 1
659 # assert a.last_index_of_from(20, 0) == -1
660 fun last_index_of_from
(item
: E
, pos
: Int): Int
667 if i
.item
== item
then res
= p
674 # Two sequences are equals if they have the same items in the same order.
676 # var a = new List[Int]
680 # assert a == [1,2,3]
681 # assert a != [1,3,2]
684 if not o
isa SequenceRead[nullable Object] then return false
686 if o
.length
!= l
then return false
689 if self[i
] != o
[i
] then return false
695 # Because of the law between `==` and `hash`, `hash` is redefined to be the sum of the hash of the elements
698 # The 17 and 2/3 magic numbers were determined empirically.
699 # Note: the standard hash functions djb2, sbdm and fnv1 were also
700 # tested but were comparable (or worse).
701 var res
= 17 + length
704 if e
!= null then res
+= e
.hash
709 redef fun iterator
: IndexedIterator[E
] is abstract
711 # Gets a new Iterator starting at position `pos`
713 # var iter = [10,20,30,40,50].iterator_from(2)
714 # assert iter.to_a == [30, 40, 50]
715 fun iterator_from
(pos
: Int): IndexedIterator[E
]
718 while pos
> 0 and res
.is_ok
do
725 # Gets an iterator starting at the end and going backwards
727 # var reviter = [1,2,3].reverse_iterator
728 # assert reviter.to_a == [3,2,1]
729 fun reverse_iterator
: IndexedIterator[E
] is abstract
731 # Gets an iterator on the chars of self starting from `pos`
733 # var reviter = [10,20,30,40,50].reverse_iterator_from(2)
734 # assert reviter.to_a == [30,20,10]
735 fun reverse_iterator_from
(pos
: Int): IndexedIterator[E
]
737 var res
= reverse_iterator
738 while pos
> 0 and res
.is_ok
do
746 # Sequence are indexed collection.
747 # The first item is 0. The last is `length-1`.
748 interface Sequence[E
]
749 super SequenceRead[E
]
750 super SimpleCollection[E
]
752 # Set the first item.
753 # Is equivalent with `self[0] = item`.
757 # assert a == [10,2,3]
759 do self[0] = item
end
762 # Is equivalent with `self[length-1] = item`.
766 # assert a == [1,2,10]
768 # If the sequence is empty, `last=` is equivalent with `self[0]=` (thus with `first=`)
770 # var b = new Array[Int]
783 # A synonym of `push`
784 redef fun add
(e
) do push
(e
)
786 # Add an item after the last one.
791 # assert a == [1,2,3,10,20]
792 fun push
(e
: E
) is abstract
794 # Add each item of `coll` after the last.
798 # assert a == [1,2,3,7,8,9]
801 fun append
(coll
: Collection[E
]) do add_all
(coll
)
803 # Remove the last item.
810 # REQUIRE `not is_empty`
811 fun pop
: E
is abstract
813 # Add an item before the first one.
818 # assert a == [20,10,1,2,3]
819 fun unshift
(e
: E
) is abstract
821 # Add all items of `coll` before the first one.
825 # assert a == [7,8,9,1,2,3]
827 # Alias of `insert_at(coll, 0)`
828 fun prepend
(coll
: Collection[E
]) do insert_all
(coll
, 0)
830 # Remove the first item.
831 # The second item thus become the first.
834 # assert a.shift == 1
835 # assert a.shift == 2
838 # REQUIRE `not is_empty`
839 fun shift
: E
is abstract
841 # Set the `item` at `index`.
845 # assert a == [10,200,30]
847 # like with `[]`, index should be between `0` and `length-1`
848 # However, if `index==length`, `[]=` works like `push`.
851 # assert a == [10,200,30,400]
853 # REQUIRE `index >= 0 and index <= length`
854 fun []=(index
: Int, item
: E
) is abstract
856 # Insert an element at a given position, following elements are shifted.
858 # var a = [10, 20, 30, 40]
860 # assert a == [10, 20, 100, 30, 40]
862 # REQUIRE `index >= 0 and index <= length`
863 # ENSURE `self[index] == item`
864 fun insert
(item
: E
, index
: Int) is abstract
866 # Insert all elements at a given position, following elements are shifted.
868 # var a = [10, 20, 30, 40]
869 # a.insert_all([100..102], 2)
870 # assert a == [10, 20, 100, 101, 102, 30, 40]
872 # REQUIRE `index >= 0 and index <= length`
873 # ENSURE `self[index] == coll.first`
874 fun insert_all
(coll
: Collection[E
], index
: Int)
876 assert index
>= 0 and index
< length
877 if index
== length
then
886 # Remove the item at `index` and shift all following elements
890 # assert a == [10,30]
892 # REQUIRE `index >= 0 and index < length`
893 fun remove_at
(index
: Int) is abstract
896 # Iterators on indexed collections.
897 interface IndexedIterator[E
]
899 # The index of the current item.
900 fun index
: Int is abstract
903 # Associative arrays that internally uses couples to represent each (key, value) pairs.
904 # This is an helper class that some specific implementation of Map may implements.
905 interface CoupleMap[K
: Object, V
]
908 # Return the couple of the corresponding key
909 # Return null if the key is no associated element
910 protected fun couple_at
(key
: K
): nullable Couple[K
, V
] is abstract
912 # Return a new iteralot on all couples
913 # Used to provide `iterator` and others
914 protected fun couple_iterator
: Iterator[Couple[K
,V
]] is abstract
916 redef fun iterator
do return new CoupleMapIterator[K
,V
](couple_iterator
)
920 var c
= couple_at
(key
)
922 return provide_default_value
(key
)
929 # Iterator on CoupleMap
931 # Actually it is a wrapper around an iterator of the internal array of the map.
932 private class CoupleMapIterator[K
: Object, V
]
933 super MapIterator[K
, V
]
934 redef fun item
do return _iter
.item
.second
936 #redef fun item=(e) do _iter.item.second = e
938 redef fun key
do return _iter
.item
.first
940 redef fun is_ok
do return _iter
.is_ok
947 private var iter
: Iterator[Couple[K
,V
]]
950 # Some tools ###################################################################
952 # Two objects in a simple structure.
955 # The first element of the couple.
956 var first
: F
is writable
958 # The second element of the couple.
959 var second
: S
is writable