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.
39 # var x: Collection[U]
47 # that is equivalent with the following:
50 # var x: Collection[U]
54 # var u = i.item # u is a U
59 interface Collection[E
]
60 # Get a new iterator on the collection.
61 fun iterator
: Iterator[E
] is abstract
63 # Is there no item in the collection?
65 # assert [1,2,3].is_empty == false
66 # assert [1..1[.is_empty == true
67 fun is_empty
: Bool do return length
== 0
69 # Alias for `not is_empty`.
71 # Some people prefer to have conditions grammatically easier to read.
73 # assert [1,2,3].not_empty == true
74 # assert [1..1[.not_empty == false
75 fun not_empty
: Bool do return not self.is_empty
77 # Number of items in the collection.
79 # assert [10,20,30].length == 3
80 # assert [20..30[.length == 10
84 for i
in self do nb
+= 1
88 # Is `item` in the collection ?
89 # Comparisons are done with ==
91 # assert [1,2,3].has(2) == true
92 # assert [1,2,3].has(9) == false
93 # assert [1..5[.has(2) == true
94 # assert [1..5[.has(9) == false
95 fun has
(item
: E
): Bool
97 for i
in self do if i
== item
then return true
101 # Is the collection contain only `item`?
102 # Comparisons are done with ==
103 # Return true if the collection is empty.
105 # assert [1,1,1].has_only(1) == true
106 # assert [1,2,3].has_only(1) == false
107 # assert [1..1].has_only(1) == true
108 # assert [1..3].has_only(1) == false
109 # assert [3..3[.has_only(1) == true # empty collection
111 # ENSURE `is_empty implies result == true`
112 fun has_only
(item
: E
): Bool
114 for i
in self do if i
!= item
then return false
118 # How many occurrences of `item` are in the collection?
119 # Comparisons are done with ==
121 # assert [10,20,10].count(10) == 2
122 fun count
(item
: E
): Int
125 for i
in self do if i
== item
then nb
+= 1
129 # Return the first item of the collection
131 # assert [1,2,3].first == 1
138 # Does the collection contain at least each element of `other`?
140 # assert [1,3,4,2].has_all([1..2]) == true
141 # assert [1,3,4,2].has_all([1..5]) == false
143 # Repeated elements in the collections are not considered.
145 # assert [1,1,1].has_all([1]) == true
146 # assert [1..5].has_all([1,1,1]) == true
148 # Note that the default implementation is general and correct for any lawful Collections.
149 # It is memory-efficient but relies on `has` so may be CPU-inefficient for some kind of collections.
150 fun has_all
(other
: Collection[E
]): Bool
152 for x
in other
do if not has
(x
) then return false
156 # Does the collection contain exactly all the elements of `other`?
158 # The same elements must be present in both `self` and `other`,
159 # but the order of the elements in the collections are not considered.
161 # assert [1..3].has_exactly([3,1,2]) == true # the same elements
162 # assert [1..3].has_exactly([3,1]) == false # 2 is not in the array
163 # assert [1..2].has_exactly([3,1,2]) == false # 3 is not in the range
165 # Repeated elements must be present in both collections in the same amount.
166 # So basically it is a multi-set comparison.
168 # assert [1,2,3,2].has_exactly([1,2,2,3]) == true # the same elements
169 # assert [1,2,3,2].has_exactly([1,2,3]) == false # more 2 in the first array
170 # assert [1,2,3].has_exactly([1,2,2,3]) == false # more 2 in the second array
172 # Note that the default implementation is general and correct for any lawful Collections.
173 # It is memory-efficient but relies on `count` so may be CPU-inefficient for some kind of collections.
174 fun has_exactly
(other
: Collection[E
]): Bool
176 if length
!= other
.length
then return false
177 for e
in self do if self.count
(e
) != other
.count
(e
) then return false
182 # Instances of the Iterator class generates a series of elements, one at a time.
183 # They are mainly used with collections.
184 interface Iterator[E
]
187 fun item
: E
is abstract
189 # Jump to the next item.
193 # Is there a current item ?
194 fun is_ok
: Bool is abstract
196 # Iterate over `self`
197 fun iterator
: Iterator[E
] do return self
199 # Post-iteration hook.
201 # Used to inform `self` that the iteration is over.
202 # Specific iterators can use this to free some resources.
204 # Is automatically invoked at the end of `for` structures.
206 # Do nothing by default.
210 # A collection that contains only one item.
212 # Used to pass arguments by reference.
214 # Also used when one want to give a single element when a full
215 # collection is expected
219 redef fun first
do return item
221 redef fun is_empty
do return false
223 redef fun length
do return 1
225 redef fun has
(an_item
) do return item
== an_item
227 redef fun has_only
(an_item
) do return item
== an_item
229 redef fun count
(an_item
)
231 if item
== an_item
then
238 redef fun iterator
do return new ContainerIterator[E
](self)
241 var item
: E
is writable
244 # This iterator is quite stupid since it is used for only one item.
245 private class ContainerIterator[E
]
247 redef fun item
do return _container
.item
249 redef fun next
do is_ok
= false
251 redef var is_ok
: Bool = true
253 var container
: Container[E
]
256 # Items can be removed from this collection
257 interface RemovableCollection[E
]
264 # assert a.length == 0
267 fun clear
is abstract
269 # Remove an occucence of `item`
271 # var a = [1,2,3,1,2,3]
273 # assert a == [1,3,1,2,3]
274 fun remove
(item
: E
) is abstract
276 # Remove all occurences of `item`
278 # var a = [1,2,3,1,2,3]
280 # assert a == [1,3,1,3]
281 fun remove_all
(item
: E
) do while has
(item
) do remove
(item
)
284 # Items can be added to these collections.
285 interface SimpleCollection[E
]
286 super RemovableCollection[E
]
288 # Add an item in a collection.
292 # assert a.has(3) == true
293 # assert a.has(10) == false
295 # Ensure col.has(item)
296 fun add
(item
: E
) is abstract
298 # Add each item of `coll`.
301 # assert a.has(4) == true
302 # assert a.has(10) == false
303 fun add_all
(coll
: Collection[E
]) do for i
in coll
do add
(i
)
308 # Set is a collection without duplicates (according to `==`)
310 # var s: Set[String] = new ArraySet[String]
312 # var b = "Hel" + "lo"
315 # assert s.has(b) == true
317 super SimpleCollection[E
]
319 redef fun has_only
(item
)
332 redef fun count
(item
)
341 # Synonym of remove since there is only one item
342 redef fun remove_all
(item
) do remove
(item
)
344 # Equality is defined on set and means that each set contains the same elements
347 if not other
isa Set[Object] then return false
348 if other
.length
!= length
then return false
349 return has_all
(other
)
352 # Because of the law between `==` and `hash`, `hash` is redefined to be the sum of the hash of the elements
355 # 23 is a magic number empirically determined to be not so bad.
356 var res
= 23 + length
357 # Note: the order of the elements must not change the hash value.
358 # So, unlike usual hash functions, the accumulator is not combined with itself.
359 for e
in self do res
+= e
.hash
363 # Returns the union of this set with the `other` set
364 fun union
(other
: Set[E
]): Set[E
]
372 # Returns the intersection of this set with the `other` set
373 fun intersection
(other
: Set[E
]): Set[E
]
376 for v
in self do if other
.has
(v
) then nhs
.add
(v
)
380 # Returns a new instance of `Set`.
382 # Depends on the subclass, mainly used for copy services
383 # like `union` or `intersection`.
384 protected fun new_set
: Set[E
] is abstract
387 # MapRead are abstract associative collections: `key` -> `item`.
388 interface MapRead[K
, V
]
389 # Get the item at `key`
391 # var x = new HashMap[String, Int]
393 # assert x["four"] == 4
394 # # assert x["five"] #=> abort
396 # If the key is not in the map, `provide_default_value` is called (that aborts by default)
397 # See `get_or_null` and `get_or_default` for safe variations.
398 fun [](key
: K
): V
is abstract
400 # Get the item at `key` or null if `key` is not in the map.
402 # var x = new HashMap[String, Int]
404 # assert x.get_or_null("four") == 4
405 # assert x.get_or_null("five") == null
407 # Note: use `has_key` and `[]` if you need the distinction between a key associated with null, and no key.
408 fun get_or_null
(key
: K
): nullable V
410 if has_key
(key
) then return self[key
]
414 # Get the item at `key` or return `default` if not in map
416 # var x = new HashMap[String, Int]
418 # assert x.get_or_default("four", 40) == 4
419 # assert x.get_or_default("five", 50) == 50
421 fun get_or_default
(key
: K
, default
: V
): V
423 if has_key
(key
) then return self[key
]
427 # Is there an item associated with `key`?
429 # var x = new HashMap[String, Int]
431 # assert x.has_key("four") == true
432 # assert x.has_key("five") == false
434 # By default it is a synonymous to `keys.has` but could be redefined with a direct implementation.
435 fun has_key
(key
: K
): Bool do return self.keys
.has
(key
)
437 # Get a new iterator on the map.
438 fun iterator
: MapIterator[K
, V
] is abstract
440 # Return the point of view of self on the values only.
441 # Note that `self` and `values` are views on the same data;
442 # therefore any modification of one is visible on the other.
444 # var x = new HashMap[String, Int]
446 # assert x.values.has(4) == true
447 # assert x.values.has(5) == false
448 fun values
: Collection[V
] is abstract
450 # Return the point of view of self on the keys only.
451 # Note that `self` and `keys` are views on the same data;
452 # therefore any modification of one is visible on the other.
454 # var x = new HashMap[String, Int]
456 # assert x.keys.has("four") == true
457 # assert x.keys.has("five") == false
458 fun keys
: Collection[K
] is abstract
460 # Is there no item in the collection?
462 # var x = new HashMap[String, Int]
463 # assert x.is_empty == true
465 # assert x.is_empty == false
466 fun is_empty
: Bool is abstract
468 # Number of items in the collection.
470 # var x = new HashMap[String, Int]
471 # assert x.length == 0
473 # assert x.length == 1
475 # assert x.length == 2
476 fun length
: Int is abstract
478 # Called by the underling implementation of `[]` to provide a default value when a `key` has no value
479 # By default the behavior is to abort.
481 # Note: the value is returned *as is*, implementations may want to store the value in the map before returning it
483 protected fun provide_default_value
(key
: K
): V
do abort
485 # Does `self` and `other` have the same keys associated with the same values?
488 # var a = new HashMap[String, Int]
489 # var b = new ArrayMap[Object, Numeric]
500 if not other
isa MapRead[nullable Object, nullable Object] then return false
501 if other
.length
!= self.length
then return false
503 if not other
.has_key
(k
) then return false
504 if other
[k
] != v
then return false
509 # A hashcode based on the hashcode of the keys and the values.
512 # var a = new HashMap[String, Int]
513 # var b = new ArrayMap[Object, Numeric]
516 # assert a.hash == b.hash
522 if k
!= null then res
+= k
.hash
* 7
523 if v
!= null then res
+= v
.hash
* 11
529 # Maps are associative collections: `key` -> `item`.
531 # The main operator over maps is [].
533 # var map: Map[String, Int] = new ArrayMap[String, Int]
535 # map["one"] = 1 # Associate 'one' to '1'
536 # map["two"] = 2 # Associate 'two' to '2'
537 # assert map["one"] == 1
538 # assert map["two"] == 2
540 # Instances of maps can be used with the for structure
542 # for key, value in map do
543 # assert (key == "one" and value == 1) or (key == "two" and value == 2)
546 # The keys and values in the map can also be manipulated directly with the `keys` and `values` methods.
548 # assert map.keys.has("one") == true
549 # assert map.keys.has("tree") == false
550 # assert map.values.has(1) == true
551 # assert map.values.has(3) == false
556 # Set the `value` at `key`.
558 # Values can then get retrieved with `[]`.
560 # var x = new HashMap[String, Int]
562 # assert x["four"] == 4
564 # If the key was associated with a value, this old value is discarded
565 # and replaced with the new one.
568 # assert x["four"] == 40
569 # assert x.values.has(4) == false
571 fun []=(key
: K
, value
: V
) is abstract
573 # Add each (key,value) of `map` into `self`.
574 # If a same key exists in `map` and `self`, then the value in self is discarded.
576 # It is the analogous of `SimpleCollection::add_all`
578 # var x = new HashMap[String, Int]
581 # var y = new HashMap[String, Int]
585 # assert x["four"] == 40
586 # assert x["five"] == 5
587 # assert x["nine"] == 90
588 fun recover_with
(map
: MapRead[K
, V
])
599 # var x = new HashMap[String, Int]
602 # assert x.keys.has("four") == false
605 fun clear
is abstract
607 redef fun values
: RemovableCollection[V
] is abstract
609 redef fun keys
: RemovableCollection[K
] is abstract
613 interface MapIterator[K
, V
]
616 fun item
: V
is abstract
618 # The key of the current item.
620 fun key
: K
is abstract
622 # Jump to the next item.
626 # Is there a current item ?
627 fun is_ok
: Bool is abstract
629 # Set a new `item` at `key`.
630 #fun item=(item: E) is abstract
632 # Post-iteration hook.
634 # Used to inform `self` that the iteration is over.
635 # Specific iterators can use this to free some resources.
637 # Is automatically invoked at the end of `for` structures.
639 # Do nothing by default.
643 # Iterator on a 'keys' point of view of a map
644 class MapKeysIterator[K
, V
]
646 # The original iterator
647 var original_iterator
: MapIterator[K
, V
]
649 redef fun is_ok
do return self.original_iterator
.is_ok
650 redef fun next
do self.original_iterator
.next
651 redef fun item
do return self.original_iterator
.key
654 # Iterator on a 'values' point of view of a map
655 class MapValuesIterator[K
, V
]
657 # The original iterator
658 var original_iterator
: MapIterator[K
, V
]
660 redef fun is_ok
do return self.original_iterator
.is_ok
661 redef fun next
do self.original_iterator
.next
662 redef fun item
do return self.original_iterator
.item
665 # Sequences are indexed collections.
666 # The first item is 0. The last is `length-1`.
668 # The order is the main caracteristic of sequence
669 # and all concrete implementation of sequences are basically interchangeable.
670 interface SequenceRead[E
]
673 # Get the first item.
674 # Is equivalent with `self[0]`.
677 # assert a.first == 1
679 # REQUIRE `not is_empty`
682 assert not_empty
: not is_empty
686 # Return the index-th element of the sequence.
687 # The first element is 0 and the last is `length-1`
688 # If index is invalid, the program aborts
695 # REQUIRE `index >= 0 and index < length`
696 fun [](index
: Int): E
is abstract
699 # Is equivalent with `self[length-1]`.
704 # REQUIRE `not is_empty`
707 assert not_empty
: not is_empty
708 return self[length-1
]
711 # The index of the first occurrence of `item`.
712 # Return -1 if `item` is not found.
713 # Comparison is done with `==`.
715 # var a = [10,20,30,10,20,30]
716 # assert a.index_of(20) == 1
717 # assert a.index_of(40) == -1
718 fun index_of
(item
: E
): Int do return index_of_from
(item
, 0)
720 # The index of the last occurrence of `item`.
721 # Return -1 if `item` is not found.
722 # Comparison is done with `==`.
724 # var a = [10,20,30,10,20,30]
725 # assert a.last_index_of(20) == 4
726 # assert a.last_index_of(40) == -1
727 fun last_index_of
(item
: E
): Int do return last_index_of_from
(item
, length-1
)
729 # The index of the first occurrence of `item`, starting from pos.
730 # Return -1 if `item` is not found.
731 # Comparison is done with `==`.
733 # var a = [10,20,30,10,20,30]
734 # assert a.index_of_from(20, 3) == 4
735 # assert a.index_of_from(20, 4) == 4
736 # assert a.index_of_from(20, 5) == -1
737 fun index_of_from
(item
: E
, pos
: Int): Int
742 if p
>=pos
and i
.item
== item
then return i
.index
749 # The index of the last occurrence of `item` starting from `pos` and decrementing.
750 # Return -1 if `item` is not found.
751 # Comparison is done with `==`.
753 # var a = [10,20,30,10,20,30]
754 # assert a.last_index_of_from(20, 2) == 1
755 # assert a.last_index_of_from(20, 1) == 1
756 # assert a.last_index_of_from(20, 0) == -1
757 fun last_index_of_from
(item
: E
, pos
: Int): Int
764 if i
.item
== item
then res
= p
771 # Two sequences are equals if they have the same items in the same order.
773 # var a = new List[Int]
777 # assert a == [1,2,3]
778 # assert a != [1,3,2]
781 if not o
isa SequenceRead[nullable Object] then return false
783 if o
.length
!= l
then return false
786 if self[i
] != o
[i
] then return false
792 # Because of the law between `==` and `hash`, `hash` is redefined to be the sum of the hash of the elements
795 # The 17 and 2/3 magic numbers were determined empirically.
796 # Note: the standard hash functions djb2, sbdm and fnv1 were also
797 # tested but were comparable (or worse).
798 var res
= 17 + length
801 if e
!= null then res
+= e
.hash
806 redef fun iterator
: IndexedIterator[E
] is abstract
808 # Gets a new Iterator starting at position `pos`
810 # var iter = [10,20,30,40,50].iterator_from(2)
811 # assert iter.to_a == [30, 40, 50]
812 fun iterator_from
(pos
: Int): IndexedIterator[E
]
815 while pos
> 0 and res
.is_ok
do
822 # Gets an iterator starting at the end and going backwards
824 # var reviter = [1,2,3].reverse_iterator
825 # assert reviter.to_a == [3,2,1]
826 fun reverse_iterator
: IndexedIterator[E
] is abstract
828 # Gets an iterator on the chars of self starting from `pos`
830 # var reviter = [10,20,30,40,50].reverse_iterator_from(2)
831 # assert reviter.to_a == [30,20,10]
832 fun reverse_iterator_from
(pos
: Int): IndexedIterator[E
]
834 var res
= reverse_iterator
835 while pos
> 0 and res
.is_ok
do
843 # Sequence are indexed collection.
844 # The first item is 0. The last is `length-1`.
845 interface Sequence[E
]
846 super SequenceRead[E
]
847 super SimpleCollection[E
]
849 # Set the first item.
850 # Is equivalent with `self[0] = item`.
854 # assert a == [10,2,3]
856 do self[0] = item
end
859 # Is equivalent with `self[length-1] = item`.
863 # assert a == [1,2,10]
865 # If the sequence is empty, `last=` is equivalent with `self[0]=` (thus with `first=`)
867 # var b = new Array[Int]
880 # A synonym of `push`
881 redef fun add
(e
) do push
(e
)
883 # Add an item after the last one.
888 # assert a == [1,2,3,10,20]
889 fun push
(e
: E
) is abstract
891 # Add each item of `coll` after the last.
895 # assert a == [1,2,3,7,8,9]
898 fun append
(coll
: Collection[E
]) do add_all
(coll
)
900 # Remove the last item.
907 # REQUIRE `not is_empty`
908 fun pop
: E
is abstract
910 # Add an item before the first one.
915 # assert a == [20,10,1,2,3]
916 fun unshift
(e
: E
) is abstract
918 # Add all items of `coll` before the first one.
922 # assert a == [7,8,9,1,2,3]
924 # Alias of `insert_at(coll, 0)`
925 fun prepend
(coll
: Collection[E
]) do insert_all
(coll
, 0)
927 # Remove the first item.
928 # The second item thus become the first.
931 # assert a.shift == 1
932 # assert a.shift == 2
935 # REQUIRE `not is_empty`
936 fun shift
: E
is abstract
938 # Set the `item` at `index`.
942 # assert a == [10,200,30]
944 # like with `[]`, index should be between `0` and `length-1`
945 # However, if `index==length`, `[]=` works like `push`.
948 # assert a == [10,200,30,400]
950 # REQUIRE `index >= 0 and index <= length`
951 fun []=(index
: Int, item
: E
) is abstract
953 # Insert an element at a given position, following elements are shifted.
955 # var a = [10, 20, 30, 40]
957 # assert a == [10, 20, 100, 30, 40]
959 # REQUIRE `index >= 0 and index <= length`
960 # ENSURE `self[index] == item`
961 fun insert
(item
: E
, index
: Int) is abstract
963 # Insert all elements at a given position, following elements are shifted.
965 # var a = [10, 20, 30, 40]
966 # a.insert_all([100..102], 2)
967 # assert a == [10, 20, 100, 101, 102, 30, 40]
969 # REQUIRE `index >= 0 and index <= length`
970 # ENSURE `self[index] == coll.first`
971 fun insert_all
(coll
: Collection[E
], index
: Int)
973 assert index
>= 0 and index
< length
974 if index
== length
then
983 # Remove the item at `index` and shift all following elements
987 # assert a == [10,30]
989 # REQUIRE `index >= 0 and index < length`
990 fun remove_at
(index
: Int) is abstract
993 # Iterators on indexed collections.
994 interface IndexedIterator[E
]
996 # The index of the current item.
997 fun index
: Int is abstract
1000 # Associative arrays that internally uses couples to represent each (key, value) pairs.
1001 # This is an helper class that some specific implementation of Map may implements.
1002 interface CoupleMap[K
, V
]
1005 # Return the couple of the corresponding key
1006 # Return null if the key is no associated element
1007 protected fun couple_at
(key
: K
): nullable Couple[K
, V
] is abstract
1009 # Return a new iteralot on all couples
1010 # Used to provide `iterator` and others
1011 protected fun couple_iterator
: Iterator[Couple[K
,V
]] is abstract
1013 redef fun iterator
do return new CoupleMapIterator[K
,V
](couple_iterator
)
1017 var c
= couple_at
(key
)
1019 return provide_default_value
(key
)
1025 redef fun has_key
(key
) do return couple_at
(key
) != null
1028 # Iterator on CoupleMap
1030 # Actually it is a wrapper around an iterator of the internal array of the map.
1031 private class CoupleMapIterator[K
, V
]
1032 super MapIterator[K
, V
]
1033 redef fun item
do return _iter
.item
.second
1035 #redef fun item=(e) do _iter.item.second = e
1037 redef fun key
do return _iter
.item
.first
1039 redef fun is_ok
do return _iter
.is_ok
1046 var iter
: Iterator[Couple[K
,V
]]
1049 # Some tools ###################################################################
1051 # Two objects in a simple structure.
1054 # The first element of the couple.
1055 var first
: F
is writable
1057 # The second element of the couple.
1058 var second
: S
is writable