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
: nullable Object): 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
: nullable Object): 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
: nullable Object): 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[nullable Object]): 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[nullable Object]): 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 # Iterators generate a series of elements, one at a time.
184 # They are mainly used with collections and obtained from `Collection::iterator`.
185 interface Iterator[E
]
188 fun item
: E
is abstract
190 # Jump to the next item.
194 # Jump to the next item `step` times.
197 # var i = [11, 22, 33, 44].iterator
198 # assert i.item == 11
200 # assert i.item == 33
203 # `next_by` should be used instead of looping on `next` because is takes care
204 # of stopping if the end of iteration is reached prematurely whereas a loop of
205 # `next` will abort because of the precondition on `is_ok`.
212 # If `step` is negative, this method aborts.
213 # But specific subclasses can change this and do something more meaningful instead.
216 fun next_by
(step
: Int)
219 while is_ok
and step
> 0 do
225 # Is there a current item ?
226 fun is_ok
: Bool is abstract
228 # Iterate over `self`
229 fun iterator
: Iterator[E
] do return self
231 # Pre-iteration hook.
233 # Used to inform `self` that the iteration is starting.
234 # Specific iterators can use this to prepare some resources.
236 # Is automatically invoked at the beginning of `for` structures.
238 # Do nothing by default.
241 # Post-iteration hook.
243 # Used to inform `self` that the iteration is over.
244 # Specific iterators can use this to free some resources.
246 # Is automatically invoked at the end of `for` structures.
248 # Do nothing by default.
251 # A decorator around `self` that advance self a given number of steps instead of one.
254 # var i = [11, 22, 33, 44, 55].iterator
255 # var i2 = i.to_step(2)
257 # assert i2.item == 11
259 # assert i2.item == 33
261 # assert i.item == 33
263 fun to_step
(step
: Int): Iterator[E
] do return new StepIterator[E
](self, step
)
266 # A basic helper class to specialize specific Iterator decorators
267 abstract class IteratorDecorator[E
]
270 # The underling iterator
271 protected var real
: Iterator[E
]
273 redef fun is_ok
do return real
.is_ok
274 redef fun item
do return real
.item
275 redef fun finish
do real
.finish
276 redef fun next
do real
.next
277 redef fun next_by
(step
) do real
.next_by
(step
)
280 # A decorator that advance a given number of steps
281 private class StepIterator[E
]
282 super IteratorDecorator[E
]
285 redef fun next
do real
.next_by
(step
)
286 redef fun next_by
(step
) do real
.next_by
(step
* self.step
)
289 # A collection that contains only one item.
291 # Used to pass arguments by reference.
293 # Also used when one want to give a single element when a full
294 # collection is expected
298 redef fun first
do return item
300 redef fun is_empty
do return false
302 redef fun length
do return 1
304 redef fun has
(an_item
) do return item
== an_item
306 redef fun has_only
(an_item
) do return item
== an_item
308 redef fun count
(an_item
)
310 if item
== an_item
then
317 redef fun iterator
do return new RefIterator[E
](self)
320 var item
: E
is writable
323 # This iterator is quite stupid since it is used for only one item.
324 private class RefIterator[E
]
326 redef fun item
do return _container
.item
328 redef fun next
do is_ok
= false
330 redef var is_ok
= true
332 var container
: Ref[E
]
335 # Items can be removed from this collection
336 interface RemovableCollection[E
]
343 # assert a.length == 0
346 fun clear
is abstract
348 # Remove an occurrence of `item`
350 # var a = [1,2,3,1,2,3]
352 # assert a == [1,3,1,2,3]
353 fun remove
(item
: nullable Object) is abstract
355 # Remove all occurrences of `item`
357 # var a = [1,2,3,1,2,3]
359 # assert a == [1,3,1,3]
360 fun remove_all
(item
: nullable Object) do while has
(item
) do remove
(item
)
363 # Items can be added to these collections.
364 interface SimpleCollection[E
]
365 super RemovableCollection[E
]
367 # Add an item in a collection.
371 # assert a.has(3) == true
372 # assert a.has(10) == false
374 # Ensure col.has(item)
375 fun add
(item
: E
) is abstract
377 # Add each item of `coll`.
380 # assert a.has(4) == true
381 # assert a.has(10) == false
382 fun add_all
(coll
: Collection[E
]) do for i
in coll
do add
(i
)
387 # Set is a collection without duplicates (according to `==`)
389 # var s: Set[String] = new ArraySet[String]
391 # var b = "Hel" + "lo"
394 # assert s.has(b) == true
396 super SimpleCollection[E
]
398 redef fun has_only
(item
)
411 redef fun count
(item
)
420 # Synonym of remove since there is only one item
421 redef fun remove_all
(item
) do remove
(item
)
423 # Equality is defined on set and means that each set contains the same elements
426 if not other
isa Set[nullable Object] then return false
427 if other
.length
!= length
then return false
428 return has_all
(other
)
431 # Because of the law between `==` and `hash`, `hash` is redefined to be the sum of the hash of the elements
434 # 23 is a magic number empirically determined to be not so bad.
435 var res
= 23 + length
436 # Note: the order of the elements must not change the hash value.
437 # So, unlike usual hash functions, the accumulator is not combined with itself.
438 for e
in self do res
+= e
.hash
442 # Returns the union of this set with the `other` set
443 fun union
(other
: Set[E
]): Set[E
]
451 # Returns the intersection of this set with the `other` set
452 fun intersection
(other
: Set[E
]): Set[E
]
455 for v
in self do if other
.has
(v
) then nhs
.add
(v
)
459 # Returns a new instance of `Set`.
461 # Depends on the subclass, mainly used for copy services
462 # like `union` or `intersection`.
463 protected fun new_set
: Set[E
] is abstract
466 # MapRead are abstract associative collections: `key` -> `item`.
467 interface MapRead[K
, V
]
468 # Get the item at `key`
470 # var x = new HashMap[String, Int]
472 # assert x["four"] == 4
473 # # assert x["five"] #=> abort
475 # If the key is not in the map, `provide_default_value` is called (that aborts by default)
476 # See `get_or_null` and `get_or_default` for safe variations.
477 fun [](key
: nullable Object): V
is abstract
479 # Get the item at `key` or null if `key` is not in the map.
481 # var x = new HashMap[String, Int]
483 # assert x.get_or_null("four") == 4
484 # assert x.get_or_null("five") == null
486 # Note: use `has_key` and `[]` if you need the distinction between a key associated with null, and no key.
487 fun get_or_null
(key
: nullable Object): nullable V
489 if has_key
(key
) then return self[key
]
493 # Get the item at `key` or return `default` if not in map
495 # var x = new HashMap[String, Int]
497 # assert x.get_or_default("four", 40) == 4
498 # assert x.get_or_default("five", 50) == 50
500 fun get_or_default
(key
: nullable Object, default
: V
): V
502 if has_key
(key
) then return self[key
]
506 # Is there an item associated with `key`?
508 # var x = new HashMap[String, Int]
510 # assert x.has_key("four") == true
511 # assert x.has_key("five") == false
513 # By default it is a synonymous to `keys.has` but could be redefined with a direct implementation.
514 fun has_key
(key
: nullable Object): Bool do return self.keys
.has
(key
)
516 # Get a new iterator on the map.
517 fun iterator
: MapIterator[K
, V
] is abstract
519 # Return the point of view of self on the values only.
520 # Note that `self` and `values` are views on the same data;
521 # therefore any modification of one is visible on the other.
523 # var x = new HashMap[String, Int]
525 # assert x.values.has(4) == true
526 # assert x.values.has(5) == false
527 fun values
: Collection[V
] is abstract
529 # Return the point of view of self on the keys only.
530 # Note that `self` and `keys` are views on the same data;
531 # therefore any modification of one is visible on the other.
533 # var x = new HashMap[String, Int]
535 # assert x.keys.has("four") == true
536 # assert x.keys.has("five") == false
537 fun keys
: Collection[K
] is abstract
539 # Is there no item in the collection?
541 # var x = new HashMap[String, Int]
542 # assert x.is_empty == true
544 # assert x.is_empty == false
545 fun is_empty
: Bool is abstract
547 # Alias for `not is_empty`.
549 # Some people prefer to have conditions grammatically easier to read.
551 # var map = new HashMap[String, Int]
552 # assert map.not_empty == false
554 # assert map.not_empty == true
555 fun not_empty
: Bool do return not self.is_empty
557 # Number of items in the collection.
559 # var x = new HashMap[String, Int]
560 # assert x.length == 0
562 # assert x.length == 1
564 # assert x.length == 2
565 fun length
: Int is abstract
567 # Called by the underling implementation of `[]` to provide a default value when a `key` has no value
568 # By default the behavior is to abort.
570 # Note: the value is returned *as is*, implementations may want to store the value in the map before returning it
572 protected fun provide_default_value
(key
: nullable Object): V
do abort
574 # Does `self` and `other` have the same keys associated with the same values?
577 # var a = new HashMap[String, Int]
578 # var b = new ArrayMap[Object, Numeric]
589 if not other
isa MapRead[nullable Object, nullable Object] then return false
590 if other
.length
!= self.length
then return false
592 if not other
.has_key
(k
) then return false
593 if other
[k
] != v
then return false
598 # A hashcode based on the hashcode of the keys and the values.
601 # var a = new HashMap[String, Int]
602 # var b = new ArrayMap[Object, Numeric]
605 # assert a.hash == b.hash
611 if k
!= null then res
+= k
.hash
* 7
612 if v
!= null then res
+= v
.hash
* 11
618 # Maps are associative collections: `key` -> `item`.
620 # The main operator over maps is [].
622 # var map: Map[String, Int] = new ArrayMap[String, Int]
624 # map["one"] = 1 # Associate 'one' to '1'
625 # map["two"] = 2 # Associate 'two' to '2'
626 # assert map["one"] == 1
627 # assert map["two"] == 2
629 # Instances of maps can be used with the for structure
631 # for key, value in map do
632 # assert (key == "one" and value == 1) or (key == "two" and value == 2)
635 # The keys and values in the map can also be manipulated directly with the `keys` and `values` methods.
637 # assert map.keys.has("one") == true
638 # assert map.keys.has("tree") == false
639 # assert map.values.has(1) == true
640 # assert map.values.has(3) == false
645 # Set the `value` at `key`.
647 # Values can then get retrieved with `[]`.
649 # var x = new HashMap[String, Int]
651 # assert x["four"] == 4
653 # If the key was associated with a value, this old value is discarded
654 # and replaced with the new one.
657 # assert x["four"] == 40
658 # assert x.values.has(4) == false
660 fun []=(key
: K
, value
: V
) is abstract
662 # Add each (key,value) of `map` into `self`.
663 # If a same key exists in `map` and `self`, then the value in self is discarded.
665 # It is the analogous of `SimpleCollection::add_all`
667 # var x = new HashMap[String, Int]
670 # var y = new HashMap[String, Int]
674 # assert x["four"] == 40
675 # assert x["five"] == 5
676 # assert x["nine"] == 90
677 fun recover_with
(map
: MapRead[K
, V
])
688 # var x = new HashMap[String, Int]
691 # assert x.keys.has("four") == false
694 fun clear
is abstract
696 redef fun values
: RemovableCollection[V
] is abstract
698 redef fun keys
: RemovableCollection[K
] is abstract
702 interface MapIterator[K
, V
]
705 fun item
: V
is abstract
707 # The key of the current item.
709 fun key
: K
is abstract
711 # Jump to the next item.
715 # Is there a current item ?
716 fun is_ok
: Bool is abstract
718 # Set a new `item` at `key`.
719 #fun item=(item: E) is abstract
721 # Pre-iteration hook.
723 # Used to inform `self` that the iteration is starting.
724 # Specific iterators can use this to prepare some resources.
726 # Is automatically invoked at the beginning of `for` structures.
728 # Do nothing by default.
731 # Post-iteration hook.
733 # Used to inform `self` that the iteration is over.
734 # Specific iterators can use this to free some resources.
736 # Is automatically invoked at the end of `for` structures.
738 # Do nothing by default.
742 # Iterator on a 'keys' point of view of a map
743 class MapKeysIterator[K
, V
]
745 # The original iterator
746 var original_iterator
: MapIterator[K
, V
]
748 redef fun is_ok
do return self.original_iterator
.is_ok
749 redef fun next
do self.original_iterator
.next
750 redef fun item
do return self.original_iterator
.key
753 # Iterator on a 'values' point of view of a map
754 class MapValuesIterator[K
, V
]
756 # The original iterator
757 var original_iterator
: MapIterator[K
, V
]
759 redef fun is_ok
do return self.original_iterator
.is_ok
760 redef fun next
do self.original_iterator
.next
761 redef fun item
do return self.original_iterator
.item
764 # Sequences are indexed collections.
765 # The first item is 0. The last is `length-1`.
767 # The order is the main caracteristic of sequence
768 # and all concrete implementation of sequences are basically interchangeable.
769 interface SequenceRead[E
]
772 # Get the first item.
773 # Is equivalent with `self[0]`.
776 # assert a.first == 1
778 # REQUIRE `not is_empty`
781 assert not_empty
: not is_empty
785 # Return the index-th element of the sequence.
786 # The first element is 0 and the last is `length-1`
787 # If index is invalid, the program aborts
794 # REQUIRE `index >= 0 and index < length`
795 fun [](index
: Int): E
is abstract
798 # Is equivalent with `self[length-1]`.
803 # REQUIRE `not is_empty`
806 assert not_empty
: not is_empty
807 return self[length-1
]
810 # The index of the first occurrence of `item`.
811 # Return -1 if `item` is not found.
812 # Comparison is done with `==`.
814 # var a = [10,20,30,10,20,30]
815 # assert a.index_of(20) == 1
816 # assert a.index_of(40) == -1
817 fun index_of
(item
: nullable Object): Int do return index_of_from
(item
, 0)
819 # The index of the last occurrence of `item`.
820 # Return -1 if `item` is not found.
821 # Comparison is done with `==`.
823 # var a = [10,20,30,10,20,30]
824 # assert a.last_index_of(20) == 4
825 # assert a.last_index_of(40) == -1
826 fun last_index_of
(item
: nullable Object): Int do return last_index_of_from
(item
, length-1
)
828 # The index of the first occurrence of `item`, starting from pos.
829 # Return -1 if `item` is not found.
830 # Comparison is done with `==`.
832 # var a = [10,20,30,10,20,30]
833 # assert a.index_of_from(20, 3) == 4
834 # assert a.index_of_from(20, 4) == 4
835 # assert a.index_of_from(20, 5) == -1
836 fun index_of_from
(item
: nullable Object, pos
: Int): Int
841 if p
>=pos
and i
.item
== item
then return i
.index
848 # The index of the last occurrence of `item` starting from `pos` and decrementing.
849 # Return -1 if `item` is not found.
850 # Comparison is done with `==`.
852 # var a = [10,20,30,10,20,30]
853 # assert a.last_index_of_from(20, 2) == 1
854 # assert a.last_index_of_from(20, 1) == 1
855 # assert a.last_index_of_from(20, 0) == -1
856 fun last_index_of_from
(item
: nullable Object, pos
: Int): Int do
859 if self[i
] == item
then return i
865 # Two sequences are equals if they have the same items in the same order.
867 # var a = new List[Int]
871 # assert a == [1,2,3]
872 # assert a != [1,3,2]
875 if not o
isa SequenceRead[nullable Object] then return false
877 if o
.length
!= l
then return false
880 if self[i
] != o
[i
] then return false
886 # Because of the law between `==` and `hash`, `hash` is redefined to be the sum of the hash of the elements
889 # The 17 and 2/3 magic numbers were determined empirically.
890 # Note: the standard hash functions djb2, sbdm and fnv1 were also
891 # tested but were comparable (or worse).
892 var res
= 17 + length
895 if e
!= null then res
+= e
.hash
900 redef fun iterator
: IndexedIterator[E
] is abstract
902 # Gets a new Iterator starting at position `pos`
904 # var iter = [10,20,30,40,50].iterator_from(2)
905 # assert iter.to_a == [30, 40, 50]
906 fun iterator_from
(pos
: Int): IndexedIterator[E
]
909 while pos
> 0 and res
.is_ok
do
916 # Gets an iterator starting at the end and going backwards
918 # var reviter = [1,2,3].reverse_iterator
919 # assert reviter.to_a == [3,2,1]
920 fun reverse_iterator
: IndexedIterator[E
] is abstract
922 # Gets an iterator on the chars of self starting from `pos`
924 # var reviter = [10,20,30,40,50].reverse_iterator_from(2)
925 # assert reviter.to_a == [30,20,10]
926 fun reverse_iterator_from
(pos
: Int): IndexedIterator[E
]
928 var res
= reverse_iterator
929 while pos
> 0 and res
.is_ok
do
937 # Sequence are indexed collection.
938 # The first item is 0. The last is `length-1`.
939 interface Sequence[E
]
940 super SequenceRead[E
]
941 super SimpleCollection[E
]
943 # Set the first item.
944 # Is equivalent with `self[0] = item`.
948 # assert a == [10,2,3]
950 do self[0] = item
end
953 # Is equivalent with `self[length-1] = item`.
957 # assert a == [1,2,10]
959 # If the sequence is empty, `last=` is equivalent with `self[0]=` (thus with `first=`)
961 # var b = new Array[Int]
974 # A synonym of `push`
975 redef fun add
(e
) do push
(e
)
977 # Add an item after the last one.
982 # assert a == [1,2,3,10,20]
983 fun push
(e
: E
) is abstract
985 # Add each item of `coll` after the last.
989 # assert a == [1,2,3,7,8,9]
992 fun append
(coll
: Collection[E
]) do add_all
(coll
)
994 # Remove the last item.
1001 # REQUIRE `not is_empty`
1002 fun pop
: E
is abstract
1004 # Add an item before the first one.
1009 # assert a == [20,10,1,2,3]
1010 fun unshift
(e
: E
) is abstract
1012 # Add all items of `coll` before the first one.
1016 # assert a == [7,8,9,1,2,3]
1018 # Alias of `insert_at(coll, 0)`
1019 fun prepend
(coll
: Collection[E
]) do insert_all
(coll
, 0)
1021 # Remove the first item.
1022 # The second item thus become the first.
1025 # assert a.shift == 1
1026 # assert a.shift == 2
1029 # REQUIRE `not is_empty`
1030 fun shift
: E
is abstract
1032 # Set the `item` at `index`.
1034 # var a = [10,20,30]
1036 # assert a == [10,200,30]
1038 # like with `[]`, index should be between `0` and `length-1`
1039 # However, if `index==length`, `[]=` works like `push`.
1042 # assert a == [10,200,30,400]
1044 # REQUIRE `index >= 0 and index <= length`
1045 fun []=(index
: Int, item
: E
) is abstract
1047 # Insert an element at a given position, following elements are shifted.
1049 # var a = [10, 20, 30, 40]
1051 # assert a == [10, 20, 100, 30, 40]
1053 # REQUIRE `index >= 0 and index <= length`
1054 # ENSURE `self[index] == item`
1055 fun insert
(item
: E
, index
: Int) is abstract
1057 # Insert all elements at a given position, following elements are shifted.
1059 # var a = [10, 20, 30, 40]
1060 # a.insert_all([100..102], 2)
1061 # assert a == [10, 20, 100, 101, 102, 30, 40]
1063 # REQUIRE `index >= 0 and index <= length`
1064 # ENSURE `self[index] == coll.first`
1065 fun insert_all
(coll
: Collection[E
], index
: Int)
1067 assert index
>= 0 and index
< length
1068 if index
== length
then
1077 # Remove the item at `index` and shift all following elements
1079 # var a = [10,20,30]
1081 # assert a == [10,30]
1083 # REQUIRE `index >= 0 and index < length`
1084 fun remove_at
(index
: Int) is abstract
1087 # Iterators on indexed collections.
1088 interface IndexedIterator[E
]
1090 # The index of the current item.
1091 fun index
: Int is abstract
1094 # Associative arrays that internally uses couples to represent each (key, value) pairs.
1095 # This is an helper class that some specific implementation of Map may implements.
1096 interface CoupleMap[K
, V
]
1099 # Return the couple of the corresponding key
1100 # Return null if the key is no associated element
1101 protected fun couple_at
(key
: nullable Object): nullable Couple[K
, V
] is abstract
1103 # Return a new iteralot on all couples
1104 # Used to provide `iterator` and others
1105 protected fun couple_iterator
: Iterator[Couple[K
,V
]] is abstract
1107 redef fun iterator
do return new CoupleMapIterator[K
,V
](couple_iterator
)
1111 var c
= couple_at
(key
)
1113 return provide_default_value
(key
)
1119 redef fun has_key
(key
) do return couple_at
(key
) != null
1122 # Iterator on CoupleMap
1124 # Actually it is a wrapper around an iterator of the internal array of the map.
1125 private class CoupleMapIterator[K
, V
]
1126 super MapIterator[K
, V
]
1127 redef fun item
do return _iter
.item
.second
1129 #redef fun item=(e) do _iter.item.second = e
1131 redef fun key
do return _iter
.item
.first
1133 redef fun is_ok
do return _iter
.is_ok
1140 var iter
: Iterator[Couple[K
,V
]]
1143 # Some tools ###################################################################
1145 # Two objects in a simple structure.
1148 # The first element of the couple.
1149 var first
: F
is writable
1151 # The second element of the couple.
1152 var second
: S
is writable