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 # Post-iteration hook.
233 # Used to inform `self` that the iteration is over.
234 # Specific iterators can use this to free some resources.
236 # Is automatically invoked at the end of `for` structures.
238 # Do nothing by default.
241 # A decorator around `self` that advance self a given number of steps instead of one.
244 # var i = [11, 22, 33, 44, 55].iterator
245 # var i2 = i.to_step(2)
247 # assert i2.item == 11
249 # assert i2.item == 33
251 # assert i.item == 33
253 fun to_step
(step
: Int): Iterator[E
] do return new StepIterator[E
](self, step
)
256 # A basic helper class to specialize specific Iterator decorators
257 abstract class IteratorDecorator[E
]
260 # The underling iterator
261 protected var real
: Iterator[E
]
263 redef fun is_ok
do return real
.is_ok
264 redef fun item
do return real
.item
265 redef fun finish
do real
.finish
266 redef fun next
do real
.next
267 redef fun next_by
(step
) do real
.next_by
(step
)
270 # A decorator that advance a given number of steps
271 private class StepIterator[E
]
272 super IteratorDecorator[E
]
275 redef fun next
do real
.next_by
(step
)
276 redef fun next_by
(step
) do real
.next_by
(step
* self.step
)
279 # A collection that contains only one item.
281 # Used to pass arguments by reference.
283 # Also used when one want to give a single element when a full
284 # collection is expected
288 redef fun first
do return item
290 redef fun is_empty
do return false
292 redef fun length
do return 1
294 redef fun has
(an_item
) do return item
== an_item
296 redef fun has_only
(an_item
) do return item
== an_item
298 redef fun count
(an_item
)
300 if item
== an_item
then
307 redef fun iterator
do return new ContainerIterator[E
](self)
310 var item
: E
is writable
313 # This iterator is quite stupid since it is used for only one item.
314 private class ContainerIterator[E
]
316 redef fun item
do return _container
.item
318 redef fun next
do is_ok
= false
320 redef var is_ok
= true
322 var container
: Container[E
]
325 # Items can be removed from this collection
326 interface RemovableCollection[E
]
333 # assert a.length == 0
336 fun clear
is abstract
338 # Remove an occurrence of `item`
340 # var a = [1,2,3,1,2,3]
342 # assert a == [1,3,1,2,3]
343 fun remove
(item
: nullable Object) is abstract
345 # Remove all occurrences of `item`
347 # var a = [1,2,3,1,2,3]
349 # assert a == [1,3,1,3]
350 fun remove_all
(item
: nullable Object) do while has
(item
) do remove
(item
)
353 # Items can be added to these collections.
354 interface SimpleCollection[E
]
355 super RemovableCollection[E
]
357 # Add an item in a collection.
361 # assert a.has(3) == true
362 # assert a.has(10) == false
364 # Ensure col.has(item)
365 fun add
(item
: E
) is abstract
367 # Add each item of `coll`.
370 # assert a.has(4) == true
371 # assert a.has(10) == false
372 fun add_all
(coll
: Collection[E
]) do for i
in coll
do add
(i
)
377 # Set is a collection without duplicates (according to `==`)
379 # var s: Set[String] = new ArraySet[String]
381 # var b = "Hel" + "lo"
384 # assert s.has(b) == true
386 super SimpleCollection[E
]
388 redef fun has_only
(item
)
401 redef fun count
(item
)
410 # Synonym of remove since there is only one item
411 redef fun remove_all
(item
) do remove
(item
)
413 # Equality is defined on set and means that each set contains the same elements
416 if not other
isa Set[nullable Object] then return false
417 if other
.length
!= length
then return false
418 return has_all
(other
)
421 # Because of the law between `==` and `hash`, `hash` is redefined to be the sum of the hash of the elements
424 # 23 is a magic number empirically determined to be not so bad.
425 var res
= 23 + length
426 # Note: the order of the elements must not change the hash value.
427 # So, unlike usual hash functions, the accumulator is not combined with itself.
428 for e
in self do res
+= e
.hash
432 # Returns the union of this set with the `other` set
433 fun union
(other
: Set[E
]): Set[E
]
441 # Returns the intersection of this set with the `other` set
442 fun intersection
(other
: Set[E
]): Set[E
]
445 for v
in self do if other
.has
(v
) then nhs
.add
(v
)
449 # Returns a new instance of `Set`.
451 # Depends on the subclass, mainly used for copy services
452 # like `union` or `intersection`.
453 protected fun new_set
: Set[E
] is abstract
456 # MapRead are abstract associative collections: `key` -> `item`.
457 interface MapRead[K
, V
]
458 # Get the item at `key`
460 # var x = new HashMap[String, Int]
462 # assert x["four"] == 4
463 # # assert x["five"] #=> abort
465 # If the key is not in the map, `provide_default_value` is called (that aborts by default)
466 # See `get_or_null` and `get_or_default` for safe variations.
467 fun [](key
: nullable Object): V
is abstract
469 # Get the item at `key` or null if `key` is not in the map.
471 # var x = new HashMap[String, Int]
473 # assert x.get_or_null("four") == 4
474 # assert x.get_or_null("five") == null
476 # Note: use `has_key` and `[]` if you need the distinction between a key associated with null, and no key.
477 fun get_or_null
(key
: nullable Object): nullable V
479 if has_key
(key
) then return self[key
]
483 # Get the item at `key` or return `default` if not in map
485 # var x = new HashMap[String, Int]
487 # assert x.get_or_default("four", 40) == 4
488 # assert x.get_or_default("five", 50) == 50
490 fun get_or_default
(key
: nullable Object, default
: V
): V
492 if has_key
(key
) then return self[key
]
496 # Is there an item associated with `key`?
498 # var x = new HashMap[String, Int]
500 # assert x.has_key("four") == true
501 # assert x.has_key("five") == false
503 # By default it is a synonymous to `keys.has` but could be redefined with a direct implementation.
504 fun has_key
(key
: nullable Object): Bool do return self.keys
.has
(key
)
506 # Get a new iterator on the map.
507 fun iterator
: MapIterator[K
, V
] is abstract
509 # Return the point of view of self on the values only.
510 # Note that `self` and `values` are views on the same data;
511 # therefore any modification of one is visible on the other.
513 # var x = new HashMap[String, Int]
515 # assert x.values.has(4) == true
516 # assert x.values.has(5) == false
517 fun values
: Collection[V
] is abstract
519 # Return the point of view of self on the keys only.
520 # Note that `self` and `keys` 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.keys.has("four") == true
526 # assert x.keys.has("five") == false
527 fun keys
: Collection[K
] is abstract
529 # Is there no item in the collection?
531 # var x = new HashMap[String, Int]
532 # assert x.is_empty == true
534 # assert x.is_empty == false
535 fun is_empty
: Bool is abstract
537 # Number of items in the collection.
539 # var x = new HashMap[String, Int]
540 # assert x.length == 0
542 # assert x.length == 1
544 # assert x.length == 2
545 fun length
: Int is abstract
547 # Called by the underling implementation of `[]` to provide a default value when a `key` has no value
548 # By default the behavior is to abort.
550 # Note: the value is returned *as is*, implementations may want to store the value in the map before returning it
552 protected fun provide_default_value
(key
: nullable Object): V
do abort
554 # Does `self` and `other` have the same keys associated with the same values?
557 # var a = new HashMap[String, Int]
558 # var b = new ArrayMap[Object, Numeric]
569 if not other
isa MapRead[nullable Object, nullable Object] then return false
570 if other
.length
!= self.length
then return false
572 if not other
.has_key
(k
) then return false
573 if other
[k
] != v
then return false
578 # A hashcode based on the hashcode of the keys and the values.
581 # var a = new HashMap[String, Int]
582 # var b = new ArrayMap[Object, Numeric]
585 # assert a.hash == b.hash
591 if k
!= null then res
+= k
.hash
* 7
592 if v
!= null then res
+= v
.hash
* 11
598 # Maps are associative collections: `key` -> `item`.
600 # The main operator over maps is [].
602 # var map: Map[String, Int] = new ArrayMap[String, Int]
604 # map["one"] = 1 # Associate 'one' to '1'
605 # map["two"] = 2 # Associate 'two' to '2'
606 # assert map["one"] == 1
607 # assert map["two"] == 2
609 # Instances of maps can be used with the for structure
611 # for key, value in map do
612 # assert (key == "one" and value == 1) or (key == "two" and value == 2)
615 # The keys and values in the map can also be manipulated directly with the `keys` and `values` methods.
617 # assert map.keys.has("one") == true
618 # assert map.keys.has("tree") == false
619 # assert map.values.has(1) == true
620 # assert map.values.has(3) == false
625 # Set the `value` at `key`.
627 # Values can then get retrieved with `[]`.
629 # var x = new HashMap[String, Int]
631 # assert x["four"] == 4
633 # If the key was associated with a value, this old value is discarded
634 # and replaced with the new one.
637 # assert x["four"] == 40
638 # assert x.values.has(4) == false
640 fun []=(key
: K
, value
: V
) is abstract
642 # Add each (key,value) of `map` into `self`.
643 # If a same key exists in `map` and `self`, then the value in self is discarded.
645 # It is the analogous of `SimpleCollection::add_all`
647 # var x = new HashMap[String, Int]
650 # var y = new HashMap[String, Int]
654 # assert x["four"] == 40
655 # assert x["five"] == 5
656 # assert x["nine"] == 90
657 fun recover_with
(map
: MapRead[K
, V
])
668 # var x = new HashMap[String, Int]
671 # assert x.keys.has("four") == false
674 fun clear
is abstract
676 redef fun values
: RemovableCollection[V
] is abstract
678 redef fun keys
: RemovableCollection[K
] is abstract
682 interface MapIterator[K
, V
]
685 fun item
: V
is abstract
687 # The key of the current item.
689 fun key
: K
is abstract
691 # Jump to the next item.
695 # Is there a current item ?
696 fun is_ok
: Bool is abstract
698 # Set a new `item` at `key`.
699 #fun item=(item: E) is abstract
701 # Post-iteration hook.
703 # Used to inform `self` that the iteration is over.
704 # Specific iterators can use this to free some resources.
706 # Is automatically invoked at the end of `for` structures.
708 # Do nothing by default.
712 # Iterator on a 'keys' point of view of a map
713 class MapKeysIterator[K
, V
]
715 # The original iterator
716 var original_iterator
: MapIterator[K
, V
]
718 redef fun is_ok
do return self.original_iterator
.is_ok
719 redef fun next
do self.original_iterator
.next
720 redef fun item
do return self.original_iterator
.key
723 # Iterator on a 'values' point of view of a map
724 class MapValuesIterator[K
, V
]
726 # The original iterator
727 var original_iterator
: MapIterator[K
, V
]
729 redef fun is_ok
do return self.original_iterator
.is_ok
730 redef fun next
do self.original_iterator
.next
731 redef fun item
do return self.original_iterator
.item
734 # Sequences are indexed collections.
735 # The first item is 0. The last is `length-1`.
737 # The order is the main caracteristic of sequence
738 # and all concrete implementation of sequences are basically interchangeable.
739 interface SequenceRead[E
]
742 # Get the first item.
743 # Is equivalent with `self[0]`.
746 # assert a.first == 1
748 # REQUIRE `not is_empty`
751 assert not_empty
: not is_empty
755 # Return the index-th element of the sequence.
756 # The first element is 0 and the last is `length-1`
757 # If index is invalid, the program aborts
764 # REQUIRE `index >= 0 and index < length`
765 fun [](index
: Int): E
is abstract
768 # Is equivalent with `self[length-1]`.
773 # REQUIRE `not is_empty`
776 assert not_empty
: not is_empty
777 return self[length-1
]
780 # The index of the first occurrence of `item`.
781 # Return -1 if `item` is not found.
782 # Comparison is done with `==`.
784 # var a = [10,20,30,10,20,30]
785 # assert a.index_of(20) == 1
786 # assert a.index_of(40) == -1
787 fun index_of
(item
: nullable Object): Int do return index_of_from
(item
, 0)
789 # The index of the last occurrence of `item`.
790 # Return -1 if `item` is not found.
791 # Comparison is done with `==`.
793 # var a = [10,20,30,10,20,30]
794 # assert a.last_index_of(20) == 4
795 # assert a.last_index_of(40) == -1
796 fun last_index_of
(item
: nullable Object): Int do return last_index_of_from
(item
, length-1
)
798 # The index of the first occurrence of `item`, starting from pos.
799 # Return -1 if `item` is not found.
800 # Comparison is done with `==`.
802 # var a = [10,20,30,10,20,30]
803 # assert a.index_of_from(20, 3) == 4
804 # assert a.index_of_from(20, 4) == 4
805 # assert a.index_of_from(20, 5) == -1
806 fun index_of_from
(item
: nullable Object, pos
: Int): Int
811 if p
>=pos
and i
.item
== item
then return i
.index
818 # The index of the last occurrence of `item` starting from `pos` and decrementing.
819 # Return -1 if `item` is not found.
820 # Comparison is done with `==`.
822 # var a = [10,20,30,10,20,30]
823 # assert a.last_index_of_from(20, 2) == 1
824 # assert a.last_index_of_from(20, 1) == 1
825 # assert a.last_index_of_from(20, 0) == -1
826 fun last_index_of_from
(item
: nullable Object, pos
: Int): Int
833 if i
.item
== item
then res
= p
840 # Two sequences are equals if they have the same items in the same order.
842 # var a = new List[Int]
846 # assert a == [1,2,3]
847 # assert a != [1,3,2]
850 if not o
isa SequenceRead[nullable Object] then return false
852 if o
.length
!= l
then return false
855 if self[i
] != o
[i
] then return false
861 # Because of the law between `==` and `hash`, `hash` is redefined to be the sum of the hash of the elements
864 # The 17 and 2/3 magic numbers were determined empirically.
865 # Note: the standard hash functions djb2, sbdm and fnv1 were also
866 # tested but were comparable (or worse).
867 var res
= 17 + length
870 if e
!= null then res
+= e
.hash
875 redef fun iterator
: IndexedIterator[E
] is abstract
877 # Gets a new Iterator starting at position `pos`
879 # var iter = [10,20,30,40,50].iterator_from(2)
880 # assert iter.to_a == [30, 40, 50]
881 fun iterator_from
(pos
: Int): IndexedIterator[E
]
884 while pos
> 0 and res
.is_ok
do
891 # Gets an iterator starting at the end and going backwards
893 # var reviter = [1,2,3].reverse_iterator
894 # assert reviter.to_a == [3,2,1]
895 fun reverse_iterator
: IndexedIterator[E
] is abstract
897 # Gets an iterator on the chars of self starting from `pos`
899 # var reviter = [10,20,30,40,50].reverse_iterator_from(2)
900 # assert reviter.to_a == [30,20,10]
901 fun reverse_iterator_from
(pos
: Int): IndexedIterator[E
]
903 var res
= reverse_iterator
904 while pos
> 0 and res
.is_ok
do
912 # Sequence are indexed collection.
913 # The first item is 0. The last is `length-1`.
914 interface Sequence[E
]
915 super SequenceRead[E
]
916 super SimpleCollection[E
]
918 # Set the first item.
919 # Is equivalent with `self[0] = item`.
923 # assert a == [10,2,3]
925 do self[0] = item
end
928 # Is equivalent with `self[length-1] = item`.
932 # assert a == [1,2,10]
934 # If the sequence is empty, `last=` is equivalent with `self[0]=` (thus with `first=`)
936 # var b = new Array[Int]
949 # A synonym of `push`
950 redef fun add
(e
) do push
(e
)
952 # Add an item after the last one.
957 # assert a == [1,2,3,10,20]
958 fun push
(e
: E
) is abstract
960 # Add each item of `coll` after the last.
964 # assert a == [1,2,3,7,8,9]
967 fun append
(coll
: Collection[E
]) do add_all
(coll
)
969 # Remove the last item.
976 # REQUIRE `not is_empty`
977 fun pop
: E
is abstract
979 # Add an item before the first one.
984 # assert a == [20,10,1,2,3]
985 fun unshift
(e
: E
) is abstract
987 # Add all items of `coll` before the first one.
991 # assert a == [7,8,9,1,2,3]
993 # Alias of `insert_at(coll, 0)`
994 fun prepend
(coll
: Collection[E
]) do insert_all
(coll
, 0)
996 # Remove the first item.
997 # The second item thus become the first.
1000 # assert a.shift == 1
1001 # assert a.shift == 2
1004 # REQUIRE `not is_empty`
1005 fun shift
: E
is abstract
1007 # Set the `item` at `index`.
1009 # var a = [10,20,30]
1011 # assert a == [10,200,30]
1013 # like with `[]`, index should be between `0` and `length-1`
1014 # However, if `index==length`, `[]=` works like `push`.
1017 # assert a == [10,200,30,400]
1019 # REQUIRE `index >= 0 and index <= length`
1020 fun []=(index
: Int, item
: E
) is abstract
1022 # Insert an element at a given position, following elements are shifted.
1024 # var a = [10, 20, 30, 40]
1026 # assert a == [10, 20, 100, 30, 40]
1028 # REQUIRE `index >= 0 and index <= length`
1029 # ENSURE `self[index] == item`
1030 fun insert
(item
: E
, index
: Int) is abstract
1032 # Insert all elements at a given position, following elements are shifted.
1034 # var a = [10, 20, 30, 40]
1035 # a.insert_all([100..102], 2)
1036 # assert a == [10, 20, 100, 101, 102, 30, 40]
1038 # REQUIRE `index >= 0 and index <= length`
1039 # ENSURE `self[index] == coll.first`
1040 fun insert_all
(coll
: Collection[E
], index
: Int)
1042 assert index
>= 0 and index
< length
1043 if index
== length
then
1052 # Remove the item at `index` and shift all following elements
1054 # var a = [10,20,30]
1056 # assert a == [10,30]
1058 # REQUIRE `index >= 0 and index < length`
1059 fun remove_at
(index
: Int) is abstract
1062 # Iterators on indexed collections.
1063 interface IndexedIterator[E
]
1065 # The index of the current item.
1066 fun index
: Int is abstract
1069 # Associative arrays that internally uses couples to represent each (key, value) pairs.
1070 # This is an helper class that some specific implementation of Map may implements.
1071 interface CoupleMap[K
, V
]
1074 # Return the couple of the corresponding key
1075 # Return null if the key is no associated element
1076 protected fun couple_at
(key
: nullable Object): nullable Couple[K
, V
] is abstract
1078 # Return a new iteralot on all couples
1079 # Used to provide `iterator` and others
1080 protected fun couple_iterator
: Iterator[Couple[K
,V
]] is abstract
1082 redef fun iterator
do return new CoupleMapIterator[K
,V
](couple_iterator
)
1086 var c
= couple_at
(key
)
1088 return provide_default_value
(key
)
1094 redef fun has_key
(key
) do return couple_at
(key
) != null
1097 # Iterator on CoupleMap
1099 # Actually it is a wrapper around an iterator of the internal array of the map.
1100 private class CoupleMapIterator[K
, V
]
1101 super MapIterator[K
, V
]
1102 redef fun item
do return _iter
.item
.second
1104 #redef fun item=(e) do _iter.item.second = e
1106 redef fun key
do return _iter
.item
.first
1108 redef fun is_ok
do return _iter
.is_ok
1115 var iter
: Iterator[Couple[K
,V
]]
1118 # Some tools ###################################################################
1120 # Two objects in a simple structure.
1123 # The first element of the couple.
1124 var first
: F
is writable
1126 # The second element of the couple.
1127 var second
: S
is writable