# another product.
# This module define several abstract collection classes.
-package abstract_collection
+module abstract_collection
import kernel
# The root of the collection hierarchy.
#
-# Instances of this class offers an iterator method.
+# Collections modelize finite groups of objects, called elements.
#
-# Collections instances can use the "for" structure:
-# var x: Collection[U]
-# ...
+# The specific behavior and representation of collections is determined
+# by the subclasses of the hierarchy.
+#
+# The main service of Collection is to provide a stable `iterator`
+# method usable to retrieve all the elements of the collection.
+#
+# Additional services are provided.
+# For an implementation point of view, Collection provide a basic
+# implementation of these services using the `iterator` method.
+# Subclasses often provide a more efficient implementation.
+#
+# Because of the `iterator` method, Collections instances can use
+# the `for` control structure:
+#
+# var x: Collection[U]
+# # ...
# for u in x do
# # u is a U
-# ...
+# # ...
# end
+#
# that is equivalent with
+#
# var x: Collection[U]
-# ...
+# # ...
# var i = x.iterator
# while i.is_ok do
# var u = i.item # u is a U
-# ...
+# # ...
# i.next
# end
-#
-# This abstract class implements its others methods with an iterator.
-# Subclasses may redefine them with an efficient implementation.
interface Collection[E]
# Get a new iterator on the collection.
fun iterator: Iterator[E] is abstract
- # Iterate over each element of the collection
- fun iterate
- !each(e: E)
- do
- var i = iterator
- while i.is_ok do
- each(i.item)
- i.next
- end
- end
-
- # Is there no item in the collection ?
- fun is_empty: Bool is abstract
+ # Is there no item in the collection?
+ #
+ # assert [1,2,3].is_empty == false
+ # assert [1..1[.is_empty == true
+ fun is_empty: Bool do return length == 0
# Number of items in the collection.
- fun length: Int is abstract
-
- # Is `item' in the collection ?
- # Comparisons are done with ==
- fun has(item: E): Bool is abstract
-
- # Is the collection contain only `item' ?
- # Comparisons are done with ==
- # Return true if the collection is empty.
- fun has_only(item: E): Bool is abstract
-
- # How many occurrences of `item' are in the collection ?
- # Comparisons are done with ==
- fun count(item: E): Int is abstract
-
- # Return one the item of the collection
- fun first: E is abstract
-end
-
-# Naive implementation of collections method
-# You only have to define iterator!
-interface NaiveCollection[E]
- super Collection[E]
- redef fun is_empty do return length == 0
-
- redef fun length
+ #
+ # assert [10,20,30].length == 3
+ # assert [20..30[.length == 10
+ fun length: Int
do
var nb = 0
- for i in self do nb += 1
+ for i in self do nb += 1
return nb
end
- redef fun has(item)
+
+ # Is `item` in the collection ?
+ # Comparisons are done with ==
+ #
+ # assert [1,2,3].has(2) == true
+ # assert [1,2,3].has(9) == false
+ # assert [1..5[.has(2) == true
+ # assert [1..5[.has(9) == false
+ fun has(item: E): Bool
do
for i in self do if i == item then return true
return false
end
- redef fun has_only(item)
+ # Is the collection contain only `item`?
+ # Comparisons are done with ==
+ # Return true if the collection is empty.
+ #
+ # assert [1,1,1].has_only(1) == true
+ # assert [1,2,3].has_only(1) == false
+ # assert [1..1].has_only(1) == true
+ # assert [1..3].has_only(1) == false
+ # assert [3..3[.has_only(1) == true # empty collection
+ #
+ # ENSURE `is_empty implies result == true`
+ fun has_only(item: E): Bool
do
for i in self do if i != item then return false
return true
end
- redef fun count(item)
+ # How many occurrences of `item` are in the collection?
+ # Comparisons are done with ==
+ #
+ # assert [10,20,10].count(10) == 2
+ fun count(item: E): Int
do
var nb = 0
for i in self do if i == item then nb += 1
return nb
end
- redef fun first
+ # Return the first item of the collection
+ #
+ # assert [1,2,3].first == 1
+ fun first: E
do
assert length > 0
return iterator.item
end
+
+ # Is the collection contains all the elements of `other`?
+ #
+ # assert [1,1,1].has_all([1]) == true
+ # assert [1,1,1].has_all([1,2]) == false
+ # assert [1,3,4,2].has_all([1..2]) == true
+ # assert [1,3,4,2].has_all([1..5]) == false
+ fun has_all(other: Collection[E]): Bool
+ do
+ for x in other do if not has(x) then return false
+ return true
+ end
end
# Instances of the Iterator class generates a series of elements, one at a time.
# They are mainly used with collections.
interface Iterator[E]
# The current item.
- # Require `is_ok'.
+ # Require `is_ok`.
fun item: E is abstract
# Jump to the next item.
- # Require `is_ok'.
+ # Require `is_ok`.
fun next is abstract
# Is there a current item ?
end
# A collection that contains only one item.
+# Used to pass arguments by reference
class Container[E]
super Collection[E]
# Remove all items
fun clear is abstract
- # Remove an occucence of `item'
+ # Remove an occucence of `item`
fun remove(item: E) is abstract
- # Remove all occurences of `item'
+ # Remove all occurences of `item`
fun remove_all(item: E) do while has(item) do remove(item)
end
# Abstract sets.
#
-# Set contains contains only one element with the same value (according to ==).
-# var s: Set[E]
-# var a = "Hello"
-# var b = "Hel" + "lo"
-# ...
-# s.add(a)
-# s.has(b) # --> true
+# Set is a collection without ducplicates (according to ==)
+# var s: Set[String] = new ArraySet[String]
+# var a = "Hello"
+# var b = "Hel" + "lo"
+# # ...
+# s.add(a)
+# assert s.has(b) == true
interface Set[E: Object]
super SimpleCollection[E]
# Synonym of remove since there is only one item
redef fun remove_all(item) do remove(item)
+
+ # Equality is defined on set and means that each set contains the same elements
+ redef fun ==(other)
+ do
+ if not other isa Set[Object] then return false
+ if other.length != length then return false
+ return has_all(other)
+ end
+
+ # because of the law between `==` and `hash`, hash is redefined to be the sum of the hash of the elements
+ redef fun hash
+ do
+ var res = 0
+ for e in self do res += res.hash
+ return res
+ end
end
-# MapRead are abstract associative collections: `key' -> `item'.
+# MapRead are abstract associative collections: `key` -> `item`.
interface MapRead[K: Object, E]
- # Get the item at `key'.
+ # Get the item at `key`.
fun [](key: K): E is abstract
- # Depreciated alias for `keys.has'
+ # Get the item at `key` or null if `key` is not in the map.
+ #
+ # var x = new HashMap[String, Int]
+ # x["four"] = 4
+ # assert x.get_or_null("four") == 4
+ # assert x.get_or_null("five") == null
+ #
+ # Note: use `has_key` and `[]` if you need the distinction bewteen a key associated with null, and no key.
+ fun get_or_null(key: K): nullable E
+ do
+ if has_key(key) then return self[key]
+ return null
+ end
+
+ # Get the item at `key` or return `default` if not in map
+ fun get_or_default(key: K, default: E): E
+ do
+ if has_key(key) then return self[key]
+ return default
+ end
+
+ # Depreciated alias for `keys.has`
fun has_key(key: K): Bool do return self.keys.has(key)
# Get a new iterator on the map.
fun iterator: MapIterator[K, E] is abstract
- # Iterate over each element of the collection
- fun iterate
- !each(k: K, v: E)
- do
- var i = iterator
- while i.is_ok do
- each(i.key, i.item)
- i.next
- end
- end
-
# Return the point of view of self on the values only.
- # Note that `self' and `values' are views on the same data;
+ # Note that `self` and `values` are views on the same data;
# therefore any modification of one is visible on the other.
fun values: Collection[E] is abstract
# Return the point of view of self on the keys only.
- # Note that `self' and `keys' are views on the same data;
+ # Note that `self` and `keys` are views on the same data;
# therefore any modification of one is visible on the other.
fun keys: Collection[K] is abstract
# Is there no item in the collection?
- fun is_empty: Bool is abstract
+ fun is_empty: Bool is abstract
# Number of items in the collection.
fun length: Int is abstract
+
+ # Called by the underling implementation of `[]` to provide a default value when a `key` has no value
+ # By default the behavior is to abort.
+ #
+ # Note: the value is returned *as is*, implementations may want to store the value in the map before returning it
+ # @toimplement
+ protected fun provide_default_value(key: K): E do abort
end
-# Maps are associative collections: `key' -> `item'.
+# Maps are associative collections: `key` -> `item`.
#
# The main operator over maps is [].
#
-# var map: Map[U, V]
-# ...
-# map[u1] = v1 # Associate 'v1' to 'u1'
-# map[u2] = v2 # Associate 'v2' to 'u2'
-# map[u1] # -> v1
-# map[u2] # -> v2
+# var map: Map[String, Int] = new ArrayMap[String, Int]
+# # ...
+# map["one"] = 1 # Associate 'one' to '1'
+# map["two"] = 2 # Associate 'two' to '2'
+# assert map["one"] == 1
+# assert map["two"] == 2
#
# Instances of maps can be used with the for structure
#
-# for key, value in map do ..
+# for key, value in map do
+# assert (key == "one" and value == 1) or (key == "two" and value == 2)
+# end
#
-# The keys and values in the map can also be manipulated directly with the `keys' and `values' methods.
+# The keys and values in the map can also be manipulated directly with the `keys` and `values` methods.
#
-# map.keys.has(u1) # -> true
-# map.keys.has(u3) # -> false
-# map.values.has(v1) # -> true
-# map.values.has(v3) # -> false
+# assert map.keys.has("one") == true
+# assert map.keys.has("tree") == false
+# assert map.values.has(1) == true
+# assert map.values.has(3) == false
#
interface Map[K: Object, E]
super MapRead[K, E]
- # Set the`item' at `key'.
+ # Set the`item` at `key`.
fun []=(key: K, item: E) is abstract
- # Add each (key,value) of `map' into `self'.
- # If a same key exists in `map' and `self', then the value in self is discarded.
+ # Add each (key,value) of `map` into `self`.
+ # If a same key exists in `map` and `self`, then the value in self is discarded.
fun recover_with(map: Map[K, E])
do
var i = map.iterator
# Iterators for Map.
interface MapIterator[K: Object, E]
# The current item.
- # Require `is_ok'.
+ # Require `is_ok`.
fun item: E is abstract
# The key of the current item.
- # Require `is_ok'.
+ # Require `is_ok`.
fun key: K is abstract
# Jump to the next item.
- # Require `is_ok'.
+ # Require `is_ok`.
fun next is abstract
# Is there a current item ?
fun is_ok: Bool is abstract
- # Set a new `item' at `key'.
+ # Set a new `item` at `key`.
#fun item=(item: E) is abstract
end
end
# Sequences are indexed collections.
-# The first item is 0. The last is `length'-1.
+# The first item is 0. The last is `length-1`.
interface SequenceRead[E]
super Collection[E]
# Get the first item.
- # Is equivalent with `self'[0].
+ # Is equivalent with `self[0]`.
redef fun first
do
assert not_empty: not is_empty
end
# Return the index=th element of the sequence.
- # The first element is 0 and the last if `length-1'
+ # The first element is 0 and the last if `length-1`
# If index is invalid, the program aborts
fun [](index: Int): E is abstract
# Get the last item.
- # Is equivalent with `self'[`length'-1].
+ # Is equivalent with `self[length-1]`.
fun last: E
do
assert not_empty: not is_empty
return self[length-1]
end
- # Return the index of the first occurrence of `item'.
- # Return -1 if `item' is not found
+ # Return the index of the first occurrence of `item`.
+ # Return -1 if `item` is not found
# Comparison is done with ==
fun index_of(item: E): Int
do
end
redef fun iterator: IndexedIterator[E] is abstract
+
+ # Two sequences are equals if they have the same items in the same order.
+ redef fun ==(o)
+ do
+ if not o isa SequenceRead[nullable Object] then return false
+ var l = length
+ if o.length != l then return false
+ var i = 0
+ while i < l do
+ if self[i] != o[i] then return false
+ i += 1
+ end
+ return true
+ end
+
+ # because of the law between `==` and `hash`, hash is redefined to be the sum of the hash of the elements
+ redef fun hash
+ do
+ var res = 0
+ for e in self do res += res.hash
+ return res
+ end
end
# Sequence are indexed collection.
-# The first item is 0. The last is `length'-1.
+# The first item is 0. The last is `length-1`.
interface Sequence[E]
super SequenceRead[E]
super SimpleCollection[E]
# Set the first item.
- # Is equivalent with `self'[0] = `item'.
+ # Is equivalent with `self[0] = item`.
fun first=(item: E)
do self[0] = item end
# Set the last item.
- # Is equivalent with `self'[length-1] = `item'.
+ # Is equivalent with `self[length-1] = item`.
fun last=(item: E)
do
var l = length
end
end
- # A synonym of `push'
+ # A synonym of `push`
redef fun add(e) do push(e)
# Add an item after the last.
# The second item become the first.
fun shift: E is abstract
- # Set the`item' at `index'.
+ # Set the `item` at `index`.
fun []=(index: Int, item: E) is abstract
- # Remove the item at `index' and shift all following elements
+ # Remove the item at `index` and shift all following elements
fun remove_at(index: Int) is abstract
end
do
var c = couple_at(key)
if c == null then
- abort
+ return provide_default_value(key)
else
return c.second
end
nitlanguage / nit.git / blobdiff