| Class DS_QUEUE |
indexing
description:
"Queues (First-In, First-Out)"
library: "Gobo Eiffel Structure Library"
author: "Eric Bezault <ericb@gobosoft.com>"
copyright: "Copyright (c) 1999, Eric Bezault and others"
license: "Eiffel Forum Freeware License v1 (see forum.txt)"
deferred class interface
DS_QUEUE [G]
inherit
DS_DISPENSER [G]
DS_SEARCHABLE [G]
DS_CONTAINER [G]
feature -- Access
item: G -- Item at front of queue -- (From DS_DISPENSER.) require not_empty: not is_empty deferredequality_tester: DS_EQUALITY_TESTER [G] -- Equality tester; -- A void equality tester means that `=' -- will be used as comparison criterion. -- (From DS_SEARCHABLE.)
feature -- Measurement
count: INTEGER -- Number of items in queue -- (From DS_CONTAINER.) deferredoccurrences (v: G): INTEGER -- Number of times v appears in queue -- (Use equality_tester's comparison criterion -- if not void, use `=' criterion otherwise.) -- (From DS_SEARCHABLE.) deferred ensure positive: Result >= 0 has: has (v) implies Result >= 1
feature -- Status report
has (v: G): BOOLEAN -- Does queue include v? -- (Use equality_tester's comparison criterion -- if not void, use `=' criterion otherwise.) -- (From DS_SEARCHABLE.) deferred ensure not_empty: Result implies not is_emptyis_empty: BOOLEAN -- Is queue empty? -- (From DS_CONTAINER.)extendible (n: INTEGER): BOOLEAN -- May queue be extended with n items? require positive_n: n >= 0 deferred
feature -- Comparison
is_equal (other: like Current): BOOLEAN
-- Is current queue equal to other?
-- (From GENERAL.)
require
other_not_void: other /= Void
deferred
ensure
consistent: standard_is_equal (other) implies Result
same_type: Result implies same_type (other)
symmetric: Result implies other.is_equal (Current)
same_count: Result implies count = other.count
feature -- Duplication
copy (other: like Current)
-- Copy other to current queue.
-- (From GENERAL.)
require
other_not_void: other /= Void
type_identity: same_type (other)
deferred
ensure
is_equal: is_equal (other)
feature -- Setting
set_equality_tester (a_tester: like equality_tester)
-- Set equality_tester to a_tester.
-- A void equality tester means that `='
-- will be used as comparison criterion.
-- (From DS_SEARCHABLE.)
ensure
equality_tester_set: equality_tester = a_tester
feature -- Element change
put (v: G) -- Add v to back of queue. -- (From DS_DISPENSER.) require extendible: extendible (1) deferred ensure one_more: count = old count + 1force (v: G) -- Add v to back of queue. -- (From DS_DISPENSER.) deferred ensure one_more: count = old count + 1extend (other: DS_LINEAR [G]) -- Add items of other to back of queue. -- Add other.first first, etc. -- (From DS_DISPENSER.) require other_not_void: other /= Void extendible: extendible (other.count) deferred ensure new_count: count = old count + other.countappend (other: DS_LINEAR [G]) -- Add items of other to back of queue. -- Add other.first first, etc. -- (From DS_DISPENSER.) require other_not_void: other /= Void deferred ensure new_count: count = old count + other.count
feature -- Removal
remove -- Remove front item from queue. -- (From DS_DISPENSER.) require not_empty: not is_empty deferred ensure one_less: count = old count - 1prune (n: INTEGER) -- Remove n items from queue. -- (From DS_DISPENSER.) require valid_n: 0 <= n and n <= count deferred ensure new_count: count = old count - nkeep (n: INTEGER) -- Keep n items in queue. -- (From DS_DISPENSER.) require valid_n: 0 <= n and n <= count deferred ensure new_count: count = nwipe_out -- Remove all items from queue. -- (From DS_CONTAINER.) deferred ensure wiped_out: is_empty
invariant
positive_count: count >= 0
empty_definition: is_empty = (count = 0)
-- (From DS_CONTAINER.)
end -- class DS_QUEUE
|
Copyright © 1999, Eric
Bezault mailto:ericb@gobosoft.com http://www.gobosoft.com Last Updated: 25 September 1999 |