Class DS_TABLE

Class DS_TABLE

note

description:

    "Data structures whose items are accessible through keys"

library:    "Gobo Eiffel Structure Library"
author:     "Eric Bezault <ericb@gobosoft.com>"
copyright:  "Copyright (c) 2000-2001, Eric Bezault and others"
license:    "MIT License"

deferred class interface

DS_TABLE [G, K]

inherit

DS_CONTAINER [G]

feature {NONE} -- Initialization

make_default
        -- Create an empty container.
        -- (From DS_CONTAINER.)
    deferred
    ensure
        empty: is_empty

feature -- Access

infix "@", item (k: K): G
        -- Item associated with k
    require
        has_k: has (k)
    deferred

feature -- Measurement

count: INTEGER
        -- Number of items in container
        -- (From DS_CONTAINER.)
    deferred

feature -- Status report

is_empty: BOOLEAN
        -- Is container empty?
        -- (From DS_CONTAINER.)

valid_key (k: K): BOOLEAN
        -- Is k a valid key?
    deferred

has (k: K): BOOLEAN
        -- Is there an item associated with k?
    deferred
    ensure
        valid_key: Result implies valid_key (k)

feature -- Comparison

is_equal (other: like Current): BOOLEAN
        -- Is current container 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 container.
        -- (From GENERAL.)
    require
        other_not_void: other /= Void
        type_identity: same_type (other)
    deferred
    ensure
        is_equal: is_equal (other)

feature -- Element change

replace (v: G; k: K)
        -- Replace item associated with k by v.
    require
        has_k: has (k)
    deferred
    ensure
        replaced: item (k) = v
        same_count: count = old count

put (v: G; k: K)
        -- Associate v with key k.
    require
        valid_key: valid_key (k)
    deferred
    ensure
        inserted: has (k) and then item (k) = v
        same_count: (old has (k)) implies (count = old count)
        one_more: (not old has (k)) implies (count = old count + 1)

put_new (v: G; k: K)
        -- Associate v with key k.
    require
        valid_key: valid_key (k)
        new_item: not has (k)
    deferred
    ensure
        one_more: count = old count + 1
        inserted: has (k) and then item (k) = v

swap (k, l: K)
        -- Exchange items associated with k and l.
    require
        valid_k: has (k)
        valid_l: has (l)
    ensure
        same_count: count = old count
        new_k: item (k) = old item (l)
        new_l: item (l) = old item (k)

feature -- Removal

remove (k: K)
        -- Remove item associated with k.
    require
        valid_key: valid_key (k)
    deferred
    ensure
        same_count: (not old has (k)) implies (count = old count)
        one_less: (old has (k)) implies (count = old count - 1)
        removed: not has (k)

wipe_out
        -- Remove all items from container.
        -- (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_TABLE