Eiffel Media API
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structure.container

Class DS_LINEAR_CURSOR


Direct ancestors

DS_CURSOR

Known direct descendants

DS_BILINEAR_CURSOR, DS_SET_CURSOR

Features

Invariants

indexing

description

Cursors for data structures that can be traversed forward

library

Gobo Eiffel Structure Library

copyright

Copyright (c) 1999-2001, Eric Bezault and others

license

Eiffel Forum License v2 (see forum.txt)

date

$Date: 2003/02/07 12:58:08 $

revision

$Revision: 1.5 $

deferred class

DS_LINEAR_CURSOR [G]

inherit

DS_CURSOR

feature -- Access

any_: KL_ANY_ROUTINES

-- Routines that ought to be in class ANY

-- (From KL_IMPORTED_ANY_ROUTINES)

ensure
any_routines_not_void: Result /= Void
container: DS_LINEAR [G]

-- Data structure traversed

-- (From DS_CURSOR)

item: G

-- Item at cursor position

-- (From DS_CURSOR)

require
not_off: not off

feature -- Comparison

is_equal (other: like Current): BOOLEAN

-- Are other and current cursor at the same position?

-- (From ANY)

require
other_not_void: other /= Void
ensure
symmetric: Result implies other.is_equal (Current)
consistent: standard_is_equal (other) implies Result

feature -- Status report

after: BOOLEAN

-- Is there no valid position to right of cursor?

is_first: BOOLEAN

-- Is cursor on first item?

ensure
not_empty: Result implies not container.is_empty
not_off: Result implies not off
is_valid: BOOLEAN

-- Is cursor valid?

-- (From DS_CURSOR)

obsolete

Backward compatibility with Gobo 1.4

ensure
definition: Result = True
off: BOOLEAN

-- Is there no item at cursor position?

-- (From DS_CURSOR)

same_position (other: like Current): BOOLEAN

-- Is current cursor at same position as other?

-- (From DS_CURSOR)

require
other_not_void: other /= Void
valid_cursor (other: like Current): BOOLEAN

-- Is other a valid cursor according
-- to current traversal strategy?

-- (From DS_CURSOR)

require
other_not_void: other /= Void
ensure
Result implies container.valid_cursor (other)

feature -- Cursor movement

forth

-- Move cursor to next position.

require
not_after: not after
go_after

-- Move cursor to after position.

ensure
after: after
go_to (other: like Current)

-- Move cursor to other's position.

-- (From DS_CURSOR)

require
other_not_void: other /= Void
other_valid: valid_cursor (other)
ensure
same_position: same_position (other)
search_forth (v: G)

-- Move to first position at or after current
-- position where item and v are equal.
-- (Use equality_tester's criterion from container
-- if not void, use = criterion otherwise.)
-- Move after if not found.

require
not_off: not off or after
start

-- Move cursor to first position.

ensure
empty_behavior: container.is_empty implies after
first_or_after: is_first xor after

feature -- Duplication

copy (other: like Current)

-- Copy other to current cursor.

-- (From ANY)

require
other_not_void: other /= Void
type_identity: same_type (other)
ensure
is_equal: is_equal (other)

feature {DS_LINEAR} -- Implementation

next_cursor: DS_LINEAR_CURSOR [G]

-- Next cursor
-- (Used by container to keep track of traversing
-- cursors (i.e. cursors associated with container
-- and which are not currently off).)

-- (From DS_CURSOR)

set_next_cursor (a_cursor: like next_cursor)

-- Set next_cursor to a_cursor.

-- (From DS_CURSOR)

ensure
next_cursor_set: next_cursor = a_cursor

invariant

after_constraint: after implies off

-- From DS_CURSOR
container_not_void: container /= Void
empty_constraint: container.is_empty implies off

-- From ANY
reflexive_equality: standard_is_equal (Current)
reflexive_conformance: conforms_to (Current)

end