    indexing
    	status: "See notice at end of class."
    	date: "$Date: 2006-01-22 18:25:44 -0800 (Sun, 22 Jan 2006) $"
    	revision: "$Revision: 56675 $"
    	access: perform_select, search, retrieve
    	product: eiffelstore
    	database: all_bases

    class interface
    	DB_SELECTION

    create
    	make
    			-- Create an interface objet to query active base.

    feature -- Initialization

    	make
    			-- Create an interface objet to query active base.

    feature -- Access

    	generating_type: STRING_8
    			-- Name of current object's generating type
    			-- (type of which it is a direct instance)
    			-- (from ANY)

    	generator: STRING_8
    			-- Name of current object's generating class
    			-- (base class of the type of which it is a direct instance)
    			-- (from ANY)

    	last_parsed_query: STRING_8
    			-- Last parsed SQL query

    feature -- Comparison

    	frozen deep_equal (some: ANY; other: like arg #1): BOOLEAN
    			-- Are `some' and `other' either both void
    			-- or attached to isomorphic object structures?
    			-- (from ANY)
    		ensure -- from ANY
    			shallow_implies_deep: standard_equal (some, other) implies Result
    			both_or_none_void: (some = Void) implies (Result = (other = Void))
    			same_type: (Result and (some /= Void)) implies some.same_type (other)
    			symmetric: Result implies deep_equal (other, some)

    	frozen equal (some: ANY; other: like arg #1): BOOLEAN
    			-- Are `some' and `other' either both void or attached
    			-- to objects considered equal?
    			-- (from ANY)
    		ensure -- from ANY
    			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.is_equal (other))

    	is_equal (other: like Current): BOOLEAN
    			-- Is `other' attached to an object considered
    			-- equal to current object?
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    		ensure -- from ANY
    			symmetric: Result implies other.is_equal (Current)
    			consistent: standard_is_equal (other) implies Result

    	frozen standard_equal (some: ANY; other: like arg #1): BOOLEAN
    			-- Are `some' and `other' either both void or attached to
    			-- field-by-field identical objects of the same type?
    			-- Always uses default object comparison criterion.
    			-- (from ANY)
    		ensure -- from ANY
    			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.standard_is_equal (other))

    	frozen standard_is_equal (other: like Current): BOOLEAN
    			-- Is `other' attached to an object of the same type
    			-- as current object, and field-by-field identical to it?
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    		ensure -- from ANY
    			same_type: Result implies same_type (other)
    			symmetric: Result implies other.standard_is_equal (Current)

    feature -- Status report

    	after: BOOLEAN
    			-- Is the container after?
    		require
    			container_exists: container /= Void

    	conforms_to (other: ANY): BOOLEAN
    			-- Does type of current object conform to type
    			-- of `other' (as per Eiffel: The Language, chapter 13)?
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void

    	container: LIST [DB_RESULT]
    			-- Stored cursors.

    	cursor: DB_RESULT
    			-- Cursor pointing to last fetched query result

    	ht: HASH_TABLE [ANY, STRING_8]
    			-- Correspondence table between object references
    			-- and mapped keys
    			-- (from STRING_HDL)

    	ht_order: ARRAYED_LIST [STRING_8]
    			-- Keys of ht in order of mapping
    			-- (from STRING_HDL)

    	immediate_execution: BOOLEAN
    			-- Are requests immediately executed?
    			-- (default is `no').
    			-- (from DB_EXEC_USE)

    	is_allocatable: BOOLEAN
    			-- Can `Current' be added to other concurrently opened selections?

    	is_exiting: BOOLEAN
    			-- Is exit condition of load_result iteration loop met?
    		ensure
    			Result implies (not is_ok or else exhausted or else (stop_condition /= Void and then stop_condition.found))

    	is_mapped (key: STRING_8): BOOLEAN
    			-- Is `key' mapped to an Eiffel entity?
    			-- (from STRING_HDL)
    		require -- from STRING_HDL
    			ht_not_void: ht /= Void
    			keys_exists: key /= Void

    	is_tracing: BOOLEAN
    			-- Is trace option for SQL queries on?
    			-- (from DB_EXEC_USE)

    	last_query: STRING_8
    			-- Last SQL statement used
    			-- (from DB_EXPRESSION)

    	mapped_value (key: STRING_8): ANY
    			-- Value mapped with `key'
    			-- (from STRING_HDL)
    		require -- from STRING_HDL
    			ht_not_void: ht /= Void
    			key_exists: key /= Void
    			key_mapped: is_mapped (key)
    		ensure -- from STRING_HDL
    			result_exists: Result /= Void

    	object: ANY
    			-- Eiffel object to be filled in by cursor_to_object

    	same_type (other: ANY): BOOLEAN
    			-- Is type of current object identical to type of `other'?
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    		ensure -- from ANY
    			definition: Result = (conforms_to (other) and other.conforms_to (Current))

    	stop_condition: ACTION
    			-- Object providing an `execute' routine called
    			-- after each load_result iteration step

    	trace_output: FILE
    			-- Trace destination file
    			-- (from DB_EXEC_USE)

    feature {ANY} -- Status report

    	is_connected: BOOLEAN
    			-- Has connection to the database server succeeded?
    			-- (from DB_STATUS_USE)

    	is_ok: BOOLEAN
    			-- Is last SQL statement ok ?
    			-- (from DB_STATUS_USE)

    feature -- Status setting

    	clear_all
    			-- Remove all mapped keys.
    			-- (from STRING_HDL)
    		require -- from STRING_HDL
    			ht_not_void: ht /= Void

    	cursor_to_object
    			-- Assign object attributes with cursor field values.
    		require
    			cursor_exists: cursor /= Void
    			object_exists: object /= Void

    	forth
    			-- Move cursor to next element of container.
    		require else
    			container_exists: container /= Void
    		ensure then
    			container_index_moved: container.index = old container.index + 1
    			cursor_updated: not after implies cursor = container.item

    	no_object_convert
    			-- Do not transform cursor into an Eiffel object
    			-- while reading in selection results.
    		ensure
    			object = Void

    	object_convert (ref: ANY)
    			-- Set object with `reference', reference to an Eiffel
    			-- object to be filled in with cursor field values.
    			-- Use this before load_result for performance.
    		require
    			reference_exists: ref /= Void
    		ensure
    			object_set: object = ref

    	reset_cursor (c: DB_RESULT)
    			-- Reset cursor with `c'.
    		require
    			arguments_exists: c /= Void
    			connected: is_connected
    		ensure
    			cursor_reset: cursor = c

    	set_action (action: ACTION)
    			-- Set stop_condition with `action'.
    		require
    			action_exists: action /= Void
    		ensure
    			stop_condition_set: stop_condition = action

    	set_container (one_container: like container)
    			-- Make results of selection query persist in container.
    		require
    			container_exists: one_container /= Void
    		ensure
    			container_set: container = one_container

    	set_immediate
    			-- Set queries to be executed with a
    			-- `EXECUTE IMMEDIATE' SQL  statement.
    			-- (from DB_EXEC_USE)
    		ensure -- from DB_EXEC_USE
    			execution_status: immediate_execution

    	set_map_name (n: ANY; key: STRING_8)
    			-- Store item `n' with key `key'.
    			-- `n' can be `Void'.
    			-- (from STRING_HDL)
    		require -- from STRING_HDL
    			ht_not_void: ht /= Void
    			key_exists: key /= Void
    			not_key_in_table: not is_mapped (key)
    		ensure -- from STRING_HDL
    			ht.count = old ht.count + 1

    	set_query (query: STRING_8)
    			-- Set last_query with query.
    			-- (from DB_EXPRESSION)
    		require -- from DB_EXPRESSION
    			query_not_void: query /= Void
    		ensure -- from DB_EXPRESSION
    			last_query_changed: last_query = query

    	set_trace
    			-- Trace queries sent to database server.
    			-- (from DB_EXEC_USE)
    		ensure -- from DB_EXEC_USE
    			trace_status: is_tracing

    	start
    			-- Set cursor on first element of container.
    		require else
    			container_exists: container /= Void
    		ensure then
    			container_on_first: container.isfirst
    			cursor_updated: cursor = container.item

    	unset_action
    			-- Reset stop_condition to Void.
    		ensure
    			stop_condition_void: stop_condition = Void

    	unset_container
    			-- Do not store in container results of selection.
    		require
    			container_exists: container /= Void
    		ensure
    			container_is_void: container = Void

    	unset_immediate
    			-- Set queries to be executed with a
    			-- `PREPARE' followed by a `EXECUTE' SQL statement.
    			-- (from DB_EXEC_USE)
    		ensure -- from DB_EXEC_USE
    			execution_status: not immediate_execution

    	unset_map_name (key: STRING_8)
    			-- Remove item associated with key `key'.
    			-- (from STRING_HDL)
    		require -- from STRING_HDL
    			ht_not_void: ht /= Void
    			key_exists: key /= Void
    			item_exists: is_mapped (key)
    		ensure -- from STRING_HDL
    			ht.count = old ht.count - 1

    	unset_trace
    			-- Do not trace queries sent to database server.
    			-- (from DB_EXEC_USE)
    		ensure -- from DB_EXEC_USE
    			trace_status: not is_tracing

    feature -- Duplication

    	copy (other: like Current)
    			-- Update current object using fields of object attached
    			-- to `other', so as to yield equal objects.
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    			type_identity: same_type (other)
    		ensure -- from ANY
    			is_equal: is_equal (other)

    	frozen deep_copy (other: like Current)
    			-- Effect equivalent to that of:
    			--		copy (`other' . deep_twin)
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    		ensure -- from ANY
    			deep_equal: deep_equal (Current, other)

    	frozen deep_twin: like Current
    			-- New object structure recursively duplicated from Current.
    			-- (from ANY)
    		ensure -- from ANY
    			deep_equal: deep_equal (Current, Result)

    	frozen standard_copy (other: like Current)
    			-- Copy every field of `other' onto corresponding field
    			-- of current object.
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    			type_identity: same_type (other)
    		ensure -- from ANY
    			is_standard_equal: standard_is_equal (other)

    	frozen standard_twin: like Current
    			-- New object field-by-field identical to `other'.
    			-- Always uses default copying semantics.
    			-- (from ANY)
    		ensure -- from ANY
    			standard_twin_not_void: Result /= Void
    			equal: standard_equal (Result, Current)

    	frozen twin: like Current
    			-- New object equal to `Current'
    			-- twin calls copy; to change copying/twining semantics, redefine copy.
    			-- (from ANY)
    		ensure -- from ANY
    			twin_not_void: Result /= Void
    			is_equal: Result.is_equal (Current)

    feature -- Basic operations

    	frozen default: like Current
    			-- Default value of object's type
    			-- (from ANY)

    	frozen default_pointer: POINTER
    			-- Default value of type `POINTER'
    			-- (Avoid the need to write `p'.default for
    			-- some `p' of type `POINTER'.)
    			-- (from ANY)

    	default_rescue
    			-- Process exception for routines with no Rescue clause.
    			-- (Default: do nothing.)
    			-- (from ANY)

    	frozen do_nothing
    			-- Execute a null action.
    			-- (from ANY)

    	execute_query
    			-- Execute query with last_query.
    		require -- from DB_EXPRESSION
    			last_query_not_void: last_query /= Void

    	load_result
    			-- Iterate through selection results,
    			-- load container if requested and call action routine
    			-- for each iteration step until `exit_condition' is met.
    		require
    			connected: is_connected
    			is_ok: is_ok
    		ensure
    			cursor_not_void: cursor /= Void
    			exit_condition_met: is_exiting

    	next
    			-- Move to next element matching the query.
    		require
    			connected: is_connected

    	query (s: STRING_8)
    			-- Select stored objects using `s' and make
    			-- them retrievable using load_result.
    		require
    			connected: is_connected
    			argument_exists: s /= Void
    			argument_is_not_empty: not s.is_empty
    			is_ok: is_ok
    			is_allocatable: is_allocatable
    		ensure
    			last_query_changed: last_query = s

    	terminate
    			-- Clear database cursor.
    		require
    			connected: is_connected
    		ensure
    			is_allocatable: is_allocatable

    	wipe_out
    			-- Clear selection results.
    		ensure
    			container_is_empty: container /= Void implies container.is_empty
    			object_model_void: object = Void
    			cursor_void: cursor = Void

    feature -- Output

    	io: STD_FILES
    			-- Handle to standard file setup
    			-- (from ANY)

    	out: STRING_8
    			-- New string containing terse printable representation
    			-- of current object
    			-- Was declared in ANY as synonym of tagged_out.
    			-- (from ANY)

    	print (some: ANY)
    			-- Write terse external representation of `some'
    			-- on standard output.
    			-- (from ANY)

    	frozen tagged_out: STRING_8
    			-- New string containing terse printable representation
    			-- of current object
    			-- Was declared in ANY as synonym of out.
    			-- (from ANY)

    feature -- Platform

    	operating_environment: OPERATING_ENVIRONMENT
    			-- Objects available from the operating system
    			-- (from ANY)

    invariant
    		-- from ANY
    	reflexive_equality: standard_is_equal (Current)
    	reflexive_conformance: conforms_to (Current)

    indexing
    	copyright: "Copyright (c) 1984-2006, Eiffel Software and others"
    	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
    	source: "[
    		Eiffel Software
    		356 Storke Road, Goleta, CA 93117 USA
    		Telephone 805-685-1006, Fax 805-685-6869
    		Website http://www.eiffel.com
    		Customer support http://support.eiffel.com
    	]"

    end -- class DB_SELECTION