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note description: "Hash tables, used to store items identified by hashable keys" library: "Free implementation of ELKS library" instructions: "See instructions at the end of the class." warning: "[ Modifying an object used as a key by an item present in a table will cause incorrect behavior. If you will be modifying key objects, pass a clone, not the object itself, as key argument to put and replace_key. ]" class interface HASH_TABLE [G -> , K -> detachable HASHABLE] create make (n: INTEGER_32) -- Allocate hash table for at least n items. -- The table will be resized automatically -- if more than n items are inserted. require n_non_negative: n >= 0 ensure breathing_space: n < capacity more_than_minimum: capacity > Minimum_capacity no_status: not special_status make_equal (n: INTEGER_32) -- Allocate hash table for at least n items. -- The table will be resized automatically -- if more than n items are inserted. -- Use ~ to compare items. require n_non_negative: n >= 0 ensure breathing_space: n < capacity more_than_minimum: capacity > Minimum_capacity no_status: not special_status compare_objects: object_comparison feature -- Initialization accommodate (n: INTEGER_32) -- Reallocate table with enough space for n items; -- keep all current items. require n >= 0 ensure count_not_changed: count = old count breathing_space: count < capacity make (n: INTEGER_32) -- Allocate hash table for at least n items. -- The table will be resized automatically -- if more than n items are inserted. require n_non_negative: n >= 0 ensure breathing_space: n < capacity more_than_minimum: capacity > Minimum_capacity no_status: not special_status make_equal (n: INTEGER_32) -- Allocate hash table for at least n items. -- The table will be resized automatically -- if more than n items are inserted. -- Use ~ to compare items. require n_non_negative: n >= 0 ensure breathing_space: n < capacity more_than_minimum: capacity > Minimum_capacity no_status: not special_status compare_objects: object_comparison feature -- Access at alias "@" (key: K): detachable G assign force -- Item associated with key, if present -- otherwise default value of type G. -- Was declared in HASH_TABLE as synonym of item. note option: stable ensure then default_value_if_not_present: (not has (key)) implies (Result = computed_default_value) current_keys: ARRAY [K] -- New array containing actually used keys, from 1 to count ensure good_count: Result.count = count cursor: CURSOR -- Current cursor position ensure cursor_not_void: Result /= Void definite_item (key: K): G -- Entry of key k. require -- from TABLE valid_key: has (key) require -- from TABLE valid_key: has (key) found_item: detachable G -- Item, if any, yielded by last search operation generating_type: TYPE [detachable HASH_TABLE [G, K]] -- Type of current object -- (type of which it is a direct instance) -- (from ANY) ensure -- from ANY generating_type_not_void: Result /= Void generator: STRING_8 -- Name of current object's generating class -- (base class of the type of which it is a direct instance) -- (from ANY) ensure -- from ANY generator_not_void: Result /= Void generator_not_empty: not Result.is_empty has (key: K): BOOLEAN -- Is there an item in the table with key key? require -- from TABLE True ensure then default_case: (key = computed_default_key) implies (Result = has_default) has_item (v: G): BOOLEAN -- Does structure include v? -- (Reference or object equality, based on object_comparison.) ensure -- from CONTAINER not_found_in_empty: Result implies not is_empty has_key (key: K): BOOLEAN -- Is there an item in the table with key key? -- Set found_item to the found item. ensure then default_case: (key = computed_default_key) implies (Result = has_default) found: Result = found item_if_found: found implies (found_item = item (key)) hash_code_of (a_key: attached K): INTEGER_32 -- Hash_code value associated to a_key. ensure non_negative: Result >= 0 item alias "[]" (key: K): detachable G assign force -- Item associated with key, if present -- otherwise default value of type G. -- Was declared in HASH_TABLE as synonym of at. note option: stable ensure then default_value_if_not_present: (not has (key)) implies (Result = computed_default_value) item_for_iteration: G -- Element at current iteration position require not_off: not off iteration_item (i: INTEGER_32): G -- Entry at position i. require -- from READABLE_INDEXABLE valid_index: valid_iteration_index (i) key_for_iteration: K -- Key at current iteration position require not_off: not off new_cursor: HASH_TABLE_ITERATION_CURSOR [G, K] -- Fresh cursor associated with current structure require -- from ITERABLE True ensure -- from ITERABLE result_attached: Result /= Void feature -- Measurement capacity: INTEGER_32 -- Number of items that may be stored. count: INTEGER_32 -- Number of items in table iteration_lower: INTEGER_32 -- Minimum index. iteration_upper: INTEGER_32 -- Maximum index. occurrences (v: G): INTEGER_32 -- Number of table items equal to v. ensure -- from BAG non_negative_occurrences: Result >= 0 feature -- Comparison frozen deep_equal (a: detachable ANY; b: like arg #1): BOOLEAN -- Are a and b either both void -- or attached to isomorphic object structures? -- (from ANY) ensure -- from ANY instance_free: class shallow_implies_deep: standard_equal (a, b) implies Result both_or_none_void: (a = Void) implies (Result = (b = Void)) same_type: (Result and (a /= Void)) implies (b /= Void and then a.same_type (b)) symmetric: Result implies deep_equal (b, a) disjoint (other: HASH_TABLE [G, K]): BOOLEAN -- Is Current and other disjoint on their keys? -- Use same_keys for comparison. frozen equal (a: detachable ANY; b: like arg #1): BOOLEAN -- Are a and b either both void or attached -- to objects considered equal? -- (from ANY) ensure -- from ANY instance_free: class definition: Result = (a = Void and b = Void) or else ((a /= Void and b /= Void) and then a.is_equal (b)) frozen is_deep_equal alias "≡≡≡" (other: HASH_TABLE [G, K]): BOOLEAN -- Are Current and other attached to isomorphic object structures? -- (from ANY) require -- from ANY other_not_void: other /= Void ensure -- from ANY shallow_implies_deep: standard_is_equal (other) implies Result same_type: Result implies same_type (other) symmetric: Result implies other.is_deep_equal (Current) is_equal (other: like Current): BOOLEAN -- Does table contain the same information as other? require -- from ANY other_not_void: other /= Void ensure -- from ANY symmetric: Result implies other ~ Current consistent: standard_is_equal (other) implies Result same_keys (a_search_key, a_key: K): BOOLEAN -- Does a_search_key equal to a_key? frozen standard_equal (a: detachable ANY; b: like arg #1): BOOLEAN -- Are a and b 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 instance_free: class definition: Result = (a = Void and b = Void) or else ((a /= Void and b /= Void) and then a.standard_is_equal (b)) frozen standard_is_equal alias "" (other: HASH_TABLE [G, K]): 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 cursor past last item? -- Was declared in HASH_TABLE as synonym of off. changeable_comparison_criterion: BOOLEAN -- May object_comparison be changed? -- (Answer: yes by default.) -- (from CONTAINER) conflict: BOOLEAN -- Did last operation cause a conflict? 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 Extendible: BOOLEAN = False -- May new items be added? found: BOOLEAN -- Did last operation find the item sought? Full: BOOLEAN = False -- Is structure filled to capacity? inserted: BOOLEAN -- Did last operation insert an item? is_empty: BOOLEAN -- Is structure empty? -- (from FINITE) require -- from CONTAINER True is_inserted (v: G): BOOLEAN -- Has v been inserted by the most recent insertion? -- (By default, the value returned is equivalent to calling -- has (v). However, descendants might be able to provide more -- efficient implementations.) -- (from COLLECTION) not_found: BOOLEAN -- Did last operation fail to find the item sought? object_comparison: BOOLEAN -- Must search operations use equal rather than = -- for comparing references? (Default: no, use =.) -- (from CONTAINER) off: BOOLEAN -- Is cursor past last item? -- Was declared in HASH_TABLE as synonym of after. prunable: BOOLEAN -- May items be removed? (Answer: yes.) -- (from DYNAMIC_TABLE) removed: BOOLEAN -- Did last operation remove an item? replaced: BOOLEAN -- Did last operation replace an item? 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)) valid_cursor (c: CURSOR): BOOLEAN -- Can cursor be moved to position c? require c_not_void: c /= Void valid_iteration_index (i: INTEGER_32): BOOLEAN -- Is i a valid index? ensure -- from READABLE_INDEXABLE only_if_in_index_set: Result implies (iteration_lower <= i and i <= iteration_upper) feature -- Status setting compare_objects -- Ensure that future search operations will use equal -- rather than = for comparing references. -- (from CONTAINER) require -- from CONTAINER changeable_comparison_criterion: changeable_comparison_criterion ensure -- from CONTAINER object_comparison compare_references -- Ensure that future search operations will use = -- rather than equal for comparing references. -- (from CONTAINER) require -- from CONTAINER changeable_comparison_criterion: changeable_comparison_criterion ensure -- from CONTAINER reference_comparison: not object_comparison feature -- Cursor movement forth -- Advance cursor to next occupied position, -- or off if no such position remains. require not_off: not off go_to (c: CURSOR) -- Move to position c. require c_not_void: c /= Void valid_cursor: valid_cursor (c) search (key: K) -- Search for item of key key. -- If found, set found to true, and set -- found_item to item associated with key. ensure found_or_not_found: found or not_found item_if_found: found implies (found_item = item (key)) start -- Bring cursor to first position. feature -- Element change extend (new: G; key: K) -- Assuming there is no item of key key, -- insert new with key. -- Set inserted. -- -- To choose between various insert/replace procedures, -- see usage instructions at end of class. require not_present: not has (key) ensure inserted: inserted insertion_done: item (key) = new one_more: count = old count + 1 default_property: has_default = ((key = computed_default_key) or (old has_default)) fill (other: CONTAINER [G]) -- Fill with as many items of other as possible. -- The representations of other and current structure -- need not be the same. -- (from COLLECTION) require -- from COLLECTION other_not_void: other /= Void extendible: Extendible force (new: G; key: K) -- Update table so that new will be the item associated -- with key. -- If there was an item for that key, set found -- and set found_item to that item. -- If there was none, set not_found and set -- found_item to the default value. -- -- To choose between various insert/replace procedures, -- see usage instructions at end of class. require -- from TABLE valid_key: has (key) require else True ensure -- from TABLE inserted: definite_item (key) = new ensure then insertion_done: item (key) = new now_present: has (key) found_or_not_found: found or not_found not_found_if_was_not_present: not_found = not (old has (key)) same_count_or_one_more: (count = old count) or (count = old count + 1) found_item_is_old_item: found implies (found_item = old (item (key))) default_value_if_not_found: not_found implies (found_item = computed_default_value) default_property: has_default = ((key = computed_default_key) or ((key /= computed_default_key) and (old has_default))) merge (other: HASH_TABLE [G, K]) -- Merge other into Current. If other has some elements -- with same key as in Current, replace them by one from -- other. require other_not_void: other /= Void ensure inserted: across other as other_cursor all has (other_cursor.key) end put (new: G; key: K) -- Insert new with key if there is no other item -- associated with the same key. -- Set inserted if and only if an insertion has -- been made (i.e. key was not present). -- If so, set position to the insertion position. -- If not, set conflict. -- In either case, set found_item to the item -- now associated with key (previous item if -- there was one, new otherwise). -- -- To choose between various insert/replace procedures, -- see usage instructions at end of class. require -- from TABLE valid_key: has (key) require else True ensure then conflict_or_inserted: conflict or inserted insertion_done: inserted implies item (key) = new now_present: inserted implies has (key) one_more_if_inserted: inserted implies (count = old count + 1) unchanged_if_conflict: conflict implies (count = old count) same_item_if_conflict: conflict implies (item (key) = old (item (key))) found_item_associated_with_key: found_item = item (key) new_item_if_inserted: inserted implies (found_item = new) old_item_if_conflict: conflict implies (found_item = old (item (key))) default_property: has_default = ((inserted and (key = computed_default_key)) or ((conflict or (key /= computed_default_key)) and (old has_default))) replace (new: G; key: K) -- Replace item at key, if present, -- with new; do not change associated key. -- Set replaced if and only if a replacement has been made -- (i.e. key was present); otherwise set not_found. -- Set found_item to the item previously associated -- with key (default value if there was none). -- -- To choose between various insert/replace procedures, -- see usage instructions at end of class. ensure replaced_or_not_found: replaced or not_found insertion_done: replaced implies item (key) = new no_change_if_not_found: not_found implies item (key) = old item (key) found_item_is_old_item: found_item = old item (key) replace_key (new_key: K; old_key: K) -- If there is an item of key old_key and no item of key -- new_key, replace the former's key by new_key, -- set replaced, and set found_item to the item -- previously associated with old_key. -- Otherwise set not_found or conflict respectively. -- If conflict, set found_item to the item previously -- associated with new_key. -- -- To choose between various insert/replace procedures, -- see usage instructions at end of class. ensure same_count: count = old count replaced_or_conflict_or_not_found: replaced or conflict or not_found old_absent: (replaced and not same_keys (new_key, old_key)) implies (not has (old_key)) new_present: (replaced or conflict) = has (new_key) new_item: replaced implies (item (new_key) = old (item (old_key))) not_found_implies_no_old_key: not_found implies old (not has (old_key)) conflict_iff_already_present: conflict = old has (new_key) not_inserted_if_conflict: conflict implies (item (new_key) = old item (new_key)) feature -- Removal prune (v: G) -- Remove first occurrence of v, if any, -- after cursor position. -- Move cursor to right neighbor. -- (or after if no right neighbor or v does not occur) require -- from COLLECTION prunable: prunable prune_all (v: G) -- Remove all occurrences of v. -- (Reference or object equality, -- based on object_comparison.) -- (from COLLECTION) require -- from COLLECTION prunable: prunable ensure -- from COLLECTION no_more_occurrences: not has_item (v) remove (key: K) -- Remove item associated with key, if present. -- Set removed if and only if an item has been -- removed (i.e. key was present); -- if so, set position to index of removed element. -- If not, set not_found. -- Reset found_item to its default value if removed. require -- from DYNAMIC_TABLE prunable: prunable valid_key: has (key) require else prunable ensure then removed_or_not_found: removed or not_found not_present: not has (key) one_less: found implies (count = old count - 1) default_case: (key = computed_default_key) implies (not has_default) non_default_case: (key /= computed_default_key) implies (has_default = old has_default) wipe_out -- Reset all items to default values; reset status. require -- from COLLECTION prunable: prunable ensure -- from COLLECTION wiped_out: is_empty ensure then position_equal_to_zero: item_position = 0 count_equal_to_zero: count = 0 has_default_set: not has_default no_status: not special_status feature -- Transformation correct_mismatch -- Attempt to correct object mismatch during retrieve using Mismatch_information. feature -- Conversion linear_representation: ARRAYED_LIST [G] -- Representation as a linear structure require -- from CONTAINER True ensure then result_exists: Result /= Void good_count: Result.count = count feature -- Duplication copy (other: like Current) -- Re-initialize from other. require -- from ANY other_not_void: other /= Void type_identity: same_type (other) ensure -- from ANY is_equal: Current ~ other frozen deep_copy (other: HASH_TABLE [G, K]) -- 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: HASH_TABLE [G, K] -- New object structure recursively duplicated from Current. -- (from ANY) ensure -- from ANY deep_twin_not_void: Result /= Void deep_equal: deep_equal (Current, Result) frozen standard_copy (other: HASH_TABLE [G, K]) -- 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: HASH_TABLE [G, K] -- 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: HASH_TABLE [G, K] -- New object equal to Current -- twin calls copy; to change copying/twinning semantics, redefine copy. -- (from ANY) ensure -- from ANY twin_not_void: Result /= Void is_equal: Result ~ Current feature -- Basic operations frozen default: detachable HASH_TABLE [G, K] -- 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) ensure -- from ANY instance_free: class default_rescue -- Process exception for routines with no Rescue clause. -- (Default: do nothing.) -- (from ANY) frozen do_nothing -- Execute a null action. -- (from ANY) ensure -- from ANY instance_free: class feature -- Inapplicable bag_put (v: G) -- Ensure that structure includes v. -- (from TABLE) require -- from COLLECTION extendible: Extendible ensure -- from COLLECTION item_inserted: is_inserted (v) collection_extend (v: G) -- Insert a new occurrence of v. require -- from COLLECTION extendible: Extendible ensure -- from COLLECTION item_inserted: is_inserted (v) feature -- Correction Mismatch_information: MISMATCH_INFORMATION -- Original attribute values of mismatched object -- (from MISMATCH_CORRECTOR) feature -- Output Io: STD_FILES -- Handle to standard file setup -- (from ANY) ensure -- from ANY instance_free: class io_not_void: Result /= Void out: STRING_8 -- New string containing terse printable representation -- of current object -- (from ANY) ensure -- from ANY out_not_void: Result /= Void print (o: detachable ANY) -- Write terse external representation of o -- on standard output. -- (from ANY) ensure -- from ANY instance_free: class frozen tagged_out: STRING_8 -- New string containing terse printable representation -- of current object -- (from ANY) ensure -- from ANY tagged_out_not_void: Result /= Void feature -- Platform Operating_environment: OPERATING_ENVIRONMENT -- Objects available from the operating system -- (from ANY) ensure -- from ANY instance_free: class operating_environment_not_void: Result /= Void invariant keys_not_void: keys /= Void content_not_void: content /= Void keys_enough_capacity: keys.count <= capacity + 1 content_enough_capacity: content.count <= capacity + 1 valid_iteration_position: off or truly_occupied (iteration_position) control_non_negative: control >= 0 special_status: special_status = (conflict or inserted or replaced or removed or found or not_found) count_big_enough: 0 <= count count_small_enough: count <= capacity slot_count_big_enough: 0 <= count -- from FINITE empty_definition: is_empty = (count = 0) -- from ANY reflexive_equality: standard_is_equal (Current) reflexive_conformance: conforms_to (Current) -- from READABLE_INDEXABLE consistent_boundaries: iteration_lower <= iteration_upper or else iteration_lower = iteration_upper + 1 note instruction: "[ Several procedures are provided for inserting an item with a given key. Here is how to choose between them: - Use put if you want to do an insertion only if  there was no item with the given key, doing nothing  otherwise. (You can find out on return if there was one,  and what it was.) - Use force if you always want to insert the item;  if there was one for the given key it will be removed,  (and you can find out on return what it was). - Use extend if you are sure there is no item with  the given key, enabling faster insertion (but  unpredictable behavior if this assumption is not true). - Use replace if you want to replace an already present  item with the given key, and do nothing if there is none. In addition you can use replace_key to change the key of an already present item, identified by its previous key, or do nothing if there is nothing for that previous key. You can find out on return. To find out whether a key appears in the table, use has. To find out the item, if any, associated with a certain key, use item. Both of these routines perform a search. If you need both pieces of information (does a key appear? And, if so, what is the associated item?), you can avoid performing two redundant traversals by using instead the combination of search, found and found_item as follows: your_table.search (your_key) if your_table.found then what_you_where_looking_for := your_table.found_item ... Do whatever is needed to what_you_were_looking_for ... else ... No item was present for your_key ... end ]" date: "$Date: 2020-09-18 00:49:21 -0800 (Fri, 18 Sep 2020) $" revision: "$Revision: 104681 $" copyright: "Copyright (c) 1984-2019, Eiffel Software and others" license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)" source: "[ Eiffel Software 5949 Hollister Ave., 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 HASH_TABLE
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