note description: "SET data structure for both specification and implementation." author: "JSO and JW" class interface SET [G -> attached ANY] create make_empty -- Initialize an empty set. ensure is_empty make_from_array (a: ARRAY [G]) ensure all_items_are_intended: across Current as it all a.has (it.item) end all_intended_items_added: across a as it all Current.has (it.item) end make_one (a_singleton: G) -- make a singleton set ensure count = 1 has (a_singleton) convert make_one ({ARRAY [G]}), make_one: {ARRAY [G]} feature -- Access generating_type: TYPE [detachable SET [G]] -- 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 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) 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 (other: SET [G]): 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) 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 (other: SET [G]): 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 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 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)) feature -- Duplication copy (other: SET [G]) -- 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: Current ~ other frozen deep_copy (other: SET [G]) -- 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: SET [G] -- 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: SET [G]) -- 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: SET [G] -- 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: SET [G] -- 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 SET [G] -- 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 -- Commands for implementation difference (other: like Current) -- Subtract the current set by 'other'. ensure definition: old Current.deep_twin ~ Current |\/| (old Current.deep_twin |/\| other) extend (g: G) -- Extend the current set by 'g'. ensure case_of_no_extension: (old Current.deep_twin).has (g) implies old Current.deep_twin ~ Current case_of_extension: not (old Current.deep_twin).has (g) implies old Current.deep_twin ~ Current - g intersect (other: like Current) -- Intersect current set with 'other'. ensure Current |<: old Current.deep_twin Current |<: other definition: hold_count (agent in_both_set (?, old Current.deep_twin, other)) = count subtract (g: G) -- Subtract the current set by 'g'. ensure case_of_subtraction: (old Current.deep_twin).has (g) implies old Current.deep_twin ~ Current + g case_of_no_subtraction: not (old Current.deep_twin).has (g) implies old Current.deep_twin ~ Current union (other: like Current) -- Extend the current set by 'other'. ensure old Current.deep_twin |<: Current other |<: Current definition: hold_count (agent in_either_set (?, old Current.deep_twin, other)) = count feature -- Constructor make_empty -- Initialize an empty set. ensure is_empty make_from_array (a: ARRAY [G]) ensure all_items_are_intended: across Current as it all a.has (it.item) end all_intended_items_added: across a as it all Current.has (it.item) end make_one (a_singleton: G) -- make a singleton set ensure count = 1 has (a_singleton) feature -- Conversion to array. -- as_array: ARRAY[G] -- do -- create Result.make_empty -- across -- Current as c -- loop -- Result.force (c.item, Result.upper + 1) -- end ---- Result.compare_objects -- ensure -- Current ~ create {SET[G]}.make_from_array (Result) -- -- why does this fail in {REL}.t8 -- end as_array: ARRAY [G] feature -- Debug output debug_output: STRING_8 -- String that should be displayed in debugger to represent Current. ensure -- from DEBUG_OUTPUT result_not_void: Result /= Void out: STRING_8 -- New string containing terse printable representation -- of current object ensure -- from ANY out_not_void: Result /= Void feature -- Equality is_equal (other: like Current): BOOLEAN -- Is curren set equal to 'other'? require -- from ANY other_not_void: other /= Void ensure -- from ANY symmetric: Result implies other ~ Current consistent: standard_is_equal (other) implies Result ensure then Result = (Current |<: other and then other |<: Current) feature -- Iteration new_cursor: ITERATION_CURSOR [G] -- Fresh cursor associated with current structure ensure -- from ITERABLE result_attached: Result /= Void feature -- Output Io: STD_FILES -- Handle to standard file setup -- (from ANY) ensure -- from ANY instance_free: class io_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 feature -- Quantifiers comprehension alias "|" (exp: PREDICATE [G]): like Current -- Largest subset of the current set whose elements satisfy exp -- e.g. for set: MSL_SET[STRING], -- (set | agent {STRING}.has_substring ("xy")) = {g:set | g.has_substring("xy")} ensure current_set_unchanged: Current ~ old Current.deep_twin is_subset: Result |<: Current all_satisfying_exp: Result.hold_count (exp) = # Result consistent_satisfying_items: Current.hold_count (exp) = # Result hold_count (exp: PREDICATE [G]): INTEGER_32 -- How many items satisfying exp are in Current? ensure current_set_unchanged: Current ~ old Current.deep_twin maximum_result: Result <= count feature -- Queries for specification. count alias "#": INTEGER_32 -- Return the cardinality of the set. ensure current_set_unchanged: Current ~ old Current.deep_twin definition: Result = hold_count (agent g_to_true) differenced alias "|\" (other: like Current): like Current -- Return a new set representing the difference between Current and 'other'. ensure current_set_unchanged: Current ~ old Current.deep_twin definition: Current ~ Result |\/| (Current |/\| other) extended alias "+" (g: G): like Current -- Return a new set representing the addtion of current and 'g'. ensure current_set_unchanged: Current ~ old Current.deep_twin case_of_no_extension: has (g) implies Current ~ Result case_of_extension: not has (g) implies Current ~ Result - g has (g: G): BOOLEAN -- Does the set contain 'g'? ensure current_set_unchanged: Current ~ old Current.deep_twin definition_1: Result = (hold_count (agent eq (?, g)) = 1) definition_2: Result = across Current as it some it.item ~ g end intersected alias "|/\|" (other: like Current): like Current -- Return a new set representing the intersection of current and 'other'. ensure current_set_unchanged: Current ~ old Current.deep_twin items_from_both_set: across Result as it all Current.has (it.item) and other.has (it.item) end is_empty: BOOLEAN -- Is the set empty? ensure current_set_unchanged: Current ~ old Current.deep_twin Result = (# Current = 0) is_subset_of alias "|<:" (other: like Current): BOOLEAN ensure current_set_unchanged: Current ~ old Current.deep_twin Result = across Current as cur all other.has (cur.item) end subtracted alias "-" (g: G): like Current -- Return a new set representing the difference between Current and 'other'. ensure current_set_unchanged: Current ~ old Current.deep_twin case_of_subtraction: has (g) implies Current ~ Result + g case_of_no_subtraction: not has (g) implies Current ~ Result unioned alias "|\/|" (other: like Current): like Current -- Return a new set representing the union of current and 'other'. ensure current_set_unchanged: Current ~ old Current.deep_twin items_from_either_set: across Result as it all Current.has (it.item) or other.has (it.item) end feature -- Query and command for arbitrary set members choose_item -- Choose an arbitrary element of the -- set and store it in item require not is_empty ensure has (item) chosen chosen: BOOLEAN item: G -- Return an arbitrary member from the set. require not is_empty chosen ensure has (Result) remove_item -- Remove an arbitrary member (i.e., 'item') from the set. require not is_empty chosen ensure Current ~ old Current.deep_twin - old item not chosen invariant imp.object_comparison no_duplicates: across imp.Lower |..| imp.upper as i all across imp.Lower |..| imp.upper as j all imp [i.item] ~ imp [j.item] implies i.item = j.item end end -- from ANY reflexive_equality: standard_is_equal (Current) reflexive_conformance: conforms_to (Current) end -- class SET
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