note description: "Summary description for {REGISTRATION}." author: "" date: "$Date$" revision: "$Revision$" class REGISTRATION create default_create feature -- Access generating_type: TYPE [detachable REGISTRATION] -- Type of current object -- (type of which it is a direct instance) -- (from ANY) external "built_in" ensure -- from ANY generating_type_not_void: Result /= Void end generator: STRING_8 -- Name of current object's generating class -- (base class of the type of which it is a direct instance) -- (from ANY) external "built_in" ensure -- from ANY generator_not_void: Result /= Void generator_not_empty: not Result.is_empty end 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) do if a = Void then Result := b = Void else Result := b /= Void and then a.is_deep_equal (b) end 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) end 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) do if a = Void then Result := b = Void else Result := b /= Void and then a.is_equal (b) end 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)) end frozen is_deep_equal (other: REGISTRATION): BOOLEAN -- Are Current and other attached to isomorphic object structures? -- (from ANY) require -- from ANY other_not_void: other /= Void external "built_in" 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) end is_equal (other: REGISTRATION): BOOLEAN -- Is other attached to an object considered -- equal to current object? -- (from ANY) require -- from ANY other_not_void: other /= Void external "built_in" ensure -- from ANY symmetric: Result implies other ~ Current consistent: standard_is_equal (other) implies Result end 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) do if a = Void then Result := b = Void else Result := b /= Void and then a.standard_is_equal (b) end 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)) end frozen standard_is_equal (other: REGISTRATION): 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 external "built_in" ensure -- from ANY same_type: Result implies same_type (other) symmetric: Result implies other.standard_is_equal (Current) end 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 external "built_in" end 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 external "built_in" ensure -- from ANY definition: Result = (conforms_to (other) and other.conforms_to (Current)) end feature -- Duplication frozen clone (other: detachable ANY): like other obsolete "Use `twin' instead. [2017-05-31]" -- Void if other is void; otherwise new object -- equal to other -- -- For non-void other, clone calls copy; -- to change copying/cloning semantics, redefine copy. -- (from ANY) do if other /= Void then Result := other.twin end ensure -- from ANY instance_free: class equal: Result ~ other end copy (other: REGISTRATION) -- 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) external "built_in" ensure -- from ANY is_equal: Current ~ other end frozen deep_clone (other: detachable ANY): like other obsolete "Use `deep_twin' instead. [2017-05-31]" -- Void if other is void: otherwise, new object structure -- recursively duplicated from the one attached to other -- (from ANY) do if other /= Void then Result := other.deep_twin end ensure -- from ANY instance_free: class deep_equal: deep_equal (other, Result) end frozen deep_copy (other: REGISTRATION) -- Effect equivalent to that of: -- copy (other . deep_twin) -- (from ANY) require -- from ANY other_not_void: other /= Void do copy (other.deep_twin) ensure -- from ANY deep_equal: deep_equal (Current, other) end frozen deep_twin: REGISTRATION -- New object structure recursively duplicated from Current. -- (from ANY) external "built_in" ensure -- from ANY deep_twin_not_void: Result /= Void deep_equal: deep_equal (Current, Result) end frozen standard_clone (other: detachable ANY): like other obsolete "Use `standard_twin' instead. [2017-05-31]" -- Void if other is void; otherwise new object -- field-by-field identical to other. -- Always uses default copying semantics. -- (from ANY) do if other /= Void then Result := other.standard_twin end ensure -- from ANY instance_free: class equal: standard_equal (Result, other) end frozen standard_copy (other: REGISTRATION) -- 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) external "built_in" ensure -- from ANY is_standard_equal: standard_is_equal (other) end frozen standard_twin: REGISTRATION -- New object field-by-field identical to other. -- Always uses default copying semantics. -- (from ANY) external "built_in" ensure -- from ANY standard_twin_not_void: Result /= Void equal: standard_equal (Result, Current) end frozen twin: REGISTRATION -- New object equal to Current -- twin calls copy; to change copying/twinning semantics, redefine copy. -- (from ANY) external "built_in" ensure -- from ANY twin_not_void: Result /= Void is_equal: Result ~ Current end feature -- Basic operations frozen as_attached: attached REGISTRATION obsolete "Remove calls to this feature. [2017-05-31]" -- Attached version of Current. -- (Can be used during transitional period to convert -- non-void-safe classes to void-safe ones.) -- (from ANY) do Result := Current end frozen default: detachable REGISTRATION -- Default value of object's type -- (from ANY) do end frozen default_pointer: POINTER -- Default value of type POINTER -- (Avoid the need to write p.default for -- some p of type POINTER.) -- (from ANY) do ensure -- from ANY instance_free: class end default_rescue -- Process exception for routines with no Rescue clause. -- (Default: do nothing.) -- (from ANY) do end frozen do_nothing -- Execute a null action. -- (from ANY) do ensure -- from ANY instance_free: class end feature -- Attributes registrations: REL [STUDENT, COURSE] feature -- Auxiliary functions conflict (c1, c2: COURSE): BOOLEAN -- Do courses 'c1' and 'c2' conflict with each other? do Result := (c1.day = c2.day) and then ((c1.start ~ c2.start or (c1.start < c2.start and then c1.start + c1.duration >= c2.start) or (c2.start < c1.start and then c2.start + c2.duration >= c1.start))) ensure Result = ((c1.day = c2.day) and ((c1.start ~ c2.start or (c1.start < c2.start and c1.start + c1.duration >= c2.start) or (c2.start < c1.start and c2.start + c2.duration >= c1.start)))) end no_conflicts (regs: REL [STUDENT, COURSE]): BOOLEAN -- ∀ (s1, c1), (s2, c2) ∈ regs : -- c1 ≠ c2 ⋀ s1 = s2 ⇒ ¬(conflict (c1, c2)) local it1, it2: ITERATION_CURSOR [PAIR [STUDENT, COURSE]] c1, c2: COURSE s1, s2: STUDENT do Result := True from it1 := regs.new_cursor until not Result or else it1.after loop from it2 := regs.new_cursor until not Result or else it2.after loop s1 := it1.item.first c1 := it1.item.second s2 := it2.item.first c2 := it2.item.second if c1 /~ c2 and then s1 ~ s2 and then conflict (c1, c2) then Result := False end it2.forth end it1.forth end ensure Result = across regs as r1 all across regs as r2 all r1.item /~ r2.item and r1.item.first ~ r2.item.first implies not (conflict (r1.item.second, r2.item.second)) end end end feature -- Auxiliary functions for contracts pair (s: STUDENT; c: COURSE): PAIR [STUDENT, COURSE] do create Result.make (s, c) end feature -- Commands for registrations extend (s: STUDENT; c: COURSE) -- Register student 's' for course 'c'. require not_registered_yet: not registrations.has (pair (s, c)) no_conflicting_registrations: no_conflicts (registrations + pair (s, c)) do registrations.extend (pair (s, c)) ensure registrations ~ old registrations.deep_twin.extended (pair (s, c)) end extend_by_array (a: ARRAY [TUPLE [s: STUDENT; c: COURSE]]) -- Register the list of students and courses. require not_registered_yet: across a as it all not registrations.has (pair (it.item.s, it.item.c)) end no_conflicting_registrations: no_conflicts (registrations.unioned (create {REL [STUDENT, COURSE]}.make_from_tuple_array (a))) do across a as it loop extend (it.item.s, it.item.c) end ensure registrations ~ old registrations.deep_twin.unioned (create {REL [STUDENT, COURSE]}.make_from_tuple_array (a)) end remove (s: STUDENT; c: COURSE) -- Unregister student 's' for course 'c'. require registrations.has (pair (s, c)) do registrations.subtract (pair (s, c)) ensure registrations ~ old registrations.deep_twin.subtracted (pair (s, c)) end feature -- Constructor default_create -- Process instances of classes with no creation clause. -- (Default: do nothing.) do create registrations.make_empty end feature -- Output Io: STD_FILES -- Handle to standard file setup -- (from ANY) once create Result Result.set_output_default ensure -- from ANY instance_free: class io_not_void: Result /= Void end out: STRING_8 -- New string containing terse printable representation -- of current object -- (from ANY) do Result := tagged_out ensure -- from ANY out_not_void: Result /= Void end print (o: detachable ANY) -- Write terse external representation of o -- on standard output. -- (from ANY) do if o /= Void then Io.put_string (o.out) end ensure -- from ANY instance_free: class end frozen tagged_out: STRING_8 -- New string containing terse printable representation -- of current object -- (from ANY) external "built_in" ensure -- from ANY tagged_out_not_void: Result /= Void end feature -- Platform Operating_environment: OPERATING_ENVIRONMENT -- Objects available from the operating system -- (from ANY) once create Result ensure -- from ANY instance_free: class operating_environment_not_void: Result /= Void end feature -- Queries Max_course_load: INTEGER_32 = 3 feature {NONE} -- Retrieval frozen internal_correct_mismatch -- Called from runtime to perform a proper dynamic dispatch on correct_mismatch -- from MISMATCH_CORRECTOR. -- (from ANY) local l_msg: STRING_8 l_exc: EXCEPTIONS do if attached {MISMATCH_CORRECTOR} Current as l_corrector then l_corrector.correct_mismatch else create l_msg.make_from_string ("Mismatch: ") create l_exc l_msg.append (generating_type.name) l_exc.raise_retrieval_exception (l_msg) end end invariant max_course_load: across registrations as r all # registrations.image (r.item.first) <= Max_course_load end no_conflicting_registrations: no_conflicts (registrations) -- from ANY reflexive_equality: standard_is_equal (Current) reflexive_conformance: conforms_to (Current) end -- class REGISTRATION
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