Annotated King Reference Manual/Declarations

This page is work in progress. Declarations Syntax declarative_part ::= declarative_item {declarative_item} declarative_item ::= basic_declarative_item | body basic_declarative_item ::= basic_declaration | aspect_clause basic_declaration ::= null_declaration | type_declaration | subtype_declaration | object_declaration | named_value_declaration | subprogram_declaration | statement_procedure_declaration | expression_function_declaration | module_declaration | renaming_declaration | macro_declaration | macro_expansion defining_program_unit_name ::= [parent_unit_name.] defining_identifier Rationale Inside basic_declaration, defining_program_unit_name shall be only an identifier. The mention of parent_unit_name may appear only at library level. It is provided here as some declarations apply at library level. Discussion - Null Declarations Examples null; Syntax null_declaration ::= null; Rationale - Discussion - Type Declarations See section Types. Subtype Declarations Examples subtype Month_Number is Integer range 1 .. 12; Syntax subtype_declaration ::= subtype defining_identifier is subtype_indication [aspect_specification]; subtype_indication ::= subtype_mark [constraint] subtype_mark ::= subtype_name constraint ::= scalar_constraint | composite_constraint scalar_constraint ::= range_constraint range_constraint ::= range range_specification range_specification ::= range_attribute_reference | simple_expression .. simple_expression range_attribute_reference ::= prefix'range_attribute_designator range_attribute_designator ::= range composite_constraint ::= discriminant_constraint discriminant_constraint ::= (discriminant_association {, discriminant_association}) discriminant_association ::= discriminant_selector_name => expression Rationale - Discussion - Object Declarations Examples Owner : State_Map is State_Map'(others => False); Syntax object_declaration ::= defining_identifier : [constant] subtype_indication [is expression] [aspect_specification]; Rationale - Discussion - Named Value Declarations Examples Thinking = 10.0; Message = "Hello, World!"; Syntax named_value_declaration ::= defining_identifier = static_expression; Rationale - Discussion - Subprogram Declarations Examples Set_Seed : procedure (State : out State; Seed : in Result <- Result'Last); Random : function (State : in out State) return Result; Syntax subprogram_declaration ::= subprogram_specification [aspect_specification]; subprogram_specification ::= procedure_specification | function_specification procedure_specification ::= defining_program_unit_name : procedure parameter_profile function_specification ::= defining_designator : function parameter_and_result_profile defining_designator ::= defining_program_unit_name | defining_operator_symbol operator_symbol ::= string_literal parameter_profile ::= [formal_part] parameter_and_result_profile ::= [formal_part] return subtype_mark formal_part ::= (parameter_specification {; parameter_specification}) parameter_specification ::= defining_identifier : parameter_mode subtype_mark [<- default_expression] parameter_mode ::= in | in out | out Rationale - Discussion - Statement Procedure Declarations Examples Set_Seed : procedure (Seed : in Result <- 0) is (State <- Seed); Nothing : procedure is (null); Syntax statement_procedure_declaration ::= simple_statement_procedure | declare_statement_procedure simple_statement_procedure ::= procedure_specification [aspect_specification] is (simple_statement); declare_statement_procedure ::= procedure_specification [aspect_specification] is (declare declare_declaration {declare_declaration} begin simple_statement); declare_declaration ::= subtype_declaration | object_declaration | named_value_declaration Rationale Inner declared objects can only be constant declarations. Discussion - Expression Function Declarations Examples Has_Sticks : function (ID : in Philosopher_ID) return Boolean is (Owner (ID) ); Syntax expression_function_declaration ::=            function_specification [aspect_specification] is (expression); Rationale - Discussion - Module Declarations Examples Bad_Random : module is type State is hidden; type Result is range 0 .. 2 ^ 16 - 1; Set_Seed : procedure (State : out State; Seed : in Result <- Result'Last); Random : function (State : in out State) return Result; Bad_Random : end module; Syntax module_declaration ::= module_specification; module_specification ::= defining_program_unit_name : module [aspect_specification] is           {basic_declarative_item}           [parent_unit_name.]identifier : end module Rationale - Discussion - Renaming Declarations Examples Main_Window : constant Window_ID renames King.GUI.Main_Window; Syntax renaming_declaration ::=             object_renaming_declaration           | module_renaming_declaration           | subprogram_renaming_declaration           | macro_renaming_declaration object_renaming_declaration ::= defining_identifier : [constant] subtype_mark renames object_name [aspect_specification]; module_renaming_declaration ::= defining_program_unit_name : module renames module_name [aspect_specification]; subprogram_renaming_declaration ::= subprogram_specification renames callable_entity_name [aspect_specification]; macro_renaming_declaration ::= defining_program_unit_name : macro module renames macro_module_name [aspect_specification]; Rationale The subtype of renaming object must be the same as for the renamed object. Renaming a constant object shall include the reserved word constant, on the contrary variable object shall not. Use a new name value for renaming a named value. Use a new subtype name for renaming a subtype. Discussion - Macro Declarations Examples Bounded_Lists : macro type Element is hidden with <-; "=" : function (Left : in Element; Right : in Element) return Boolean is <>; Bounded_Lists : module is type List (Max_Length : Position_Value) is hidden with Default_Initial_Condition => List.Is_Empty; Length : function (List : in List) return Count_Value; Is_Empty : function (List : in List) return Boolean is (List.Length = 0); Is_Full : function (List : in List) return Boolean is (List.Length = List.Max_Length); -- ... Bounded_Lists : end module; Syntax macro_declaration ::= macro_module_declaration macro_module_declaration ::= defining_program_unit_name : macro_formal_part module_specification; macro_formal_part ::= macro macro_formal_parameter_declaration {macro_formal_parameter_declaration} macro_formal_parameter_declaration ::=             formal_object_declaration           | formal_type_declaration           | formal_subprogram_declaration formal_object_declaration ::= defining_identifier : constant subtype_mark [<- default_expression] [aspect_specification]; formal_type_declaration ::= formal_complete_type_declaration formal_complete_type_declaration ::= type defining_identifier[discriminant_part] is formal_type_definition [or use default_subtype_mark] [aspect_specification]; formal_type_definition ::= formal_hidden_type_definition | formal_map_type_definition | formal_sequence_type_definition | formal_set_type_definition | formal_discrete_type_definition | formal_signed_integer_type_definition | formal_floating_point_definition | formal_ordinary_fixed_point_definition | formal_any_numeric_definition formal_hidden_type_definition ::= hidden [(<>)] [with <-] formal_map_type_definition ::= map_type_definition formal_sequence_type_definition ::= sequence_type_definition formal_set_type_definition ::= set_type_definition formal_discrete_type_definition ::= [range] (<>) formal_signed_integer_type_definition ::= range <> formal_floating_point_definition ::= digits <> formal_ordinary_fixed_point_definition ::= delta <> formal_any_numeric_definition ::= delta digits [range] <> formal_subprogram_declaration ::= formal_concrete_subprogram_declaration formal_concrete_subprogram_declaration ::= subprogram_specification [is subprogram_default][aspect_specification]; | statement_procedure_declaration | expression_function_declaration subprogram_default ::= default_name | <> Rationale - Discussion - Macro Expansions Examples Wrap : module is new King.Algorithms.Wrapping (Element => Philosopher_ID); Syntax macro_expansion ::=           defining_program_unit_name : module is new macro_module_name [macro_actual_part] [aspect_specification]; macro_actual_part ::= (macro_association {, macro_association}) macro_association ::= macro_formal_parameter_selector_name => explicit_macro_actual_parameter explicit_macro_actual_parameter ::= expression           | subprogram_name | subtype_mark Rationale - Discussion -