9.5.2 Entries and Accept Statements

Entry_declarations, with the corresponding entry_bodies or accept_statements, are used to define potentially queued operations on tasks and protected objects.

Syntax

entry_declaration ::=
entry defining_identifier [(discrete_subtype_definition)] parameter_profile;

accept_statement ::=
   accept entry_direct_name [(entry_index)] parameter_profile [do
     handled_sequence_of_statements
   end [entry_identifier]];

entry_index ::= expression

entry_body ::=
  entry defining_identifier  entry_body_formal_part  entry_barrier is
    declarative_part
  begin
    handled_sequence_of_statements
  end [entry_identifier];

entry_body_formal_part ::= [(entry_index_specification)] parameter_profile

entry_barrier ::= when condition

entry_index_specification ::= for defining_identifier in discrete_subtype_definition

If an entry_identifier appears at the end of an accept_statement, it shall repeat the entry_direct_name. If an entry_identifier appears at the end of an entry_body, it shall repeat the defining_identifier.

An entry_declaration is allowed only in a protected or task declaration.

Name Resolution Rules

In an accept_statement, the expected profile for the entry_direct_name is that of the entry_declaration; the expected type for an entry_index is that of the subtype defined by the discrete_subtype_definition of the corresponding entry_declaration.

Within the handled_sequence_of_statements of an accept_statement, if a selected_component has a prefix that denotes the corresponding entry_declaration, then the entity denoted by the prefix is the accept_statement, and the selected_component is interpreted as an expanded name (see 4.1.3); the selector_name of the selected_component has to be the identifier for some formal parameter of the accept_statement.

Legality Rules

An entry_declaration in a task declaration shall not contain a specification for an access parameter (see 3.10).

For an accept_statement, the innermost enclosing body shall be a task_body, and the entry_direct_name shall denote an entry_declaration in the corresponding task declaration; the profile of the accept_statement shall conform fully to that of the corresponding entry_declaration. An accept_statement shall have a parenthesized entry_index if and only if the corresponding entry_declaration has a discrete_subtype_definition.

An accept_statement shall not be within another accept_statement that corresponds to the same entry_declaration, nor within an asynchronous_select inner to the enclosing task_body.

An entry_declaration of a protected unit requires a completion, which shall be an entry_body, and every entry_body shall be the completion of an entry_declaration of a protected unit. The profile of the entry_body shall conform fully to that of the corresponding declaration.

An entry_body_formal_part shall have an entry_index_specification if and only if the corresponding entry_declaration has a discrete_subtype_definition. In this case, the discrete_subtype_definitions of the entry_declaration and the entry_index_specification shall fully conform to one another (see 6.3.1).

A name that denotes a formal parameter of an entry_body is not allowed within the entry_barrier of the entry_body.

Static Semantics

The parameter modes defined for parameters in the parameter_profile of an entry_declaration are the same as for a subprogram_declaration and have the same meaning (see 6.2).

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