5.1 Simple and Compound Statements - Sequences of Statements
1
A statement is either
simple or compound. A simple_statement encloses
no other statement. A compound_statement
can enclose simple_statements and other compound_statements.
Syntax
2
sequence_of_statements ::= statement {
statement}
3
statement ::=
{
label}
simple_statement | {
label}
compound_statement
4/2
simple_statement ::= null_statement
|
assignment_statement |
exit_statement
|
goto_statement |
procedure_call_statement
|
simple_return_statement |
entry_call_statement
|
requeue_statement |
delay_statement
|
abort_statement |
raise_statement
|
code_statement
5/2
compound_statement ::=
if_statement |
case_statement
|
loop_statement |
block_statement
|
extended_return_statement
|
accept_statement |
select_statement
6
7
label ::= <<
label_statement_identifier>>
8
statement_identifier ::= direct_name
9
The direct_name
of a statement_identifier shall be an identifier
(not an operator_symbol).
Name Resolution Rules
10
The direct_name of a statement_identifier
shall resolve to denote its corresponding implicit declaration (see below).
Legality Rules
11
Distinct identifiers shall
be used for all statement_identifiers that
appear in the same body, including inner block_statements
but excluding inner program units.
Static Semantics
12
For each statement_identifier,
there is an implicit declaration (with the specified identifier)
at the end of the declarative_part of the
innermost block_statement or body that encloses
the statement_identifier. The implicit declarations
occur in the same order as the statement_identifiers
occur in the source text. If a usage name denotes such an implicit declaration,
the entity it denotes is the label, loop_statement,
or block_statement with the given statement_identifier.
Dynamic Semantics
13
The execution of a
null_statement
has no effect.
14/2
A
transfer of control
is the run-time action of an
exit_statement,
return statement,
goto_statement, or
requeue_statement,
selection of a
terminate_alternative, raising
of an exception, or an abort, which causes the next action performed
to be one other than what would normally be expected from the other rules
of the language. As explained in
7.6.1, a
transfer of control can cause the execution of constructs to be completed
and then left, which may trigger finalization.
15
The execution of a
sequence_of_statements
consists of the execution of the individual
statements
in succession until the
sequence_ is completed.
16
1 A statement_identifier
that appears immediately within the declarative region of a named loop_statement
or an accept_statement is nevertheless implicitly
declared immediately within the declarative region of the innermost enclosing
body or block_statement; in other words, the
expanded name for a named statement is not affected by whether the statement
occurs inside or outside a named loop or an accept_statement
— only nesting within block_statements
is relevant to the form of its expanded name.
Examples
17
Examples of labeled
statements:
18
<<Here>> <<Ici>> <<Aqui>> <<Hier>> null;
19
<<After>> X := 1;
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