5.7. Exit Statements

danger

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[An exit_statement is used to complete the execution of an enclosing loop_statement; the completion is conditional if the exit_statement includes a condition.]

Syntax

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exit_statement ::= 
   exit [loop_name] [when condition];

Name Resolution Rules

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The loop_name, if any, in an exit_statement shall resolve to denote a loop_statement.

Legality Rules

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Each exit_statement applies to a loop_statement; this is the loop_statement being exited. An exit_statement with a name is only allowed within the loop_statement denoted by the name, and applies to that loop_statement. An exit_statement without a name is only allowed within a loop_statement, and applies to the innermost enclosing one. An exit_statement that applies to a given loop_statement shall not appear within a body or accept_statement, if this construct is itself enclosed by the given loop_statement.

Dynamic Semantics

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For the execution of an exit_statement, the condition, if present, is first evaluated. If the value of the condition is True, or if there is no condition, a transfer of control is done to complete the loop_statement. If the value of the condition is False, no transfer of control takes place.

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NOTE Several nested loops can be exited by an exit_statement that names the outer loop.

Examples

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Examples of loops with exit statements:

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for N in 1 .. Max_Num_Items loop
   Get_New_Item(New_Item);
   Merge_Item(New_Item, Storage_File);
   exit when New_Item = Terminal_Item;
end loop;


Main_Cycle:
   loop
      --  initial statements
      exit Main_Cycle when Found;
      --  final statements
   end loop Main_Cycle;