203 lines
7.9 KiB
Ada
203 lines
7.9 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT COMPILER COMPONENTS --
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-- --
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-- P A R . L A B L --
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-- --
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-- B o d y --
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-- --
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-- $Revision: 1.18 $ --
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-- --
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-- Copyright (C) 1992-1998, Free Software Foundation, Inc. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 2, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
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-- for more details. You should have received a copy of the GNU General --
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-- Public License distributed with GNAT; see file COPYING. If not, write --
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-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
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-- MA 02111-1307, USA. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
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-- --
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------------------------------------------------------------------------------
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separate (Par)
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procedure Labl is
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Enclosing_Body_Or_Block : Node_Id;
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-- Innermost enclosing body or block statement
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Label_Decl_Node : Node_Id;
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-- Implicit label declaration node
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Defining_Ident_Node : Node_Id;
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-- Defining identifier node for implicit label declaration
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Next_Label_Elmt : Elmt_Id;
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-- Next element on label element list
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Label_Node : Node_Id;
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-- Next label node to process
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function Find_Enclosing_Body_Or_Block (N : Node_Id) return Node_Id;
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-- Find the innermost body or block that encloses N.
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function Find_Enclosing_Body (N : Node_Id) return Node_Id;
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-- Find the innermost body that encloses N.
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procedure Check_Distinct_Labels;
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-- Checks the rule in RM-5.1(11), which requires distinct identifiers
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-- for all the labels in a given body.
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---------------------------
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-- Check_Distinct_Labels --
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---------------------------
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procedure Check_Distinct_Labels is
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Label_Id : constant Node_Id := Identifier (Label_Node);
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Enclosing_Body : constant Node_Id :=
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Find_Enclosing_Body (Enclosing_Body_Or_Block);
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-- Innermost enclosing body
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Next_Other_Label_Elmt : Elmt_Id := First_Elmt (Label_List);
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-- Next element on label element list
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Other_Label : Node_Id;
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-- Next label node to process
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begin
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-- Loop through all the labels, and if we find some other label
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-- (i.e. not Label_Node) that has the same identifier,
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-- and whose innermost enclosing body is the same,
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-- then we have an error.
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-- Note that in the worst case, this is quadratic in the number
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-- of labels. However, labels are not all that common, and this
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-- is only called for explicit labels.
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-- ???Nonetheless, the efficiency could be improved. For example,
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-- call Labl for each body, rather than once per compilation.
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while Present (Next_Other_Label_Elmt) loop
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Other_Label := Node (Next_Other_Label_Elmt);
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exit when Label_Node = Other_Label;
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if Chars (Label_Id) = Chars (Identifier (Other_Label))
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and then Enclosing_Body = Find_Enclosing_Body (Other_Label)
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then
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Error_Msg_Sloc := Sloc (Other_Label);
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Error_Msg_N ("& conflicts with label#", Label_Id);
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exit;
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end if;
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Next_Elmt (Next_Other_Label_Elmt);
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end loop;
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end Check_Distinct_Labels;
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-------------------------
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-- Find_Enclosing_Body --
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-------------------------
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function Find_Enclosing_Body (N : Node_Id) return Node_Id is
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Result : Node_Id := N;
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begin
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-- This is the same as Find_Enclosing_Body_Or_Block, except
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-- that we skip block statements and accept statements, instead
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-- of stopping at them.
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while Present (Result)
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and then Nkind (Result) /= N_Entry_Body
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and then Nkind (Result) /= N_Task_Body
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and then Nkind (Result) /= N_Package_Body
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and then Nkind (Result) /= N_Subprogram_Body
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loop
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Result := Parent (Result);
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end loop;
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return Result;
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end Find_Enclosing_Body;
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----------------------------------
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-- Find_Enclosing_Body_Or_Block --
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----------------------------------
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function Find_Enclosing_Body_Or_Block (N : Node_Id) return Node_Id is
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Result : Node_Id := Parent (N);
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begin
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-- Climb up the parent chain until we find a body or block.
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while Present (Result)
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and then Nkind (Result) /= N_Accept_Statement
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and then Nkind (Result) /= N_Entry_Body
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and then Nkind (Result) /= N_Task_Body
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and then Nkind (Result) /= N_Package_Body
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and then Nkind (Result) /= N_Subprogram_Body
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and then Nkind (Result) /= N_Block_Statement
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loop
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Result := Parent (Result);
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end loop;
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return Result;
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end Find_Enclosing_Body_Or_Block;
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-- Start of processing for Par.Labl
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begin
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Next_Label_Elmt := First_Elmt (Label_List);
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while Present (Next_Label_Elmt) loop
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Label_Node := Node (Next_Label_Elmt);
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if not Comes_From_Source (Label_Node) then
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goto Next_Label;
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end if;
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-- Find the innermost enclosing body or block, which is where
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-- we need to implicitly declare this label
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Enclosing_Body_Or_Block := Find_Enclosing_Body_Or_Block (Label_Node);
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-- If we didn't find a parent, then the label in question never got
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-- hooked into a reasonable declarative part. This happens only in
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-- error situations, and we simply ignore the entry (we aren't going
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-- to get into the semantics in any case given the error).
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if Present (Enclosing_Body_Or_Block) then
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Check_Distinct_Labels;
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-- Now create the implicit label declaration node and its
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-- corresponding defining identifier. Note that the defining
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-- occurrence of a label is the implicit label declaration that
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-- we are creating. The label itself is an applied occurrence.
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Label_Decl_Node :=
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New_Node (N_Implicit_Label_Declaration, Sloc (Label_Node));
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Defining_Ident_Node :=
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New_Entity (N_Defining_Identifier, Sloc (Identifier (Label_Node)));
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Set_Chars (Defining_Ident_Node, Chars (Identifier (Label_Node)));
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Set_Defining_Identifier (Label_Decl_Node, Defining_Ident_Node);
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Set_Label_Construct (Label_Decl_Node, Label_Node);
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-- Now attach the implicit label declaration to the appropriate
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-- declarative region, creating a declaration list if none exists
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if not Present (Declarations (Enclosing_Body_Or_Block)) then
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Set_Declarations (Enclosing_Body_Or_Block, New_List);
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end if;
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Append (Label_Decl_Node, Declarations (Enclosing_Body_Or_Block));
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end if;
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<<Next_Label>>
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Next_Elmt (Next_Label_Elmt);
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end loop;
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end Labl;
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