+++ /dev/null
-------------------------------------------------------------------------------
--- --
--- GNAT COMPILER COMPONENTS --
--- --
--- S E M _ M A P S --
--- --
--- S p e c --
--- --
--- $Revision: 1.3.10.1 $
--- --
--- Copyright (C) 1996-2001 Free Software Foundation, Inc. --
--- --
--- GNAT is free software; you can redistribute it and/or modify it under --
--- terms of the GNU General Public License as published by the Free Soft- --
--- ware Foundation; either version 2, or (at your option) any later ver- --
--- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
--- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
--- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
--- for more details. You should have received a copy of the GNU General --
--- Public License distributed with GNAT; see file COPYING. If not, write --
--- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
--- MA 02111-1307, USA. --
--- --
--- GNAT was originally developed by the GNAT team at New York University. --
--- Extensive contributions were provided by Ada Core Technologies Inc. --
--- --
-------------------------------------------------------------------------------
-
--- This package contains the operations on the renaming maps used for
--- generic analysis and instantiation. Renaming maps are created when
--- a generic unit is analyzed, in order to capture all references to
--- global variables within the unit. The renaming map of a generic unit
--- copied prior to each instantiation, and then updated by mapping the
--- formals into the actuals and the local entities into entities local to
--- the instance. When the generic tree is copied to produce the instance,
--- all references are updated by means of the renaming map.
-
--- Map composition of renaming maps takes place for nested instantiations,
--- for generic child units, and for formal packages.
-
--- For additional details, see the documentation in sem_ch12.
-
-with Table;
-with Types; use Types;
-
-package Sem_Maps is
-
- type Map is new Int;
-
- type Assoc is private;
-
- type Scope_Kind is (S_Global, S_Formal, S_Local);
-
- function New_Map (Num_Assoc : Int) return Map;
- -- Build empty map with the given number of associations, and a
- -- headers table of the appropriate size.
-
- function Compose (Orig_Map : Map; New_Map : Map) return Map;
- -- Update the associations in Orig_Map, so that if Orig_Map (e1) = e2
- -- and New_Map (e2) = e3, then the image of e1 under the result is e3.
-
- function Copy (M : Map) return Map;
- -- Full copy of contents and headers.
-
- function Lookup (M : Map; E : Entity_Id) return Entity_Id;
- -- Retrieve image of E under M, Empty if undefined.
-
- procedure Add_Association
- (M : in out Map;
- O_Id : Entity_Id;
- N_Id : Entity_Id;
- Kind : Scope_Kind := S_Local);
- -- Update M in place. On entry M (O_Id) must not be defined.
-
- procedure Update_Association
- (M : in out Map;
- O_Id : Entity_Id;
- N_Id : Entity_Id;
- Kind : Scope_Kind := S_Local);
- -- Update the entry in M for O_Id.
-
- function Build_Instance_Map (M : Map) return Map;
- -- Copy renaming map of generic, and create new entities for all the
- -- local entities within.
-
-private
-
- -- New maps are created when a generic is analyzed, and for each of
- -- its instantiations. Maps are also updated for nested generics, for
- -- child units, and for formal packages. As a result we need to allocate
- -- maps dynamically.
-
- -- When analyzing a generic, we do not know how many references are
- -- in it. We build an initial map after generic analysis, using a static
- -- structure that relies on the compiler's extensible table mechanism.
- -- After constructing this initial map, all subsequent uses and updates
- -- of this map do not modify its domain, so that dynamically allocated
- -- maps have a fixed size and never need to be reallocated. Furthermore,
- -- the headers of the hash table of a dynamically allocated map can be
- -- chosen according to the total number of entries in the map, to
- -- accommodate efficiently generic units of different sizes (Unchecked_
- -- Conversion vs. Generic_Elementary_Functions, for example). So in
- -- fact both components of a map have fixed size, and can be allocated
- -- using the standard table mechanism. A Maps_Table holds records that
- -- contain indices into the global Headers table and the Associations
- -- table, and a Map is an index into the Maps_Table.
- --
- -- Maps_Table Headers_Table Associations_Table
- --
- -- |_____| |___________ |
- -- |_____| | | | |
- -- ------>|Map |------------------------------>|Associations|
- -- |Info |------------->| |=========>| for one |
- -- |_____| | |====| | unit |
- -- | | | | |====>| |
- -- |_____| |____________|
- -- | | | |
- type Header_Index is new Int;
- type Assoc_Index is new Int;
- No_Assoc : constant Assoc_Index := -1;
-
- type Map_Info is record
- Header_Offset : Header_Index;
- Header_Num : Header_Index;
- Assoc_Offset : Assoc_Index;
- Assoc_Num : Assoc_Index;
- Assoc_Next : Assoc_Index;
- end record;
-
- type Assoc is record
- Old_Id : Entity_Id := Empty;
- New_Id : Entity_Id := Empty;
- Kind : Scope_Kind := S_Local;
- Next : Assoc_Index := No_Assoc;
- end record;
-
- -- All maps are accessed through the following table. The map attribute
- -- of a generic unit or an instance is an index into this table.
-
- package Maps_Table is new Table.Table (
- Table_Component_Type => Map_Info,
- Table_Index_Type => Map,
- Table_Low_Bound => 0,
- Table_Initial => 100,
- Table_Increment => 10,
- Table_Name => "Maps_Table");
-
- -- All headers for hash tables are allocated in one global table. Each
- -- map stores the offset into this table at which its own headers start.
-
- package Headers_Table is new Table.Table (
- Table_Component_Type => Assoc_Index,
- Table_Index_Type => Header_Index,
- Table_Low_Bound => 0,
- Table_Initial => 1000,
- Table_Increment => 10,
- Table_Name => "Headers_Table");
-
- -- All associations are allocated in one global table. Each map stores
- -- the offset into this table at which its own associations start.
-
- package Associations_Table is new Table.Table (
- Table_Component_Type => Assoc,
- Table_Index_Type => Assoc_Index,
- Table_Low_Bound => 1,
- Table_Initial => 1000,
- Table_Increment => 10,
- Table_Name => "Associations_Table");
-
-end Sem_Maps;
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