New Language: Ada

From-SVN: r45956

1 files changed, 253 insertions, 0 deletions

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+------------------------------------------------------------------------------
+--                                                                          --
+--                         GNAT COMPILER COMPONENTS                         --
+--                                                                          --
+--                             R E S T R I C T                              --
+--                                                                          --
+--                                 S p e c                                  --
+--                                                                          --
+--                            $Revision: 1.27 $
+--                                                                          --
+--          Copyright (C) 1992-2001 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. --
+-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
+--                                                                          --
+------------------------------------------------------------------------------
+
+--  This package deals with the implementation of the Restrictions pragma
+
+with Rident;
+with Types;  use Types;
+with Uintp;  use Uintp;
+
+package Restrict is
+
+   type Restriction_Id is new Rident.Restriction_Id;
+   --  The type Restriction_Id defines the set of restriction identifiers,
+   --  which take no parameter (i.e. they are either present or not present).
+   --  The actual definition is in the separate package Rident, so that it
+   --  can easily be accessed by the binder without dragging in lots of stuff.
+
+   subtype Partition_Restrictions is
+     Restriction_Id range
+       Restriction_Id (Rident.Partition_Restrictions'First) ..
+       Restriction_Id (Rident.Partition_Restrictions'Last);
+   --  Range of restriction identifiers that are checked by the binder
+
+   subtype Compilation_Unit_Restrictions is
+     Restriction_Id range
+       Restriction_Id (Rident.Compilation_Unit_Restrictions'First) ..
+       Restriction_Id (Rident.Compilation_Unit_Restrictions'Last);
+   --  Range of restriction identifiers not checked by binder
+
+   type Restriction_Parameter_Id is new Rident.Restriction_Parameter_Id;
+   --  The type Restriction_Parameter_Id records cases where a parameter is
+   --  present in the corresponding pragma. These cases are not checked for
+   --  consistency by the binder. The actual definition is in the separate
+   --  package Rident for consistency.
+
+   type Restrictions_Flags is array (Restriction_Id) of Boolean;
+   --  Type used for arrays indexed by Restriction_Id.
+
+   Restrictions : Restrictions_Flags := (others => False);
+   --  Corresponding entry is False if restriction is not active, and
+   --  True if the restriction is active, i.e. if a pragma Restrictions
+   --  has been seen anywhere. Note that we are happy to pick up any
+   --  restrictions pragmas in with'ed units, since we are required to
+   --  be consistent at link time, and we might as well find the error
+   --  at compile time. Clients must NOT use this array for checking to
+   --  see if a restriction is violated, instead it is required that the
+   --  Check_Restrictions subprograms be used for this purpose. The only
+   --  legitimate direct use of this array is when the code is modified
+   --  as a result of the restriction in some way.
+
+   Restrictions_Loc : array (Restriction_Id) of Source_Ptr;
+   --  Locations of Restrictions pragmas for error message purposes.
+   --  Valid only if corresponding entry in Restrictions is set.
+
+   Main_Restrictions : Restrictions_Flags := (others => False);
+   --  This variable saves the cumulative restrictions in effect compiling
+   --  any unit that is part of the extended main unit (i.e. the compiled
+   --  unit, its spec if any, and its subunits if any). The reason we keep
+   --  track of this is for the information that goes to the binder about
+   --  restrictions that are set. The binder will identify a unit that has
+   --  a restrictions pragma for error message purposes, and we do not want
+   --  to pick up a restrictions pragma in a with'ed unit for this purpose.
+
+   Violations : Restrictions_Flags := (others => False);
+   --  Corresponding entry is False if the restriction has not been
+   --  violated in the current main unit, and True if it has been violated.
+
+   Restriction_Parameters :
+     array (Restriction_Parameter_Id) of Uint := (others => No_Uint);
+   --  This array indicates the setting of restriction parameter identifier
+   --  values. All values are initially set to No_Uint indicating that the
+   --  parameter is not set, and are set to the appropriate non-negative
+   --  value if a Restrictions pragma specifies the corresponding
+   --  restriction parameter identifier with an appropriate value.
+
+   Restriction_Parameters_Loc :
+     array (Restriction_Parameter_Id) of Source_Ptr;
+   --  Locations of Restrictions pragmas for error message purposes.
+   --  Valid only if corresponding entry in Restriction_Parameters is
+   --  set to a value other than No_Uint.
+
+   type Unit_Entry is record
+      Res_Id : Restriction_Id;
+      Filenm : String (1 .. 8);
+   end record;
+
+   type Unit_Array_Type is array (Positive range <>) of Unit_Entry;
+
+   Unit_Array : constant Unit_Array_Type := (
+     (No_Asynchronous_Control,    "a-astaco"),
+     (No_Calendar,                "a-calend"),
+     (No_Calendar,                "calendar"),
+     (No_Delay,                   "a-calend"),
+     (No_Delay,                   "calendar"),
+     (No_Dynamic_Priorities,      "a-dynpri"),
+     (No_IO,                      "a-direio"),
+     (No_IO,                      "directio"),
+     (No_IO,                      "a-sequio"),
+     (No_IO,                      "sequenio"),
+     (No_IO,                      "a-ststio"),
+     (No_IO,                      "a-textio"),
+     (No_IO,                      "text_io "),
+     (No_IO,                      "a-witeio"),
+     (No_Task_Attributes,         "a-tasatt"),
+     (No_Streams,                 "a-stream"),
+     (No_Unchecked_Conversion,    "a-unccon"),
+     (No_Unchecked_Conversion,    "unchconv"),
+     (No_Unchecked_Deallocation,  "a-uncdea"),
+     (No_Unchecked_Deallocation,  "unchdeal"));
+   --  This array defines the mapping between restriction identifiers and
+   --  predefined language files containing units for which the identifier
+   --  forbids semantic dependence.
+
+   type Save_Compilation_Unit_Restrictions is private;
+   --  Type used for saving and restoring compilation unit restrictions.
+   --  See Compilation_Unit_Restrictions_[Save|Restore] subprograms.
+
+   -----------------
+   -- Subprograms --
+   -----------------
+
+   procedure Check_Restricted_Unit (U : Unit_Name_Type; N : Node_Id);
+   --  Checks if loading of unit U is prohibited by the setting of some
+   --  restriction (e.g. No_IO restricts the loading of unit Ada.Text_IO).
+   --  If a restriction exists post error message at the given node.
+
+   procedure Check_Restriction (R : Restriction_Id; N : Node_Id);
+   --  Checks that the given restriction is not set, and if it is set, an
+   --  appropriate message is posted on the given node. Also records the
+   --  violation in the violations array. Note that it is mandatory to
+   --  always use this routine to check if a restriction is violated. Such
+   --  checks must never be done directly by the caller, since otherwise
+   --  they are not properly recorded in the violations array.
+
+   procedure Check_Restriction
+     (R : Restriction_Parameter_Id;
+      N : Node_Id);
+   --  Checks that the given restriction parameter identifier is not set to
+   --  zero. If it is set to zero, then the node N is replaced by a node
+   --  that raises Storage_Error, and a warning is issued.
+
+   procedure Check_Restriction
+     (R : Restriction_Parameter_Id;
+      V : Uint;
+      N : Node_Id);
+   --  Checks that the count in V does not exceed the maximum value of the
+   --  restriction parameter value corresponding to the given restriction
+   --  parameter identifier (if it has been set). If the count in V exceeds
+   --  the maximum, then post an error message on node N.
+
+   procedure Check_Elaboration_Code_Allowed (N : Node_Id);
+   --  Tests to see if elaboration code is allowed by the current restrictions
+   --  settings. This function is called by Gigi when it needs to define
+   --  an elaboration routine. If elaboration code is not allowed, an error
+   --  message is posted on the node given as argument.
+
+   function No_Exception_Handlers_Set return Boolean;
+   --  Test to see if current restrictions settings specify that no exception
+   --  handlers are present. This function is called by Gigi when it needs to
+   --  expand an AT END clean up identifier with no exception handler.
+
+   function Compilation_Unit_Restrictions_Save
+     return Save_Compilation_Unit_Restrictions;
+   --  This function saves the compilation unit restriction settings, and
+   --  resets them to False. This is used e.g. when compiling a with'ed
+   --  unit to avoid incorrectly propagating restrictions. Note that it
+   --  would not be wrong to also save and reset the partition restrictions,
+   --  since the binder would catch inconsistencies, but actually it is a
+   --  good thing to acquire restrictions from with'ed units if they are
+   --  required to be partition wide, because it allows the restriction
+   --  violation message to be given at compile time instead of link time.
+
+   procedure Compilation_Unit_Restrictions_Restore
+     (R : Save_Compilation_Unit_Restrictions);
+   --  This is the corresponding restore procedure to restore restrictions
+   --  previously saved by Compilation_Unit_Restrictions_Save.
+
+   procedure Disallow_In_No_Run_Time_Mode (Enode : Node_Id);
+   --  If in No_Run_Time mode, then the construct represented by Enode is
+   --  not permitted, and will be appropriately flagged.
+
+   procedure Set_No_Run_Time_Mode;
+   --  Set the no run time mode, and associated restriction pragmas.
+
+   function Get_Restriction_Id
+     (N    : Name_Id)
+      return Restriction_Id;
+   --  Given an identifier name, determines if it is a valid restriction
+   --  identifier, and if so returns the corresponding Restriction_Id
+   --  value, otherwise returns Not_A_Restriction_Id.
+
+   function Get_Restriction_Parameter_Id
+     (N    : Name_Id)
+      return Restriction_Parameter_Id;
+   --  Given an identifier name, determines if it is a valid restriction
+   --  parameter identifier, and if so returns the corresponding
+   --  Restriction_Parameter_Id value, otherwise returns
+   --  Not_A_Restriction_Parameter_Id.
+
+   function Abort_Allowed return Boolean;
+   pragma Inline (Abort_Allowed);
+   --  Tests to see if abort is allowed by the current restrictions settings.
+   --  For abort to be allowed, either No_Abort_Statements must be False,
+   --  or Max_Asynchronous_Select_Nesting must be non-zero.
+
+   function Restricted_Profile return Boolean;
+   --  Tests to see if tasking operations follow the GNAT restricted run time
+   --  profile.
+
+   procedure Set_Ravenscar;
+   --  Sets the set of rerstrictions fro Ravenscar
+
+   procedure Set_Restricted_Profile;
+   --  Sets the set of restrictions for pragma Restricted_Run_Time
+
+   function Tasking_Allowed return Boolean;
+   pragma Inline (Tasking_Allowed);
+   --  Tests to see if tasking operations are allowed by the current
+   --  restrictions settings. For tasking to be allowed Max_Tasks must
+   --  be non-zero.
+
+private
+   type Save_Compilation_Unit_Restrictions is
+     array (Compilation_Unit_Restrictions) of Boolean;
+   --  Type used for saving and restoring compilation unit restrictions.
+   --  See Compilation_Unit_Restrictions_[Save|Restore] subprograms.
+
+end Restrict;