-- --
-- S p e c --
-- --
--- $Revision$
--- --
--- Copyright (C) 1992-2002, Free Software Foundation, Inc. --
+-- Copyright (C) 1992-2007, 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- --
-- 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. --
+-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
+-- Boston, MA 02110-1301, 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). --
+-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
-- This spec also documents all GNAT implementation defined pragmas
-with Snames; use Snames;
-with Types; use Types;
+with Exp_Tss; use Exp_Tss;
+with Namet; use Namet;
+with Snames; use Snames;
+with Types; use Types;
package Sem_Attr is
- type Attribute_Class_Array is array (Attribute_Id) of Boolean;
- -- Type used to build attribute classification flag arrays
-
-----------------------------------------
-- Implementation Dependent Attributes --
-----------------------------------------
------------------
Attribute_Abort_Signal => True,
- --
- -- Standard'Abort_Signal (Standard is the only allowed prefix)
- -- provides the entity for the special exception used to signal
- -- task abort or asynchronous transfer of control. Normally this
- -- attribute should only be used in the tasking runtime (it is
- -- highly peculiar, and completely outside the normal semantics
- -- of Ada, for a user program to intercept the abort exception).
+ -- Standard'Abort_Signal (Standard is the only allowed prefix) provides
+ -- the entity for the special exception used to signal task abort or
+ -- asynchronous transfer of control. Normally this attribute should only
+ -- be used in the tasking runtime (it is highly peculiar, and completely
+ -- outside the normal semantics of Ada, for a user program to intercept
+ -- the abort exception).
------------------
-- Address_Size --
------------------
Attribute_Address_Size => True,
- --
-- Standard'Address_Size (Standard is the only allowed prefix) is
-- a static constant giving the number of bits in an Address. It
-- is used primarily for constructing the definition of Memory_Size
---------------
Attribute_Asm_Input => True,
- --
- -- Used only in conjunction with the Asm and Asm_Volatile subprograms
- -- in package Machine_Code to construct machine instructions. See
- -- documentation in package Machine_Code in file s-maccod.ads.
+ -- Used only in conjunction with the Asm subprograms in package
+ -- Machine_Code to construct machine instructions. See documentation
+ -- in package Machine_Code in file s-maccod.ads.
----------------
-- Asm_Output --
----------------
Attribute_Asm_Output => True,
- --
- -- Used only in conjunction with the Asm and Asm_Volatile subprograms
- -- in package Machine_Code to construct machine instructions. See
- -- documentation in package Machine_Code in file s-maccod.ads.
+ -- Used only in conjunction with the Asm subprograms in package
+ -- Machine_Code to construct machine instructions. See documentation
+ -- in package Machine_Code in file s-maccod.ads.
---------------
-- AST_Entry --
---------------
Attribute_AST_Entry => True,
- --
-- E'Ast_Entry, where E is a task entry, yields a value of the
-- predefined type System.DEC.AST_Handler, that enables the given
-- entry to be called when an AST occurs. If the name to which the
---------
Attribute_Bit => True,
- --
- -- Obj'Bit, where Obj is any object, yields the bit offset within
- -- the storage unit (byte) that contains the first bit of storage
- -- allocated for the object. The value of this attribute is of the
- -- type Universal_Integer, and is always a non-negative number not
- -- exceeding the value of System.Storage_Unit.
+ -- Obj'Bit, where Obj is any object, yields the bit offset within the
+ -- storage unit (byte) that contains the first bit of storage allocated
+ -- for the object. The attribute value is of type Universal_Integer,
+ -- and is always a non-negative number not exceeding the value of
+ -- System.Storage_Unit.
--
-- For an object that is a variable or a constant allocated in a
-- register, the value is zero. (The use of this attribute does not
-- force the allocation of a variable to memory).
--
- -- For an object that is a formal parameter, this attribute applies
- -- to either the matching actual parameter or to a copy of the
- -- matching actual parameter.
+ -- For an object that is a formal parameter, this attribute applies to
+ -- either the matching actual parameter or to a copy of the matching
+ -- actual parameter.
--
-- For an access object the value is zero. Note that Obj.all'Bit is
-- subject to an Access_Check for the designated object. Similarly
------------------
Attribute_Code_Address => True,
- --
- -- subp'Code_Address, where subp is a subprogram entity, gives the
- -- address of the first generated instruction for a subprogram. This
- -- is often, but not always the same as the 'Address value, which is
- -- the address to be used in a call. The differences occur in the case
- -- of a nested procedure (where Address yields the address of the
- -- trampoline code used to load the static link), and on some systems
- -- which use procedure descriptors (in which case Address yields the
- -- address of the descriptor).
+ -- The reference subp'Code_Address, where subp is a subprogram entity,
+ -- gives the address of the first generated instruction for the sub-
+ -- program. This is often, but not always the same as the 'Address
+ -- value, which is the address to be used in a call. The differences
+ -- occur in the case of a nested procedure (where Address yields the
+ -- address of the trampoline code used to load the static link), and on
+ -- some systems which use procedure descriptors (in which case Address
+ -- yields the address of the descriptor).
-----------------------
-- Default_Bit_Order --
-----------------------
Attribute_Default_Bit_Order => True,
- --
-- Standard'Default_Bit_Order (Standard is the only permissible prefix),
-- provides the value System.Default_Bit_Order as a Pos value (0 for
-- High_Order_First, 1 for Low_Order_First). This is used to construct
---------------
Attribute_Elab_Body => True,
- --
- -- This attribute can only be applied to a program unit name. It
- -- returns the entity for the corresponding elaboration procedure
- -- for elaborating the body of the referenced unit. This is used
- -- in the main generated elaboration procedure by the binder, and
- -- is not normally used in any other context, but there may be
- -- specialized situations in which it is useful to be able to
- -- call this elaboration procedure from Ada code, e.g. if it
- -- is necessary to do selective reelaboration to fix some error.
+ -- This attribute can only be applied to a program unit name. It returns
+ -- the entity for the corresponding elaboration procedure for elabor-
+ -- ating the body of the referenced unit. This is used in the main
+ -- generated elaboration procedure by the binder, and is not normally
+ -- used in any other context, but there may be specialized situations in
+ -- which it is useful to be able to call this elaboration procedure from
+ -- Ada code, e.g. if it is necessary to do selective reelaboration to
+ -- fix some error.
---------------
-- Elab_Spec --
---------------
Attribute_Elab_Spec => True,
- --
-- This attribute can only be applied to a program unit name. It
-- returns the entity for the corresponding elaboration procedure
-- for elaborating the spec of the referenced unit. This is used
----------------
Attribute_Elaborated => True,
- --
-- Lunit'Elaborated, where Lunit is a library unit, yields a boolean
-- value indicating whether or not the body of the designated library
-- unit has been elaborated yet.
--------------
Attribute_Enum_Rep => True,
- --
-- For every enumeration subtype S, S'Enum_Rep denotes a function
-- with the following specification:
--
-----------------
Attribute_Fixed_Value => True,
- --
-- For every fixed-point type S, S'Fixed_Value denotes a function
-- with the following specification:
--
--
-- V = Arg * S'Small
--
- -- The effect is thus equivalent to first converting the argument
- -- to the integer type used to represent S, and then doing an
- -- unchecked conversion to the fixed-point type. This attribute is
- -- primarily intended for use in implementation of the input-output
- -- functions for fixed-point values.
+ -- The effect is thus equivalent to first converting the argument to
+ -- the integer type used to represent S, and then doing an unchecked
+ -- conversion to the fixed-point type. This attribute is primarily
+ -- intended for use in implementation of the input-output functions for
+ -- fixed-point values.
-----------------------
-- Has_Discriminants --
-----------------------
Attribute_Has_Discriminants => True,
- --
-- Gtyp'Has_Discriminants, where Gtyp is a generic formal type, yields
-- a Boolean value indicating whether or not the actual instantiation
-- type has discriminants.
---------
Attribute_Img => True,
- --
-- The 'Img function is defined for any prefix, P, that denotes an
-- object of scalar type T. P'Img is equivalent to T'Image (P). This
-- is convenient for debugging. For example:
-------------------
Attribute_Integer_Value => True,
- --
-- For every integer type S, S'Integer_Value denotes a function
-- with the following specification:
--
------------------
Attribute_Machine_Size => True,
- --
-- This attribute is identical to the Object_Size attribute. It is
-- provided for compatibility with the DEC attribute of this name.
-----------------------
Attribute_Maximum_Alignment => True,
- --
-- Standard'Maximum_Alignment (Standard is the only permissible prefix)
-- provides the maximum useful alignment value for the target. This
-- is a static value that can be used to specify the alignment for an
--------------------
Attribute_Mechanism_Code => True,
- --
-- function'Mechanism_Code yeilds an integer code for the mechanism
-- used for the result of function, and subprogram'Mechanism_Code (n)
-- yields the mechanism used for formal parameter number n (a static
--------------------
Attribute_Null_Parameter => True,
+ -- A reference T'Null_Parameter denotes an (imaginary) object of type or
+ -- subtype T allocated at (machine) address zero. The attribute is
+ -- allowed only as the default expression of a formal parameter, or as
+ -- an actual expression of a subporgram call. In either case, the
+ -- subprogram must be imported.
--
- -- A reference T'Null_Parameter denotes an (imaginary) object of
- -- type or subtype T allocated at (machine) address zero. The
- -- attribute is allowed only as the default expression of a formal
- -- parameter, or as an actual expression of a subporgram call. In
- -- either case, the subprogram must be imported.
+ -- The identity of the object is represented by the address zero in the
+ -- argument list, independent of the passing mechanism (explicit or
+ -- default).
--
- -- The identity of the object is represented by the address zero
- -- in the argument list, independent of the passing mechanism
- -- (explicit or default).
- --
- -- The reason that this capability is needed is that for a record
- -- or other composite object passed by reference, there is no other
- -- way of specifying that a zero address should be passed.
+ -- The reason that this capability is needed is that for a record or
+ -- other composite object passed by reference, there is no other way of
+ -- specifying that a zero address should be passed.
-----------------
-- Object_Size --
-----------------
Attribute_Object_Size => True,
- --
-- Type'Object_Size is the same as Type'Size for all types except
-- fixed-point types and discrete types. For fixed-point types and
-- discrete types, this attribute gives the size used for default
- -- allocation of objects and components of the size. See section
- -- in Einfo ("Handling of type'Size values") for further details.
+ -- allocation of objects and components of the size. See section in
+ -- Einfo ("Handling of type'Size values") for further details.
-------------------------
-- Passed_By_Reference --
-------------------------
Attribute_Passed_By_Reference => True,
- --
- -- T'Passed_By_Reference for any subtype T returns a boolean value
- -- that is true if the type is normally passed by reference and
- -- false if the type is normally passed by copy in calls. For scalar
- -- types, the result is always False and is static. For non-scalar
- -- types, the result is non-static (since it is computed by Gigi).
+ -- T'Passed_By_Reference for any subtype T returns a boolean value that
+ -- is true if the type is normally passed by reference and false if the
+ -- type is normally passed by copy in calls. For scalar types, the
+ -- result is always False and is static. For non-scalar types, the
+ -- result is non-static (since it is computed by Gigi).
------------------
-- Range_Length --
------------------
Attribute_Range_Length => True,
- --
- -- T'Range_Length for any discrete type T yields the number of
- -- values represented by the subtype (zero for a null range). The
- -- result is static for static subtypes. Note that Range_Length
- -- applied to the index subtype of a one dimensional array always
- -- gives the same result as Range applied to the array itself.
- -- The result is of type universal integer.
+ -- T'Range_Length for any discrete type T yields the number of values
+ -- represented by the subtype (zero for a null range). The result is
+ -- static for static subtypes. Note that Range_Length applied to the
+ -- index subtype of a one dimensional array always gives the same result
+ -- as Range applied to the array itself. The result is of type universal
+ -- integer.
------------------
-- Storage_Unit --
------------------
Attribute_Storage_Unit => True,
- --
-- Standard'Storage_Unit (Standard is the only permissible prefix)
-- provides the value System.Storage_Unit, and is intended primarily
-- for constructing this definition in package System (see note above
-- in Default_Bit_Order description). The is a static attribute.
+ ---------------
+ -- Stub_Type --
+ ---------------
+
+ Attribute_Stub_Type => True,
+ -- The GNAT implementation of remote access-to-classwide types is
+ -- organised as described in AARM E.4(20.t): a value of an RACW type
+ -- (designating a remote object) is represented as a normal access
+ -- value, pointing to a "stub" object which in turn contains the
+ -- necessary information to contact the designated remote object. A
+ -- call on any dispatching operation of such a stub object does the
+ -- remote call, if necessary, using the information in the stub object
+ -- to locate the target partition, etc.
+ --
+ -- For a prefix T that denotes a remote access-to-classwide type,
+ -- T'Stub_Type denotes the type of the corresponding stub objects.
+ --
+ -- By construction, the layout of T'Stub_Type is identical to that of
+ -- System.Partition_Interface.RACW_Stub_Type (see implementation notes
+ -- in body of Exp_Dist).
+
+ -----------------
+ -- Target_Name --
+ -----------------
+
+ Attribute_Target_Name => True,
+ -- Standard'Target_Name yields the string identifying the target for the
+ -- compilation, taken from Sdefault.Target_Name.
+
----------------
-- To_Address --
----------------
Attribute_To_Address => True,
- --
- -- System'To_Address (Address is the only permissible prefix)
- -- is a function that takes any integer value, and converts it into
- -- an address value. The semantics is to first convert the integer
- -- value to type Integer_Address according to normal conversion
- -- rules, and then to convert this to an address using the same
- -- semantics as the System.Storage_Elements.To_Address function.
- -- The important difference is that this is a static attribute
- -- so it can be used in initializations in preealborate packages.
+ -- System'To_Address (Address is the only permissible prefix) is a
+ -- function that takes any integer value, and converts it into an
+ -- address value. The semantics is to first convert the integer value to
+ -- type Integer_Address according to normal conversion rules, and then
+ -- to convert this to an address using the same semantics as the
+ -- System.Storage_Elements.To_Address function. The important difference
+ -- is that this is a static attribute so it can be used in
+ -- initializations in preealborate packages.
----------------
-- Type_Class --
----------------
Attribute_Type_Class => True,
- --
- -- T'Type_Class for any type or subtype T yields the value of the
- -- type class for the full type of T. If T is a generic formal type,
- -- then the value is the value for the corresponding actual subtype.
- -- The value of this attribute is of type System.Aux_DEC.Type_Class,
- -- which has the following definition:
+ -- T'Type_Class for any type or subtype T yields the value of the type
+ -- class for the full type of T. If T is a generic formal type, then the
+ -- value is the value for the corresponding actual subtype. The value of
+ -- this attribute is of type System.Aux_DEC.Type_Class, which has the
+ -- following definition:
--
-- type Type_Class is
-- (Type_Class_Enumeration,
-- Type_Class_Task,
-- Type_Class_Address);
--
- -- Protected types yield the value Type_Class_Task, which thus
- -- applies to all concurrent types. This attribute is designed to
- -- be compatible with the DEC Ada attribute of the same name.
+ -- Protected types yield the value Type_Class_Task, which thus applies
+ -- to all concurrent types. This attribute is designed to be compatible
+ -- with the DEC Ada attribute of the same name.
--
-- Note: if pragma Extend_System is used to merge the definitions of
-- Aux_DEC into System, then the type Type_Class can be referenced
-----------------
Attribute_UET_Address => True,
- --
-- Unit'UET_Address, where Unit is a program unit, yields the address
-- of the unit exception table for the specified unit. This is only
-- used in the internal implementation of exception handling. See the
------------------------------
Attribute_Universal_Literal_String => True,
- --
- -- The prefix of 'Universal_Literal_String must be a named number.
- -- The static result is the string consisting of the characters of
- -- the number as defined in the original source. This allows the
- -- user program to access the actual text of named numbers without
- -- intermediate conversions and without the need to enclose the
- -- strings in quotes (which would preclude their use as numbers).
- -- This is used internally for the construction of values of the
- -- floating-point attributes from the file ttypef.ads, but may
- -- also be used by user programs.
+ -- The prefix of 'Universal_Literal_String must be a named number. The
+ -- static result is the string consisting of the characters of the
+ -- number as defined in the original source. This allows the user
+ -- program to access the actual text of named numbers without
+ -- intermediate conversions and without the need to enclose the strings
+ -- in quotes (which would preclude their use as numbers). This is used
+ -- internally for the construction of values of the floating-point
+ -- attributes from the file ttypef.ads, but may also be used by user
+ -- programs.
-------------------------
-- Unrestricted_Access --
-------------------------
Attribute_Unrestricted_Access => True,
- --
-- The Unrestricted_Access attribute is similar to Access except that
-- all accessibility and aliased view checks are omitted. This is very
-- much a user-beware attribute. Basically its status is very similar
---------------
Attribute_VADS_Size => True,
- --
- -- Typ'VADS_Size yields the Size value typically yielded by some
- -- Ada 83 compilers. The differences between VADS_Size and Size
- -- is that for scalar types for which no Size has been specified,
- -- VADS_Size yields the Object_Size rather than the Value_Size.
- -- For example, while Natural'Size is typically 31, the value of
- -- Natural'VADS_Size is 32. For all other types, Size and VADS_Size
- -- yield the same value.
+ -- Typ'VADS_Size yields the Size value typically yielded by some Ada 83
+ -- compilers. The differences between VADS_Size and Size is that for
+ -- scalar types for which no Size has been specified, VADS_Size yields
+ -- the Object_Size rather than the Value_Size. For example, while
+ -- Natural'Size is typically 31, the value of Natural'VADS_Size is 32.
+ -- For all other types, Size and VADS_Size yield the same value.
----------------
-- Value_Size --
----------------
Attribute_Value_Size => True,
- --
- -- Type'Value_Size is the number of bits required to represent a
- -- value of the given subtype. It is the same as Type'Size, but,
- -- unlike Size, may be set for non-first subtypes. See section
- -- in Einfo ("Handling of type'Size values") for further details.
+ -- Type'Value_Size is the number of bits required to represent value of
+ -- the given subtype. It is the same as Type'Size, but, unlike Size, may
+ -- be set for non-first subtypes. See section in Einfo ("Handling of
+ -- type'Size values") for further details.
---------------
-- Word_Size --
---------------
Attribute_Word_Size => True,
- --
-- Standard'Word_Size (Standard is the only permissible prefix)
-- provides the value System.Word_Size, and is intended primarily
-- for constructing this definition in package System (see note above
-- in appropriate contexts (i.e. in subtype marks, or as prefixes for
-- other attributes).
+ function Name_Implies_Lvalue_Prefix (Nam : Name_Id) return Boolean;
+ -- Determine whether the name of an attribute reference categorizes its
+ -- prefix as an lvalue. The following attributes fall under this bracket
+ -- by directly or indirectly modifying their prefixes.
+ -- Access
+ -- Address
+ -- Input
+ -- Read
+ -- Unchecked_Access
+ -- Unrestricted_Access
+
procedure Resolve_Attribute (N : Node_Id; Typ : Entity_Id);
- -- Performs type resolution of attribute. If the attribute yields
- -- a universal value, mark its type as that of the context. On
- -- the other hand, if the context itself is universal (as in
- -- T'Val (T'Pos (X)), mark the type as being the largest type of
- -- that class that can be used at run-time. This is correct since
- -- either the value gets folded (in which case it doesn't matter
- -- what type of the class we give if, since the folding uses universal
- -- arithmetic anyway) or it doesn't get folded (in which case it is
- -- going to be dealt with at runtime, and the largest type is right).
+ -- Performs type resolution of attribute. If the attribute yields a
+ -- universal value, mark its type as that of the context. On the other
+ -- hand, if the context itself is universal (as in T'Val (T'Pos (X)), mark
+ -- the type as being the largest type of that class that can be used at
+ -- run-time. This is correct since either the value gets folded (in which
+ -- case it doesn't matter what type of the class we give if, since the
+ -- folding uses universal arithmetic anyway) or it doesn't get folded (in
+ -- which case it is going to be dealt with at runtime, and the largest type
+ -- is right).
+
+ function Stream_Attribute_Available
+ (Typ : Entity_Id;
+ Nam : TSS_Name_Type;
+ Partial_View : Entity_Id := Empty) return Boolean;
+ -- For a limited type Typ, return True iff the given attribute is
+ -- available. For Ada 05, availability is defined by 13.13.2(36/1). For Ada
+ -- 95, an attribute is considered to be available if it has been specified
+ -- using an attribute definition clause for the type, or for its full view,
+ -- or for an ancestor of either. Parameter Partial_View is used only
+ -- internally, when checking for an attribute definition clause that is not
+ -- visible (Ada 95 only).
end Sem_Attr;
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