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--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                              S E M _ D I M                               --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--          Copyright (C) 2011-2012, 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 3,  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 COPYING3.  If not, go to --

-- http://www.gnu.org/licenses for a complete copy of the license.          --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

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--  This package provides support for numerical systems with dimensions. A

--  "dimension" is a compile-time property of a numerical type which represents

--  a relation between various quantifiers such as length, velocity, etc.

--  Package System.Dim.Mks offers a ready-to-use system of SI base units. In

--  addition, the implementation of this feature offers the ability to define

--  an arbitrary system of units through the use of Ada 2012 aspects.

--  Dimensionality checking is part of type analysis performed by the compiler.

--  It ensures that manipulation of quantified numeric values is sensible with

--  respect to the system of units.

-----------------------------

-- Aspect_Dimension_System --

-----------------------------

--  In order to enable the user to create their own dimension system, a new

--  aspect: Aspect_Dimension_System has been created.

--  Note that this aspect applies for type declaration of type derived from any

--  numeric type.

--  It defines the names of each dimension

----------------------

-- Aspect_Dimension --

----------------------

--  This new aspect applies for subtype and object declarations in order to

--  define new dimensions.

--  Using this aspect, the user is able to create new subtype/object with any

--  dimension needed.

--  Note that the base type of the subtype/object must be the type that defines

--  the corresponding dimension system.

--  The expression of this aspect is an aggregate of rational values for each

--  dimension in the corresponding dimension system.

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-- Dimensionality checking & propagation --

-------------------------------------------

--  For each node (when needed), a dimension analysis (Analyze_Dimension) is

--  performed as part of the Resolution routine or the Analysis routine if no

--  Resolution.

--  The dimension analysis is divided into two phases:

--  Phase 1: dimension checking

--  Phase 2: propagation of dimensions

--  Depending on the node kind, either none, one phase or two phases are

--  executed.

--  Phase 2 is called only when the node allows a dimension (see body of

--  Sem_Dim to get the list of nodes that permit dimensions).

with Types; use Types;

package Sem_Dim is

   procedure Analyze_Aspect_Dimension

     (N    : Node_Id;

      Id   : Entity_Id;

      Aggr : Node_Id);

   --  Analyze the contents of aspect Dimension. Associate the provided values

   --  and quantifiers with the related context N. Id is the corresponding

   --  Aspect_Id (Aspect_Dimension) Aggr is the corresponding expression for

   --  the aspect Dimension declared by the declaration of N.

   procedure Analyze_Aspect_Dimension_System

     (N    : Node_Id;

      Id   : Entity_Id;

      Aggr : Node_Id);

   --  Analyze the contents of aspect Dimension_System. Extract the numerical

   --  type, unit name and corresponding symbol from each indivitual dimension.

   --  Id is the corresponding Aspect_Id (Aspect_Dimension_System)

   --  Aggr is the corresponding expression for the aspect Dimension_System

   --  declared by the declaration of N.

   procedure Analyze_Dimension (N : Node_Id);

   --  N may denote any of the following contexts:

   --    * assignment statement

   --    * attribute reference

   --    * binary operator

   --    * compontent declaration

   --    * extended return statement

   --    * function call

   --    * identifier

   --    * indexed component

   --    * object declaration

   --    * object renaming declaration

   --    * qualified expression

   --    * selected component

   --    * simple return statement

   --    * slice

   --    * subtype declaration

   --    * type conversion

   --    * unary operator

   --    * unchecked type conversion

   --  Depending on the context, ensure that all expressions and entities

   --  involved do not violate the rules of a system.

   procedure Eval_Op_Expon_For_Dimensioned_Type

     (N    : Node_Id;

      Btyp : Entity_Id);

   --  Evaluate the Expon operator for dimensioned type with rational exponent.

   --  Indeed the regular Eval_Op_Expon routine (see package Sem_Eval) is

   --  restricted to Integer exponent. This routine deals only with rational

   --  exponent which is not an integer if Btyp is a dimensioned type.

   procedure Expand_Put_Call_With_Dimension_Symbol (N : Node_Id);

   --  Determine whether N denotes a subprogram call to one of the routines

   --  defined in System.Dim.Float_IO or System.Dim.Integer_IO and add an

   --  extra actual to the call to represent the symbolic representation of

   --  a dimension.

   function Has_Dimension_System (Typ : Entity_Id) return Boolean;

   --  Return True if type Typ has aspect Dimension_System applied to it

   function Is_Dim_IO_Package_Instantiation (N : Node_Id) return Boolean;

   --  Return True if N is a package instantiation of System.Dim.Integer_IO or

   --  of System.Dim.Float_IO.

   procedure Remove_Dimension_In_Call (Call : Node_Id);

   --  Remove the dimensions from all formal parameters of Call

   procedure Remove_Dimension_In_Statement (Stmt : Node_Id);

   --  Remove the dimensions associated with Stmt

end Sem_Dim;