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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S E M _ D I M --
-- --
-- S p e c --
-- --
-- Copyright (C) 2011-2017, 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. --
-- --
------------------------------------------------------------------------------
-- 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.
-------------------------------------------
-- 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).
-- In principle every node that is a component of a floating-point expression
-- may have a dimension vector. However, the dimensionality checking is for
-- the most part a bottom-up tree traversal, and the dimensions of operands
-- become irrelevant once the dimensions of an operation have been computed.
-- To minimize space use, the dimensions of operands are removed after the
-- computation of the dimensions of the parent operation. This may complicate
-- the analysis of nodes that have been constant-folded or otherwise rewritten
-- when removing side effects. In such cases, the (sub)type of the expression
-- is used to determine the applicable 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 from the
-- declaration of N.
procedure Analyze_Dimension (N : Node_Id);
-- N may denote any of the following contexts:
-- * aggregate
-- * assignment statement
-- * attribute reference
-- * binary operator
-- * call
-- * compontent declaration
-- * extended return statement
-- * expanded name
-- * explicit dereference
-- * identifier
-- * indexed component
-- * number declaration
-- * object declaration
-- * object renaming declaration
-- * procedure call statement
-- * 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 Analyze_Dimension_Array_Aggregate
(N : Node_Id;
Comp_Typ : Entity_Id);
-- Check, for each component of the array aggregate denoted by N, the
-- dimensions of the component expression match the dimensions of the
-- component type Comp_Typ.
procedure Analyze_Dimension_Call (N : Node_Id; Nam : Entity_Id);
-- This routine is split in two steps. Note the second step applies only to
-- function calls.
-- Step 1. Dimension checking:
-- * General case: check the dimensions of each actual parameter match
-- the dimensions of the corresponding formal parameter.
-- * Elementary function case: check each actual is dimensionless except
-- for Sqrt call.
-- Step 2. Dimension propagation (only for functions):
-- * General case: propagate the dimensions from the returned type to the
-- function call.
-- * Sqrt case: the resulting dimensions equal to half the dimensions of
-- the actual
procedure Analyze_Dimension_Extension_Or_Record_Aggregate (N : Node_Id);
-- Check, for each component of the extension or record aggregate denoted
-- by N, the dimensions of the component expression match the dimensions of
-- the component type.
procedure Analyze_Dimension_Formals (N : Node_Id; Formals : List_Id);
-- For sub spec N, issue a warning for each dimensioned formal with a
-- literal default value in the list of formals Formals.
procedure Check_Expression_Dimensions
(Expr : Node_Id;
Typ : Entity_Id);
-- Compute dimensions of a floating-point expression and compare them with
-- the dimensions of a the given type. Used to verify dimensions of the
-- components of a multidimensional array type, for which components are
-- typically themselves arrays. The resolution of such arrays delays the
-- resolution of the ultimate components to a separate phase, which forces
-- this separate dimension verification.
procedure Copy_Dimensions (From : Node_Id; To : Node_Id);
-- Copy dimension vector of node From to node To. Note that To must be a
-- node that is allowed to contain a dimension (see OK_For_Dimension in
-- body of Sem_Dim).
procedure Copy_Dimensions_Of_Components (Rec : Entity_Id);
-- Propagate the dimensions of the components of a record type T to the
-- components of a record type derived from T. The derivation creates
-- a full copy of the type declaration of the parent, and the dimension
-- information of individual components must be transferred explicitly.
function Dimensions_Match (T1 : Entity_Id; T2 : Entity_Id) return Boolean;
-- If the common base type has a dimension system, verify that two
-- subtypes have the same dimensions. Used for conformance checking.
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_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.
function New_Copy_Tree_And_Copy_Dimensions
(Source : Node_Id;
Map : Elist_Id := No_Elist;
New_Sloc : Source_Ptr := No_Location;
New_Scope : Entity_Id := Empty) return Node_Id;
-- Same as New_Copy_Tree (defined in Sem_Util), except that this routine
-- also copies the dimensions of Source to the returned node.
procedure Remove_Dimension_In_Statement (Stmt : Node_Id);
-- Remove the dimensions associated with Stmt
end Sem_Dim;
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