235 lines
11 KiB
Ada
235 lines
11 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT COMPILER COMPONENTS --
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-- --
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-- S E M _ D I M --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 2011-2020, Free Software Foundation, Inc. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
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-- for more details. You should have received a copy of the GNU General --
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-- Public License distributed with GNAT; see file COPYING3. If not, go to --
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-- http://www.gnu.org/licenses for a complete copy of the license. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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-- This package provides support for numerical systems with dimensions. A
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-- "dimension" is a compile-time property of a numerical type which represents
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-- a relation between various quantifiers such as length, velocity, etc.
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-- Package System.Dim.Mks offers a ready-to-use system of SI base units. In
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-- addition, the implementation of this feature offers the ability to define
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-- an arbitrary system of units through the use of Ada 2012 aspects.
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-- Dimensionality checking is part of type analysis performed by the compiler.
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-- It ensures that manipulation of quantified numeric values is sensible with
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-- respect to the system of units.
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-----------------------------
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-- Aspect_Dimension_System --
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-----------------------------
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-- In order to enable the user to create their own dimension system, a new
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-- aspect: Aspect_Dimension_System has been created.
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-- Note that this aspect applies for type declaration of type derived from any
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-- numeric type.
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-- It defines the names of each dimension
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----------------------
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-- Aspect_Dimension --
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----------------------
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-- This new aspect applies for subtype and object declarations in order to
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-- define new dimensions.
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-- Using this aspect, the user is able to create new subtype/object with any
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-- dimension needed.
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-- Note that the base type of the subtype/object must be the type that defines
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-- the corresponding dimension system.
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-- The expression of this aspect is an aggregate of rational values for each
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-- dimension in the corresponding dimension system.
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-------------------------------------------
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-- Dimensionality checking & propagation --
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-------------------------------------------
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-- For each node (when needed), a dimension analysis (Analyze_Dimension) is
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-- performed as part of the Resolution routine or the Analysis routine if no
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-- Resolution.
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-- The dimension analysis is divided into two phases:
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-- Phase 1: dimension checking
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-- Phase 2: propagation of dimensions
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-- Depending on the node kind, either none, one phase or two phases are
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-- executed.
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-- Phase 2 is called only when the node allows a dimension (see body of
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-- Sem_Dim to get the list of nodes that permit dimensions).
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-- In principle every node that is a component of a floating-point expression
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-- may have a dimension vector. However, the dimensionality checking is for
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-- the most part a bottom-up tree traversal, and the dimensions of operands
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-- become irrelevant once the dimensions of an operation have been computed.
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-- To minimize space use, the dimensions of operands are removed after the
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-- computation of the dimensions of the parent operation. This may complicate
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-- the analysis of nodes that have been constant-folded or otherwise rewritten
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-- when removing side effects. In such cases, the (sub)type of the expression
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-- is used to determine the applicable dimensions.
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with Types; use Types;
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package Sem_Dim is
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procedure Analyze_Aspect_Dimension
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(N : Node_Id;
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Id : Entity_Id;
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Aggr : Node_Id);
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-- Analyze the contents of aspect Dimension. Associate the provided values
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-- and quantifiers with the related context N. Id is the corresponding
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-- Aspect_Id (Aspect_Dimension) Aggr is the corresponding expression for
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-- the aspect Dimension declared by the declaration of N.
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procedure Analyze_Aspect_Dimension_System
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(N : Node_Id;
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Id : Entity_Id;
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Aggr : Node_Id);
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-- Analyze the contents of aspect Dimension_System. Extract the numerical
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-- type, unit name and corresponding symbol from each indivitual dimension.
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-- Id is the corresponding Aspect_Id (Aspect_Dimension_System). Aggr is
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-- the corresponding expression for the aspect Dimension_System from the
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-- declaration of N.
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procedure Analyze_Dimension (N : Node_Id);
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-- N may denote any of the following contexts:
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-- * aggregate
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-- * assignment statement
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-- * attribute reference
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-- * binary operator
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-- * call
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-- * compontent declaration
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-- * extended return statement
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-- * expanded name
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-- * explicit dereference
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-- * identifier
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-- * indexed component
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-- * number declaration
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-- * object declaration
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-- * object renaming declaration
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-- * procedure call statement
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-- * qualified expression
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-- * selected component
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-- * simple return statement
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-- * slice
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-- * subtype declaration
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-- * type conversion
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-- * unary operator
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-- * unchecked type conversion
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-- Depending on the context, ensure that all expressions and entities
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-- involved do not violate the rules of a system.
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procedure Analyze_Dimension_Array_Aggregate
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(N : Node_Id;
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Comp_Typ : Entity_Id);
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-- Check, for each component of the array aggregate denoted by N, the
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-- dimensions of the component expression match the dimensions of the
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-- component type Comp_Typ.
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procedure Analyze_Dimension_Call (N : Node_Id; Nam : Entity_Id);
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-- This routine is split in two steps. Note the second step applies only to
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-- function calls.
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-- Step 1. Dimension checking:
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-- * General case: check the dimensions of each actual parameter match
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-- the dimensions of the corresponding formal parameter.
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-- * Elementary function case: check each actual is dimensionless except
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-- for Sqrt call.
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-- Step 2. Dimension propagation (only for functions):
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-- * General case: propagate the dimensions from the returned type to the
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-- function call.
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-- * Sqrt case: the resulting dimensions equal to half the dimensions of
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-- the actual
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procedure Analyze_Dimension_Extension_Or_Record_Aggregate (N : Node_Id);
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-- Check, for each component of the extension or record aggregate denoted
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-- by N, the dimensions of the component expression match the dimensions of
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-- the component type.
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procedure Analyze_Dimension_Formals (N : Node_Id; Formals : List_Id);
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-- For sub spec N, issue a warning for each dimensioned formal with a
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-- literal default value in the list of formals Formals.
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procedure Check_Expression_Dimensions
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(Expr : Node_Id;
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Typ : Entity_Id);
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-- Compute dimensions of a floating-point expression and compare them with
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-- the dimensions of a the given type. Used to verify dimensions of the
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-- components of a multidimensional array type, for which components are
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-- typically themselves arrays. The resolution of such arrays delays the
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-- resolution of the ultimate components to a separate phase, which forces
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-- this separate dimension verification.
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procedure Copy_Dimensions (From : Node_Id; To : Node_Id);
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-- Copy dimension vector of node From to node To. Note that To must be a
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-- node that is allowed to contain a dimension (see OK_For_Dimension in
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-- body of Sem_Dim).
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procedure Copy_Dimensions_Of_Components (Rec : Entity_Id);
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-- Propagate the dimensions of the components of a record type T to the
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-- components of a record type derived from T. The derivation creates
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-- a full copy of the type declaration of the parent, and the dimension
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-- information of individual components must be transferred explicitly.
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function Dimensions_Match (T1 : Entity_Id; T2 : Entity_Id) return Boolean;
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-- If the common base type has a dimension system, verify that two
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-- subtypes have the same dimensions. Used for conformance checking.
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procedure Eval_Op_Expon_For_Dimensioned_Type
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(N : Node_Id;
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Btyp : Entity_Id);
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-- Evaluate the Expon operator for dimensioned type with rational exponent.
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-- Indeed the regular Eval_Op_Expon routine (see package Sem_Eval) is
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-- restricted to Integer exponent. This routine deals only with rational
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-- exponent which is not an integer if Btyp is a dimensioned type.
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procedure Expand_Put_Call_With_Symbol (N : Node_Id);
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-- Determine whether N denotes a subprogram call to one of the routines
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-- defined in System.Dim.Float_IO or System.Dim.Integer_IO and add an
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-- extra actual to the call to represent the symbolic representation of
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-- a dimension.
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function Has_Dimension_System (Typ : Entity_Id) return Boolean;
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-- Return True if type Typ has aspect Dimension_System applied to it
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function Is_Dim_IO_Package_Instantiation (N : Node_Id) return Boolean;
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-- Return True if N is a package instantiation of System.Dim.Integer_IO or
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-- of System.Dim.Float_IO.
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function New_Copy_Tree_And_Copy_Dimensions
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(Source : Node_Id;
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Map : Elist_Id := No_Elist;
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New_Sloc : Source_Ptr := No_Location;
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New_Scope : Entity_Id := Empty) return Node_Id;
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-- Same as New_Copy_Tree (defined in Sem_Util), except that this routine
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-- also copies the dimensions of Source to the returned node.
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procedure Remove_Dimension_In_Statement (Stmt : Node_Id);
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-- Remove the dimensions associated with Stmt
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end Sem_Dim;
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