1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- S E M _ D I M -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 2011-2019, Free Software Foundation, Inc. -- 10-- -- 11-- GNAT is free software; you can redistribute it and/or modify it under -- 12-- terms of the GNU General Public License as published by the Free Soft- -- 13-- ware Foundation; either version 3, or (at your option) any later ver- -- 14-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- 15-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- 16-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- 17-- for more details. You should have received a copy of the GNU General -- 18-- Public License distributed with GNAT; see file COPYING3. If not, go to -- 19-- http://www.gnu.org/licenses for a complete copy of the license. -- 20-- -- 21-- GNAT was originally developed by the GNAT team at New York University. -- 22-- Extensive contributions were provided by Ada Core Technologies Inc. -- 23-- -- 24------------------------------------------------------------------------------ 25 26-- This package provides support for numerical systems with dimensions. A 27-- "dimension" is a compile-time property of a numerical type which represents 28-- a relation between various quantifiers such as length, velocity, etc. 29 30-- Package System.Dim.Mks offers a ready-to-use system of SI base units. In 31-- addition, the implementation of this feature offers the ability to define 32-- an arbitrary system of units through the use of Ada 2012 aspects. 33 34-- Dimensionality checking is part of type analysis performed by the compiler. 35-- It ensures that manipulation of quantified numeric values is sensible with 36-- respect to the system of units. 37 38----------------------------- 39-- Aspect_Dimension_System -- 40----------------------------- 41 42-- In order to enable the user to create their own dimension system, a new 43-- aspect: Aspect_Dimension_System has been created. 44 45-- Note that this aspect applies for type declaration of type derived from any 46-- numeric type. 47 48-- It defines the names of each dimension 49 50---------------------- 51-- Aspect_Dimension -- 52---------------------- 53 54-- This new aspect applies for subtype and object declarations in order to 55-- define new dimensions. 56 57-- Using this aspect, the user is able to create new subtype/object with any 58-- dimension needed. 59 60-- Note that the base type of the subtype/object must be the type that defines 61-- the corresponding dimension system. 62 63-- The expression of this aspect is an aggregate of rational values for each 64-- dimension in the corresponding dimension system. 65 66------------------------------------------- 67-- Dimensionality checking & propagation -- 68------------------------------------------- 69 70-- For each node (when needed), a dimension analysis (Analyze_Dimension) is 71-- performed as part of the Resolution routine or the Analysis routine if no 72-- Resolution. 73 74-- The dimension analysis is divided into two phases: 75 76-- Phase 1: dimension checking 77 78-- Phase 2: propagation of dimensions 79 80-- Depending on the node kind, either none, one phase or two phases are 81-- executed. 82 83-- Phase 2 is called only when the node allows a dimension (see body of 84-- Sem_Dim to get the list of nodes that permit dimensions). 85 86-- In principle every node that is a component of a floating-point expression 87-- may have a dimension vector. However, the dimensionality checking is for 88-- the most part a bottom-up tree traversal, and the dimensions of operands 89-- become irrelevant once the dimensions of an operation have been computed. 90-- To minimize space use, the dimensions of operands are removed after the 91-- computation of the dimensions of the parent operation. This may complicate 92-- the analysis of nodes that have been constant-folded or otherwise rewritten 93-- when removing side effects. In such cases, the (sub)type of the expression 94-- is used to determine the applicable dimensions. 95 96with Types; use Types; 97 98package Sem_Dim is 99 100 procedure Analyze_Aspect_Dimension 101 (N : Node_Id; 102 Id : Entity_Id; 103 Aggr : Node_Id); 104 -- Analyze the contents of aspect Dimension. Associate the provided values 105 -- and quantifiers with the related context N. Id is the corresponding 106 -- Aspect_Id (Aspect_Dimension) Aggr is the corresponding expression for 107 -- the aspect Dimension declared by the declaration of N. 108 109 procedure Analyze_Aspect_Dimension_System 110 (N : Node_Id; 111 Id : Entity_Id; 112 Aggr : Node_Id); 113 -- Analyze the contents of aspect Dimension_System. Extract the numerical 114 -- type, unit name and corresponding symbol from each indivitual dimension. 115 -- Id is the corresponding Aspect_Id (Aspect_Dimension_System). Aggr is 116 -- the corresponding expression for the aspect Dimension_System from the 117 -- declaration of N. 118 119 procedure Analyze_Dimension (N : Node_Id); 120 -- N may denote any of the following contexts: 121 -- * aggregate 122 -- * assignment statement 123 -- * attribute reference 124 -- * binary operator 125 -- * call 126 -- * compontent declaration 127 -- * extended return statement 128 -- * expanded name 129 -- * explicit dereference 130 -- * identifier 131 -- * indexed component 132 -- * number declaration 133 -- * object declaration 134 -- * object renaming declaration 135 -- * procedure call statement 136 -- * qualified expression 137 -- * selected component 138 -- * simple return statement 139 -- * slice 140 -- * subtype declaration 141 -- * type conversion 142 -- * unary operator 143 -- * unchecked type conversion 144 -- Depending on the context, ensure that all expressions and entities 145 -- involved do not violate the rules of a system. 146 147 procedure Analyze_Dimension_Array_Aggregate 148 (N : Node_Id; 149 Comp_Typ : Entity_Id); 150 -- Check, for each component of the array aggregate denoted by N, the 151 -- dimensions of the component expression match the dimensions of the 152 -- component type Comp_Typ. 153 154 procedure Analyze_Dimension_Call (N : Node_Id; Nam : Entity_Id); 155 -- This routine is split in two steps. Note the second step applies only to 156 -- function calls. 157 -- Step 1. Dimension checking: 158 -- * General case: check the dimensions of each actual parameter match 159 -- the dimensions of the corresponding formal parameter. 160 -- * Elementary function case: check each actual is dimensionless except 161 -- for Sqrt call. 162 -- Step 2. Dimension propagation (only for functions): 163 -- * General case: propagate the dimensions from the returned type to the 164 -- function call. 165 -- * Sqrt case: the resulting dimensions equal to half the dimensions of 166 -- the actual 167 168 procedure Analyze_Dimension_Extension_Or_Record_Aggregate (N : Node_Id); 169 -- Check, for each component of the extension or record aggregate denoted 170 -- by N, the dimensions of the component expression match the dimensions of 171 -- the component type. 172 173 procedure Analyze_Dimension_Formals (N : Node_Id; Formals : List_Id); 174 -- For sub spec N, issue a warning for each dimensioned formal with a 175 -- literal default value in the list of formals Formals. 176 177 procedure Check_Expression_Dimensions 178 (Expr : Node_Id; 179 Typ : Entity_Id); 180 -- Compute dimensions of a floating-point expression and compare them with 181 -- the dimensions of a the given type. Used to verify dimensions of the 182 -- components of a multidimensional array type, for which components are 183 -- typically themselves arrays. The resolution of such arrays delays the 184 -- resolution of the ultimate components to a separate phase, which forces 185 -- this separate dimension verification. 186 187 procedure Copy_Dimensions (From : Node_Id; To : Node_Id); 188 -- Copy dimension vector of node From to node To. Note that To must be a 189 -- node that is allowed to contain a dimension (see OK_For_Dimension in 190 -- body of Sem_Dim). 191 192 procedure Copy_Dimensions_Of_Components (Rec : Entity_Id); 193 -- Propagate the dimensions of the components of a record type T to the 194 -- components of a record type derived from T. The derivation creates 195 -- a full copy of the type declaration of the parent, and the dimension 196 -- information of individual components must be transferred explicitly. 197 198 function Dimensions_Match (T1 : Entity_Id; T2 : Entity_Id) return Boolean; 199 -- If the common base type has a dimension system, verify that two 200 -- subtypes have the same dimensions. Used for conformance checking. 201 202 procedure Eval_Op_Expon_For_Dimensioned_Type 203 (N : Node_Id; 204 Btyp : Entity_Id); 205 -- Evaluate the Expon operator for dimensioned type with rational exponent. 206 -- Indeed the regular Eval_Op_Expon routine (see package Sem_Eval) is 207 -- restricted to Integer exponent. This routine deals only with rational 208 -- exponent which is not an integer if Btyp is a dimensioned type. 209 210 procedure Expand_Put_Call_With_Symbol (N : Node_Id); 211 -- Determine whether N denotes a subprogram call to one of the routines 212 -- defined in System.Dim.Float_IO or System.Dim.Integer_IO and add an 213 -- extra actual to the call to represent the symbolic representation of 214 -- a dimension. 215 216 function Has_Dimension_System (Typ : Entity_Id) return Boolean; 217 -- Return True if type Typ has aspect Dimension_System applied to it 218 219 function Is_Dim_IO_Package_Instantiation (N : Node_Id) return Boolean; 220 -- Return True if N is a package instantiation of System.Dim.Integer_IO or 221 -- of System.Dim.Float_IO. 222 223 function New_Copy_Tree_And_Copy_Dimensions 224 (Source : Node_Id; 225 Map : Elist_Id := No_Elist; 226 New_Sloc : Source_Ptr := No_Location; 227 New_Scope : Entity_Id := Empty) return Node_Id; 228 -- Same as New_Copy_Tree (defined in Sem_Util), except that this routine 229 -- also copies the dimensions of Source to the returned node. 230 231 procedure Remove_Dimension_In_Statement (Stmt : Node_Id); 232 -- Remove the dimensions associated with Stmt 233 234end Sem_Dim; 235