BS ISO IEC 8652-2013 Information technology Programming languages Ada《信息技术 编程语言 Ada》.pdf

1、raising standards worldwide NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BSI Standards Publication BS ISO/IEC 8652:2012 Information technology Programming languages AdaBS ISO/IEC 8652:2012 BRITISH STANDARD National foreword This British Standard is the UK implementation of

2、ISO/IEC 8652:2012. It supersedes BS ISO/IEC 8652:1995 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee IST/5/-/9, Ada Panel. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not pu

3、rport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2013. Published by BSI Standards Limited 2013 ISBN 978 0 580 79670 8 ICS 35.060 Compliance with a British Standard cannot confer immunity from legal oblig

4、ations. This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 May 2013. Amendments issued since publication Date Text affectedBS ISO/IEC 8652:2012Reference number ISO/IEC 8652:2012(E) ISO/IEC 2012INTERNATIONAL STANDARD ISO/IEC 8652 Third edition

5、 2012-12-15Information technology Programming languages Ada Technologies de linformation Langages de programmation Ada BS ISO/IEC 8652:2012 ISO/IEC 8652:2012(E) COPYRIGHT PROTECTED DOCUMENT ISO/IEC 2012 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or

6、 utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11

7、 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO/IEC 2012 All rights reservedISO/IEC 8652:2012(E) i ISO/IEC 2012 All rights reserved Table of Contents Table of Contents.i Foreword xi Introduction.xii 1 General .1 1.1 Scope 1 1.1.1 Extent 1 1.1.2 Structur

8、e. 2 1.1.3 Conformity of an Implementation with the Standard . 4 1.1.4 Method of Description and Syntax Notation. 5 1.1.5 Classification of Errors . 6 1.2 Normative References. 7 1.3 Terms and Definitions . 8 2 Lexical Elements9 2.1 Character Set . 9 2.2 Lexical Elements, Separators, and Delimiters

9、11 2.3 Identifiers 12 2.4 Numeric Literals. 13 2.4.1 Decimal Literals. 13 2.4.2 Based Literals 13 2.5 Character Literals 14 2.6 String Literals. 14 2.7 Comments 15 2.8 Pragmas 15 2.9 Reserved Words 17 3 Declarations and Types.19 3.1 Declarations . 19 3.2 Types and Subtypes 20 3.2.1 Type Declarations

10、 21 3.2.2 Subtype Declarations 23 3.2.3 Classification of Operations. 24 3.2.4 Subtype Predicates . 24 3.3 Objects and Named Numbers. 26 3.3.1 Object Declarations. 28 3.3.2 Number Declarations 31 3.4 Derived Types and Classes 31 3.4.1 Derivation Classes 34 3.5 Scalar Types. 35 3.5.1 Enumeration Type

11、s . 40 3.5.2 Character Types 41 3.5.3 Boolean Types . 42 3.5.4 Integer Types . 42 3.5.5 Operations of Discrete Types. 44 3.5.6 Real Types 45 3.5.7 Floating Point Types . 46 3.5.8 Operations of Floating Point Types. 48 3.5.9 Fixed Point Types 48 3.5.10 Operations of Fixed Point Types . 50 BS ISO/IEC

12、8652:2012ISO/IEC 8652:2012(E) ISO/IEC 2012 All rights reserved ii 3.6 Array Types.51 3.6.1 Index Constraints and Discrete Ranges 54 3.6.2 Operations of Array Types 55 3.6.3 String Types56 3.7 Discriminants56 3.7.1 Discriminant Constraints.59 3.7.2 Operations of Discriminated Types60 3.8 Record Types

13、60 3.8.1 Variant Parts and Discrete Choices62 3.9 Tagged Types and Type Extensions.64 3.9.1 Type Extensions.67 3.9.2 Dispatching Operations of Tagged Types .68 3.9.3 Abstract Types and Subprograms71 3.9.4 Interface Types.72 3.10 Access Types75 3.10.1 Incomplete Type Declarations 77 3.10.2 Operations

14、 of Access Types .79 3.11 Declarative Parts 85 3.11.1 Completions of Declarations.85 4 Names and Expressions .87 4.1 Names87 4.1.1 Indexed Components.88 4.1.2 Slices.89 4.1.3 Selected Components89 4.1.4 Attributes 91 4.1.5 User-Defined References.92 4.1.6 User-Defined Indexing .93 4.2 Literals.95 4.

15、3 Aggregates96 4.3.1 Record Aggregates 96 4.3.2 Extension Aggregates .98 4.3.3 Array Aggregates .99 4.4 Expressions 102 4.5 Operators and Expression Evaluation .103 4.5.1 Logical Operators and Short-circuit Control Forms .104 4.5.2 Relational Operators and Membership Tests 105 4.5.3 Binary Adding Op

16、erators.109 4.5.4 Unary Adding Operators110 4.5.5 Multiplying Operators 110 4.5.6 Highest Precedence Operators.112 4.5.7 Conditional Expressions .113 4.5.8 Quantified Expressions .114 4.6 Type Conversions 115 4.7 Qualified Expressions119 4.8 Allocators 120 4.9 Static Expressions and Static Subtypes

17、122 4.9.1 Statically Matching Constraints and Subtypes .125 5 Statements . 127 5.1 Simple and Compound Statements - Sequences of Statements .127 5.2 Assignment Statements.128 5.3 If Statements .129 5.4 Case Statements.130 BS ISO/IEC 8652:2012ISO/IEC 8652:2012(E) iii ISO/IEC 2012 All rights reserved

18、5.5 Loop Statements 131 5.5.1 User-Defined Iterator Types . 133 5.5.2 Generalized Loop Iteration . 134 5.6 Block Statements. 136 5.7 Exit Statements 137 5.8 Goto Statements 137 6 Subprograms139 6.1 Subprogram Declarations. 139 6.1.1 Preconditions and Postconditions 142 6.2 Formal Parameter Modes 144

19、 6.3 Subprogram Bodies 145 6.3.1 Conformance Rules. 146 6.3.2 Inline Expansion of Subprograms . 148 6.4 Subprogram Calls 148 6.4.1 Parameter Associations 150 6.5 Return Statements. 153 6.5.1 Nonreturning Procedures . 155 6.6 Overloading of Operators . 156 6.7 Null Procedures . 157 6.8 Expression Fun

20、ctions . 158 7 Packages 159 7.1 Package Specifications and Declarations. 159 7.2 Package Bodies . 160 7.3 Private Types and Private Extensions. 161 7.3.1 Private Operations. 163 7.3.2 Type Invariants 165 7.4 Deferred Constants . 167 7.5 Limited Types. 168 7.6 Assignment and Finalization 170 7.6.1 Co

21、mpletion and Finalization. 172 8 Visibility Rules .175 8.1 Declarative Region 175 8.2 Scope of Declarations . 176 8.3 Visibility 177 8.3.1 Overriding Indicators 179 8.4 Use Clauses . 180 8.5 Renaming Declarations. 181 8.5.1 Object Renaming Declarations 182 8.5.2 Exception Renaming Declarations 183 8

22、.5.3 Package Renaming Declarations . 183 8.5.4 Subprogram Renaming Declarations 184 8.5.5 Generic Renaming Declarations 186 8.6 The Context of Overload Resolution 186 9 Tasks and Synchronization.189 9.1 Task Units and Task Objects 189 9.2 Task Execution - Task Activation. 192 9.3 Task Dependence - T

23、ermination of Tasks. 193 9.4 Protected Units and Protected Objects . 194 9.5 Intertask Communication 197 9.5.1 Protected Subprograms and Protected Actions. 199 9.5.2 Entries and Accept Statements 200 BS ISO/IEC 8652:2012ISO/IEC 8652:2012(E) ISO/IEC 2012 All rights reserved iv 9.5.3 Entry Calls.203 9

24、.5.4 Requeue Statements205 9.6 Delay Statements, Duration, and Time .207 9.6.1 Formatting, Time Zones, and other operations for Time209 9.7 Select Statements.215 9.7.1 Selective Accept.215 9.7.2 Timed Entry Calls .217 9.7.3 Conditional Entry Calls218 9.7.4 Asynchronous Transfer of Control.219 9.8 Ab

25、ort of a Task - Abort of a Sequence of Statements.220 9.9 Task and Entry Attributes221 9.10 Shared Variables 222 9.11 Example of Tasking and Synchronization223 10 Program Structure and Compilation Issues 225 10.1 Separate Compilation.225 10.1.1 Compilation Units - Library Units .225 10.1.2 Context C

26、lauses - With Clauses .228 10.1.3 Subunits of Compilation Units230 10.1.4 The Compilation Process 232 10.1.5 Pragmas and Program Units.233 10.1.6 Environment-Level Visibility Rules 234 10.2 Program Execution.234 10.2.1 Elaboration Control236 11 Exceptions . 241 11.1 Exception Declarations241 11.2 Ex

27、ception Handlers 242 11.3 Raise Statements243 11.4 Exception Handling 243 11.4.1 The Package Exceptions .244 11.4.2 Pragmas Assert and Assertion_Policy 246 11.4.3 Example of Exception Handling248 11.5 Suppressing Checks 249 11.6 Exceptions and Optimization 252 12 Generic Units .253 12.1 Generic Decl

28、arations253 12.2 Generic Bodies .255 12.3 Generic Instantiation256 12.4 Formal Objects .258 12.5 Formal Types 259 12.5.1 Formal Private and Derived Types .261 12.5.2 Formal Scalar Types 263 12.5.3 Formal Array Types263 12.5.4 Formal Access Types 264 12.5.5 Formal Interface Types265 12.6 Formal Subpr

29、ograms .265 12.7 Formal Packages 267 12.8 Example of a Generic Package .269 13 Representation Issues 273 13.1 Operational and Representation Aspects 273 13.1.1 Aspect Specifications276 13.2 Packed Types278 BS ISO/IEC 8652:2012ISO/IEC 8652:2012(E) v ISO/IEC 2012 All rights reserved 13.3 Operational a

30、nd Representation Attributes 279 13.4 Enumeration Representation Clauses. 285 13.5 Record Layout 286 13.5.1 Record Representation Clauses 286 13.5.2 Storage Place Attributes. 288 13.5.3 Bit Ordering 289 13.6 Change of Representation 290 13.7 The Package System . 291 13.7.1 The Package System.Storage

31、_Elements 293 13.7.2 The Package System.Address_To_Access_Conversions. 294 13.8 Machine Code Insertions 294 13.9 Unchecked Type Conversions 295 13.9.1 Data Validity. 296 13.9.2 The Valid Attribute. 297 13.10 Unchecked Access Value Creation 298 13.11 Storage Management 298 13.11.1 Storage Allocation

32、Attributes. 301 13.11.2 Unchecked Storage Deallocation. 302 13.11.3 Default Storage Pools . 303 13.11.4 Storage Subpools 304 13.11.5 Subpool Reclamation 306 13.11.6 Storage Subpool Example 307 13.12 Pragma Restrictions and Pragma Profile 309 13.12.1 Language-Defined Restrictions and Profiles 310 13.

33、13 Streams. 312 13.13.1 The Package Streams . 312 13.13.2 Stream-Oriented Attributes 313 13.14 Freezing Rules . 318 The Standard Libraries.321 Annex A (normative) Predefined Language Environment 323 A.1 The Package Standard 326 A.2 The Package Ada 330 A.3 Character Handling . 330 A.3.1 The Packages

34、Characters, Wide_Characters, and Wide_Wide_Characters 330 A.3.2 The Package Characters.Handling 331 A.3.3 The Package Characters.Latin_1. 333 A.3.4 The Package Characters.Conversions . 338 A.3.5 The Package Wide_Characters.Handling . 340 A.3.6 The Package Wide_Wide_Characters.Handling. 342 A.4 Strin

35、g Handling . 343 A.4.1 The Package Strings. 343 A.4.2 The Package Strings.Maps 343 A.4.3 Fixed-Length String Handling 346 A.4.4 Bounded-Length String Handling . 354 A.4.5 Unbounded-Length String Handling . 361 A.4.6 String-Handling Sets and Mappings . 366 A.4.7 Wide_String Handling. 366 A.4.8 Wide_W

36、ide_String Handling 368 A.4.9 String Hashing 371 A.4.10 String Comparison 372 A.4.11 String Encoding 373 A.5 The Numerics Packages. 378 BS ISO/IEC 8652:2012ISO/IEC 8652:2012(E) ISO/IEC 2012 All rights reserved vi A.5.1 Elementary Functions .378 A.5.2 Random Number Generation381 A.5.3 Attributes of F

37、loating Point Types .386 A.5.4 Attributes of Fixed Point Types390 A.6 Input-Output .390 A.7 External Files and File Objects.390 A.8 Sequential and Direct Files .391 A.8.1 The Generic Package Sequential_IO .392 A.8.2 File Management393 A.8.3 Sequential Input-Output Operations395 A.8.4 The Generic Pac

38、kage Direct_IO .395 A.8.5 Direct Input-Output Operations396 A.9 The Generic Package Storage_IO 397 A.10 Text Input-Output.397 A.10.1 The Package Text_IO.399 A.10.2 Text File Management .403 A.10.3 Default Input, Output, and Error Files404 A.10.4 Specification of Line and Page Lengths405 A.10.5 Opera

39、tions on Columns, Lines, and Pages.406 A.10.6 Get and Put Procedures409 A.10.7 Input-Output of Characters and Strings 410 A.10.8 Input-Output for Integer Types.412 A.10.9 Input-Output for Real Types .414 A.10.10 Input-Output for Enumeration Types.416 A.10.11 Input-Output for Bounded Strings .417 A.1

40、0.12 Input-Output for Unbounded Strings.418 A.11 Wide Text Input-Output and Wide Wide Text Input-Output419 A.12 Stream Input-Output 420 A.12.1 The Package Streams.Stream_IO.420 A.12.2 The Package Text_IO.Text_Streams422 A.12.3 The Package Wide_Text_IO.Text_Streams .423 A.12.4 The Package Wide_Wide_T

41、ext_IO.Text_Streams.423 A.13 Exceptions in Input-Output.423 A.14 File Sharing 425 A.15 The Package Command_Line .425 A.16 The Package Directories .426 A.16.1 The Package Directories.Hierarchical_File_Names .433 A.17 The Package Environment_Variables 435 A.18 Containers 438 A.18.1 The Package Contain

42、ers.438 A.18.2 The Generic Package Containers.Vectors 438 A.18.3 The Generic Package Containers.Doubly_Linked_Lists454 A.18.4 Maps465 A.18.5 The Generic Package Containers.Hashed_Maps .471 A.18.6 The Generic Package Containers.Ordered_Maps 475 A.18.7 Sets .479 A.18.8 The Generic Package Containers.H

43、ashed_Sets .486 A.18.9 The Generic Package Containers.Ordered_Sets 491 A.18.10 The Generic Package Containers.Multiway_Trees.496 A.18.11 The Generic Package Containers.Indefinite_Vectors 510 A.18.12 The Generic Package Containers.Indefinite_Doubly_Linked_Lists510 A.18.13 The Generic Package Containe

44、rs.Indefinite_Hashed_Maps .511 A.18.14 The Generic Package Containers.Indefinite_Ordered_Maps.511 A.18.15 The Generic Package Containers.Indefinite_Hashed_Sets .511 BS ISO/IEC 8652:2012ISO/IEC 8652:2012(E) vii ISO/IEC 2012 All rights reserved A.18.16 The Generic Package Containers.Indefinite_Ordered

45、_Sets . 512 A.18.17 The Generic Package Containers.Indefinite_Multiway_Trees 512 A.18.18 The Generic Package Containers.Indefinite_Holders 512 A.18.19 The Generic Package Containers.Bounded_Vectors 516 A.18.20 The Generic Package Containers.Bounded_Doubly_Linked_Lists . 516 A.18.21 The Generic Packa

46、ge Containers.Bounded_Hashed_Maps . 518 A.18.22 The Generic Package Containers.Bounded_Ordered_Maps 519 A.18.23 The Generic Package Containers.Bounded_Hashed_Sets. 520 A.18.24 The Generic Package Containers.Bounded_Ordered_Sets 521 A.18.25 The Generic Package Containers.Bounded_Multiway_Trees. 522 A

47、.18.26 Array Sorting . 524 A.18.27 The Generic Package Containers.Synchronized_Queue_Interfaces . 525 A.18.28 The Generic Package Containers.Unbounded_Synchronized_Queues 526 A.18.29 The Generic Package Containers.Bounded_Synchronized_Queues. 527 A.18.30 The Generic Package Containers.Unbounded_Prio

48、rity_Queues . 527 A.18.31 The Generic Package Containers.Bounded_Priority_Queues 529 A.18.32 Example of Container Use . 530 A.19 The Package Locales 532 Annex B (normative) Interface to Other Languages533 B.1 Interfacing Aspects. 533 B.2 The Package Interfaces 536 B.3 Interfacing with C and C+. 537

49、B.3.1 The Package Interfaces.C.Strings . 543 B.3.2 The Generic Package Interfaces.C.Pointers. 546 B.3.3 Unchecked Union Types 548 B.4 Interfacing with COBOL 550 B.5 Interfacing with Fortran 556 Annex C (normative) Systems Programming 559 C.1 Access to Machine Operations 559 C.2 Required Representation Support. 560 C.3 Interrupt Support. 560 C.3.1 Protected Procedure Handlers 562 C.3.2 The Package Interrupts 564 C.4 Preelaboration Requirements 566 C.5 Pragma Discard_Names . 566 C.6 Shared Variable Control . 567 C.7 Task Information