ISO IEC 8652-2012 Information technology - Programming languages - Ada《信息技术 程序设计语言 Ada》.pdf

1、 Reference number ISO/IEC 8652:2012(E) ISO/IEC 2012INTERNATIONAL STANDARD ISO/IEC 8652 Third edition 2012-12-15Information technology Programming languages Ada Technologies de linformation Langages de programmation Ada ISO/IEC 8652:2012(E) COPYRIGHT PROTECTED DOCUMENT ISO/IEC 2012 All rights reserve

2、d. Unless otherwise specified, no part of this publication may be reproduced or 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

3、. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 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 Fore

4、word xi Introduction.xii 1 General .1 1.1 Scope 1 1.1.1 Extent 1 1.1.2 Structure.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 Ele

5、ments9 2.1 Character Set .9 2.2 Lexical Elements, Separators, and Delimiters 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 Type

6、s.19 3.1 Declarations . 19 3.2 Types and Subtypes 20 3.2.1 Type Declarations 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 Classe

7、s 31 3.4.1 Derivation Classes 34 3.5 Scalar Types. 35 3.5.1 Enumeration Types . 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

8、Fixed Point Types 48 3.5.10 Operations of Fixed Point Types . 50 ISO/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.

9、7.2 Operations of Discriminated Types60 3.8 Record Types60 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

10、3.10.1 Incomplete Type Declarations 77 3.10.2 Operations 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 Referenc

11、es.92 4.1.6 User-Defined Indexing .93 4.2 Literals.95 4.3 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 O

12、perators and Membership Tests 105 4.5.3 Binary Adding Operators.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 Al

13、locators 120 4.9 Static Expressions and Static Subtypes 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 ISO/IEC 8652:2012(E) ii

14、i ISO/IEC 2012 All rights reserved 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

15、 142 6.2 Formal Parameter Modes 144 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

16、Procedures . 157 6.8 Expression Functions . 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 Assig

17、nment and Finalization 170 7.6.1 Completion 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 Ex

18、ception Renaming Declarations 183 8.5.3 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 Acti

19、vation. 192 9.3 Task Dependence - Termination 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 ISO/IEC 8652:2012(E) ISO/IEC 2012 All rights reserved iv 9.5.3 En

20、try Calls.203 9.5.4 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 Con

21、trol.219 9.8 Abort 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 1

22、0.1.2 Context Clauses - 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 Declarat

23、ions241 11.2 Exception 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

24、.1 Generic Declarations253 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 Types 265 1

25、2.6 Formal Subprograms .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 ISO/IEC 8652:2012(E) v ISO/IEC 2012 All rights reserved 13.3 Operational and R

26、epresentation 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_Ele

27、ments 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 Attr

28、ibutes. 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 13.13 S

29、treams. 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 Char

30、acters, 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 String Ha

31、ndling . 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_Wide_

32、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 ISO/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 Floating Point Types .386

33、 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 Package Direct_IO .395 A.8.

34、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 Operations on Columns, Lines,

35、 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.10.12 Input-Output for Un

36、bounded 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_Streams 422 A.12.3 The Package Wide_Text_IO.Text_Streams .423 A.12.4 The Package Wide_Wide_Text_IO.Text_Streams.423

37、 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 Containers.438 A.18.2 The Gene

38、ric 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.Hashed_Sets .486 A.18.9

39、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 Containers.Indefinite_Hashed_Ma

40、ps .511 A.18.14 The Generic Package Containers.Indefinite_Ordered_Maps.511 A.18.15 The Generic Package Containers.Indefinite_Hashed_Sets .511 ISO/IEC 8652:2012(E) vii ISO/IEC 2012 All rights reserved A.18.16 The Generic Package Containers.Indefinite_Ordered_Sets . 512 A.18.17 The Generic Package Con

41、tainers.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 Package Containers.Bounded_Hashed_Maps . 518 A.1

42、8.22 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.18.26 Array Sorting . 524 A.18.27 The Gene

43、ric 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_Priority_Queues . 527 A.18.31 The Generic Packa

44、ge 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 B.3.1 The Package Interfaces.C.Strings . 54

45、3 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

46、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 . 569 C.7.1 The Package Task_Identification 569 C.7.2 The Package Task_Attributes 571 C.7.3 The Package Ta

47、sk_Termination 573 Annex D (normative) Real-Time Systems 575 D.1 Task Priorities . 575 D.2 Priority Scheduling . 577 D.2.1 The Task Dispatching Model . 577 D.2.2 Task Dispatching Pragmas 578 D.2.3 Preemptive Dispatching . 580 D.2.4 Non-Preemptive Dispatching. 580 D.2.5 Round Robin Dispatching 582 D.

48、2.6 Earliest Deadline First Dispatching. 583 D.3 Priority Ceiling Locking 585 D.4 Entry Queuing Policies. 587 D.5 Dynamic Priorities. 588 ISO/IEC 8652:2012(E) ISO/IEC 2012 All rights reserved viii D.5.1 Dynamic Priorities for Tasks 588 D.5.2 Dynamic Priorities for Protected Objects589 D.6 Preemptive

49、 Abort .590 D.7 Tasking Restrictions591 D.8 Monotonic Time .593 D.9 Delay Accuracy 596 D.10 Synchronous Task Control .597 D.10.1 Synchronous Barriers .598 D.11 Asynchronous Task Control.599 D.12 Other Optimizations and Determinism Rules600 D.13 The Ravenscar Profile .601 D.14 Execution Time 602 D.14.1 Execution Time Timers .604 D.14.2 Group Execution Time Budgets .606 D.14.3 Execution Time of Interrupt Handlers608 D.15 Timing Events 608 D.16 Multiprocessor Implementation610 D.16.1 Multiprocessor Dispatching Domains .611 Annex E (norm