TECHNICAL ISO/IEC TS SPECIFICATION 19568 Second edition 2017-03 Programming languages C++ extensions for library fundamentals Langages de programmation - Extensions C++ pour la bibliotheque fondamentaux Reference number IEC IS0/IEC TS 19568:2017(E) os1 International Organization for Standardization F STANDARDIZATION C1 5956617 @IS0/IEC2017 mitted without license from IHS IS0/IEC TS 19568:2017(E) COPYRIGHTPROTECTEDDOCUMENT IS0/IEC 2017, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISO's member body in the country of the requester. ISO copyright office Ch. de Blandonnet 8 . CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 [email protected] www.iso.org Internationai ibrg DrganizationforStandardization icensee-ZHEJIANG INSTOF STANDRJSA/IEC07 -All rights reserved networking permited without license from IHS IS0/IEC TS 19568:2017 (E) Contents Foreword .vii General 1.1 Scope 1.2 Normativereferences 1.3 Namespaces, headers, and modifications to standard classes 1.4 Terms and definitions 2 1.5 Future plans (Informative) 2 1.6 Feature-testing recommendations (Informative) 3 2 Modifications to the C++ Standard Library ...... 5 2.1 Uses-allocator construction 5 3 General utilities library 6 3.1 Utility components 6 3.1.1 Header <experimental/utility> synopsis 6 3.1.2 Class erased_type 6 3.2 Tuples 6 3.2.1 Header <experimental/tuple> synopsis 6 3.2.2 Calling a function with a tuple of arguments 3.3 Metaprogramming and type traits 3.3.1 Header <experimental/type_traits> synopsis 7 3.3.2 Other type transformations 11 3.3.3 Logical operator traits 12 3.3.4 Detection idiom . 13 3.4 Compile-time rational arithmetic 14 3.4.1 Header <experimental/ratio> synopsis 14 3.5 Time utilities 15 3.5.1 Header <experimental/chrono> synopsis 15 3.6 System error support . ... 15 3.6.1 Header <experimental/system_error> synopsis 15 3.7 Class template propagate_const 15 3.7.1 Class template propagate_const general 15 3.7.2 Header <experimental/propagate_const> synopsis 16 3.7.3 propagate_const requirements on T 18 3.7.3.1 propagate_const requirements on class type T 18 3.7.4 propagate_const constructors 19 3.7.5 propagate_const assignment 19 3.7.6 propagate_const const observers 20 ... 3.7.7 propagate_const non-const observers 20 3.7.8 propagate_const modifiers 21 3.7.9 propagate_const relational operators 21 3.7.10 propagate_const specialized algorithms 23 3.7.11 propagate_const underlying pointer access 23 3.7.12 propagate_const hash support 23 3.7.13 propagate_const comparison function objects 23 Function objects 25 4.1 Header <experimental/functional> synopsis 25 4.2 Class template function 26 4.2.1 function construct/copy/destroy 28 4.2.2 function modifiers 29 @ ISO/IEC 2017 - All rights reserved" ii IntenatinalganizatinforStandardization Noreproductionornetworking permited without license from IHS IS0/IEC TS 19568:2017 (E) 4.3 Searchers 29 4.3.1 Class template default _ searcher 29 4.3.1.1 default searcher creation functions 30 4.3.2 Class template boyer_moore_searcher 30 4.3.2.1 boyer_moore_searcher creation functions 31 4.3.3 Class template boyer_moore_horspool_searcher 31 4.3.3.1 boyer_moore_horspool_searcher creation functions 32 4.4 Function template not _fn 33 Optional objects 34 5.1 In general 34 5.2 Header <experimental/optional> synopsis 34 5.3 optional for object types 35 5.3.1 Constructors 37 5.3.2 Destructor 39 5.3.3 Assignment 40 5.3.4 Swap 43 5.3.5 Observers 43 5.4 In-place construction 44 5.5 No-value state indicator 44 5.6 Class bad_optional_access 45 5.7 Relational operators 45 5.8 Comparison with nullopt 45 5.9 Comparison with T 46 5.10 Specialized algorithms 47 5.11 Hash supp