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2503. multiline option should be added tosyntax_option_type

Section: 28.6.4.2[re.synopt]Status:C++17Submitter: Nozomu KatōOpened: 2015-05-22Last modified: 2017-07-30

Priority:2

View all otherissues in [re.synopt].

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Discussion:

The specification of ECMAScript defines the Multiline property for itsRegExp and the regular expressions ^ and $ behave differently accordingto the value of this property. Thus, this property should be availablealso in the ECMAScript compatible engine instd::regex.

[2015-05-22, Daniel comments]

This issue interacts somewhat with LWG2343⁽ⁱ⁾.

[Telecon 2015-07]

Set the priority to match LWG2343⁽ⁱ⁾.

[2016-08, Chicago]

Monday PM: Moved to Tentatively Ready. This also resolves2343⁽ⁱ⁾

Proposed resolution:

This wording is relative to N4431.

1. Change 28.6.4.2[re.synopt] as indicated:

   namespace std::regex_constants {  typedef T1 syntax_option_type;  constexpr syntax_option_type icase =unspecified ;  constexpr syntax_option_type nosubs =unspecified ;  constexpr syntax_option_type optimize =unspecified ;  constexpr syntax_option_type collate =unspecified ;  constexpr syntax_option_type ECMAScript =unspecified ;  constexpr syntax_option_type basic =unspecified ;  constexpr syntax_option_type extended =unspecified ;  constexpr syntax_option_type awk =unspecified ;  constexpr syntax_option_type grep =unspecified ;  constexpr syntax_option_type egrep =unspecified ;constexpr syntax_option_type multiline =unspecified ;}

2. Change 28.6.4.3[re.matchflag], Table 138 — "syntax_option_type effects" as indicated:

   Table 138 —syntax_option_type effects

   Element	Effect(s) if set
   …
   multiline	Specifies that^ shall match the beginning of a lineand$ shall match the end of a line, if the ECMAScript engine isselected.
   …