Merge 2017-11 LWG Motion 18

Author: zygoloid

source/strings.tex

@@ -1109,6 +1109,13 @@
     int compare(const charT* s) const;
     int compare(size_type pos1, size_type n1, const charT* s) const;
     int compare(size_type pos1, size_type n1, const charT* s, size_type n2) const;
+
+    bool starts_with(basic_string_view<charT, traits> x) const noexcept;
+    bool starts_with(charT x) const noexcept;
+    bool starts_with(const charT* x) const;
+    bool ends_with(basic_string_view<charT, traits> x) const noexcept;
+    bool ends_with(charT x) const noexcept;
+    bool ends_with(const charT* x) const;
   };
 
   template<class InputIterator,
@@ -3677,6 +3684,42 @@
 \returns \tcode{basic_string(*this, pos, n1).compare(basic_string(s, n2))}.
 \end{itemdescr}
 
+\rSec4[string.starts.with]{\tcode{basic_string::starts_with}}
+
+\indexlibrarymember{starts_with}{basic_string}%
+\begin{itemdecl}
+bool starts_with(basic_string_view<charT, traits> x) const noexcept;
+bool starts_with(charT x) const noexcept;
+bool starts_with(const charT* x) const;
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+\effects
+Equivalent to:
+\begin{codeblock}
+return basic_string_view<charT, traits>(data(), size()).starts_with(x);
+\end{codeblock}
+\end{itemdescr}
+
+\rSec4[string.ends.with]{\tcode{basic_string::ends_with}}
+
+\indexlibrarymember{ends_with}{basic_string}%
+\begin{itemdecl}
+bool ends_with(basic_string_view<charT, traits> x) const noexcept;
+bool ends_with(charT x) const noexcept;
+bool ends_with(const charT* x) const;
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+\effects
+Equivalent to:
+\begin{codeblock}
+return basic_string_view<charT, traits>(data(), size()).ends_with(x);
+\end{codeblock}
+\end{itemdescr}
+
 \rSec2[string.nonmembers]{\tcode{basic_string} non-member functions}
 
 \indexlibrary{\idxcode{basic_string}}
@@ -4703,6 +4746,13 @@
   constexpr int compare(size_type pos1, size_type n1, const charT* s) const;
   constexpr int compare(size_type pos1, size_type n1, const charT* s, size_type n2) const;
 
+  constexpr bool starts_with(basic_string_view x) const noexcept;
+  constexpr bool starts_with(charT x) const noexcept;
+  constexpr bool starts_with(const charT* x) const;
+  constexpr bool ends_with(basic_string_view x) const noexcept;
+  constexpr bool ends_with(charT x) const noexcept;
+  constexpr bool ends_with(const charT* x) const;
+
   constexpr size_type find(basic_string_view s, size_type pos = 0) const noexcept;
   constexpr size_type find(charT c, size_type pos = 0) const noexcept;
   constexpr size_type find(const charT* s, size_type pos, size_type n) const;
@@ -5205,6 +5255,75 @@
 Equivalent to: \tcode{return substr(pos1, n1).compare(basic_string_view(s, n2));}
 \end{itemdescr}
 
+\indexlibrarymember{starts_with}{basic_string_view}%
+\begin{itemdecl}
+constexpr bool starts_with(basic_string_view x) const noexcept;
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+\effects
+Equivalent to: \tcode{return compare(0, npos, x) == 0;}
+\end{itemdescr}
+
+\indexlibrarymember{starts_with}{basic_string_view}%
+\begin{itemdecl}
+constexpr bool starts_with(charT x) const noexcept;
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+\effects
+Equivalent to: \tcode{return starts_with(basic_string_view(\&x, 1));}
+\end{itemdescr}
+
+\indexlibrarymember{starts_with}{basic_string_view}%
+\begin{itemdecl}
+constexpr bool starts_with(const charT* x) const;
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+\effects
+Equivalent to: \tcode{return starts_with(basic_string_view(x));}
+\end{itemdescr}
+
+\indexlibrarymember{ends_with}{basic_string_view}%
+\begin{itemdecl}
+constexpr bool ends_with(basic_string_view x) const noexcept;
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+\effects
+Equivalent to:
+\begin{codeblock}
+return size() >= x.size() && compare(size() - x.size(), npos, x) == 0;
+\end{codeblock}
+\end{itemdescr}
+
+\indexlibrarymember{ends_with}{basic_string_view}%
+\begin{itemdecl}
+constexpr bool ends_with(charT x) const noexcept;
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+\effects
+Equivalent to: \tcode{return ends_with(basic_string_view(\&x, 1));}
+\end{itemdescr}
+
+\indexlibrarymember{ends_with}{basic_string_view}%
+\begin{itemdecl}
+constexpr bool ends_with(const charT* x) const;
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+\effects
+Equivalent to: \tcode{return ends_with(basic_string_view(x));}
+\end{itemdescr}
+
 \rSec3[string.view.find]{Searching}
 
 \pnum