[glibmm/wip/dboles/ustring: 3/5] ustring: Use std::initializer_list instead of pointer + size

[Daniel Boles <dboles src gnome org>]

commit e73af9bb8d76f7cc7d8c7004883c025eae600edf
Author: Daniel Boles <dboles src gnome org>
Date:   Thu Jul 6 21:58:26 2017 +0100

    ustring: Use std::initializer_list instead of pointer + size
    
    Acrobatics are needed so that the main compose function does not have to
    be templated on the number of strings due to the bloat that would cause.
    
    Since C++11, instead of a pointer to an array & its size, we can pass an
    std::initializer_list, which pretty much exists for this purpose, as it
    uses compiler magic to abstract a variable sized array behind iterators.
    
    The only drawback is that initializer_list does not have an operator[],
    but its elements are guaranteed to be allocated in the order defined, so
    we can use (*(begin() + index)) – a bit ugly, but we only need it once!
    
    https://bugzilla.gnome.org/show_bug.cgi?id=784211

 glib/glibmm/ustring.cc |   12 ++++++------
 glib/glibmm/ustring.h  |   36 +++++++++++++-----------------------
 2 files changed, 19 insertions(+), 29 deletions(-)
---
diff --git a/glib/glibmm/ustring.cc b/glib/glibmm/ustring.cc
index f26fe68..2668347 100644
--- a/glib/glibmm/ustring.cc
+++ b/glib/glibmm/ustring.cc
@@ -1288,13 +1288,13 @@ ustring::casefold_collate_key() const
 
 // static
 ustring
-ustring::compose_argv(const Glib::ustring& fmt, int argc, const ustring* const* argv)
+ustring::compose_private(const Glib::ustring& fmt, std::initializer_list<const ustring*> const ilist)
 {
   std::string::size_type result_size = fmt.raw().size();
 
   // Guesstimate the final string size.
-  for (int i = 0; i < argc; ++i)
-    result_size += argv[i]->raw().size();
+  for (auto const it: ilist)
+    result_size += it->raw().size();
 
   std::string result;
   result.reserve(result_size);
@@ -1311,12 +1311,12 @@ ustring::compose_argv(const Glib::ustring& fmt, int argc, const ustring* const*
     }
     else
     {
-      const int index = Ascii::digit_value(stop[1]) - 1;
+      const std::size_t index = Ascii::digit_value(stop[1]) - 1;
 
-      if (index >= 0 && index < argc)
+      if (index >= 0 && index < ilist.size())
       {
         result.append(start, stop - start);
-        result += argv[index]->raw();
+        result += (*(ilist.begin() + index))->raw();
         start = stop + 2;
       }
       else
diff --git a/glib/glibmm/ustring.h b/glib/glibmm/ustring.h
index 7a07848..a076a90 100644
--- a/glib/glibmm/ustring.h
+++ b/glib/glibmm/ustring.h
@@ -22,6 +22,7 @@
 #include <glib.h>
 
 #include <cstddef> // for std::size_t and optionally std::ptrdiff_t
+#include <initializer_list>
 #include <iosfwd>
 #include <iterator>
 #include <sstream>
@@ -828,9 +829,10 @@ private:
 
   template <class T>
   class Stringify;
+
   class FormatStream;
 
-  static ustring compose_argv(const ustring& fmt, int argc, const ustring* const* argv);
+  static ustring compose_private(const ustring& fmt, std::initializer_list<const ustring*> ilist);
 
 #endif /* DOXYGEN_SHOULD_SKIP_THIS */
 
@@ -1356,7 +1358,7 @@ inline // static
   ustring
   ustring::compose(const ustring& fmt)
 {
-  return ustring::compose_argv(fmt, 0, nullptr);
+  return ustring::compose_private(fmt, {});
 }
 
 template <class T1>
@@ -1366,8 +1368,7 @@ inline // static
 {
   const ustring::Stringify<T1> s1(a1);
 
-  const ustring* const argv[] = { s1.ptr() };
-  return ustring::compose_argv(fmt, G_N_ELEMENTS(argv), argv);
+  return compose_private(fmt, { s1.ptr() });
 }
 
 template <class T1, class T2>
@@ -1378,8 +1379,7 @@ inline // static
   const ustring::Stringify<T1> s1(a1);
   const ustring::Stringify<T2> s2(a2);
 
-  const ustring* const argv[] = { s1.ptr(), s2.ptr() };
-  return ustring::compose_argv(fmt, G_N_ELEMENTS(argv), argv);
+  return compose_private(fmt, { s1.ptr(), s2.ptr() });
 }
 
 template <class T1, class T2, class T3>
@@ -1391,8 +1391,7 @@ inline // static
   const ustring::Stringify<T2> s2(a2);
   const ustring::Stringify<T3> s3(a3);
 
-  const ustring* const argv[] = { s1.ptr(), s2.ptr(), s3.ptr() };
-  return ustring::compose_argv(fmt, G_N_ELEMENTS(argv), argv);
+  return compose_private(fmt, { s1.ptr(), s2.ptr(), s3.ptr() });
 }
 
 template <class T1, class T2, class T3, class T4>
@@ -1405,8 +1404,7 @@ inline // static
   const ustring::Stringify<T3> s3(a3);
   const ustring::Stringify<T4> s4(a4);
 
-  const ustring* const argv[] = { s1.ptr(), s2.ptr(), s3.ptr(), s4.ptr() };
-  return ustring::compose_argv(fmt, G_N_ELEMENTS(argv), argv);
+  return compose_private(fmt, { s1.ptr(), s2.ptr(), s3.ptr(), s4.ptr() });
 }
 
 template <class T1, class T2, class T3, class T4, class T5>
@@ -1421,8 +1419,7 @@ inline // static
   const ustring::Stringify<T4> s4(a4);
   const ustring::Stringify<T5> s5(a5);
 
-  const ustring* const argv[] = { s1.ptr(), s2.ptr(), s3.ptr(), s4.ptr(), s5.ptr() };
-  return ustring::compose_argv(fmt, G_N_ELEMENTS(argv), argv);
+  return compose_private(fmt, { s1.ptr(), s2.ptr(), s3.ptr(), s4.ptr(), s5.ptr() });
 }
 
 template <class T1, class T2, class T3, class T4, class T5, class T6>
@@ -1438,8 +1435,7 @@ inline // static
   const ustring::Stringify<T5> s5(a5);
   const ustring::Stringify<T6> s6(a6);
 
-  const ustring* const argv[] = { s1.ptr(), s2.ptr(), s3.ptr(), s4.ptr(), s5.ptr(), s6.ptr() };
-  return ustring::compose_argv(fmt, G_N_ELEMENTS(argv), argv);
+  return compose_private(fmt, { s1.ptr(), s2.ptr(), s3.ptr(), s4.ptr(), s5.ptr(), s6.ptr() });
 }
 
 template <class T1, class T2, class T3, class T4, class T5, class T6, class T7>
@@ -1456,9 +1452,7 @@ inline // static
   const ustring::Stringify<T6> s6(a6);
   const ustring::Stringify<T7> s7(a7);
 
-  const ustring* const argv[] = { s1.ptr(), s2.ptr(), s3.ptr(), s4.ptr(), s5.ptr(), s6.ptr(),
-    s7.ptr() };
-  return ustring::compose_argv(fmt, G_N_ELEMENTS(argv), argv);
+  return compose_private(fmt, { s1.ptr(), s2.ptr(), s3.ptr(), s4.ptr(), s5.ptr(), s6.ptr(), s7.ptr() });
 }
 
 template <class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8>
@@ -1476,9 +1470,7 @@ inline // static
   const ustring::Stringify<T7> s7(a7);
   const ustring::Stringify<T8> s8(a8);
 
-  const ustring* const argv[] = { s1.ptr(), s2.ptr(), s3.ptr(), s4.ptr(), s5.ptr(), s6.ptr(),
-    s7.ptr(), s8.ptr() };
-  return ustring::compose_argv(fmt, G_N_ELEMENTS(argv), argv);
+  return compose_private(fmt, { s1.ptr(), s2.ptr(), s3.ptr(), s4.ptr(), s5.ptr(), s6.ptr(), s7.ptr(), 
s8.ptr() });
 }
 
 template <class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8, class T9>
@@ -1497,9 +1489,7 @@ inline // static
   const ustring::Stringify<T8> s8(a8);
   const ustring::Stringify<T9> s9(a9);
 
-  const ustring* const argv[] = { s1.ptr(), s2.ptr(), s3.ptr(), s4.ptr(), s5.ptr(), s6.ptr(),
-    s7.ptr(), s8.ptr(), s9.ptr() };
-  return ustring::compose_argv(fmt, G_N_ELEMENTS(argv), argv);
+  return compose_private(fmt, { s1.ptr(), s2.ptr(), s3.ptr(), s4.ptr(), s5.ptr(), s6.ptr(), s7.ptr(), 
s8.ptr(), s9.ptr() });
 }
 
 #endif /* DOXYGEN_SHOULD_SKIP_THIS */