Reusable iteration of glyphs in a string.

include/pqxx/internal/encodings.hxx

@@ -68,6 +68,30 @@ std::string::size_type find_with_encoding(
   std::string::size_type start = 0
 );
 
+
+/// Iterate over the glyphs in a buffer.
+/** Scans the glyphs in the buffer, and for each, passes its begin and its
+ * one-past-end pointers to @c callback.
+ */
+template<typename CALLBACK> inline void for_glyphs(
+        encoding_group enc,
+        CALLBACK callback,
+        const char buffer[],
+        std::string::size_type buffer_len,
+        std::string::size_type start = 0
+)
+{
+  const auto scan = get_glyph_scanner(enc);
+  for (
+        std::string::size_type here = start, next;
+        here < buffer_len;
+        here = next
+  )
+  {
+    next = scan(buffer, buffer_len, here);
+    callback(buffer + here, buffer + next);
+  }
+}
 } // namespace pqxx::internal
 } // namespace pqxx
 

src/array.cxx

@@ -1,6 +1,6 @@
 /** Handling of SQL arrays.
  *
- * Copyright (c) 2019, Jeroen T. Vermeulen.
+ * Copyright (c) 2018-2019, Jeroen T. Vermeulen.
  *
  * See COPYING for copyright license.  If you did not receive a file called
  * COPYING with this source code, please notify the distributor of this mistake,

src/sql_cursor.cxx

@@ -71,19 +71,18 @@ std::string::size_type find_query_end(
     // Complex encoding.  We only know how to iterate forwards, so start from
     // the beginning.
     end = 0;
-    const auto scan = pqxx::internal::get_glyph_scanner(enc);
-    for (
-	auto here = 0ul, next = 0ul;
-	here < size;
-	here = next
-    )
-    {
-      next = scan(text, size, here);
-      if (next - here > 1 or not useless_trail(text[here]))
-        end = next;
-    }
+
+    pqxx::internal::for_glyphs(
+        enc,
+        [text, &end](const char *gbegin, const char *gend)
+        {
+          if (gend - gbegin > 1 or not useless_trail(*gbegin))
+            end = gend - text;
+        },
+        text, size);
   }
-    return end;
+
+  return end;
 }
 } // namespace