refactor: upgrade multi-key sort (#77)

As suggested by @bkietz this PR upgrades the sort routine to utilize
tuple's built-in compare behavior. This reduces the complexity of
evaluating each set of four possibilities for each key manually.

---------

Co-authored-by: Benjamin Kietzman <bengilgit@gmail.com>

src/substrait/textplan/converter/ReferenceNormalizer.cpp

@@ -14,27 +14,19 @@ namespace {
 bool compareExtensionFunctions(
  const ::substrait::proto::extensions::SimpleExtensionDeclaration& a,
  const ::substrait::proto::extensions::SimpleExtensionDeclaration& b) {
- // First sort so that extension functions proceed any other kind of extension.
- if (a.has_extension_function() && !b.has_extension_function()) {
- return true;
- } else if (!a.has_extension_function() && b.has_extension_function()) {
- // Extension functions always come first.
- return false;
- } else if (!a.has_extension_function() && !b.has_extension_function()) {
- // Both are not extension functions, no difference in ordering.
- return false;
- }
- // Now sort by space.
- if (a.extension_function().extension_uri_reference() <
- b.extension_function().extension_uri_reference()) {
- return true;
- } else if (
- a.extension_function().extension_uri_reference() >
- b.extension_function().extension_uri_reference()) {
- return false;
- }
- // Finally sort by name within a space.
- return a.extension_function().name() < b.extension_function().name();
+ auto ord = [](const auto& decl) {
+ return make_tuple(
+ // First sort so that extension functions precede any other kind of
+ // extension.
+ not decl.has_extension_function(),
+ // Next sort by space.
+ decl.extension_function().extension_uri_reference(),
+ // Finally sort by name within a space.
+ std::string_view{decl.extension_function().name()});
+ };
+
+ // Now let the default tuple compare do the rest of the work.
+ return ord(a) > ord(b);
 }
 
 void normalizeFunctionsForExpression(