Use C++20 default comparisons for section objects

Author: jwakely

src/section_data.cpp

@@ -10,6 +10,8 @@ struct section_num
 {
     std::string prefix;
     std::vector<int> num;
+
+    auto operator<=>(const section_num&) const = default;
 };
 
 std::istream&
@@ -82,30 +84,6 @@ operator << (std::ostream& os, const section_num& sn)
     return os;
 }
 
-bool
-operator<(const section_num& x, const section_num& y)
-{
-    if (x.prefix < y.prefix)
-        return true;
-    else if (y.prefix < x.prefix)
-        return false;
-    return x.num < y.num;
-}
-
-bool
-operator==(const section_num& x, const section_num& y)
-{
-    if (x.prefix != y.prefix)
-        return false;
-    return x.num == y.num;
-}
-
-bool
-operator!=(const section_num& x, const section_num& y)
-{
-    return !(x == y);
-}
-
 typedef std::string section_tag;
 
 std::string

src/sections.cpp

@@ -6,20 +6,6 @@
 #include <cctype>
 #include <utility>
 
-auto lwg::operator<(section_tag const & x, section_tag const & y) noexcept -> bool {
-   return (x.prefix < y.prefix) ?  true
-        : (y.prefix < x.prefix) ? false
-        : x.name < y.name;
-}
-
-auto lwg::operator==(section_tag const & x, section_tag const & y) noexcept -> bool {
-   return x.prefix == y.prefix && x.name == y.name;
-}
-
-auto lwg::operator!=(section_tag const & x, section_tag const & y) noexcept -> bool {
-   return !(x == y);
-}
-
 auto lwg::operator << (std::ostream& os, section_tag const & tag) -> std::ostream & {
   os << '[';
    if (!tag.prefix.empty()) { os << tag.prefix << "::"; }
@@ -34,23 +20,6 @@ std::string lwg::as_string(section_tag const & x)
     : x.prefix + "::" + x.name;
 }
 
-auto lwg::operator < (section_num const & x, section_num const & y) noexcept -> bool {
-   // prefixes are unique, so there should be no need for a tiebreak.
-   return (x.prefix < y.prefix) ?  true
-        : (y.prefix < x.prefix) ? false
-        : x.num < y.num;
-}
-
-auto lwg::operator == (section_num const & x, section_num const & y) noexcept -> bool {
-   return (x.prefix != y.prefix)
-        ? false
-        : x.num == y.num;
-}
-
-auto lwg::operator != (section_num const & x, section_num const & y) noexcept -> bool {
-   return !(x == y);
-}
-
 auto lwg::operator >> (std::istream& is, section_num& sn) -> std::istream & {
    sn.prefix.clear();
    sn.num.clear();

src/sections.h

@@ -13,33 +13,22 @@ struct section_tag
 {
   std::string  prefix;        // example: fund.ts.v2 
   std::string  name;          // example: meta.logical
+  auto operator<=>(const section_tag&) const = default;
 };
 
 struct section_num {
   std::string       prefix;    // example: fund.ts.v2 
   std::vector<int>  num;       // sequence of numbers corresponding to section number
                                // in relevant doc, e.g,, 17.5.2.1.4.2
+  auto operator<=>(const section_num&) const = default;
 };
 
 using section_map = std::map<section_tag, section_num>;
 
-auto operator <  (section_tag const & x, section_tag const & y) noexcept -> bool;
-auto operator == (section_tag const & x, section_tag const & y) noexcept -> bool;
-auto operator != (section_tag const & x, section_tag const & y) noexcept -> bool;
 auto operator << (std::ostream & os,
   section_tag const & tag) -> std::ostream &; // with square brackets
 std::string as_string(section_tag const & x); // without square brackets
 
-auto operator <  (section_num const & x, section_num const & y) noexcept -> bool;
-   // section 'x' sorts before section 'y' if its 'prefix' field lexicographically
-   // precedes that of 'y',  and its 'nun' field lexicographically precedes that
-   // of 'y' if the prefix fields are equivalent.
-
-auto operator == (section_num const & x, section_num const & y) noexcept -> bool;
-auto operator != (section_num const & x, section_num const & y) noexcept -> bool;
-   // Two 'section_num' objects compare equal if their 'prefix' and 'num' both
-   // compare equal.
-
 auto operator >> (std::istream & is, section_num & sn) -> std::istream &;
 auto operator << (std::ostream & os, section_num const & sn) -> std::ostream &;