From d40c5be796f30efd426b83535c078065a62d9bca Mon Sep 17 00:00:00 2001
From: Benzinnos <grigorevalexeyit@gmail.com>
Date: Sat, 16 Mar 2024 14:29:49 +0300
Subject: [PATCH] feature/add utils compare equality operator (#865)

* Add eq and ne operators

* Add three-way comparison to compare utils.

* Three-way comparison test now using own test data.

* Rename test struct for three-way comparison test.

* Quick fix for pre c++20 aggregate initialization.

---------

Co-authored-by: grigorev <grigorev@protei.ru>
---
 include/etl/compare.h | 34 ++++++++++++++++++++++-
 test/test_compare.cpp | 63 ++++++++++++++++++++++++++++++++++++-------
 2 files changed, 87 insertions(+), 10 deletions(-)

diff --git a/include/etl/compare.h b/include/etl/compare.h
index 479758d95..5a28c83df 100644
--- a/include/etl/compare.h
+++ b/include/etl/compare.h
@@ -44,7 +44,7 @@ SOFTWARE.
 namespace etl
 {
   //***************************************************************************
-  /// Defines <=, >, >= in terms of <
+  /// Defines <=, >, >=, ==, !=, <=> in terms of <
   /// Default
   //***************************************************************************
   template <typename T, typename TLess = etl::less<T> >
@@ -54,6 +54,13 @@ namespace etl
     typedef typename etl::parameter_type<T>::type second_argument_type;
     typedef bool result_type;
 
+    enum cmp_result
+    {
+      LESS = -1,
+      EQUAL = 0,
+      GREATER = 1
+    };
+
     static result_type lt(first_argument_type lhs, second_argument_type rhs)
     {
       return TLess()(lhs, rhs);
@@ -73,6 +80,31 @@ namespace etl
     {
       return !lt(lhs, rhs);
     }
+
+    static result_type eq(first_argument_type lhs, second_argument_type rhs)
+    {
+      return gte(lhs, rhs) && lte(lhs, rhs);
+    }
+
+    static result_type ne(first_argument_type lhs, second_argument_type rhs)
+    {
+      return !eq(lhs, rhs);
+    }
+
+    static cmp_result cmp(first_argument_type lhs, second_argument_type rhs)
+    {
+      if (lt(lhs, rhs))
+      {
+        return LESS;
+      }
+
+      if (gt(lhs, rhs))
+      {
+        return GREATER;
+      }
+
+      return EQUAL;
+    }
   };
 }
 
diff --git a/test/test_compare.cpp b/test/test_compare.cpp
index a11d611ad..076dc9ec7 100644
--- a/test/test_compare.cpp
+++ b/test/test_compare.cpp
@@ -37,49 +37,61 @@ namespace
 
   typedef etl::compare<int> CompareInt;
 
-  struct Test
+  struct Object
   {
     int a;
     int b;
   };
 
-  Test ta = { 1, 2 };
-  Test tb = { 2, 3 };
+  Object ta = { 1, 2 };
+  Object tb = { 2, 3 };
 
   //***********************************
-  bool operator <(const Test& lhs, const Test& rhs)
+  bool operator <(const Object& lhs, const Object& rhs)
   {
     return (lhs.a + lhs.b) < (rhs.a + rhs.b);
   }
 
   //***********************************
-  bool operator >(const Test& lhs, const Test& rhs)
+  bool operator >(const Object& lhs, const Object& rhs)
   {
     return (lhs.a + lhs.b) > (rhs.a + rhs.b);
   }
 
   //***********************************
-  bool operator <=(const Test& lhs, const Test& rhs)
+  bool operator <=(const Object& lhs, const Object& rhs)
   {
     return (lhs.a + lhs.b) <= (rhs.a + rhs.b);
   }
 
   //***********************************
-  bool operator >=(const Test& lhs, const Test& rhs)
+  bool operator >=(const Object& lhs, const Object& rhs)
   {
     return (lhs.a + lhs.b) >= (rhs.a + rhs.b);
   }
 
+  //***********************************
+  bool operator ==(const Object& lhs, const Object& rhs)
+  {
+    return (lhs.a + lhs.b) == (rhs.a + rhs.b);
+  }
+
+  //***********************************
+  bool operator !=(const Object& lhs, const Object& rhs)
+  {
+    return (lhs.a + lhs.b) != (rhs.a + rhs.b);
+  }
+
   //***********************************
   struct LessTest
   {
-    bool operator()(const Test& lhs, const Test& rhs) const
+    bool operator()(const Object& lhs, const Object& rhs) const
     {
       return (lhs.a + lhs.b) < (rhs.a + rhs.b);
     }
   };
 
-  typedef etl::compare<Test, LessTest> CompareTest;
+  typedef etl::compare<Object, LessTest> CompareTest;
 
   SUITE(test_compare)
   {
@@ -126,5 +138,38 @@ namespace
       CHECK_EQUAL(tb >= ta, (CompareTest::gte(tb, ta)));
       CHECK_EQUAL(ta >= ta, (CompareTest::gte(ta, ta)));
     }
+
+    //*************************************************************************
+    TEST(test_eq)
+    {
+      CHECK_EQUAL(a == b,   (CompareInt::eq(a, b)));
+      CHECK_EQUAL(b == a,   (CompareInt::eq(b, a)));
+      CHECK_EQUAL(a == a,   (CompareInt::eq(a, a)));
+      CHECK_EQUAL(ta == tb, (CompareTest::eq(ta, tb)));
+      CHECK_EQUAL(tb == ta, (CompareTest::eq(tb, ta)));
+      CHECK_EQUAL(ta == ta, (CompareTest::eq(ta, ta)));
+    }
+
+    //*************************************************************************
+    TEST(test_ne)
+    {
+      CHECK_EQUAL(a != b,   (CompareInt::ne(a, b)));
+      CHECK_EQUAL(b != a,   (CompareInt::ne(b, a)));
+      CHECK_EQUAL(a != a,   (CompareInt::ne(a, a)));
+      CHECK_EQUAL(ta != tb, (CompareTest::ne(ta, tb)));
+      CHECK_EQUAL(tb != ta, (CompareTest::ne(tb, ta)));
+      CHECK_EQUAL(ta != ta, (CompareTest::ne(ta, ta)));
+    }
+
+    //*************************************************************************
+    TEST(test_cmp)
+    {
+      CHECK_EQUAL(CompareInt::LESS,     (CompareInt::cmp(2, 4)));
+      CHECK_EQUAL(CompareInt::GREATER,  (CompareInt::cmp(4, 2)));
+      CHECK_EQUAL(CompareInt::EQUAL,    (CompareInt::cmp(0, 0)));
+      CHECK_EQUAL(CompareTest::LESS,    (CompareTest::cmp(Object{0, 1}, Object{2, 4})));
+      CHECK_EQUAL(CompareTest::GREATER, (CompareTest::cmp(Object{2, 4}, Object{0, 1})));
+      CHECK_EQUAL(CompareTest::EQUAL,   (CompareTest::cmp(Object{2, 4}, Object{2, 4})));
+    }
   };
 }