From 857cb78e1568ccd55562f9602c247882dfa7bb0b Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 9 Sep 2023 10:37:18 +0300
Subject: [PATCH] Improvements for empty variants

There's now a function to check if an empty variant holds a value, and
two empty variants will compare as equal.
---
 source/core/variant.h | 13 ++++++++++++-
 tests/variant.cpp     | 15 +++++++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/source/core/variant.h b/source/core/variant.h
index 5cb1b93..b00f561 100644
--- a/source/core/variant.h
+++ b/source/core/variant.h
@@ -52,6 +52,7 @@ public:
 	Variant &operator=(Variant &&v) { if(&v!=this) move_from(std::move(v)); return *this; }
 
 	void clear();
+	bool has_value() const { return funcs; }
 
 private:
 	template<typename T>
@@ -80,7 +81,7 @@ public:
 
 	DEPRECATED bool check_same_type(const Variant &v) const { return has_same_type(v); }
 
-	bool operator==(const Variant &v) const { return (has_same_type(v) && funcs->compare(storage, v.storage)); }
+	bool operator==(const Variant &v) const;
 	bool operator!=(const Variant &v) const { return !(operator==(v)); }
 
 	template<typename T>
@@ -192,6 +193,16 @@ inline T &Variant::get()
 		return **reinterpret_cast<T **>(storage);
 }
 
+inline bool Variant::operator==(const Variant &other) const
+{
+	if(!funcs && !other.funcs)
+		return true;
+	else if(has_same_type(other))
+		return funcs->compare(storage, other.storage);
+	else
+		return false;
+}
+
 inline bool Variant::type_equals(const Functions *funcs1, const Functions *funcs2)
 {
 	if(!funcs1 || !funcs2)
diff --git a/tests/variant.cpp b/tests/variant.cpp
index 8ec8972..9bdfeda 100644
--- a/tests/variant.cpp
+++ b/tests/variant.cpp
@@ -18,6 +18,7 @@ private:
 	void ref_into();
 	void copying();
 	void destruction();
+	void compare();
 	void types();
 	void mismatch();
 };
@@ -41,6 +42,7 @@ VariantTests::VariantTests()
 	add(&VariantTests::ref_into, "Reference into");
 	add(&VariantTests::copying, "Copying");
 	add(&VariantTests::destruction, "Destruction");
+	add(&VariantTests::compare, "Comparisons");
 	add(&VariantTests::types, "Type checks");
 	add(&VariantTests::mismatch, "Mismatch").expect_throw<type_mismatch>();
 }
@@ -96,6 +98,19 @@ void VariantTests::destruction()
 	EXPECT_EQUAL(count, 0);
 }
 
+void VariantTests::compare()
+{
+	Variant var = 1;
+	Variant var2 = 1;
+	Variant var3 = 4.2f;
+	Variant var4;
+	Variant var5;
+	EXPECT(var==var2);
+	EXPECT(var!=var3);
+	EXPECT(var!=var4);
+	EXPECT(var4==var5);
+}
+
 void VariantTests::types()
 {
 	Variant var = 42U;
-- 
2.45.2