From 124070116fc33aabe4363e793d69019366362c05 Mon Sep 17 00:00:00 2001
From: Piotr Icikowski <piotrekicikowski@gmail.com>
Date: Fri, 21 Jul 2023 23:05:40 +0200
Subject: [PATCH] feat(pkg): add initial source code

---
 go.mod      | 11 ++++++++++
 go.sum      | 10 +++++++++
 package.go  |  4 ++++
 ptr.go      | 23 +++++++++++++++++++
 ptr_test.go | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 111 insertions(+)
 create mode 100644 go.mod
 create mode 100644 go.sum
 create mode 100644 package.go
 create mode 100644 ptr.go
 create mode 100644 ptr_test.go

diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..9884109
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,11 @@
+module pkg.icikowski.pl/generics
+
+go 1.20
+
+require github.com/stretchr/testify v1.8.4
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..fa4b6e6
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,10 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/package.go b/package.go
new file mode 100644
index 0000000..be10a51
--- /dev/null
+++ b/package.go
@@ -0,0 +1,4 @@
+/*
+Generics-related functions
+*/
+package generics
diff --git a/ptr.go b/ptr.go
new file mode 100644
index 0000000..2e91747
--- /dev/null
+++ b/ptr.go
@@ -0,0 +1,23 @@
+package generics
+
+// Ptr returns pointer for given value
+func Ptr[T any](val T) *T {
+	return &val
+}
+
+// Val returns value of given pointer or default value if pointer is nil
+func Val[T any](ptr *T) T {
+	var val T
+	if ptr != nil {
+		val = *ptr
+	}
+	return val
+}
+
+// Fallback returns value of given pointer or fallback value if pointer is nil
+func Fallback[T any](ptr *T, fallback T) T {
+	if ptr != nil {
+		return *ptr
+	}
+	return fallback
+}
diff --git a/ptr_test.go b/ptr_test.go
new file mode 100644
index 0000000..584e920
--- /dev/null
+++ b/ptr_test.go
@@ -0,0 +1,63 @@
+package generics
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestPtr(t *testing.T) {
+	num := new(int)
+	*num = 8
+
+	require.Equal(t, num, *Ptr(num))
+}
+
+func TestVal(t *testing.T) {
+	num := new(int)
+	*num = 8
+
+	tests := map[string]struct {
+		input          *int
+		expectedResult int
+	}{
+		"non-nil pointer": {
+			input:          num,
+			expectedResult: *num,
+		},
+		"nil pointer": {},
+	}
+
+	for name, tc := range tests {
+		name, tc := name, tc
+		t.Run(name, func(t *testing.T) {
+			require.Equal(t, tc.expectedResult, Val(tc.input))
+		})
+	}
+}
+
+func TestFallback(t *testing.T) {
+	num := new(int)
+	*num = 8
+	fallback := 9
+
+	tests := map[string]struct {
+		input          *int
+		expectedResult int
+	}{
+		"non-nil pointer": {
+			input:          num,
+			expectedResult: *num,
+		},
+		"nil pointer": {
+			expectedResult: fallback,
+		},
+	}
+
+	for name, tc := range tests {
+		name, tc := name, tc
+		t.Run(name, func(t *testing.T) {
+			require.Equal(t, tc.expectedResult, Fallback(tc.input, tc.expectedResult))
+		})
+	}
+}