Pull request: add-algo

Merge in DNS/golibs from add-algo to master

Squashed commit of the following:

commit c48a311
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Tue Jan 24 16:12:43 2023 +0300

    mathutil: rename from algo; imp; rm Abs

commit 416e092
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Jan 23 19:12:53 2023 +0300

    algo: add pkg

mathutil/mathutil.go

@@ -0,0 +1,37 @@
+// Package mathutil contains generic helpers for common algorithms and
+// mathematic operations.
+package mathutil
+
+import "golang.org/x/exp/constraints"
+
+// Number is a type constraint for all numbers.
+type Number interface {
+	constraints.Integer | constraints.Float
+}
+
+// BoolToNumber returns 1 if cond is true and 0 otherwise.
+func BoolToNumber[T Number](cond bool) (res T) {
+	if cond {
+		return 1
+	}
+
+	return 0
+}
+
+// Max returns the larger of x or y.
+func Max[T constraints.Integer | ~string](x, y T) (res T) {
+	if x > y {
+		return x
+	}
+
+	return y
+}
+
+// Min returns the smaller of x or y.
+func Min[T constraints.Integer | ~string](x, y T) (res T) {
+	if x < y {
+		return x
+	}
+
+	return y
+}

mathutil/mathutil_example_test.go

@@ -0,0 +1,40 @@
+package mathutil_test
+
+import (
+	"fmt"
+
+	"github.com/AdguardTeam/golibs/mathutil"
+)
+
+func ExampleBoolToNumber() {
+	fmt.Println(mathutil.BoolToNumber[int](true))
+	fmt.Println(mathutil.BoolToNumber[int](false))
+
+	type flag float64
+	fmt.Println(mathutil.BoolToNumber[flag](true))
+	fmt.Println(mathutil.BoolToNumber[flag](false))
+
+	// Output:
+	// 1
+	// 0
+	// 1
+	// 0
+}
+
+func ExampleMax() {
+	fmt.Println(mathutil.Max(1, 2))
+	fmt.Println(mathutil.Max(2, 1))
+
+	// Output:
+	// 2
+	// 2
+}
+
+func ExampleMin() {
+	fmt.Println(mathutil.Min(1, 2))
+	fmt.Println(mathutil.Min(2, 1))
+
+	// Output:
+	// 1
+	// 1
+}