From 0c6d4ed2e499e3e17165e43803d0d1c6dd0956d9 Mon Sep 17 00:00:00 2001
From: Paul Buetow <paul@buetow.org>
Date: Sun, 2 Apr 2023 20:22:13 +0300
Subject: initial generics

---
 ds/arraylist.go | 42 +++++++++++++++++++++++++-----------------
 1 file changed, 25 insertions(+), 17 deletions(-)

(limited to 'ds/arraylist.go')

diff --git a/ds/arraylist.go b/ds/arraylist.go
index feee14e..de27832 100644
--- a/ds/arraylist.go
+++ b/ds/arraylist.go
@@ -4,46 +4,54 @@ import (
 	"fmt"
 	"math/rand"
 	"strings"
+	"golang.org/x/exp/constraints"
 )
 
-// Idea: Once Go got generics use generics here instead of hard coded int type
-type ArrayList []int
+type Integer interface {
+	constraints.Integer
+}
+
+type Number interface {
+	constraints.Integer | constraints.Float
+}
+
+type ArrayList[V Number] []V
 
-func NewArrayList(l int) ArrayList {
-	return make(ArrayList, l)
+func NewArrayList[V Number](l int) ArrayList[V] {
+	return make(ArrayList[V], l)
 }
 
-func NewRandomArrayList(l, max int) ArrayList {
-	a := make(ArrayList, l)
+func NewRandomArrayList[V Number](l, max int) ArrayList[V] {
+	a := make(ArrayList[V], l)
 	for i := 0; i < l; i++ {
 		if max > 0 {
-			a[i] = rand.Intn(max)
+			a[i] = V(rand.Intn(max))
 			continue
 		}
-		a[i] = rand.Int()
+		a[i] = V(rand.Int())
 	}
 	return a
 }
 
-func NewAscendingArrayList(l int) ArrayList {
-	a := make(ArrayList, l)
+func NewAscendingArrayList[V Number](l int) ArrayList[V] {
+	a := make(ArrayList[V], l)
 	for i := 0; i < l; i++ {
-		a[i] = i
+		a[i] = V(i)
 	}
 	return a
 }
 
-func NewDescendingArrayList(l int) ArrayList {
-	a := make(ArrayList, l)
+func NewDescendingArrayList[V Number](l int) ArrayList[V] {
+	a := make(ArrayList[V], l)
 	j := l - 1
 	for i := 0; i < l; i++ {
-		a[i] = j
+		a[i] = V(j)
 		j--
 	}
 	return a
 }
 
-func (a ArrayList) FirstN(n int) string {
+func (a ArrayList[V]) FirstN(n int) string {
 	var sb strings.Builder
 	j := n
 
@@ -63,7 +71,7 @@ func (a ArrayList) FirstN(n int) string {
 	return sb.String()
 }
 
-func (a ArrayList) Sorted() bool {
+func (a ArrayList[V]) Sorted() bool {
 	for i := len(a) - 1; i > 0; i-- {
 		if a[i] < a[i-1] {
 			return false
@@ -72,7 +80,7 @@ func (a ArrayList) Sorted() bool {
 	return true
 }
 
-func (a ArrayList) Swap(i, j int) {
+func (a ArrayList[V]) Swap(i, j int) {
 	aux := a[i]
 	a[i] = a[j]
 	a[j] = aux
-- 
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