From 6853d627f457369e179edfcc5ab4e3811a3f7ec4 Mon Sep 17 00:00:00 2001
From: Cannian <2081215119@qq.com>
Date: Sat, 6 Apr 2024 09:16:28 +0800
Subject: [PATCH] refactor(slice): optimize function (#211)

---
 slice/slice.go      | 43 ++++++++++++++++++++++++++++++++-----------
 slice/slice_test.go | 16 ++++++++++++++--
 2 files changed, 46 insertions(+), 13 deletions(-)

diff --git a/slice/slice.go b/slice/slice.go
index d832a369..4d63ec3a 100644
--- a/slice/slice.go
+++ b/slice/slice.go
@@ -50,12 +50,23 @@ func ContainBy[T any](slice []T, predicate func(item T) bool) bool {
 // ContainSubSlice check if the slice contain a given subslice or not.
 // Play: https://go.dev/play/p/bcuQ3UT6Sev
 func ContainSubSlice[T comparable](slice, subSlice []T) bool {
-	for _, v := range subSlice {
-		if !Contain(slice, v) {
+	if len(subSlice) == 0 {
+		return true
+	}
+	if len(slice) == 0 {
+		return false
+	}
+
+	elementMap := make(map[T]struct{}, len(slice))
+	for _, item := range slice {
+		elementMap[item] = struct{}{}
+	}
+
+	for _, item := range subSlice {
+		if _, ok := elementMap[item]; !ok {
 			return false
 		}
 	}
-
 	return true
 }
 
@@ -81,35 +92,41 @@ func Chunk[T any](slice []T, size int) [][]T {
 	return result
 }
 
-// Compact creates an slice with all falsey values removed. The values false, nil, 0, and "" are falsey.
+// Compact creates a slice with all falsey values removed. The values false, nil, 0, and "" are falsey.
 // Play: https://go.dev/play/p/pO5AnxEr3TK
 func Compact[T comparable](slice []T) []T {
 	var zero T
 
-	result := []T{}
+	result := make([]T, 0, len(slice))
 
 	for _, v := range slice {
 		if v != zero {
 			result = append(result, v)
 		}
 	}
-
-	return result
+	return result[:len(result):len(result)]
 }
 
 // Concat creates a new slice concatenating slice with any additional slices.
 // Play: https://go.dev/play/p/gPt-q7zr5mk
 func Concat[T any](slice []T, slices ...[]T) []T {
-	result := append([]T{}, slice...)
+	totalLen := len(slice)
 
 	for _, v := range slices {
-		result = append(result, v...)
+		totalLen += len(v)
+	}
+
+	result := make([]T, 0, totalLen)
+
+	result = append(result, slice...)
+	for _, s := range slices {
+		result = append(result, s...)
 	}
 
 	return result
 }
 
-// Difference creates an slice of whose element in slice but not in comparedSlice.
+// Difference creates a slice of whose element in slice but not in comparedSlice.
 // Play: https://go.dev/play/p/VXvadzLzhDa
 func Difference[T comparable](slice, comparedSlice []T) []T {
 	result := []T{}
@@ -826,7 +843,11 @@ func UnionBy[T any, V comparable](predicate func(item T) V, slices ...[]T) []T {
 // Merge all given slices into one slice.
 // Play: https://go.dev/play/p/lbjFp784r9N
 func Merge[T any](slices ...[]T) []T {
-	result := make([]T, 0)
+	totalLen := 0
+	for _, v := range slices {
+		totalLen += len(v)
+	}
+	result := make([]T, 0, totalLen)
 
 	for _, v := range slices {
 		result = append(result, v...)
diff --git a/slice/slice_test.go b/slice/slice_test.go
index 5bb43e27..fb2c4e2c 100644
--- a/slice/slice_test.go
+++ b/slice/slice_test.go
@@ -2,12 +2,11 @@ package slice
 
 import (
 	"fmt"
+	"github.com/duke-git/lancet/v2/internal"
 	"math"
 	"reflect"
 	"strconv"
 	"testing"
-
-	"github.com/duke-git/lancet/v2/internal"
 )
 
 func TestContain(t *testing.T) {
@@ -109,6 +108,19 @@ func TestConcat(t *testing.T) {
 	assert.Equal([]int{1, 2, 3, 4, 5}, Concat([]int{1, 2, 3}, []int{4}, []int{5}))
 }
 
+func BenchmarkConcat(b *testing.B) {
+	slice1 := []int{1, 2, 3}
+	slice2 := []int{4, 5, 6}
+	slice3 := []int{7, 8, 9}
+
+	for i := 0; i < b.N; i++ {
+		result := Concat(slice1, slice2, slice3)
+		if len(result) == 0 {
+			b.Fatal("unexpected empty result")
+		}
+	}
+}
+
 func TestEqual(t *testing.T) {
 	t.Parallel()