Pre-allocate memory to reduce the number of allocations (#272)

convertor/convertor.go

@@ -74,7 +74,7 @@ func ToBytes(value any) ([]byte, error) {
 // ToChar convert string to char slice.
 // Play: https://go.dev/play/p/JJ1SvbFkVdM
 func ToChar(s string) []string {
-	c := make([]string, 0)
+	c := make([]string, 0, len(s))
 	if len(s) == 0 {
 		c = append(c, "")
 	}

datastructure/link/doublylink.go

@@ -209,7 +209,7 @@ func (dl *DoublyLink[T]) Size() int {
 
 // Values return slice of all doubly linklist node value
 func (dl *DoublyLink[T]) Values() []T {
-	result := []T{}
+	result := make([]T, 0, dl.length)
 	current := dl.Head
 	for current != nil {
 		result = append(result, current.Value)

datastructure/link/singlylink.go

@@ -212,7 +212,7 @@ func (sl *SinglyLink[T]) Size() int {
 
 // Values return slice of all singly linklist node value
 func (sl *SinglyLink[T]) Values() []T {
-	result := []T{}
+	result := make([]T, 0, sl.length)
 	current := sl.Head
 	for current != nil {
 		result = append(result, current.Value)

datastructure/queue/arrayqueue.go

@@ -31,7 +31,7 @@ func NewArrayQueue[T any](capacity int) *ArrayQueue[T] {
 
 // Data return slice of queue data
 func (q *ArrayQueue[T]) Data() []T {
-	items := []T{}
+	items := make([]T, 0, q.tail-q.head)
 	for i := q.head; i < q.tail; i++ {
 		items = append(items, q.data[i])
 	}

datastructure/queue/linkedqueue.go

@@ -27,7 +27,7 @@ func NewLinkedQueue[T any]() *LinkedQueue[T] {
 
 // Data return slice of queue data
 func (q *LinkedQueue[T]) Data() []T {
-	res := []T{}
+	res := make([]T, 0, q.length)
 	current := q.head
 
 	for current != nil {

datastructure/stack/linkedstack.go

@@ -24,7 +24,7 @@ func NewLinkedStack[T any]() *LinkedStack[T] {
 
 // Data return stack data
 func (s *LinkedStack[T]) Data() []T {
-	res := []T{}
+	res := make([]T, 0, s.length)
 	current := s.top
 
 	for current != nil {

datastructure/tree/tree_internal.go

@@ -147,7 +147,7 @@ func printTreeNodes[T any](nodes []*datastructure.TreeNode[T], level, maxLevel i
 
 	printSpaces(firstSpaces)
 
-	newNodes := []*datastructure.TreeNode[T]{}
+	newNodes := make([]*datastructure.TreeNode[T], 0, len(nodes)*2)
 	for _, node := range nodes {
 		if node != nil {
 			fmt.Printf("%v", node.Value)

fileutil/file.go

@@ -14,7 +14,6 @@ import (
 	"encoding/csv"
 	"errors"
 	"fmt"
-	"github.com/duke-git/lancet/v2/validator"
 	"io"
 	"io/fs"
 	"net/http"
@@ -24,6 +23,8 @@ import (
 	"sort"
 	"strings"
 	"sync"
+
+	"github.com/duke-git/lancet/v2/validator"
 )
 
 // FileReader is a reader supporting offset seeking and reading one
@@ -819,6 +820,7 @@ func WriteMapsToCsv(filepath string, records []map[string]any, appendToExistingF
 	if len(headers) > 0 {
 		columnHeaders = headers[0]
 	} else {
+		columnHeaders = make([]string, 0, len(records[0]))
 		for key := range records[0] {
 			columnHeaders = append(columnHeaders, key)
 		}
@@ -832,7 +834,7 @@ func WriteMapsToCsv(filepath string, records []map[string]any, appendToExistingF
 	}
 
 	for _, record := range records {
-		var row []string
+		row := make([]string, 0, len(columnHeaders))
 		for _, h := range columnHeaders {
 			row = append(row, fmt.Sprintf("%v", record[h]))
 		}

netutil/http.go

@@ -71,7 +71,7 @@ func ConvertMapToQueryString(param map[string]any) string {
 	if param == nil {
 		return ""
 	}
-	var keys []string
+	keys := make([]string, 0, len(param))
 	for key := range param {
 		keys = append(keys, key)
 	}

stream/stream.go

@@ -202,6 +202,7 @@ func (s Stream[T]) Skip(n int) Stream[T] {
 		return FromSlice(source)
 	}
 
+	source = make([]T, 0, l-n)
 	for i := n; i < l; i++ {
 		source = append(source, s.source[i])
 	}

structs/struct.go

@@ -88,8 +88,8 @@ func (s *Struct) ToMap() (map[string]any, error) {
 
 // Fields returns all the struct fields within a slice
 func (s *Struct) Fields() []*Field {
-	var fields []*Field
 	fieldNum := s.rvalue.NumField()
+	fields := make([]*Field, 0, fieldNum)
 	for i := 0; i < fieldNum; i++ {
 		v := s.rvalue.Field(i)
 		sf := s.rtype.Field(i)

xerror/xerror.go

@@ -34,7 +34,7 @@ func Wrap(cause error, message ...any) *XError {
 	err := newXError()
 
 	if len(message) > 0 {
-		var newMsgs []string
+		newMsgs := make([]string, 0, len(message))
 		for _, m := range message {
 			newMsgs = append(newMsgs, fmt.Sprintf("%v", m))
 		}