lancet/slice/slice.go

// Copyright 2021 dudaodong@gmail.com. All rights resulterved.
// Use of this source code is governed by MIT license

// Package slice implements some functions to manipulate slice.
package slice

import (
	"fmt"
	"math"
	"math/rand"
	"reflect"
	"sort"
)

// Contain check if the target value is in the slice or not
func Contain[T comparable](slice []T, target T) bool {
	for _, item := range slice {
		if item == target {
			return true
		}
	}

	return false
}

// ContainSubSlice check if the slice contain subslice or not
func ContainSubSlice[T comparable](slice, subslice []T) bool {
	for _, v := range subslice {
		if !Contain(slice, v) {
			return false
		}
	}

	return true
}

// Chunk creates an slice of elements split into groups the length of size.
func Chunk[T any](slice []T, size int) [][]T {
	result := [][]T{}

	if len(slice) == 0 || size <= 0 {
		return result
	}

	for _, item := range slice {
		l := len(result)
		if l == 0 || len(result[l-1]) == size {
			result = append(result, []T{})
			l++
		}

		result[l-1] = append(result[l-1], item)
	}

	return result

}

// Compact creates an slice with all falsey values removed. The values false, nil, 0, and "" are falsey
func Compact[T comparable](slice []T) []T {
	var zero T

	result := []T{}
	for _, item := range slice {
		if item != zero {
			result = append(result, item)
		}
	}

	return result
}

// Concat creates a new slice concatenating slice with any additional slices and/or values.
func Concat[T any](slice []T, values ...[]T) []T {
	result := append([]T{}, slice...)

	for _, v := range values {
		result = append(result, v...)
	}

	return result
}

// Difference creates an slice of whose element in slice but not in comparedSlice
func Difference[T comparable](slice, comparedSlice []T) []T {
	result := []T{}

	for _, v := range slice {
		if !Contain(comparedSlice, v) {
			result = append(result, v)
		}
	}

	return result
}

// DifferenceBy it accepts iteratee which is invoked for each element of slice
// and values to generate the criterion by which they're compared.
// like lodash.js differenceBy: https://lodash.com/docs/4.17.15#differenceBy,
func DifferenceBy[T comparable](slice []T, comparedSlice []T, iteratee func(index int, item T) T) []T {
	orginSliceAfterMap := Map(slice, iteratee)
	comparedSliceAfterMap := Map(comparedSlice, iteratee)

	result := make([]T, 0)
	for i, v := range orginSliceAfterMap {
		if !Contain(comparedSliceAfterMap, v) {
			result = append(result, slice[i])
		}
	}

	return result
}

//DifferenceWith accepts comparator which is invoked to compare elements of slice to values. The order and references of result values are determined by the first slice. The comparator is invoked with two arguments: (arrVal, othVal).
func DifferenceWith[T any](slice []T, comparedSlice []T, comparator func(value1, value2 T) bool) []T {
	result := make([]T, 0)

	getIndex := func(arr []T, item T, comparison func(v1, v2 T) bool) int {
		index := -1
		for i, v := range arr {
			if comparison(item, v) {
				index = i
				break
			}
		}
		return index
	}

	for i, v := range slice {
		index := getIndex(comparedSlice, v, comparator)
		if index == -1 {
			result = append(result, slice[i])
		}
	}

	return result
}

// Equal checks if two slices are equal: the same length and all elements' order and value are equal
func Equal[T comparable](slice1, slice2 []T) bool {
	if len(slice1) != len(slice2) {
		return false
	}

	for i := range slice1 {
		if slice1[i] != slice2[i] {
			return false
		}
	}

	return true
}

// EqualWith checks if two slices are equal with comparator func
func EqualWith[T, U any](slice1 []T, slice2 []U, comparator func(T, U) bool) bool {
	if len(slice1) != len(slice2) {
		return false
	}

	for i, v1 := range slice1 {
		v2 := slice2[i]
		if !comparator(v1, v2) {
			return false
		}
	}

	return true
}

// Every return true if all of the values in the slice pass the predicate function.
func Every[T any](slice []T, predicate func(index int, item T) bool) bool {
	for i, v := range slice {
		if !predicate(i, v) {
			return false
		}
	}

	return true
}

// None return true if all the values in the slice mismatch the criteria
func None[T any](slice []T, predicate func(index int, item T) bool) bool {
	l := 0
	for i, v := range slice {
		if !predicate(i, v) {
			l++
		}
	}

	return l == len(slice)
}

// Some return true if any of the values in the list pass the predicate function.
func Some[T any](slice []T, predicate func(index int, item T) bool) bool {
	for i, v := range slice {
		if predicate(i, v) {
			return true
		}
	}

	return false
}

// Filter iterates over elements of slice, returning an slice of all elements pass the predicate function
func Filter[T any](slice []T, predicate func(index int, item T) bool) []T {
	result := make([]T, 0)
	for i, v := range slice {
		if predicate(i, v) {
			result = append(result, v)
		}
	}

	return result
}

// Count iterates over elements of slice, returns a count of all matched elements
func Count[T any](slice []T, predicate func(index int, item T) bool) int {
	if len(slice) == 0 {
		return 0
	}

	var count int
	for i, v := range slice {
		if predicate(i, v) {
			count++
		}
	}

	return count
}

// GroupBy iterate over elements of the slice, each element will be group by criteria, returns two slices
func GroupBy[T any](slice []T, groupFn func(index int, item T) bool) ([]T, []T) {
	if len(slice) == 0 {
		return make([]T, 0), make([]T, 0)
	}

	groupB := make([]T, 0)
	groupA := make([]T, 0)

	for i, v := range slice {
		ok := groupFn(i, v)
		if ok {
			groupA = append(groupA, v)
		} else {
			groupB = append(groupB, v)
		}
	}

	return groupA, groupB
}

// GroupWith return a map composed of keys generated from the resultults of running each element of slice thru iteratee.
func GroupWith[T any, U comparable](slice []T, iteratee func(item T) U) map[U][]T {
	result := make(map[U][]T)

	for _, v := range slice {
		key := iteratee(v)
		if _, ok := result[key]; !ok {
			result[key] = []T{}
		}
		result[key] = append(result[key], v)
	}

	return result
}

// Find iterates over elements of slice, returning the first one that passes a truth test on predicate function.
// If return T is nil then no items matched the predicate func
func Find[T any](slice []T, predicate func(index int, item T) bool) (*T, bool) {
	if len(slice) == 0 {
		return nil, false
	}

	index := -1
	for i, v := range slice {
		if predicate(i, v) {
			index = i
			break
		}
	}

	if index == -1 {
		return nil, false
	}

	return &slice[index], true
}

// FindLast iterates over elements of slice from end to begin, returning the first one that passes a truth test on predicate function.
// If return T is nil then no items matched the predicate func
func FindLast[T any](slice []T, predicate func(index int, item T) bool) (*T, bool) {
	if len(slice) == 0 {
		return nil, false
	}

	index := -1
	for i := len(slice) - 1; i >= 0; i-- {
		if predicate(i, slice[i]) {
			index = i
			break
		}
	}

	if index == -1 {
		return nil, false
	}

	return &slice[index], true
}

// Flatten flattens slice with one level
func Flatten(slice any) any {
	sv := sliceValue(slice)

	var result reflect.Value
	if sv.Type().Elem().Kind() == reflect.Interface {
		result = reflect.MakeSlice(reflect.TypeOf([]interface{}{}), 0, sv.Len())
	} else if sv.Type().Elem().Kind() == reflect.Slice {
		result = reflect.MakeSlice(sv.Type().Elem(), 0, sv.Len())
	} else {
		return result
	}

	for i := 0; i < sv.Len(); i++ {
		item := reflect.ValueOf(sv.Index(i).Interface())
		if item.Kind() == reflect.Slice {
			for j := 0; j < item.Len(); j++ {
				result = reflect.Append(result, item.Index(j))
			}
		} else {
			result = reflect.Append(result, item)
		}
	}

	return result.Interface()
}

// FlattenDeep flattens slice recursive
func FlattenDeep(slice any) any {
	sv := sliceValue(slice)
	st := sliceElemType(sv.Type())
	tmp := reflect.MakeSlice(reflect.SliceOf(st), 0, 0)
	result := flattenRecursive(sv, tmp)
	return result.Interface()
}

func flattenRecursive(value reflect.Value, result reflect.Value) reflect.Value {
	for i := 0; i < value.Len(); i++ {
		item := value.Index(i)
		kind := item.Kind()

		if kind == reflect.Slice {
			result = flattenRecursive(item, result)
		} else {
			result = reflect.Append(result, item)
		}
	}

	return result
}

// ForEach iterates over elements of slice and invokes function for each element
func ForEach[T any](slice []T, iteratee func(index int, item T)) {
	for i, v := range slice {
		iteratee(i, v)
	}
}

// Map creates an slice of values by running each element of slice thru iteratee function.
func Map[T any, U any](slice []T, iteratee func(index int, item T) U) []U {
	result := make([]U, len(slice), cap(slice))
	for i, v := range slice {
		result[i] = iteratee(i, v)
	}

	return result
}

// Reduce creates an slice of values by running each element of slice thru iteratee function.
func Reduce[T any](slice []T, iteratee func(index int, item1, item2 T) T, initial T) T {

	if len(slice) == 0 {
		return initial
	}

	result := iteratee(0, initial, slice[0])

	tmp := make([]T, 2)
	for i := 1; i < len(slice); i++ {
		tmp[0] = result
		tmp[1] = slice[i]
		result = iteratee(i, tmp[0], tmp[1])
	}

	return result
}

// Replace returns a copy of the slice with the first n non-overlapping instances of old replaced by new
func Replace[T comparable](slice []T, old T, new T, n int) []T {
	result := make([]T, len(slice))
	copy(result, slice)

	for i := range result {
		if result[i] == old && n != 0 {
			result[i] = new
			n--
		}
	}

	return result
}

// ReplaceAll returns a copy of the slice with all non-overlapping instances of old replaced by new.
func ReplaceAll[T comparable](slice []T, old T, new T) []T {
	return Replace(slice, old, new, -1)
}

// Repeat creates a slice with length n whose elements are param `item`.
func Repeat[T any](item T, n int) []T {
	result := make([]T, n)
	for i := range result {
		result[i] = item
	}
	return result
}

// InterfaceSlice convert param to slice of interface.
func InterfaceSlice(slice any) []any {
	sv := sliceValue(slice)
	if sv.IsNil() {
		return nil
	}

	result := make([]any, sv.Len())
	for i := 0; i < sv.Len(); i++ {
		result[i] = sv.Index(i).Interface()
	}

	return result
}

// StringSlice convert param to slice of string.
func StringSlice(slice any) []string {
	v := sliceValue(slice)

	out := make([]string, v.Len())
	for i := 0; i < v.Len(); i++ {
		v, ok := v.Index(i).Interface().(string)
		if !ok {
			panic("invalid element type")
		}
		out[i] = v
	}

	return out
}

// IntSlice convert param to slice of int.
func IntSlice(slice any) []int {
	sv := sliceValue(slice)

	out := make([]int, sv.Len())
	for i := 0; i < sv.Len(); i++ {
		v, ok := sv.Index(i).Interface().(int)
		if !ok {
			panic("invalid element type")
		}
		out[i] = v
	}

	return out
}

// DeleteAt delete the element of slice from start index to end index - 1.
func DeleteAt[T any](slice []T, start int, end ...int) []T {
	size := len(slice)

	if start < 0 || start >= size {
		return slice
	}

	if len(end) > 0 {
		end := end[0]
		if end <= start {
			return slice
		}
		if end > size {
			end = size
		}

		slice = append(slice[:start], slice[end:]...)
		return slice
	}

	if start == size-1 {
		slice = slice[:start]
	} else {
		slice = append(slice[:start], slice[start+1:]...)
	}

	return slice
}

// Drop creates a slice with `n` elements dropped from the beginning when n > 0, or `n` elements dropped from the ending when n < 0
func Drop[T any](slice []T, n int) []T {
	size := len(slice)

	if size == 0 || n == 0 {
		return slice
	}

	if math.Abs(float64(n)) >= float64(size) {
		return []T{}
	}

	if n < 0 {
		return slice[0 : size+n]
	}

	return slice[n:size]
}

// InsertAt insert the value or other slice into slice at index.
func InsertAt[T any](slice []T, index int, value any) []T {
	size := len(slice)

	if index < 0 || index > size {
		return slice
	}

	if v, ok := value.(T); ok {
		slice = append(slice[:index], append([]T{v}, slice[index:]...)...)
		return slice
	}

	if v, ok := value.([]T); ok {
		slice = append(slice[:index], append(v, slice[index:]...)...)
		return slice
	}

	return slice
}

// UpdateAt update the slice element at index.
func UpdateAt[T any](slice []T, index int, value T) []T {
	size := len(slice)

	if index < 0 || index >= size {
		return slice
	}
	slice = append(slice[:index], append([]T{value}, slice[index+1:]...)...)

	return slice
}

// Unique remove duplicate elements in slice.
func Unique[T comparable](slice []T) []T {
	result := []T{}

	for i := 0; i < len(slice); i++ {
		v := slice[i]
		skip := true
		for j := range result {
			if v == result[j] {
				skip = false
				break
			}
		}
		if skip {
			result = append(result, v)
		}
	}

	return result
}

// UniqueBy call iteratee func with every item of slice, then remove duplicated.
func UniqueBy[T comparable](slice []T, iteratee func(item T) T) []T {
	result := []T{}

	for _, v := range slice {
		val := iteratee(v)
		result = append(result, val)
	}

	return Unique(result)
}

// Union creates a slice of unique values, in order, from all given slices.
func Union[T comparable](slices ...[]T) []T {
	result := []T{}
	contain := map[T]struct{}{}

	for _, slice := range slices {
		for _, item := range slice {
			if _, ok := contain[item]; !ok {
				contain[item] = struct{}{}
				result = append(result, item)
			}
		}
	}

	return result
}

// UnionBy is like Union, what's more it accepts iteratee which is invoked for each element of each slice
func UnionBy[T any, V comparable](predicate func(item T) V, slices ...[]T) []T {
	result := []T{}
	contain := map[V]struct{}{}

	for _, slice := range slices {
		for _, item := range slice {
			val := predicate(item)
			if _, ok := contain[val]; !ok {
				contain[val] = struct{}{}
				result = append(result, item)
			}
		}
	}

	return result
}

// Merge all given slices into one slice
func Merge[T any](slices ...[]T) []T {
	result := make([]T, 0)

	for _, item := range slices {
		result = append(result, item...)
	}

	return result
}

// Intersection creates a slice of unique values that included by all slices.
func Intersection[T comparable](slices ...[]T) []T {
	if len(slices) == 0 {
		return []T{}
	}
	if len(slices) == 1 {
		return Unique(slices[0])
	}

	reducer := func(sliceA, sliceB []T) []T {
		hashMap := make(map[T]int)
		for _, val := range sliceA {
			hashMap[val] = 1
		}

		out := make([]T, 0)
		for _, val := range sliceB {
			if v, ok := hashMap[val]; v == 1 && ok {
				out = append(out, val)
				hashMap[val]++
			}
		}
		return out
	}

	result := reducer(slices[0], slices[1])

	reduceSlice := make([][]T, 2)
	for i := 2; i < len(slices); i++ {
		reduceSlice[0] = result
		reduceSlice[1] = slices[i]
		result = reducer(reduceSlice[0], reduceSlice[1])
	}

	return result
}

// SymmetricDifference oppoiste operation of intersection function
func SymmetricDifference[T comparable](slices ...[]T) []T {
	if len(slices) == 0 {
		return []T{}
	}
	if len(slices) == 1 {
		return Unique(slices[0])
	}

	result := make([]T, 0)

	intersectSlice := Intersection(slices...)

	for i := 0; i < len(slices); i++ {
		slice := slices[i]
		for _, v := range slice {
			if !Contain(intersectSlice, v) {
				result = append(result, v)
			}
		}

	}

	return Unique(result)
}

// Reverse return slice of element order is reversed to the given slice
func Reverse[T any](slice []T) {
	for i, j := 0, len(slice)-1; i < j; i, j = i+1, j-1 {
		slice[i], slice[j] = slice[j], slice[i]
	}
}

// Shuffle creates an slice of shuffled values
func Shuffle[T any](slice []T) []T {
	result := make([]T, len(slice))
	for i, v := range rand.Perm(len(slice)) {
		result[i] = slice[v]
	}

	return result
}

// SortByField return sorted slice by field
// Slice element should be struct, field type should be int, uint, string, or bool
// default sortType is ascending (asc), if descending order, set sortType to desc
func SortByField(slice any, field string, sortType ...string) error {
	sv := sliceValue(slice)
	t := sv.Type().Elem()

	if t.Kind() == reflect.Ptr {
		t = t.Elem()
	}
	if t.Kind() != reflect.Struct {
		return fmt.Errorf("data type %T not support, shuld be struct or pointer to struct", slice)
	}

	// Find the field.
	sf, ok := t.FieldByName(field)
	if !ok {
		return fmt.Errorf("field name %s not found", field)
	}

	// Create a less function based on the field's kind.
	var compare func(a, b reflect.Value) bool
	switch sf.Type.Kind() {
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		if len(sortType) > 0 && sortType[0] == "desc" {
			compare = func(a, b reflect.Value) bool { return a.Int() > b.Int() }
		} else {
			compare = func(a, b reflect.Value) bool { return a.Int() < b.Int() }
		}
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
		if len(sortType) > 0 && sortType[0] == "desc" {
			compare = func(a, b reflect.Value) bool { return a.Uint() > b.Uint() }
		} else {
			compare = func(a, b reflect.Value) bool { return a.Uint() < b.Uint() }
		}
	case reflect.Float32, reflect.Float64:
		if len(sortType) > 0 && sortType[0] == "desc" {
			compare = func(a, b reflect.Value) bool { return a.Float() > b.Float() }
		} else {
			compare = func(a, b reflect.Value) bool { return a.Float() < b.Float() }
		}
	case reflect.String:
		if len(sortType) > 0 && sortType[0] == "desc" {
			compare = func(a, b reflect.Value) bool { return a.String() > b.String() }
		} else {
			compare = func(a, b reflect.Value) bool { return a.String() < b.String() }
		}
	case reflect.Bool:
		if len(sortType) > 0 && sortType[0] == "desc" {
			compare = func(a, b reflect.Value) bool { return a.Bool() && !b.Bool() }
		} else {
			compare = func(a, b reflect.Value) bool { return !a.Bool() && b.Bool() }
		}
	default:
		return fmt.Errorf("field type %s not supported", sf.Type)
	}

	sort.Slice(slice, func(i, j int) bool {
		a := sv.Index(i)
		b := sv.Index(j)
		if t.Kind() == reflect.Ptr {
			a = a.Elem()
			b = b.Elem()
		}
		a = a.FieldByIndex(sf.Index)
		b = b.FieldByIndex(sf.Index)
		return compare(a, b)
	})

	return nil
}

// Without creates a slice excluding all given values
func Without[T comparable](slice []T, values ...T) []T {
	if len(values) == 0 || len(slice) == 0 {
		return slice
	}

	result := make([]T, 0, len(slice))
	for _, v := range slice {
		if !Contain(values, v) {
			result = append(result, v)
		}
	}

	return result
}

// IndexOf returns the index at which the first occurrence of a value is found in a slice or return -1
// if the value cannot be found.
func IndexOf[T comparable](slice []T, value T) int {
	for i, v := range slice {
		if v == value {
			return i
		}
	}

	return -1
}

// LastIndexOf returns the index at which the last occurrence of a value is found in a slice or return -1
// if the value cannot be found.
func LastIndexOf[T comparable](slice []T, value T) int {
	for i := len(slice) - 1; i > 0; i-- {
		if value == slice[i] {
			return i
		}
	}

	return -1
}

// ToSlicePointer returns a pointer to the slices of a variable parameter transformation
func ToSlicePointer[T any](value ...T) []*T {
	result := make([]*T, len(value))
	for i := range value {
		result[i] = &value[i]
	}

	return result
}

// ToSlice returns a slices of a variable parameter transformation
func ToSlice[T any](value ...T) []T {
	result := make([]T, len(value))
	copy(result, value)

	return result
}

// AppendIfAbsent only absent append the value
func AppendIfAbsent[T comparable](slice []T, value T) []T {
	if !Contain(slice, value) {
		slice = append(slice, value)
	}
	return slice
}

// KeyBy converts a slice to a map based on a callback function
func KeyBy[T any, U comparable](slice []T, iteratee func(item T) U) map[U]T {
	result := make(map[U]T, len(slice))

	for _, v := range slice {
		k := iteratee(v)
		result[k] = v
	}

	return result
}