lancet/datastructure/list.go

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

// Package datastructure implements some data structure. eg. list, linklist, stack, queue, tree, graph.
package datastructure

import (
	"reflect"
)

// List is a linear table, implemented with slice
type List[T any] struct {
	data []T
}

// NewList return a pointer of List
func NewList[T any](data []T) *List[T] {
	return &List[T]{data: data}
}

// Data return list data
func (l *List[T]) Data() []T {
	return l.data
}

// ValueOf return the value pointer at index of list data.
func (l *List[T]) ValueOf(index int) (*T, bool) {
	if index < 0 || index >= len(l.data) {
		return nil, false
	}
	return &l.data[index], true
}

// IndexOf reture the index of value. if not found return -1
func (l *List[T]) IndexOf(value T) int {
	index := -1
	data := l.data
	for i, v := range data {
		if reflect.DeepEqual(v, value) {
			index = i
			break
		}
	}
	return index
}

// Contain checks if the value in the list or not
func (l *List[T]) Contain(value T) bool {
	data := l.data
	for _, v := range data {
		if reflect.DeepEqual(v, value) {
			return true
		}
	}
	return false
}

// Push append value to the list data
func (l *List[T]) Push(value T) {
	l.data = append(l.data, value)
}

// InsertAtFirst insert value into list at first index
func (l *List[T]) InsertAtFirst(value T) {
	l.InsertAt(0, value)
}

// InsertAtLast insert value into list at last index
func (l *List[T]) InsertAtLast(value T) {
	l.InsertAt(len(l.data), value)
}

// InsertAt insert value into list at index
func (l *List[T]) InsertAt(index int, value T) {
	data := l.data
	size := len(data)

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

// PopFirst delete the first value of list and return it
func (l *List[T]) PopFirst() (*T, bool) {
	if len(l.data) == 0 {
		return nil, false
	}

	v := l.data[0]
	l.DeleteAt(0)

	return &v, true
}

// PopLast delete the last value of list and return it
func (l *List[T]) PopLast() (*T, bool) {
	size := len(l.data)
	if size == 0 {
		return nil, false
	}

	v := l.data[size-1]
	l.DeleteAt(size - 1)

	return &v, true
}

// DeleteAt delete the value of list at index
func (l *List[T]) DeleteAt(index int) {
	data := l.data
	size := len(data)
	if index < 0 || index > size-1 {
		return
	}
	if index == size-1 {
		data = append(data[:index])
	} else {
		data = append(data[:index], data[index+1:]...)
	}
	l.data = data
}

// InsertAt insert value into list at index, index shoud between 0 and list size -1
func (l *List[T]) UpdateAt(index int, value T) {
	data := l.data
	size := len(data)

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

// EqutalTo compare list to other list, use reflect.DeepEqual
func (l *List[T]) EqutalTo(other *List[T]) bool {
	if len(l.data) != len(other.data) {
		return false
	}

	for i := 0; i < len(l.data); i++ {
		if !reflect.DeepEqual(l.data[i], other.data[i]) {
			return false
		}
	}

	return true
}

// IsEmpty check if the list is empty or not
func (l *List[T]) IsEmpty() bool {
	return len(l.data) == 0
}

// Clear the data of list
func (l *List[T]) Clear() {
	l.data = make([]T, 0, 0)
}

// Clone return a copy of list
func (l *List[T]) Clone() *List[T] {
	cl := NewList(make([]T, len(l.data)))
	copy(cl.data, l.data)

	return cl
}

// Merge two list, return new list, don't change original list
func (l *List[T]) Merge(other *List[T]) *List[T] {
	l1, l2 := len(l.data), len(other.data)
	ml := NewList(make([]T, l1+l2, l1+l2))

	data := append([]T{}, append(l.data, other.data...)...)
	ml.data = data

	return ml
}

// Size return number of list data items
func (l *List[T]) Size() int {
	return len(l.data)
}

// Swap the value of index i and j in list
func (l *List[T]) Swap(i, j int) {
	size := len(l.data)
	if i < 0 || i >= size || j < 0 || j >= size {
		return
	}
	l.data[i], l.data[j] = l.data[j], l.data[i]
}

// Reverse the item order of list
func (l *List[T]) Reverse() {
	for i, j := 0, len(l.data)-1; i < j; i, j = i+1, j-1 {
		l.data[i], l.data[j] = l.data[j], l.data[i]
	}
}

// Unique remove duplicate items in list
func (l *List[T]) Unique() {
	data := l.data
	size := len(data)

	uniqueData := make([]T, 0, 0)
	for i := 0; i < size; i++ {
		value := data[i]
		skip := true
		for _, v := range uniqueData {
			if reflect.DeepEqual(value, v) {
				skip = false
				break
			}
		}
		if skip {
			uniqueData = append(uniqueData, value)
		}
	}

	l.data = uniqueData
}

// Union creates a new list contain all element in list l and other, remove duplicate element.
func (l *List[T]) Union(other *List[T]) *List[T] {
	res := NewList([]T{})

	res.data = append(res.data, l.data...)
	res.data = append(res.data, other.data...)
	res.Unique()

	return res
}

// Intersection creates a new list whose element both be contained in list l and other
func (l *List[T]) Intersection(other *List[T]) *List[T] {
	res := NewList(make([]T, 0, 0))

	for _, v := range l.data {
		if other.Contain(v) {
			res.data = append(res.data, v)
		}
	}

	return res
}