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- // Copyright (c) 2015, Emir Pasic. All rights reserved.
- // Use of this source code is governed by a BSD-style
- // license that can be found in the LICENSE file.
-
- // Package arraylist implements the array list.
- //
- // Structure is not thread safe.
- //
- // Reference: https://en.wikipedia.org/wiki/List_%28abstract_data_type%29
- package arraylist
-
- import (
- "fmt"
- "strings"
-
- "github.com/emirpasic/gods/lists"
- "github.com/emirpasic/gods/utils"
- )
-
- func assertListImplementation() {
- var _ lists.List = (*List)(nil)
- }
-
- // List holds the elements in a slice
- type List struct {
- elements []interface{}
- size int
- }
-
- const (
- growthFactor = float32(2.0) // growth by 100%
- shrinkFactor = float32(0.25) // shrink when size is 25% of capacity (0 means never shrink)
- )
-
- // New instantiates a new list and adds the passed values, if any, to the list
- func New(values ...interface{}) *List {
- list := &List{}
- if len(values) > 0 {
- list.Add(values...)
- }
- return list
- }
-
- // Add appends a value at the end of the list
- func (list *List) Add(values ...interface{}) {
- list.growBy(len(values))
- for _, value := range values {
- list.elements[list.size] = value
- list.size++
- }
- }
-
- // Get returns the element at index.
- // Second return parameter is true if index is within bounds of the array and array is not empty, otherwise false.
- func (list *List) Get(index int) (interface{}, bool) {
-
- if !list.withinRange(index) {
- return nil, false
- }
-
- return list.elements[index], true
- }
-
- // Remove removes the element at the given index from the list.
- func (list *List) Remove(index int) {
-
- if !list.withinRange(index) {
- return
- }
-
- list.elements[index] = nil // cleanup reference
- copy(list.elements[index:], list.elements[index+1:list.size]) // shift to the left by one (slow operation, need ways to optimize this)
- list.size--
-
- list.shrink()
- }
-
- // Contains checks if elements (one or more) are present in the set.
- // All elements have to be present in the set for the method to return true.
- // Performance time complexity of n^2.
- // Returns true if no arguments are passed at all, i.e. set is always super-set of empty set.
- func (list *List) Contains(values ...interface{}) bool {
-
- for _, searchValue := range values {
- found := false
- for _, element := range list.elements {
- if element == searchValue {
- found = true
- break
- }
- }
- if !found {
- return false
- }
- }
- return true
- }
-
- // Values returns all elements in the list.
- func (list *List) Values() []interface{} {
- newElements := make([]interface{}, list.size, list.size)
- copy(newElements, list.elements[:list.size])
- return newElements
- }
-
- //IndexOf returns index of provided element
- func (list *List) IndexOf(value interface{}) int {
- if list.size == 0 {
- return -1
- }
- for index, element := range list.elements {
- if element == value {
- return index
- }
- }
- return -1
- }
-
- // Empty returns true if list does not contain any elements.
- func (list *List) Empty() bool {
- return list.size == 0
- }
-
- // Size returns number of elements within the list.
- func (list *List) Size() int {
- return list.size
- }
-
- // Clear removes all elements from the list.
- func (list *List) Clear() {
- list.size = 0
- list.elements = []interface{}{}
- }
-
- // Sort sorts values (in-place) using.
- func (list *List) Sort(comparator utils.Comparator) {
- if len(list.elements) < 2 {
- return
- }
- utils.Sort(list.elements[:list.size], comparator)
- }
-
- // Swap swaps the two values at the specified positions.
- func (list *List) Swap(i, j int) {
- if list.withinRange(i) && list.withinRange(j) {
- list.elements[i], list.elements[j] = list.elements[j], list.elements[i]
- }
- }
-
- // Insert inserts values at specified index position shifting the value at that position (if any) and any subsequent elements to the right.
- // Does not do anything if position is negative or bigger than list's size
- // Note: position equal to list's size is valid, i.e. append.
- func (list *List) Insert(index int, values ...interface{}) {
-
- if !list.withinRange(index) {
- // Append
- if index == list.size {
- list.Add(values...)
- }
- return
- }
-
- l := len(values)
- list.growBy(l)
- list.size += l
- copy(list.elements[index+l:], list.elements[index:list.size-l])
- copy(list.elements[index:], values)
- }
-
- // Set the value at specified index
- // Does not do anything if position is negative or bigger than list's size
- // Note: position equal to list's size is valid, i.e. append.
- func (list *List) Set(index int, value interface{}) {
-
- if !list.withinRange(index) {
- // Append
- if index == list.size {
- list.Add(value)
- }
- return
- }
-
- list.elements[index] = value
- }
-
- // String returns a string representation of container
- func (list *List) String() string {
- str := "ArrayList\n"
- values := []string{}
- for _, value := range list.elements[:list.size] {
- values = append(values, fmt.Sprintf("%v", value))
- }
- str += strings.Join(values, ", ")
- return str
- }
-
- // Check that the index is within bounds of the list
- func (list *List) withinRange(index int) bool {
- return index >= 0 && index < list.size
- }
-
- func (list *List) resize(cap int) {
- newElements := make([]interface{}, cap, cap)
- copy(newElements, list.elements)
- list.elements = newElements
- }
-
- // Expand the array if necessary, i.e. capacity will be reached if we add n elements
- func (list *List) growBy(n int) {
- // When capacity is reached, grow by a factor of growthFactor and add number of elements
- currentCapacity := cap(list.elements)
- if list.size+n >= currentCapacity {
- newCapacity := int(growthFactor * float32(currentCapacity+n))
- list.resize(newCapacity)
- }
- }
-
- // Shrink the array if necessary, i.e. when size is shrinkFactor percent of current capacity
- func (list *List) shrink() {
- if shrinkFactor == 0.0 {
- return
- }
- // Shrink when size is at shrinkFactor * capacity
- currentCapacity := cap(list.elements)
- if list.size <= int(float32(currentCapacity)*shrinkFactor) {
- list.resize(list.size)
- }
- }
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