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352 lines
10 KiB
Go
352 lines
10 KiB
Go
/*
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Copyright (c) 2015, Emir Pasic
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright notice, this
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list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions and the following disclaimer in the documentation
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and/or other materials provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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// Package arraylist implements the array list.
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//
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// Structure is not thread safe.
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//
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// Reference: https://en.wikipedia.org/wiki/List_%28abstract_data_type%29
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package arraylist
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import (
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"fmt"
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"github.com/emirpasic/gods/containers"
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"github.com/emirpasic/gods/lists"
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"github.com/emirpasic/gods/utils"
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"strings"
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)
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func assertInterfaceImplementation() {
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var _ lists.List = (*List)(nil)
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var _ containers.EnumerableWithIndex = (*List)(nil)
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var _ containers.ReverseIteratorWithIndex = (*Iterator)(nil)
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}
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// List holds the elements in a slice
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type List struct {
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elements []interface{}
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size int
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}
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const (
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growthFactor = float32(2.0) // growth by 100%
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shrinkFactor = float32(0.25) // shrink when size is 25% of capacity (0 means never shrink)
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)
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// New instantiates a new empty list
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func New() *List {
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return &List{}
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}
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// Add appends a value at the end of the list
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func (list *List) Add(values ...interface{}) {
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list.growBy(len(values))
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for _, value := range values {
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list.elements[list.size] = value
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list.size++
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}
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}
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// Get returns the element at index.
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// Second return parameter is true if index is within bounds of the array and array is not empty, otherwise false.
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func (list *List) Get(index int) (interface{}, bool) {
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if !list.withinRange(index) {
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return nil, false
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}
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return list.elements[index], true
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}
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// Remove removes one or more elements from the list with the supplied indices.
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func (list *List) Remove(index int) {
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if !list.withinRange(index) {
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return
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}
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list.elements[index] = nil // cleanup reference
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copy(list.elements[index:], list.elements[index+1:list.size]) // shift to the left by one (slow operation, need ways to optimize this)
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list.size--
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list.shrink()
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}
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// Contains checks if elements (one or more) are present in the set.
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// All elements have to be present in the set for the method to return true.
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// Performance time complexity of n^2.
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// Returns true if no arguments are passed at all, i.e. set is always super-set of empty set.
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func (list *List) Contains(values ...interface{}) bool {
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for _, searchValue := range values {
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found := false
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for _, element := range list.elements {
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if element == searchValue {
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found = true
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break
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}
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}
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if !found {
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return false
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}
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}
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return true
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}
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// Values returns all elements in the list.
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func (list *List) Values() []interface{} {
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newElements := make([]interface{}, list.size, list.size)
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copy(newElements, list.elements[:list.size])
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return newElements
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}
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// Empty returns true if list does not contain any elements.
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func (list *List) Empty() bool {
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return list.size == 0
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}
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// Size returns number of elements within the list.
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func (list *List) Size() int {
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return list.size
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}
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// Clear removes all elements from the list.
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func (list *List) Clear() {
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list.size = 0
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list.elements = []interface{}{}
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}
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// Sort sorts values (in-place) using.
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func (list *List) Sort(comparator utils.Comparator) {
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if len(list.elements) < 2 {
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return
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}
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utils.Sort(list.elements[:list.size], comparator)
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}
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// Swap swaps the two values at the specified positions.
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func (list *List) Swap(i, j int) {
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if list.withinRange(i) && list.withinRange(j) {
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list.elements[i], list.elements[j] = list.elements[j], list.elements[i]
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}
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}
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// Insert inserts values at specified index position shifting the value at that position (if any) and any subsequent elements to the right.
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// Does not do anything if position is negative or bigger than list's size
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// Note: position equal to list's size is valid, i.e. append.
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func (list *List) Insert(index int, values ...interface{}) {
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if !list.withinRange(index) {
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// Append
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if index == list.size {
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list.Add(values...)
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}
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return
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}
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l := len(values)
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list.growBy(l)
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list.size += l
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// Shift old to right
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for i := list.size - 1; i >= index+l; i-- {
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list.elements[i] = list.elements[i-l]
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}
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// Insert new
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for i, value := range values {
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list.elements[index+i] = value
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}
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}
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// Iterator holding the iterator's state
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type Iterator struct {
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list *List
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index int
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}
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// Iterator returns a stateful iterator whose values can be fetched by an index.
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func (list *List) Iterator() Iterator {
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return Iterator{list: list, index: -1}
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}
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// Next moves the iterator to the next element and returns true if there was a next element in the container.
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// If Next() returns true, then next element's index and value can be retrieved by Index() and Value().
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// If Next() was called for the first time, then it will point the iterator to the first element if it exists.
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// Modifies the state of the iterator.
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func (iterator *Iterator) Next() bool {
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if iterator.index < iterator.list.size {
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iterator.index++
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}
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return iterator.list.withinRange(iterator.index)
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}
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// Prev moves the iterator to the previous element and returns true if there was a previous element in the container.
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// If Prev() returns true, then previous element's index and value can be retrieved by Index() and Value().
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// Modifies the state of the iterator.
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func (iterator *Iterator) Prev() bool {
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if iterator.index >= 0 {
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iterator.index--
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}
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return iterator.list.withinRange(iterator.index)
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}
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// Value returns the current element's value.
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// Does not modify the state of the iterator.
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func (iterator *Iterator) Value() interface{} {
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return iterator.list.elements[iterator.index]
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}
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// Index returns the current element's index.
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// Does not modify the state of the iterator.
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func (iterator *Iterator) Index() int {
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return iterator.index
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}
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// Reset sets the iterator to the initial state.
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// Call Next() to fetch the first element if any.
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func (iterator *Iterator) Reset() {
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iterator.index = -1
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}
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// Last moves the iterator to the last element and returns true if there was a last element in the container.
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// If Last() returns true, then last element's index and value can be retrieved by Index() and Value().
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// Modifies the state of the iterator.
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func (iterator *Iterator) Last() bool {
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iterator.index = iterator.list.size
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return iterator.Prev()
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}
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// Each calls the given function once for each element, passing that element's index and value.
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func (list *List) Each(f func(index int, value interface{})) {
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iterator := list.Iterator()
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for iterator.Next() {
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f(iterator.Index(), iterator.Value())
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}
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}
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// Map invokes the given function once for each element and returns a
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// container containing the values returned by the given function.
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func (list *List) Map(f func(index int, value interface{}) interface{}) *List {
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newList := &List{}
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iterator := list.Iterator()
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for iterator.Next() {
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newList.Add(f(iterator.Index(), iterator.Value()))
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}
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return newList
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}
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// Select returns a new container containing all elements for which the given function returns a true value.
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func (list *List) Select(f func(index int, value interface{}) bool) *List {
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newList := &List{}
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iterator := list.Iterator()
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for iterator.Next() {
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if f(iterator.Index(), iterator.Value()) {
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newList.Add(iterator.Value())
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}
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}
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return newList
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}
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// Any passes each element of the collection to the given function and
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// returns true if the function ever returns true for any element.
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func (list *List) Any(f func(index int, value interface{}) bool) bool {
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iterator := list.Iterator()
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for iterator.Next() {
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if f(iterator.Index(), iterator.Value()) {
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return true
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}
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}
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return false
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}
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// All passes each element of the collection to the given function and
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// returns true if the function returns true for all elements.
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func (list *List) All(f func(index int, value interface{}) bool) bool {
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iterator := list.Iterator()
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for iterator.Next() {
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if !f(iterator.Index(), iterator.Value()) {
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return false
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}
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}
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return true
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}
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// Find passes each element of the container to the given function and returns
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// the first (index,value) for which the function is true or -1,nil otherwise
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// if no element matches the criteria.
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func (list *List) Find(f func(index int, value interface{}) bool) (int, interface{}) {
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iterator := list.Iterator()
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for iterator.Next() {
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if f(iterator.Index(), iterator.Value()) {
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return iterator.Index(), iterator.Value()
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}
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}
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return -1, nil
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}
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// String returns a string representation of container
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func (list *List) String() string {
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str := "ArrayList\n"
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values := []string{}
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for _, value := range list.elements[:list.size] {
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values = append(values, fmt.Sprintf("%v", value))
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}
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str += strings.Join(values, ", ")
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return str
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}
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// Check that the index is within bounds of the list
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func (list *List) withinRange(index int) bool {
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return index >= 0 && index < list.size
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}
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func (list *List) resize(cap int) {
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newElements := make([]interface{}, cap, cap)
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copy(newElements, list.elements)
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list.elements = newElements
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}
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// Expand the array if necessary, i.e. capacity will be reached if we add n elements
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func (list *List) growBy(n int) {
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// When capacity is reached, grow by a factor of growthFactor and add number of elements
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currentCapacity := cap(list.elements)
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if list.size+n >= currentCapacity {
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newCapacity := int(growthFactor * float32(currentCapacity+n))
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list.resize(newCapacity)
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}
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}
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// Shrink the array if necessary, i.e. when size is shrinkFactor percent of current capacity
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func (list *List) shrink() {
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if shrinkFactor == 0.0 {
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return
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}
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// Shrink when size is at shrinkFactor * capacity
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currentCapacity := cap(list.elements)
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if list.size <= int(float32(currentCapacity)*shrinkFactor) {
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list.resize(list.size)
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}
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}
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