com.blr19c.falowp.bot.system.utils.CollectionUtils.kt Maven / Gradle / Ivy
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FalowpBot system infrastructure
package com.blr19c.falowp.bot.system.utils
import com.blr19c.falowp.bot.system.utils.ObjectUtils.isEmpty
import com.blr19c.falowp.bot.system.utils.ObjectUtils.nullSafeEquals
import com.blr19c.falowp.bot.system.utils.ObjectUtils.toObjectArray
import java.util.*
import kotlin.math.ceil
/**
* util来源于spring
*/
@Suppress("UNCHECKED_CAST", "MemberVisibilityCanBePrivate", "UNUSED")
object CollectionUtils {
/**
* Default load factor for [HashMap]/[LinkedHashMap] variants.
*
* @see .newHashMap
* @see .newLinkedHashMap
*/
const val DEFAULT_LOAD_FACTOR = 0.75f
/**
* Return `true` if the supplied Collection is `null` or empty.
* Otherwise, return `false`.
*
* @param collection the Collection to check
* @return whether the given Collection is empty
*/
fun isEmpty(collection: Collection<*>?): Boolean {
return collection == null || collection.isEmpty()
}
/**
* Return `true` if the supplied Map is `null` or empty.
* Otherwise, return `false`.
*
* @param map the Map to check
* @return whether the given Map is empty
*/
fun isEmpty(map: Map<*, *>?): Boolean {
return map == null || map.isEmpty()
}
/**
* Instantiate a new [HashMap] with an initial capacity
* that can accommodate the specified number of elements without
* any immediate resize/rehash operations to be expected.
*
* This differs from the regular [HashMap] constructor
* which takes an initial capacity relative to a load factor
* but is effectively aligned with the JDK's
* [java.util.concurrent.ConcurrentHashMap].
*
* @param expectedSize the expected number of elements (with a corresponding
* capacity to be derived so that no resize/rehash operations are needed)
* @see .newLinkedHashMap
* @since 5.3
*/
fun newHashMap(expectedSize: Int): HashMap {
return HashMap(computeMapInitialCapacity(expectedSize), DEFAULT_LOAD_FACTOR)
}
fun newLinkedHashMap(expectedSize: Int): LinkedHashMap {
return LinkedHashMap(computeMapInitialCapacity(expectedSize), DEFAULT_LOAD_FACTOR)
}
private fun computeMapInitialCapacity(expectedSize: Int): Int {
return ceil(expectedSize / DEFAULT_LOAD_FACTOR.toDouble()).toInt()
}
/**
* Convert the supplied array into a List. A primitive array gets converted
* into a List of the appropriate wrapper type.
*
* **NOTE:** Generally prefer the standard [Arrays.asList] method.
* This `arrayToList` method is just meant to deal with an incoming Object
* value that might be an `Object[]` or a primitive array at runtime.
*
* A `null` source value will be converted to an empty List.
*
* @param source the (potentially primitive) array
* @return the converted List result
* @see ObjectUtils.toObjectArray
* @see Arrays.asList
*/
fun arrayToList(source: Any?): List<*> {
return listOf(*toObjectArray(source))
}
/**
* Merge the given array into the given Collection.
*
* @param array the array to merge (maybe `null`)
* @param collection the target Collection to merge the array into
*/
fun mergeArrayIntoCollection(array: Any?, collection: MutableCollection) {
val arr = toObjectArray(array)
Collections.addAll(collection, *arr as Array)
}
/**
* Merge the given Properties instance into the given Map,
* copying all properties (key-value pairs) over.
*
* Uses `Properties.propertyNames()` to even catch
* default properties linked into the original Properties instance.
*
* @param props the Properties instance to merge (maybe `null`)
* @param map the target Map to merge the properties into
*/
fun mergePropertiesIntoMap(props: Properties?, map: MutableMap) {
if (props != null) {
val en = props.propertyNames()
while (en.hasMoreElements()) {
val key = en.nextElement() as String
var value = props[key]
if (value == null) {
// Allow for defaults fallback or potentially overridden accessor...
value = props.getProperty(key)
}
map[key as K] = value as V?
}
}
}
/**
* Check whether the given Iterator contains the given element.
*
* @param iterator the Iterator to check
* @param element the element to look for
* @return `true` if found, `false` otherwise
*/
fun contains(iterator: Iterator<*>?, element: Any?): Boolean {
if (iterator != null) {
while (iterator.hasNext()) {
val candidate = iterator.next()!!
if (nullSafeEquals(candidate, element)) {
return true
}
}
}
return false
}
/**
* Check whether the given Enumeration contains the given element.
*
* @param enumeration the Enumeration to check
* @param element the element to look for
* @return `true` if found, `false` otherwise
*/
fun contains(enumeration: Enumeration<*>?, element: Any?): Boolean {
if (enumeration != null) {
while (enumeration.hasMoreElements()) {
val candidate = enumeration.nextElement()
if (nullSafeEquals(candidate, element)) {
return true
}
}
}
return false
}
/**
* Check whether the given Collection contains the given element instance.
*
* Enforces the given instance to be present, rather than returning
* `true` for an equal element as well.
*
* @param collection the Collection to check
* @param element the element to look for
* @return `true` if found, `false` otherwise
*/
fun containsInstance(collection: Collection<*>?, element: Any): Boolean {
if (collection != null) {
for (candidate in collection) {
if (candidate === element) {
return true
}
}
}
return false
}
/**
* Return `true` if any element in '`candidates`' is
* contained in '`source`'; otherwise returns `false`.
*
* @param source the source Collection
* @param candidates the candidates to search for
* @return whether any of the candidates has been found
*/
fun containsAny(source: Collection<*>, candidates: Collection<*>): Boolean {
return findFirstMatch(source, candidates) != null
}
/**
* Return the first element in '`candidates`' that is contained in
* '`source`'. If no element in '`candidates`' is present in
* '`source`' returns `null`. Iteration order is
* [Collection] implementation specific.
*
* @param source the source Collection
* @param candidates the candidates to search for
* @return the first present object, or `null` if not found
*/
fun findFirstMatch(source: Collection<*>, candidates: Collection): E? {
if (isEmpty(source) || isEmpty(candidates)) {
return null
}
for (candidate in candidates) {
if (source.contains(candidate)) {
return candidate
}
}
return null
}
/**
* Find a single value of the given type in the given Collection.
*
* @param collection the Collection to search
* @param type the type to look for
* @return a value of the given type found if there is a clear match,
* or `null` if none or more than one such value found
*/
fun findValueOfType(collection: Collection<*>, type: Class?): T? {
if (isEmpty(collection)) {
return null
}
var value: T? = null
for (element in collection) {
if (type == null || type.isInstance(element)) {
if (value != null) {
// More than one value found... no clear single value.
return null
}
value = element as T
}
}
return value
}
/**
* Find a single value of one of the given types in the given Collection:
* searching the Collection for a value of the first type, then
* searching for a value of the second type, etc.
*
* @param collection the collection to search
* @param types the types to look for, in prioritized order
* @return a value of one of the given types found if there is a clear match,
* or `null` if none or more than one such value found
*/
fun findValueOfType(collection: Collection<*>?, types: Array>): Any? {
if (isEmpty(collection) || isEmpty(types)) {
return null
}
for (type in types) {
val value = findValueOfType(collection!!, type)
if (value != null) {
return value
}
}
return null
}
/**
* Determine whether the given Collection only contains a single unique object.
*
* @param collection the Collection to check
* @return `true` if the collection contains a single reference or
* multiple references to the same instance, `false` otherwise
*/
fun hasUniqueObject(collection: Collection<*>): Boolean {
if (isEmpty(collection)) {
return false
}
var hasCandidate = false
var candidate: Any? = null
for (elem in collection) {
if (!hasCandidate) {
hasCandidate = true
candidate = elem
} else if (candidate !== elem) {
return false
}
}
return true
}
/**
* Find the common element type of the given Collection, if any.
*
* @param collection the Collection to check
* @return the common element type, or `null` if no clear
* common type has been found (or the collection was empty)
*/
fun findCommonElementType(collection: Collection<*>): Class<*>? {
if (isEmpty(collection)) {
return null
}
var candidate: Class<*>? = null
for (`val` in collection) {
if (`val` != null) {
if (candidate == null) {
candidate = `val`.javaClass
} else if (candidate != `val`.javaClass) {
return null
}
}
}
return candidate
}
/**
* Retrieve the first element of the given Set, using [SortedSet.first]
* or otherwise using the iterator.
*
* @param set the Set to check (maybe `null` or empty)
* @return the first element, or `null` if none
* @see SortedSet
*
* @see LinkedHashMap.keySet
* @see java.util.LinkedHashSet
*
* @since 5.2.3
*/
fun firstElement(set: Set): T? {
if (isEmpty(set)) {
return null
}
if (set is SortedSet) {
return set.first()
}
val it = set.iterator()
var first: T? = null
if (it.hasNext()) {
first = it.next()
}
return first
}
/**
* Retrieve the first element of the given List, accessing the zero index.
*
* @param list the List to check (maybe `null` or empty)
* @return the first element, or `null` if none
* @since 5.2.3
*/
fun firstElement(list: List): T? {
return if (isEmpty(list)) {
null
} else list[0]
}
/**
* Retrieve the last element of the given Set, using [SortedSet.last]
* or otherwise iterating over all elements (assuming a linked set).
*
* @param set the Set to check (maybe `null` or empty)
* @return the last element, or `null` if none
* @see SortedSet
*
* @see LinkedHashMap.keySet
* @see java.util.LinkedHashSet
*
* @since 5.0.3
*/
fun lastElement(set: Set): T? {
if (isEmpty(set)) {
return null
}
if (set is SortedSet) {
return set.last()
}
// Full iteration necessary...
val it = set.iterator()
var last: T? = null
while (it.hasNext()) {
last = it.next()
}
return last
}
/**
* Retrieve the last element of the given List, accessing the highest index.
*
* @param list the List to check (maybe `null` or empty)
* @return the last element, or `null` if none
* @since 5.0.3
*/
fun lastElement(list: List): T? {
return if (isEmpty(list)) {
null
} else list[list.size - 1]
}
/**
* Marshal the elements from the given enumeration into an array of the given type.
* Enumeration elements must be assignable to the type of the given array. The array
* returned will be a different instance than the array given.
*/
fun toArray(enumeration: Enumeration, array: Array): Array {
val elements = ArrayList()
while (enumeration.hasMoreElements()) {
elements.add(enumeration.nextElement())
}
return elements.toArray(array)
}
/**
* Adapt an [Enumeration] to an [Iterator].
*
* @param enumeration the original `Enumeration`
* @return the adapted `Iterator`
*/
fun toIterator(enumeration: Enumeration?): Iterator {
return if (enumeration != null) enumeration.asIterator() else Collections.emptyIterator()
}
}