commonMain.com.ditchoom.mqtt.topic.TopicLevelNode.kt Maven / Gradle / Ivy
package com.ditchoom.mqtt.topic
import com.ditchoom.mqtt.controlpacket.MqttUtf8String
/**
* Represent the topics in a tree like structure. Saves memory for multiple topics with a similar structure compared
* to using a string and speeds up lookups to see if a topic matches a structure
*/
data class TopicLevelNode(val value: TopicLevel) {
val children: MutableMap = mutableMapOf()
var parent: TopicLevelNode? = null
/**
* Is this topic level a wildcard
*/
val isWildcard = value is MultiLevelWildcard || value is SingleLevelWildcard
/**
* Check if this topic or any children has a wildcard
*/
fun hasWildcardInTopic(): Boolean {
if (children.isEmpty()) {
return isWildcard
}
children.forEach {
if (it.value.hasWildcardInTopic()) {
return true
}
}
return isWildcard
}
fun detachFromParent() {
val parent = parent
parent?.children?.remove(value.value)
this.parent = null
}
fun findSimilarChildNode(otherChildNode: TopicLevelNode): TopicLevelNode? {
var currentChildOtherNode: TopicLevelNode? = otherChildNode.parent
val keyPath = ArrayList()
keyPath.add(otherChildNode.value)
while (currentChildOtherNode != null) {
keyPath.add(currentChildOtherNode.value)
currentChildOtherNode = currentChildOtherNode.parent
}
keyPath.reverse()
var index = 1
val keyPathCurrent = keyPath.getOrNull(index++)?.value
var currentChildThisNode = children[keyPathCurrent]
while (index < keyPath.size) {
val nextKey = keyPath.getOrNull(index++)?.value!!
if (currentChildThisNode == null) {
return null
} else {
currentChildThisNode = currentChildThisNode.children[nextKey]
}
}
return currentChildThisNode
}
fun getAllBottomLevelChildren(): Set {
if (children.isEmpty()) {
return setOf(this)
}
val childrensChildren = mutableSetOf()
children.values.forEach {
childrensChildren += it.getAllBottomLevelChildren()
}
return childrensChildren
}
fun getCurrentPath(): CharSequence {
val parent = parent
val parentPath = parent?.getCurrentPath()
return if (parentPath == null) {
value.value
} else {
"$parentPath/${value.value}"
}
}
override fun toString() = getCurrentPath().toString()
/**
* Check and see if the other topic matches this topic structure.
*/
fun matchesTopic(other: TopicLevelNode): Boolean {
val isCurrentTopicMultiLevelWildcard = value is MultiLevelWildcard
val isOtherTopicMultiLevelWildcard = other.value is MultiLevelWildcard
if (isCurrentTopicMultiLevelWildcard || isOtherTopicMultiLevelWildcard) {
return true
}
val isCurrentTopicSingleLevelWildcard = value is SingleLevelWildcard
val isOtherTopicSingleLevelWildcard = other.value is SingleLevelWildcard
if (isCurrentTopicSingleLevelWildcard || isOtherTopicSingleLevelWildcard) {
if (children.isEmpty() && other.children.isEmpty()) {
return true
}
}
if ((isCurrentTopicSingleLevelWildcard && children.isNotEmpty()) ||
(isOtherTopicSingleLevelWildcard && other.children.isNotEmpty())
) {
val missingKeys = other.children.keys - children.keys
if (missingKeys.contains("+") || missingKeys.contains("#")) {
} else if (missingKeys.isNotEmpty()) {
return false
} else {
other.children.forEach { otherChildPair ->
val otherKey = otherChildPair.key
val otherValue = otherChildPair.value
val matchingChild = children[otherKey] ?: return false
if (!matchingChild.matchesTopic(otherValue)) {
return false
}
}
}
}
val isEitherAWildcard = isWildcard || other.isWildcard
if (!isEitherAWildcard) {
if (value != other.value) {
return false
}
}
if (children.size != other.children.size && children["#"] == null && !isEitherAWildcard) {
return false
}
other.children.forEach { otherChildPair ->
val otherKey = otherChildPair.key
if (otherKey != "+") {
val otherValue = otherChildPair.value
var matchingChild = children[otherKey]
if (matchingChild == null) {
matchingChild = children["+"]
}
if (matchingChild == null) {
matchingChild = children["#"]
}
val child = matchingChild
?: return false
if (!child.matchesTopic(otherValue)) {
return false
}
}
}
if (other.children.isEmpty() && children.isNotEmpty() && (other.value == SingleLevelWildcard || value == SingleLevelWildcard)) {
return false
}
return true
}
companion object {
private const val TOPIC_LEVEL_SEPERATOR = '/'
/**
* Convert an MQTT UTF8 Compliant string into a topic level node structure
*/
fun from(topic: MqttUtf8String): TopicLevelNode {
val topicValidated = topic.getValueOrThrow()
if (topicValidated.isEmpty()) {
return TopicLevelNode(EmptyValue)
}
return parse(topicValidated.toString()) ?: TopicLevelNode(EmptyValue)
}
/**
* Convert the string format of a suspected topic into a topic level tree structure returning the root node
*/
fun parse(topic: String, parent: TopicLevelNode? = null): TopicLevelNode? {
if (parent == null && topic.startsWith('/')) {
val topTopicLevel = EmptyValue
val child = parse(topic.substring(1), parent)
val node = TopicLevelNode(topTopicLevel)
if (child != null) {
child.parent = node
node.children[child.value.value] = child
}
return node
}
if (topic.endsWith("/")) {
val parsedWithoutSuffix = parse(topic.substringBeforeLast("/"), parent)
val bottomLevelNode = parsedWithoutSuffix?.getAllBottomLevelChildren()?.first() ?: return null
val emptyNode = TopicLevelNode(EmptyValue)
emptyNode.parent = bottomLevelNode
bottomLevelNode.children[""] = emptyNode
return parsedWithoutSuffix
}
val topics = topic.split(TOPIC_LEVEL_SEPERATOR, limit = 2)
if (topics.isEmpty()) {
return null
}
val currentTopicLevel = topics[0]
if (currentTopicLevel.isEmpty()) {
throw IllegalArgumentException("Invalid size of topic level")
}
if (currentTopicLevel.length > 1) {
val multiLevelWildcardIndex = currentTopicLevel.indexOf('#')
if (multiLevelWildcardIndex > 0) {
throw IllegalArgumentException(
"Error building topic ($currentTopicLevel): The multi-level " +
"wildcard character MUST be specified either on its own or following a topic level " +
"separator. In either case it MUST be the last character specified in the Topic Filter" +
" [MQTT-4.7.1-1]"
)
}
val singleLevelWildcardIndex = currentTopicLevel.indexOf('+')
if (singleLevelWildcardIndex > 0) {
throw IllegalArgumentException(
"Error building topic ($currentTopicLevel): The single-level " +
"wildcard MUST occupy an entire level of the filter [MQTT-4.7.1-2]."
)
}
}
when {
topics.size == 1 -> {
if (currentTopicLevel == "#") {
return TopicLevelNode(MultiLevelWildcard)
}
if (currentTopicLevel == "+") {
return TopicLevelNode(SingleLevelWildcard)
}
if (currentTopicLevel.isBlank()) {
return null
}
val node = TopicLevelNode(StringTopicLevel(currentTopicLevel))
node.parent = parent
return node
}
topics.size == 2 -> {
if (currentTopicLevel == "#") {
throw IllegalArgumentException("Invalid multilevel wildcard found at position ${currentTopicLevel.length} in topic: $topic. Was not expecting any more characters after that.")
}
val restOfTopic = topics[1]
val level = when (currentTopicLevel) {
"#" -> MultiLevelWildcard
"+" -> SingleLevelWildcard
else -> StringTopicLevel(currentTopicLevel)
}
if (restOfTopic.isEmpty()) {
return TopicLevelNode(level)
}
val childTopicLevel = parse(topics[1])
val result = if (childTopicLevel != null) {
Pair(childTopicLevel.value.value, childTopicLevel)
} else {
null
}
val currentNode = TopicLevelNode(level)
if (result != null) {
currentNode.children[result.first] = result.second
}
childTopicLevel?.parent = currentNode
currentNode.parent = parent
return currentNode
}
else -> throw RuntimeException(
"Topic split operation failing. Expected a max of two string splits, got more"
)
}
}
}
}
/**
* Add the topics in to the tree structure of the originial 'self' topic level node
*/
fun addTopicLevelNode(self: TopicLevelNode, other: TopicLevelNode) {
if (self.value == other.value) {
val missingChildren = other.children.keys - self.children.keys
missingChildren.forEach {
val missingChild = other.children[it]!!
self.children[missingChild.value.value] = missingChild
missingChild.parent = self
}
val duplicateChildrenKeys = self.children.keys.intersect(other.children.keys)
duplicateChildrenKeys.forEach {
addTopicLevelNode(self.children[it]!!, other.children[it]!!)
}
}
}
/**
* Merge the two topics together into one structure
*/
operator fun TopicLevelNode.plusAssign(other: TopicLevelNode) {
addTopicLevelNode(this, other)
}
operator fun TopicLevelNode.minusAssign(other: TopicLevelNode) {
removeTopicLevelNode(this, other)
}
fun removeTopicLevelNode(self: TopicLevelNode, other: TopicLevelNode) {
val otherChildren = other.getAllBottomLevelChildren()
otherChildren.forEach {
val node = self.findSimilarChildNode(it)
if (node != null) {
node.detachFromParent()
}
}
}
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