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package org.jetbrains.dokka.Utilities
import java.io.File
import java.util.*
import java.util.jar.JarFile
import java.util.zip.ZipEntry
data class ServiceDescriptor(val name: String, val category: String, val description: String?, val className: String)
class ServiceLookupException(message: String) : Exception(message)
public object ServiceLocator {
public fun <T : Any> lookup(clazz: Class<T>, category: String, implementationName: String): T {
val descriptor = lookupDescriptor(category, implementationName)
val loadedClass = javaClass.classLoader.loadClass(descriptor.className)
val constructor = loadedClass.constructors
.filter { it.parameterTypes.isEmpty() }
.firstOrNull() ?: throw ServiceLookupException("Class ${descriptor.className} has no corresponding constructor")
val implementationRawType: Any = if (constructor.parameterTypes.isEmpty()) constructor.newInstance() else constructor.newInstance(constructor)
if (!clazz.isInstance(implementationRawType)) {
throw ServiceLookupException("Class ${descriptor.className} is not a subtype of ${clazz.name}")
}
@Suppress("UNCHECKED_CAST")
return implementationRawType as T
}
private fun lookupDescriptor(category: String, implementationName: String): ServiceDescriptor {
val properties = javaClass.classLoader.getResourceAsStream("dokka/$category/$implementationName.properties")?.use { stream ->
Properties().let { properties ->
properties.load(stream)
properties
}
} ?: throw ServiceLookupException("No implementation with name $implementationName found in category $category")
val className = properties["class"]?.toString() ?: throw ServiceLookupException("Implementation $implementationName has no class configured")
return ServiceDescriptor(implementationName, category, properties["description"]?.toString(), className)
}
fun allServices(category: String): List<ServiceDescriptor> {
val entries = this.javaClass.classLoader.getResources("dokka/$category")?.toList() ?: emptyList()
return entries.flatMap {
when (it.protocol) {
"file" -> File(it.file).listFiles()?.filter { it.extension == "properties" }?.map { lookupDescriptor(category, it.nameWithoutExtension) } ?: emptyList()
"jar" -> {
val file = JarFile(it.file.removePrefix("file:").substringBefore("!"))
try {
val jarPath = it.file.substringAfterLast("!").removePrefix("/")
file.entries()
.asSequence()
.filter { entry -> !entry.isDirectory && entry.path == jarPath && entry.extension == "properties" }
.map { entry ->
lookupDescriptor(category, entry.fileName.substringBeforeLast("."))
}.toList()
} finally {
file.close()
}
}
else -> emptyList<ServiceDescriptor>()
}
}
}
}
public inline fun <reified T : Any> ServiceLocator.lookup(category: String, implementationName: String): T = lookup(T::class.java, category, implementationName)
private val ZipEntry.fileName: String
get() = name.substringAfterLast("/", name)
private val ZipEntry.path: String
get() = name.substringBeforeLast("/", "").removePrefix("/")
private val ZipEntry.extension: String?
get() = fileName.let { fn -> if ("." in fn) fn.substringAfterLast(".") else null }
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