Add cancel / triggerChange extension methods to watcher functions

orx-file-watcher/src/main/kotlin/FileWatcher.kt

@@ -11,22 +11,26 @@ import java.nio.file.WatchKey
 import kotlin.concurrent.thread
 
 class FileWatcher(private val program: Program, val file: File, private val onChange: (File) -> Unit) {
+    val path = file.absoluteFile.toPath()
+    val parent = path.parent
+    val key = pathKeys.getOrPut(parent) {
+        parent.register(
+                watchService, arrayOf(StandardWatchEventKinds.ENTRY_MODIFY),
+                SensitivityWatchEventModifier.HIGH
+        )
+    }
     init {
         watchThread
-        val path = file.absoluteFile.toPath()
-        val parent = path.parent
-        val key = pathKeys.getOrPut(parent) {
-            parent.register(
-                    watchService, arrayOf(StandardWatchEventKinds.ENTRY_MODIFY),
-                    SensitivityWatchEventModifier.HIGH
-            )
-        }
         watching.getOrPut(path) {
             mutableListOf()
         }.add(this)
         keyPaths.getOrPut(key) { parent }
     }
 
+    fun stop() {
+        watching[path]?.remove(this)
+    }
+
     internal fun triggerChange() {
         program.launch {
             onChange(file)
@@ -34,20 +38,45 @@ class FileWatcher(private val program: Program, val file: File, private val onCh
     }
 }
 
+private val watchers = mutableMapOf< ()->Any, FileWatcher>()
+
 fun <T> watchFile(program: Program, file: File, transducer: (File) -> T): () -> T {
     var result = transducer(file)
-    FileWatcher(program, file) {
+    val watcher = FileWatcher(program, file) {
         try {
             result = transducer(file)
         } catch (e: Throwable) {
             e.printStackTrace()
         }
     }
-    return {
+
+    val function = {
         result
     }
+
+    @Suppress("UNCHECKED_CAST")
+    watchers[function as ()->Any] = watcher
+    return function
 }
 
+/**
+ * Stops the watcher
+ */
+fun <T> (()->T).stop() {
+    @Suppress("UNCHECKED_CAST")
+    watchers[this as ()->Any]?.stop()
+
+}
+
+/**
+ * Triggers reload
+ */
+fun <T> (()->T).triggerChange() {
+    @Suppress("UNCHECKED_CAST")
+    watchers[this as ()->Any]?.triggerChange()
+}
+
+
 @JvmName("programWatchFile")
 fun <T> Program.watchFile(file: File, transducer: (File) -> T): () -> T = watchFile(this, file, transducer)
 
@@ -67,9 +96,8 @@ private val watchThread by lazy {
             key.pollEvents().forEach {
                 val contextPath = it.context() as Path
                 val fullPath = path?.resolve(contextPath)
-                watching[fullPath]?.forEach {
-
-                    it.triggerChange()
+                watching[fullPath]?.forEach { w ->
+                    w.triggerChange()
                 }
             }
             key.reset()
@@ -82,12 +110,12 @@ fun main() {
         it.readText()
     }
 
-
+    a.stop()
+    a.triggerChange()
 
     while (true) {
         println(a())
         Thread.sleep(2000)
-
     }
 }