Added simple watch mode (no-op).

cli/src/main/groovy/com/jessebrault/ssg/StaticSiteGeneratorCli.groovy

@@ -20,6 +20,8 @@ import org.apache.logging.log4j.Logger
 import org.apache.logging.log4j.core.LoggerContext
 import picocli.CommandLine
 
+import java.nio.file.FileSystems
+import java.nio.file.StandardWatchEventKinds
 import java.util.concurrent.Callable
 
 @CommandLine.Command(
@@ -32,6 +34,10 @@ class StaticSiteGeneratorCli implements Callable<Integer> {
 
     private static final Logger logger = LogManager.getLogger(StaticSiteGeneratorCli)
 
+    static void main(String[] args) {
+        new CommandLine(StaticSiteGeneratorCli)
+    }
+
     static class LogLevel {
 
         @CommandLine.Option(names = ['--info'], description = 'Log at INFO level.')
@@ -45,13 +51,12 @@ class StaticSiteGeneratorCli implements Callable<Integer> {
 
     }
 
-    static void main(String[] args) {
-        System.exit(new CommandLine(StaticSiteGeneratorCli).execute(args))
-    }
-
     @CommandLine.ArgGroup(exclusive = true, heading = 'Log Level')
     LogLevel logLevel
 
+    @CommandLine.Option(names = ['-w', '--watch'], description = 'Run in watch mode.')
+    boolean watch
+
     @Override
     Integer call() {
         logger.traceEntry()
@@ -110,6 +115,16 @@ class StaticSiteGeneratorCli implements Callable<Integer> {
         // Get ssg object
         def ssg = new SimpleStaticSiteGenerator()
 
+        if (this.watch) {
+            watch(builds, ssg)
+        } else {
+            generate(builds, ssg)
+        }
+    }
+
+    private static Integer generate(Collection<Build> builds, StaticSiteGenerator ssg) {
+        logger.traceEntry('builds: {}, ssg: {}', builds, ssg)
+
         def hadDiagnostics = false
         // Do each build
         builds.each {
@@ -131,4 +146,55 @@ class StaticSiteGeneratorCli implements Callable<Integer> {
         logger.traceExit(hadDiagnostics ? 1 : 0)
     }
 
+    private static Integer watch(Collection<Build> builds, StaticSiteGenerator ssg) {
+        logger.traceEntry('builds: {}, ssg: {}', builds, ssg)
+
+        Collection<WatchableProvider> watchableProviders = []
+
+        builds.each {
+            it.config.textProviders.each {
+                if (it instanceof WatchableProvider) {
+                    watchableProviders << it
+                }
+            }
+            it.config.templatesProviders.each {
+                if (it instanceof WatchableProvider) {
+                    watchableProviders << it
+                }
+            }
+            it.config.partsProviders.each {
+                if (it instanceof WatchableProvider) {
+                    watchableProviders << it
+                }
+            }
+            it.config.specialPagesProviders.each {
+                if (it instanceof WatchableProvider) {
+                    watchableProviders << it
+                }
+            }
+        }
+
+        def watchService = FileSystems.getDefault().newWatchService()
+
+        watchableProviders.each {
+            it.watchableDir.toPath().register(
+                    watchService,
+                    StandardWatchEventKinds.ENTRY_CREATE,
+                    StandardWatchEventKinds.ENTRY_DELETE,
+                    StandardWatchEventKinds.ENTRY_MODIFY
+            )
+        }
+
+        //noinspection GroovyInfiniteLoopStatement
+        while (true) {
+            def watchKey = watchService.take()
+            watchKey.pollEvents().each {
+                logger.debug('watchEvent: {}', it)
+            }
+        }
+
+        //noinspection GroovyUnreachableStatement
+        logger.traceExit(0)
+    }
+
 }

lib/src/main/groovy/com/jessebrault/ssg/WatchableProvider.groovy

@@ -0,0 +1,5 @@
+package com.jessebrault.ssg
+
+trait WatchableProvider {
+    File watchableDir
+}

lib/src/main/groovy/com/jessebrault/ssg/text/TextFileTextsProvider.groovy

@@ -2,23 +2,28 @@ package com.jessebrault.ssg.text
 
 import com.jessebrault.ssg.util.FileNameHandler
 import com.jessebrault.ssg.util.RelativePathHandler
+import com.jessebrault.ssg.WatchableProvider
 import groovy.io.FileType
 import groovy.transform.EqualsAndHashCode
 import groovy.transform.NullCheck
-import groovy.transform.TupleConstructor
 import org.slf4j.Logger
 import org.slf4j.LoggerFactory
 
-@TupleConstructor(includeFields = true, defaults = false)
 @NullCheck
 @EqualsAndHashCode(includeFields = true)
-class TextFileTextsProvider implements TextsProvider {
+class TextFileTextsProvider implements TextsProvider, WatchableProvider {
 
     private static final Logger logger = LoggerFactory.getLogger(TextFileTextsProvider)
 
     private final Collection<TextType> textTypes
     private final File textsDir
 
+    TextFileTextsProvider(Collection<TextType> textTypes, File textsDir) {
+        this.textTypes = textTypes
+        this.textsDir = textsDir
+        this.watchableDir = this.textsDir
+    }
+
     private TextType getTextType(File file) {
         this.textTypes.find {
             it.ids.contains(new FileNameHandler(file).getExtension())