Implement serve --[no-]watch

README.md

@@ -147,8 +147,8 @@ Muzukashii:
   - [x] `clean`
   - [x] `help`
   - [x] `serve`
-    - [x] `--open-uri`, `--host`, `--port`
-    - [ ] `--baseurl`, `--config`, `--incremental`, `--[no-]watch` (`–watch` is always enabled)
+    - [x] `--open-uri`, `--host`, `--port`, `–watch` (enabled by default)
+    - [ ] `--baseurl`, `--config`, `--incremental`
     - [ ] `--detach`, `--ssl`-* – not planned
   - [ ] `doctor`, `import`, `new`, `new-theme` – not planned
 - [ ] Windows

cmd/options.go

@@ -9,7 +9,8 @@ import (
 // Command-line options
 var (
 	buildOptions site.BuildOptions
-	configFlags  = config.Flags{}
+	watch        = true
+	configFlags  = config.Flags{Watch: &watch}
 	profile      = false
 	quiet        = false
 )
@@ -36,7 +37,7 @@ var (
 
 	serve = app.Command("serve", "Serve your site locally").Alias("server").Alias("s")
 	open  = serve.Flag("open-url", "Launch your site in a browser").Short('o').Bool()
-	_     = app.Flag("host", "Host to bind to").Short('H').Action(stringVar("host", &configFlags.Host)).String()
+	_     = serve.Flag("host", "Host to bind to").Short('H').Action(stringVar("host", &configFlags.Host)).String()
 	_     = serve.Flag("port", "Port to listen on").Short('P').Action(intVar("port", &configFlags.Port)).Int()
 
 	variables    = app.Command("variables", "Display a file or URL path's variables").Alias("v").Alias("var").Alias("vars")
@@ -50,4 +51,5 @@ func init() {
 	app.Flag("profile", "Create a Go pprof CPU profile").BoolVar(&profile)
 	app.Flag("quiet", "Silence (some) output.").Short('q').BoolVar(&quiet)
 	build.Flag("dry-run", "Dry run").Short('n').BoolVar(&buildOptions.DryRun)
+	serve.Flag("watch", "Watch for changes and rebuild").Short('w').Default("true").BoolVar(&watch)
 }

config/config.go

@@ -45,6 +45,9 @@ type Config struct {
 	// Outputting
 	Permalink string
 
+	// CLI-only
+	Watch bool `yaml:"-"`
+
 	Defaults []struct {
 		Scope struct {
 			Path string

config/flags.go

@@ -3,9 +3,9 @@ package config
 // Flags are applied after the configuration file is loaded.
 // They are pointers to represent optional types, to tell whether they have been set.
 type Flags struct {
-	Destination, Host           *string
-	Drafts, Future, Unpublished *bool
-	Port                        *int
+	Destination, Host                  *string
+	Drafts, Future, Unpublished, Watch *bool
+	Port                               *int
 }
 
 // ApplyFlags overwrites the configuration with values from flags.
@@ -28,4 +28,7 @@ func (c *Config) ApplyFlags(flags Flags) {
 	if flags.Unpublished != nil {
 		c.Unpublished = *flags.Unpublished
 	}
+	if flags.Watch != nil {
+		c.Watch = *flags.Watch
+	}
 }

server/server.go

@@ -27,11 +27,13 @@ func (s *Server) Run(open bool, logger func(label, value string)) error {
 	s.Site.SetAbsoluteURL("")
 	address := fmt.Sprintf("%s:%d", cfg.Host, cfg.Port)
 	logger("Server address:", "http://"+address+"/")
-	if err := s.StartLiveReloader(); err != nil {
-		return err
-	}
-	if err := s.watchAndReload(); err != nil {
-		return err
+	if cfg.Watch {
+		if err := s.StartLiveReloader(); err != nil {
+			return err
+		}
+		if err := s.watchAndReload(); err != nil {
+			return err
+		}
 	}
 	http.HandleFunc("/", s.handler)
 	c := make(chan error)

server/watcher.go

@@ -51,24 +51,35 @@ func (s *Server) watchFiles(fn func([]string)) error {
 	}()
 	go func() {
 		for {
-			filenames := <-debounced
-			relpaths := make([]string, 0, len(filenames))
-			seen := map[string]bool{}
-			for _, filename := range filenames {
-				relpath := utils.MustRel(sourceDir, filename)
-				if relpath == "_config.yml" || !site.Exclude(relpath) {
-					if !seen[relpath] {
-						seen[relpath] = true
-						relpaths = append(relpaths, relpath)
-					}
-				}
+			paths := s.sitePaths(<-debounced)
+			if len(paths) > 0 {
+				fn(paths)
 			}
-			fn(relpaths)
 		}
 	}()
 	return watcher.Add(sourceDir)
 }
 
+// relativize and de-dup paths and filter to those the site source
+func (s *Server) sitePaths(filenames []string) []string {
+	var (
+		site  = s.Site
+		dir   = site.SourceDir()
+		paths = make([]string, 0, len(filenames))
+		seen  = map[string]bool{}
+	)
+	for _, filename := range filenames {
+		path := utils.MustRel(dir, filename)
+		if path == "_config.yml" || !site.Exclude(path) {
+			if !seen[path] {
+				seen[path] = true
+				paths = append(paths, path)
+			}
+		}
+	}
+	return paths
+}
+
 // debounce relays values from input to output, merging successive values within interval
 // TODO consider https://github.com/ReactiveX/RxGo
 func debounce(interval time.Duration, input <-chan string) <-chan []string {