incremental pt. 1

README.md

@@ -144,14 +144,16 @@ Muzukashii:
   - [x] Directory watch
 - [ ] Commands
   - [x] `build`
-    - [x] `--source`, `--destination`, `--drafts`, `--future`, `--unpublished`, `--watch`, `--force_polling`
-    - [ ] `--baseurl`, `--config`, `--incremental`, `--lsi`
+    - [x] `--source`, `--destination`, `--drafts`, `--future`, `--unpublished`
+    - [x] `--incremental`, `--watch`, `--force_polling`
+    - [ ] `--baseurl`, `--config`, `--lsi`
     - [ ] `--limit-posts`, `JEKYLL_ENV=production` – not planned
   - [x] `clean`
   - [x] `help`
   - [x] `serve`
-    - [x] `--open-uri`, `--host`, `--port`, `–watch`, `--force_polling`
-    - [ ] `--baseurl`, `--config`, `--incremental`
+    - [x] `--open-uri`, `--host`, `--port`
+    - [x] `--incremental`, `–watch`, `--force_polling`
+    - [ ] `--baseurl`, `--config`
     - [ ] `--detach`, `--ssl`-* – not planned
   - [ ] `doctor`, `import`, `new`, `new-theme` – not planned
 - [ ] Windows

commands/commands.go

@@ -45,7 +45,7 @@ func buildCommand(site *site.Site) error {
 		if err != nil {
 			return err
 		}
-		logger.label("Auto-regeneration:", "enabled for %q\n", site.SourceDir())
+		logger.label("Auto-regeneration:", "enabled for %q", site.SourceDir())
 		for event := range events {
 			fmt.Print(event)
 		}

commands/flags.go

@@ -48,9 +48,12 @@ func init() {
 	app.Flag("profile", "Create a Go pprof CPU profile").BoolVar(&profile)
 	app.Flag("quiet", "Silence (some) output.").Short('q').BoolVar(&quiet)
 	_ = app.Flag("verbose", "Print verbose output.").Short('V').Action(boolVar("verbose", &options.Verbose)).Bool()
-	app.Flag("force_polling", "Force watch to use polling").BoolVar(&options.ForcePolling)
 	build.Flag("dry-run", "Dry run").Short('n').BoolVar(&options.DryRun)
 
+	// these flags are just present on build and serve, but I don't see a DRY way to say this
+	app.Flag("incremental", "Enable incremental rebuild.").Short('I').Action(boolVar("incremental", &options.Incremental)).Bool()
+	app.Flag("force_polling", "Force watch to use polling").BoolVar(&options.ForcePolling)
+
 	// --watch has different defaults for build and serve
 	watchText := "Watch for changes and rebuild"
 	build.Flag("watch", watchText).Short('w').BoolVar(&options.Watch)

config/config.go

@@ -107,6 +107,11 @@ type collectionsMap struct {
 	Collections map[string]map[string]interface{}
 }
 
+// IsConfigPath returns true if its arguments is a site configuration file.
+func (c *Config) IsConfigPath(rel string) bool {
+	return rel == "_config.yml"
+}
+
 // SourceDir returns the source directory as an absolute path.
 func (c *Config) SourceDir() string {
 	return utils.MustAbs(c.Source)

config/flags.go

@@ -7,17 +7,20 @@ import (
 // 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 {
-	// these are pointers so we can tell whether they've been set, and override
-	// the config file only if
-	Destination, Host                    *string
-	Drafts, Future, Unpublished, Verbose *bool
-	Port                                 *int
-	// these aren't in the config file, so they can be treated more conventionally
+	// these are pointers so we can tell whether they've been set, and leave
+	// the config file alone if not
+	Destination, Host           *string
+	Drafts, Future, Unpublished *bool
+	Incremental, Verbose        *bool
+	Port                        *int
+
+	// these aren't in the config file, so make them actual values
 	DryRun, ForcePolling, Watch bool
 }
 
 // ApplyFlags overwrites the configuration with values from flags.
 func (c *Config) ApplyFlags(f Flags) {
+	// anything you can do I can do meta
 	rs, rd := reflect.ValueOf(f), reflect.ValueOf(c).Elem()
 	rt := rs.Type()
 	for i, n := 0, rs.NumField(); i < n; i++ {

site/rebuild.go

@@ -56,10 +56,27 @@ func (s *Site) processFilesEvent(fileset FilesEvent, messages chan<- interface{}
 	return r
 }
 
+// reloads and rebuilds the site; returns a copy and count
+func (s *Site) rebuild(paths []string) (*Site, int, error) {
+	if s.requiresFullReload(paths) {
+		r, err := s.Reloaded(paths)
+		if err != nil {
+			return nil, 0, err
+		}
+		n, err := r.Build()
+		return r, n, err
+	}
+	return s, 0, nil
+}
+
 func (s *Site) requiresFullReload(paths []string) bool {
 	for _, path := range paths {
 		switch {
-		case path == "_config.yml":
+		case s.config.IsConfigPath(path):
+			return true
+		case s.Exclude(path):
+			return false
+		case !s.config.Incremental:
 			return true
 		case strings.HasPrefix(path, s.config.DataDir):
 			return true
@@ -70,29 +87,23 @@ func (s *Site) requiresFullReload(paths []string) bool {
 	return false
 }
 
-// reloads and rebuilds the site; returns a copy and count
-func (s *Site) rebuild(paths []string) (r *Site, n int, err error) {
-	r, err = s.Reloaded(paths)
-	if err != nil {
-		return
-	}
-	n, err = r.Build()
-	return
-}
-
 // relativize and de-dup filenames, and filter to those that affect the build
-func (s *Site) sitePaths(filenames []string) []string {
+func (s *Site) affectsBuildFilter(filenames []string) []string {
 	var (
-		paths = make([]string, 0, len(filenames))
-		seen  = map[string]bool{}
+		result = make([]string, 0, len(filenames))
+		seen   = map[string]bool{}
 	)
+loop:
 	for _, path := range filenames {
-		if path == "_config.yml" || !s.Exclude(path) {
-			if !seen[path] {
-				seen[path] = true
-				paths = append(paths, path)
-			}
+		switch {
+		case s.config.IsConfigPath(path):
+		case s.Exclude(path):
+			continue loop
+		case seen[path]:
+			continue loop
 		}
+		seen[path] = true
+		result = append(result, path)
 	}
-	return paths
+	return result
 }

site/watch.go

@@ -37,7 +37,7 @@ func (s *Site) WatchFiles() (<-chan FilesEvent, error) {
 	)
 	go func() {
 		for {
-			paths := s.sitePaths(<-debounced)
+			paths := s.affectsBuildFilter(<-debounced)
 			if len(paths) > 0 {
 				// Create a new timestamp. Except under pathological
 				// circumstances, it will be close enough.