Implement jekyll-default-layout plugin

pages/page.go

@@ -24,11 +24,12 @@ type Page interface {
 	// This has the side effect of causing the content to subsequently appear in the drop.
 	Render() error
 	SetContent(string)
-	FrontMatter() map[string]interface{}
+	FrontMatter() frontmatter.FrontMatter
 	// PostDate returns the date computed from the filename or frontmatter.
 	// It is an uncaught error to call this on a page that is not a Post.
 	// TODO Should posts have their own interface?
 	PostDate() time.Time
+	IsPost() bool
 
 	Categories() []string
 	Tags() []string
@@ -124,7 +125,7 @@ func readFrontMatter(f *file) (b []byte, lineNo int, err error) {
 	return
 }
 
-func (p *page) FrontMatter() map[string]interface{} {
+func (p *page) FrontMatter() frontmatter.FrontMatter {
 	return p.fm
 }
 
@@ -133,6 +134,11 @@ func (p *page) Categories() []string {
 	return p.fm.SortedStringArray("categories")
 }
 
+// IsPost is in the Page interface
+func (p *page) IsPost() bool {
+	return p.fm["collection"] == "posts"
+}
+
 // Tags is in the Page interface
 func (p *page) Tags() []string {
 	return p.fm.SortedStringArray("tags")

pages/permalinks.go

@@ -56,7 +56,7 @@ func (p *page) permalinkVariables() map[string]string {
 		"slug":       slug,
 		"title":      utils.Slugify(p.fm.String("title", name)),
 		"y_day":      strconv.Itoa(p.modTime.YearDay()),
-		// Not documented, but evident:
+		// Undocumented but evident:
 		"output_ext": p.OutputExt(),
 	}
 	for k, v := range permalinkDateVariables {

plugins/avatar_test.go

@@ -17,6 +17,7 @@ type siteFake struct {
 
 func (s siteFake) AddDocument(pages.Document, bool) {}
 func (s siteFake) Config() *config.Config           { return &s.c }
+func (s siteFake) HasLayout(string) bool            { return true }
 func (s siteFake) Pages() []pages.Page              { return nil }
 func (s siteFake) Posts() []pages.Page              { return nil }
 func (s siteFake) TemplateEngine() *liquid.Engine   { return s.e }

plugins/default_layout.go

@@ -0,0 +1,48 @@
+package plugins
+
+func init() {
+	register("jekyll-default-layout", jekyllDefaultLayout{})
+}
+
+type jekyllDefaultLayout struct{ plugin }
+
+const (
+	defaultLayout int = iota
+	pageLayout
+	postLayout
+	homeLayout
+)
+
+var layoutNames = []string{"default", "post", "page", "home"}
+
+func (p jekyllDefaultLayout) layoutNames(s Site) []string {
+	var ln string
+	names := make([]string, len(layoutNames))
+	for i, n := range layoutNames {
+		// fmt.Println("examine", i, n, names)
+		if s.HasLayout(n) {
+			ln = n
+		}
+		names[i] = ln
+	}
+	return names
+}
+
+func (p jekyllDefaultLayout) PostInitPage(s Site, pg Page) error {
+	fm := pg.FrontMatter()
+	if fm["layout"] != nil {
+		return nil
+	}
+	layoutNames := p.layoutNames(s)
+	ln := layoutNames[pageLayout]
+	switch {
+	case pg.IsPost():
+		ln = layoutNames[postLayout]
+	case pg.Permalink() == "/":
+		ln = layoutNames[homeLayout]
+	}
+	if ln != "" {
+		fm["layout"] = ln
+	}
+	return nil
+}

plugins/plugins.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/kyokomi/emoji"
 	"github.com/osteele/gojekyll/config"
+	"github.com/osteele/gojekyll/frontmatter"
 	"github.com/osteele/gojekyll/pages"
 	"github.com/osteele/gojekyll/utils"
 	"github.com/osteele/liquid"
@@ -23,17 +24,26 @@ type Plugin interface {
 	ConfigureTemplateEngine(*liquid.Engine) error
 	ModifyPluginList([]string) []string
 	ModifySiteDrop(Site, map[string]interface{}) error
+	PostInitPage(Site, Page) error
 	PostRead(Site) error
 	PostRender([]byte) ([]byte, error)
 }
 
-// Site is the site interface that is available to a plugin.
+// Site is the site interface that is available to plugins.
 type Site interface {
 	AddDocument(pages.Document, bool)
 	Config() *config.Config
 	TemplateEngine() *liquid.Engine
 	Pages() []pages.Page
 	Posts() []pages.Page
+	HasLayout(string) bool
+}
+
+// Page is the page interface that is available to plugins.
+type Page interface {
+	FrontMatter() frontmatter.FrontMatter
+	IsPost() bool
+	Permalink() string
 }
 
 // Lookup returns a plugin if it has been registered.
@@ -75,6 +85,7 @@ func (p plugin) Initialize(Site) error                             { return nil
 func (p plugin) ConfigureTemplateEngine(*liquid.Engine) error      { return nil }
 func (p plugin) ModifyPluginList(names []string) []string          { return names }
 func (p plugin) ModifySiteDrop(Site, map[string]interface{}) error { return nil }
+func (p plugin) PostInitPage(Site, Page) error                     { return nil }
 func (p plugin) PostRead(Site) error                               { return nil }
 func (p plugin) PostRender(b []byte) ([]byte, error)               { return b, nil }
 

renderers/layouts.go

@@ -35,7 +35,7 @@ func (p *Manager) ApplyLayout(name string, content []byte, vars liquid.Bindings)
 }
 
 // FindLayout returns a template for the named layout.
-func (p *Manager) FindLayout(base string, fm *map[string]interface{}) (tpl *liquid.Template, err error) {
+func (p *Manager) FindLayout(base string, fmp *map[string]interface{}) (tpl *liquid.Template, err error) {
 	// not cached, but the time here is negligible
 	exts := []string{"", ".html"}
 	for _, ext := range strings.SplitN(p.cfg.MarkdownExt, `,`, -1) {
@@ -64,10 +64,13 @@ loop:
 		return nil, fmt.Errorf("no template for %s", base)
 	}
 	lineNo := 1
-	*fm, err = frontmatter.Read(&content, &lineNo)
+	fm, err := frontmatter.Read(&content, &lineNo)
 	if err != nil {
 		return
 	}
+	if fmp != nil {
+		*fmp = fm
+	}
 	tpl, err = p.liquidEngine.ParseTemplateLocation(content, filename, lineNo)
 	if err != nil {
 		return nil, err

site/read.go

@@ -47,6 +47,14 @@ func (s *Site) Read() error {
 	if err := s.initializeRenderers(); err != nil {
 		return utils.WrapError(err, "initializing renderers")
 	}
+	for _, p := range s.Pages() {
+		err := s.runHooks(func(h plugins.Plugin) error {
+			return h.PostInitPage(s, p)
+		})
+		if err != nil {
+			return err
+		}
+	}
 	return s.runHooks(func(p plugins.Plugin) error { return p.PostRead(s) })
 }
 

site/site.go

@@ -180,6 +180,12 @@ func (s *Site) initializeRenderers() (err error) {
 	})
 }
 
+// HasLayout is in the plugins.Site interface.
+func (s *Site) HasLayout(ln string) bool {
+	l, err := s.renderer.FindLayout(ln, nil)
+	return err == nil && l != nil
+}
+
 // RelativePath is in the page.Container interface.
 func (s *Site) RelativePath(path string) string {
 	if s.themeDir != "" {