1 files changed, 41 insertions, 2 deletions
diff --git a/tpl/template.go b/tpl/template.go
index 3225814c0..07152166a 100644
--- a/tpl/template.go
+++ b/tpl/template.go
@@ -1,4 +1,4 @@
-// Copyright 2018 The Hugo Authors. All rights reserved.
+// Copyright 2019 The Hugo Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -21,6 +21,8 @@ import (
 	"strings"
 	"time"
 
+	"github.com/gohugoio/hugo/output"
+
 	"github.com/gohugoio/hugo/common/herrors"
 
 	"github.com/gohugoio/hugo/hugofs"
@@ -37,7 +39,8 @@ import (
 )
 
 var (
-	_ TemplateExecutor = (*TemplateAdapter)(nil)
+	_ TemplateExecutor     = (*TemplateAdapter)(nil)
+	_ TemplateInfoProvider = (*TemplateAdapter)(nil)
 )
 
 // TemplateHandler manages the collection of templates.
@@ -53,17 +56,47 @@ type TemplateHandler interface {
 	RebuildClone()
 }
 
+// TemplateVariants describes the possible variants of a template.
+// All of these may be empty.
+type TemplateVariants struct {
+	Language     string
+	OutputFormat output.Format
+}
+
 // TemplateFinder finds templates.
 type TemplateFinder interface {
+	TemplateLookup
+	TemplateLookupVariant
+}
+
+type TemplateLookup interface {
 	Lookup(name string) (Template, bool)
 }
 
+type TemplateLookupVariant interface {
+	// TODO(bep) this currently only works for shortcodes.
+	// We may unify and expand this variant pattern to the
+	// other templates, but we need this now for the shortcodes to
+	// quickly determine if a shortcode has a template for a given
+	// output format.
+	// It returns the template, if it was found or not and if there are
+	// alternative representations (output format, language).
+	// We are currently only interested in output formats, so we should improve
+	// this for speed.
+	LookupVariant(name string, variants TemplateVariants) (Template, bool, bool)
+}
+
 // Template is the common interface between text/template and html/template.
 type Template interface {
 	Execute(wr io.Writer, data interface{}) error
 	Name() string
 }
 
+// TemplateInfoProvider provides some contextual information about a template.
+type TemplateInfoProvider interface {
+	TemplateInfo() Info
+}
+
 // TemplateParser is used to parse ad-hoc templates, e.g. in the Resource chain.
 type TemplateParser interface {
 	Parse(name, tpl string) (Template, error)
@@ -92,6 +125,8 @@ type TemplateAdapter struct {
 	Template
 	Metrics metrics.Provider
 
+	Info Info
+
 	// The filesystem where the templates are stored.
 	Fs afero.Fs
 
@@ -133,6 +168,10 @@ func (t *TemplateAdapter) Execute(w io.Writer, data interface{}) (execErr error)
 	return
 }
 
+func (t *TemplateAdapter) TemplateInfo() Info {
+	return t.Info
+}
+
 // The identifiers may be truncated in the log, e.g.
 // "executing "main" at <$scaled.SRelPermalin...>: can't evaluate field SRelPermalink in type *resource.Image"
 var identifiersRe = regexp.MustCompile("at \\<(.*?)(\\.{3})?\\>:")