resources/page: Expand parmalinks tokens in `url`

This change allows to use permalink tokens in url front matter fields. This should be useful to target more specific pages instead of using a global permalink configuration. It's expected to be used with cascade.

Fixes #9714

7 files changed, 101 insertions, 21 deletions

diff --git a/common/hreflect/helpers.go b/common/hreflect/helpers.go
index b5a8bacc9..5113a3886 100644
--- a/common/hreflect/helpers.go
+++ b/common/hreflect/helpers.go
@@ -268,7 +268,8 @@ func IsContextType(tp reflect.Type) bool {
 		return true
 	}
 
-	return isContextCache.GetOrCreate(tp, func() bool {
-		return tp.Implements(contextInterface)
+	isContext, _ := isContextCache.GetOrCreate(tp, func() (bool, error) {
+		return tp.Implements(contextInterface), nil
 	})
+	return isContext
 }
diff --git a/common/maps/cache.go b/common/maps/cache.go
index 7cd7410c2..0175974b5 100644
--- a/common/maps/cache.go
+++ b/common/maps/cache.go
@@ -40,22 +40,25 @@ func (c *Cache[K, T]) Get(key K) (T, bool) {
 }
 
 // GetOrCreate gets the value for the given key if it exists, or creates it if not.
-func (c *Cache[K, T]) GetOrCreate(key K, create func() T) T {
+func (c *Cache[K, T]) GetOrCreate(key K, create func() (T, error)) (T, error) {
 	c.RLock()
 	v, found := c.m[key]
 	c.RUnlock()
 	if found {
-		return v
+		return v, nil
 	}
 	c.Lock()
 	defer c.Unlock()
 	v, found = c.m[key]
 	if found {
-		return v
+		return v, nil
+	}
+	v, err := create()
+	if err != nil {
+		return v, err
 	}
-	v = create()
 	c.m[key] = v
-	return v
+	return v, nil
 }
 
 // Set sets the given key to the given value.
diff --git a/hugolib/page__paths.go b/hugolib/page__paths.go
index d89388f81..6324b5871 100644
--- a/hugolib/page__paths.go
+++ b/hugolib/page__paths.go
@@ -141,6 +141,19 @@ func createTargetPathDescriptor(p *pageState) (page.TargetPathDescriptor, error)
 	desc.PrefixFilePath = s.getLanguageTargetPathLang(alwaysInSubDir)
 	desc.PrefixLink = s.getLanguagePermalinkLang(alwaysInSubDir)
 
+	if desc.URL != "" && strings.IndexByte(desc.URL, ':') >= 0 {
+		// Attempt to parse and expand an url
+		opath, err := d.ResourceSpec.Permalinks.ExpandPattern(desc.URL, p)
+		if err != nil {
+			return desc, err
+		}
+
+		if opath != "" {
+			opath, _ = url.QueryUnescape(opath)
+			desc.URL = opath
+		}
+	}
+
 	opath, err := d.ResourceSpec.Permalinks.Expand(p.Section(), p)
 	if err != nil {
 		return desc, err
diff --git a/hugolib/page_permalink_test.go b/hugolib/page_permalink_test.go
index bc89638d3..d8fd99d79 100644
--- a/hugolib/page_permalink_test.go
+++ b/hugolib/page_permalink_test.go
@@ -59,6 +59,8 @@ func TestPermalink(t *testing.T) {
 
 		// test URL overrides
 		{"x/y/z/boofar.md", "", "", "/z/y/q/", false, false, "/z/y/q/", "/z/y/q/"},
+		// test URL override with expands
+		{"x/y/z/boofar.md", "", "test", "/z/:slug/", false, false, "/z/test/", "/z/test/"},
 	}
 
 	for i, test := range tests {
diff --git a/resources/page/permalinks.go b/resources/page/permalinks.go
index 67c63c4b2..05911f0ea 100644
--- a/resources/page/permalinks.go
+++ b/resources/page/permalinks.go
@@ -40,6 +40,8 @@ type PermalinkExpander struct {
 	expanders map[string]map[string]func(Page) (string, error)
 
 	urlize func(uri string) string
+
+	patternCache *maps.Cache[string, func(Page) (string, error)]
 }
 
 // Time for checking date formats. Every field is different than the
@@ -71,7 +73,10 @@ func (p PermalinkExpander) callback(attr string) (pageToPermaAttribute, bool) {
 // NewPermalinkExpander creates a new PermalinkExpander configured by the given
 // urlize func.
 func NewPermalinkExpander(urlize func(uri string) string, patterns map[string]map[string]string) (PermalinkExpander, error) {
-	p := PermalinkExpander{urlize: urlize}
+	p := PermalinkExpander{
+		urlize:       urlize,
+		patternCache: maps.NewCache[string, func(Page) (string, error)](),
+	}
 
 	p.knownPermalinkAttributes = map[string]pageToPermaAttribute{
 		"year":           p.pageToPermalinkDate,
@@ -102,6 +107,16 @@ func NewPermalinkExpander(urlize func(uri string) string, patterns map[string]ma
 	return p, nil
 }
 
+// ExpandPattern expands the path in p with the specified expand pattern.
+func (l PermalinkExpander) ExpandPattern(pattern string, p Page) (string, error) {
+	expander, err := l.getOrParsePattern(pattern)
+	if err != nil {
+		return "", err
+	}
+
+	return expander(p)
+}
+
 // Expand expands the path in p according to the rules defined for the given key.
 // If no rules are found for the given key, an empty string is returned.
 func (l PermalinkExpander) Expand(key string, p Page) (string, error) {
@@ -129,17 +144,11 @@ func init() {
 	}
 }
 
-func (l PermalinkExpander) parse(patterns map[string]string) (map[string]func(Page) (string, error), error) {
-	expanders := make(map[string]func(Page) (string, error))
-
-	for k, pattern := range patterns {
-		k = strings.Trim(k, sectionCutSet)
-
+func (l PermalinkExpander) getOrParsePattern(pattern string) (func(Page) (string, error), error) {
+	return l.patternCache.GetOrCreate(pattern, func() (func(Page) (string, error), error) {
 		if !l.validate(pattern) {
 			return nil, &permalinkExpandError{pattern: pattern, err: errPermalinkIllFormed}
 		}
-
-		pattern := pattern
 		matches := attributeRegexp.FindAllStringSubmatch(pattern, -1)
 
 		callbacks := make([]pageToPermaAttribute, len(matches))
@@ -157,7 +166,7 @@ func (l PermalinkExpander) parse(patterns map[string]string) (map[string]func(Pa
 			callbacks[i] = callback
 		}
 
-		expanders[k] = func(p Page) (string, error) {
+		return func(p Page) (string, error) {
 			if matches == nil {
 				return pattern, nil
 			}
@@ -173,12 +182,25 @@ func (l PermalinkExpander) parse(patterns map[string]string) (map[string]func(Pa
 				}
 
 				newField = strings.Replace(newField, replacement, newAttr, 1)
-
 			}
 
 			return newField, nil
+		}, nil
+	})
+}
+
+func (l PermalinkExpander) parse(patterns map[string]string) (map[string]func(Page) (string, error), error) {
+	expanders := make(map[string]func(Page) (string, error))
+
+	for k, pattern := range patterns {
+		k = strings.Trim(k, sectionCutSet)
+
+		expander, err := l.getOrParsePattern(pattern)
+		if err != nil {
+			return nil, err
 		}
 
+		expanders[k] = expander
 	}
 
 	return expanders, nil
diff --git a/resources/page/permalinks_integration_test.go b/resources/page/permalinks_integration_test.go
index 9a76ac602..2b9e878b1 100644
--- a/resources/page/permalinks_integration_test.go
+++ b/resources/page/permalinks_integration_test.go
@@ -193,3 +193,42 @@ List.
 	b.AssertFileContent("public/libros/fiction/index.html", "List.")
 	b.AssertFileContent("public/libros/fiction/2023/book1/index.html", "Single.")
 }
+
+func TestPermalinksUrlCascade(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- layouts/_default/list.html --
+List|{{ .Kind }}|{{ .RelPermalink }}|
+-- layouts/_default/single.html --
+Single|{{ .Kind }}|{{ .RelPermalink }}|
+-- hugo.toml --
+-- content/cooking/delicious-recipes/_index.md --
+---
+url: /delicious-recipe/
+cascade:
+  url: /delicious-recipe/:slug/
+---
+-- content/cooking/delicious-recipes/example1.md --
+---
+title: Recipe 1
+---
+-- content/cooking/delicious-recipes/example2.md --
+---
+title: Recipe 2
+slug: custom-recipe-2
+---
+`
+	b := hugolib.NewIntegrationTestBuilder(
+		hugolib.IntegrationTestConfig{
+			T:           t,
+			TxtarString: files,
+			LogLevel:    logg.LevelWarn,
+		}).Build()
+
+	t.Log(b.LogString())
+	b.Assert(b.H.Log.LoggCount(logg.LevelWarn), qt.Equals, 0)
+	b.AssertFileContent("public/delicious-recipe/index.html", "List|section|/delicious-recipe/")
+	b.AssertFileContent("public/delicious-recipe/recipe-1/index.html", "Single|page|/delicious-recipe/recipe-1/")
+	b.AssertFileContent("public/delicious-recipe/custom-recipe-2/index.html", "Single|page|/delicious-recipe/custom-recipe-2/")
+}
diff --git a/tpl/templates/templates.go b/tpl/templates/templates.go
index 98b4b4c38..0be44a013 100644
--- a/tpl/templates/templates.go
+++ b/tpl/templates/templates.go
@@ -90,14 +90,14 @@ func (ns *Namespace) DoDefer(ctx context.Context, id string, optsv any) string {
 
 	id = fmt.Sprintf("%s_%s%s", id, key, tpl.HugoDeferredTemplateSuffix)
 
-	_ = ns.deps.BuildState.DeferredExecutions.Executions.GetOrCreate(id,
-		func() *tpl.DeferredExecution {
+	_, _ = ns.deps.BuildState.DeferredExecutions.Executions.GetOrCreate(id,
+		func() (*tpl.DeferredExecution, error) {
 			return &tpl.DeferredExecution{
 				TemplateName: templateName,
 				Ctx:          ctx,
 				Data:         opts.Data,
 				Executed:     false,
-			}
+			}, nil
 		})
 
 	return id