Make string sorting (e.g. ByTitle, ByLinkTitle and ByParam) language aware

Fixes #2180

4 files changed, 40 insertions, 10 deletions

diff --git a/tpl/collections/collections_test.go b/tpl/collections/collections_test.go
index 8fc43318d..bcc2855c7 100644
--- a/tpl/collections/collections_test.go
+++ b/tpl/collections/collections_test.go
@@ -133,7 +133,9 @@ func TestDelimit(t *testing.T) {
 	t.Parallel()
 	c := qt.New(t)
 
-	ns := New(&deps.Deps{})
+	ns := New(&deps.Deps{
+		Language: langs.NewDefaultLanguage(config.New()),
+	})
 
 	for i, test := range []struct {
 		seq       any
diff --git a/tpl/collections/sort.go b/tpl/collections/sort.go
index 305399eb8..ce7f27771 100644
--- a/tpl/collections/sort.go
+++ b/tpl/collections/sort.go
@@ -20,6 +20,7 @@ import (
 	"strings"
 
 	"github.com/gohugoio/hugo/common/maps"
+	"github.com/gohugoio/hugo/langs"
 	"github.com/gohugoio/hugo/tpl/compare"
 	"github.com/spf13/cast"
 )
@@ -47,8 +48,10 @@ func (ns *Namespace) Sort(seq any, args ...any) (any, error) {
 		return nil, errors.New("can't sort " + reflect.ValueOf(seq).Type().String())
 	}
 
+	collator := langs.GetCollator(ns.deps.Language)
+
 	// Create a list of pairs that will be used to do the sort
-	p := pairList{SortAsc: true, SliceType: sliceType}
+	p := pairList{Collator: collator, SortAsc: true, SliceType: sliceType}
 	p.Pairs = make([]pair, seqv.Len())
 
 	var sortByField string
@@ -124,6 +127,10 @@ func (ns *Namespace) Sort(seq any, args ...any) (any, error) {
 			}
 		}
 	}
+
+	collator.Lock()
+	defer collator.Unlock()
+
 	return p.sort(), nil
 }
 
@@ -137,6 +144,7 @@ type pair struct {
 
 // A slice of pairs that implements sort.Interface to sort by Value.
 type pairList struct {
+	Collator  *langs.Collator
 	Pairs     []pair
 	SortAsc   bool
 	SliceType reflect.Type
@@ -151,16 +159,16 @@ func (p pairList) Less(i, j int) bool {
 	if iv.IsValid() {
 		if jv.IsValid() {
 			// can only call Interface() on valid reflect Values
-			return sortComp.Lt(iv.Interface(), jv.Interface())
+			return sortComp.LtCollate(p.Collator, iv.Interface(), jv.Interface())
 		}
 
 		// if j is invalid, test i against i's zero value
-		return sortComp.Lt(iv.Interface(), reflect.Zero(iv.Type()))
+		return sortComp.LtCollate(p.Collator, iv.Interface(), reflect.Zero(iv.Type()))
 	}
 
 	if jv.IsValid() {
 		// if i is invalid, test j against j's zero value
-		return sortComp.Lt(reflect.Zero(jv.Type()), jv.Interface())
+		return sortComp.LtCollate(p.Collator, reflect.Zero(jv.Type()), jv.Interface())
 	}
 
 	return false
diff --git a/tpl/collections/sort_test.go b/tpl/collections/sort_test.go
index 698118864..a4adccf51 100644
--- a/tpl/collections/sort_test.go
+++ b/tpl/collections/sort_test.go
@@ -19,6 +19,8 @@ import (
 	"testing"
 
 	"github.com/gohugoio/hugo/common/maps"
+	"github.com/gohugoio/hugo/config"
+	"github.com/gohugoio/hugo/langs"
 
 	"github.com/gohugoio/hugo/deps"
 )
@@ -28,7 +30,9 @@ type stringsSlice []string
 func TestSort(t *testing.T) {
 	t.Parallel()
 
-	ns := New(&deps.Deps{})
+	ns := New(&deps.Deps{
+		Language: langs.NewDefaultLanguage(config.New()),
+	})
 
 	type ts struct {
 		MyInt    int
diff --git a/tpl/compare/compare.go b/tpl/compare/compare.go
index 21b9c5bcd..3e9730dad 100644
--- a/tpl/compare/compare.go
+++ b/tpl/compare/compare.go
@@ -21,6 +21,7 @@ import (
 	"time"
 
 	"github.com/gohugoio/hugo/compare"
+	"github.com/gohugoio/hugo/langs"
 
 	"github.com/gohugoio/hugo/common/types"
 )
@@ -188,10 +189,11 @@ func (n *Namespace) Le(first any, others ...any) bool {
 }
 
 // Lt returns the boolean truth of arg1 < arg2 && arg1 < arg3 && arg1 < arg4.
-func (n *Namespace) Lt(first any, others ...any) bool {
+// The provided collator will be used for string comparisons.
+func (n *Namespace) LtCollate(collator *langs.Collator, first any, others ...any) bool {
 	n.checkComparisonArgCount(1, others...)
 	for _, other := range others {
-		left, right := n.compareGet(first, other)
+		left, right := n.compareGetWithCollator(collator, first, other)
 		if !(left < right) {
 			return false
 		}
@@ -199,6 +201,11 @@ func (n *Namespace) Lt(first any, others ...any) bool {
 	return true
 }
 
+// Lt returns the boolean truth of arg1 < arg2 && arg1 < arg3 && arg1 < arg4.
+func (n *Namespace) Lt(first any, others ...any) bool {
+	return n.LtCollate(nil, first, others...)
+}
+
 func (n *Namespace) checkComparisonArgCount(min int, others ...any) bool {
 	if len(others) < min {
 		panic("missing arguments for comparison")
@@ -216,6 +223,10 @@ func (n *Namespace) Conditional(condition bool, a, b any) any {
 }
 
 func (ns *Namespace) compareGet(a any, b any) (float64, float64) {
+	return ns.compareGetWithCollator(nil, a, b)
+}
+
+func (ns *Namespace) compareGetWithCollator(collator *langs.Collator, a any, b any) (float64, float64) {
 	if ac, ok := a.(compare.Comparer); ok {
 		c := ac.Compare(b)
 		if c < 0 {
@@ -296,8 +307,13 @@ func (ns *Namespace) compareGet(a any, b any) (float64, float64) {
 		}
 	}
 
-	if ns.caseInsensitive && leftStr != nil && rightStr != nil {
-		c := compare.Strings(*leftStr, *rightStr)
+	if (ns.caseInsensitive || collator != nil) && leftStr != nil && rightStr != nil {
+		var c int
+		if collator != nil {
+			c = collator.CompareStrings(*leftStr, *rightStr)
+		} else {
+			c = compare.Strings(*leftStr, *rightStr)
+		}
 		if c < 0 {
 			return 0, 1
 		} else if c > 0 {