Create a struct with all of Hugo's config options

Primary motivation is documentation, but it will also hopefully simplify the code.

cache/docs.go

@@ -0,0 +1,2 @@
+// Package cache contains the differenct cache implementations.
+package cache

cache/filecache/filecache_config.go

@@ -11,6 +11,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// Package filecache provides a file based cache for Hugo.
 package filecache
 
 import (
@@ -39,7 +40,7 @@ const (
 	cacheDirProject = ":cacheDir/:project"
 )
 
-var defaultCacheConfig = Config{
+var defaultCacheConfig = FileCacheConfig{
 	MaxAge: -1, // Never expire
 	Dir:    cacheDirProject,
 }
@@ -53,7 +54,7 @@ const (
 	cacheKeyGetResource = "getresource"
 )
 
-type Configs map[string]Config
+type Configs map[string]FileCacheConfig
 
 func (c Configs) CacheDirModules() string {
 	return c[cacheKeyModules].Dir
@@ -74,13 +75,13 @@ var defaultCacheConfigs = Configs{
 		MaxAge: -1,
 		Dir:    resourcesGenDir,
 	},
-	cacheKeyGetResource: Config{
+	cacheKeyGetResource: FileCacheConfig{
 		MaxAge: -1, // Never expire
 		Dir:    cacheDirProject,
 	},
 }
 
-type Config struct {
+type FileCacheConfig struct {
 	// Max age of cache entries in this cache. Any items older than this will
 	// be removed and not returned from the cache.
 	// a negative value means forever, 0 means cache is disabled.

common/hstrings/strings.go

@@ -0,0 +1,47 @@
+// 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.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package hstrings
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/gohugoio/hugo/compare"
+)
+
+var _ compare.Eqer = StringEqualFold("")
+
+// StringEqualFold is a string that implements the compare.Eqer interface and considers
+// two strings equal if they are equal when folded to lower case.
+// The compare.Eqer interface is used in Hugo to compare values in templates (e.g. using the eq template function).
+type StringEqualFold string
+
+func (s StringEqualFold) EqualFold(s2 string) bool {
+	return strings.EqualFold(string(s), s2)
+}
+
+func (s StringEqualFold) String() string {
+	return string(s)
+}
+
+func (s StringEqualFold) Eq(s2 any) bool {
+	switch ss := s2.(type) {
+	case string:
+		return s.EqualFold(ss)
+	case fmt.Stringer:
+		return s.EqualFold(ss.String())
+	}
+
+	return false
+}

common/hstrings/strings_test.go

@@ -0,0 +1,36 @@
+// Copyright 2023 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.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package hstrings
+
+import (
+	"testing"
+
+	qt "github.com/frankban/quicktest"
+)
+
+func TestStringEqualFold(t *testing.T) {
+	c := qt.New(t)
+
+	s1 := "A"
+	s2 := "a"
+
+	c.Assert(StringEqualFold(s1).EqualFold(s2), qt.Equals, true)
+	c.Assert(StringEqualFold(s1).EqualFold(s1), qt.Equals, true)
+	c.Assert(StringEqualFold(s2).EqualFold(s1), qt.Equals, true)
+	c.Assert(StringEqualFold(s2).EqualFold(s2), qt.Equals, true)
+	c.Assert(StringEqualFold(s1).EqualFold("b"), qt.Equals, false)
+	c.Assert(StringEqualFold(s1).Eq(s2), qt.Equals, true)
+	c.Assert(StringEqualFold(s1).Eq("b"), qt.Equals, false)
+
+}

common/maps/maps.go

@@ -123,6 +123,23 @@ func LookupEqualFold[T any | string](m map[string]T, key string) (T, bool) {
 	return s, false
 }
 
+// MergeShallow merges src into dst, but only if the key does not already exist in dst.
+// The keys are compared case insensitively.
+func MergeShallow(dst, src map[string]any) {
+	for k, v := range src {
+		found := false
+		for dk := range dst {
+			if strings.EqualFold(dk, k) {
+				found = true
+				break
+			}
+		}
+		if !found {
+			dst[k] = v
+		}
+	}
+}
+
 type keyRename struct {
 	pattern glob.Glob
 	newKey  string

common/maps/params.go

@@ -62,7 +62,7 @@ func (p Params) IsZero() bool {
 		return false
 	}
 
-	for k, _ := range p {
+	for k := range p {
 		return k == mergeStrategyKey
 	}