hugo/navigation/menu_cache.go

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// Copyright 2021 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 navigation
import (
"sync"
)
type menuCacheEntry struct {
in []Menu
out Menu
}
func (entry menuCacheEntry) matches(menuList []Menu) bool {
if len(entry.in) != len(menuList) {
return false
}
for i, m := range menuList {
if !menuEqual(m, entry.in[i]) {
return false
}
}
return true
}
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// newMenuCache creates a new menuCache instance.
func newMenuCache() *menuCache {
return &menuCache{m: make(map[string][]menuCacheEntry)}
}
type menuCache struct {
sync.RWMutex
m map[string][]menuCacheEntry
}
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// menuEqual checks if two menus are equal.
func menuEqual(m1, m2 Menu) bool {
if len(m1) != len(m2) {
return false
}
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for i := range m1 {
if m1[i] != m2[i] {
return false
}
}
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return true
}
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// get retrieves a menu from the cache based on the provided key and menuLists.
// If the menu is not found, it applies the provided function and caches the result.
func (c *menuCache) get(key string, apply func(m Menu), menuLists ...Menu) (Menu, bool) {
return c.getP(key, func(m *Menu) {
if apply != nil {
apply(*m)
}
}, menuLists...)
}
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// getP is similar to get but also returns a boolean indicating whether the menu was found in the cache.
func (c *menuCache) getP(key string, apply func(m *Menu), menuLists ...Menu) (Menu, bool) {
c.Lock()
defer c.Unlock()
if cached, ok := c.m[key]; ok {
for _, entry := range cached {
if entry.matches(menuLists) {
return entry.out, true
}
}
}
m := menuLists[0]
menuCopy := append(Menu(nil), m...)
if apply != nil {
apply(&menuCopy)
}
entry := menuCacheEntry{in: menuLists, out: menuCopy}
if v, ok := c.m[key]; ok {
c.m[key] = append(v, entry)
} else {
c.m[key] = []menuCacheEntry{entry}
}
return menuCopy, false
}