hugo/hugolib/scratch.go

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// Copyright 2015 The Hugo Authors. All rights reserved.
//
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// 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
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// 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 hugolib
import (
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"reflect"
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"sort"
"sync"
"github.com/gohugoio/hugo/tpl/math"
)
// Scratch is a writable context used for stateful operations in Page/Node rendering.
type Scratch struct {
values map[string]interface{}
mu sync.RWMutex
}
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// Add will, for single values, add (using the + operator) the addend to the existing addend (if found).
// Supports numeric values and strings.
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//
// If the first add for a key is an array or slice, then the next value(s) will be appended.
func (c *Scratch) Add(key string, newAddend interface{}) (string, error) {
var newVal interface{}
c.mu.RLock()
existingAddend, found := c.values[key]
c.mu.RUnlock()
if found {
var err error
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addendV := reflect.ValueOf(existingAddend)
if addendV.Kind() == reflect.Slice || addendV.Kind() == reflect.Array {
nav := reflect.ValueOf(newAddend)
if nav.Kind() == reflect.Slice || nav.Kind() == reflect.Array {
newVal = reflect.AppendSlice(addendV, nav).Interface()
} else {
newVal = reflect.Append(addendV, nav).Interface()
}
} else {
newVal, err = math.DoArithmetic(existingAddend, newAddend, '+')
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if err != nil {
return "", err
}
}
} else {
newVal = newAddend
}
c.mu.Lock()
c.values[key] = newVal
c.mu.Unlock()
return "", nil // have to return something to make it work with the Go templates
}
// Set stores a value with the given key in the Node context.
// This value can later be retrieved with Get.
func (c *Scratch) Set(key string, value interface{}) string {
c.mu.Lock()
c.values[key] = value
c.mu.Unlock()
return ""
}
// Get returns a value previously set by Add or Set
func (c *Scratch) Get(key string) interface{} {
c.mu.RLock()
val := c.values[key]
c.mu.RUnlock()
return val
}
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// SetInMap stores a value to a map with the given key in the Node context.
// This map can later be retrieved with GetSortedMapValues.
func (c *Scratch) SetInMap(key string, mapKey string, value interface{}) string {
c.mu.Lock()
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_, found := c.values[key]
if !found {
c.values[key] = make(map[string]interface{})
}
c.values[key].(map[string]interface{})[mapKey] = value
c.mu.Unlock()
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return ""
}
// GetSortedMapValues returns a sorted map previously filled with SetInMap
func (c *Scratch) GetSortedMapValues(key string) interface{} {
c.mu.RLock()
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if c.values[key] == nil {
c.mu.RUnlock()
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return nil
}
unsortedMap := c.values[key].(map[string]interface{})
c.mu.RUnlock()
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var keys []string
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for mapKey := range unsortedMap {
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keys = append(keys, mapKey)
}
sort.Strings(keys)
sortedArray := make([]interface{}, len(unsortedMap))
for i, mapKey := range keys {
sortedArray[i] = unsortedMap[mapKey]
}
return sortedArray
}
func newScratch() *Scratch {
return &Scratch{values: make(map[string]interface{})}
}