hugo/resources/internal/key.go
Bjørn Erik Pedersen f9978ed164
Image resource refactor
This commit pulls most of the image related logic into its own package, to make it easier to reason about and extend.

This is also a rewrite of the transformation logic used in Hugo Pipes, mostly to allow constructs like the one below:

    {{ ($myimg | fingerprint ).Width }}

Fixes #5903
Fixes #6234
Fixes #6266
2019-08-26 15:00:44 +02:00

61 lines
2 KiB
Go

// 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 internal
import (
"strconv"
bp "github.com/gohugoio/hugo/bufferpool"
"github.com/mitchellh/hashstructure"
)
// ResourceTransformationKey are provided by the different transformation implementations.
// It identifies the transformation (name) and its configuration (elements).
// We combine this in a chain with the rest of the transformations
// with the target filename and a content hash of the origin to use as cache key.
type ResourceTransformationKey struct {
Name string
elements []interface{}
}
// NewResourceTransformationKey creates a new ResourceTransformationKey from the transformation
// name and elements. We will create a 64 bit FNV hash from the elements, which when combined
// with the other key elements should be unique for all practical applications.
func NewResourceTransformationKey(name string, elements ...interface{}) ResourceTransformationKey {
return ResourceTransformationKey{Name: name, elements: elements}
}
// Value returns the Key as a string.
// Do not change this without good reasons.
func (k ResourceTransformationKey) Value() string {
if len(k.elements) == 0 {
return k.Name
}
sb := bp.GetBuffer()
defer bp.PutBuffer(sb)
sb.WriteString(k.Name)
for _, element := range k.elements {
hash, err := hashstructure.Hash(element, nil)
if err != nil {
panic(err)
}
sb.WriteString("_")
sb.WriteString(strconv.FormatUint(hash, 10))
}
return sb.String()
}