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Diffstat (limited to 'resources/internal/key.go')
-rw-r--r-- | resources/internal/key.go | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/resources/internal/key.go b/resources/internal/key.go new file mode 100644 index 000000000..3dce8b350 --- /dev/null +++ b/resources/internal/key.go @@ -0,0 +1,61 @@ +// 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() +} |