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105 lines
2.2 KiB
Go
105 lines
2.2 KiB
Go
// Copyright 2015 The Hugo Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package transform
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import (
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"bytes"
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"io"
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bp "github.com/gohugoio/hugo/bufferpool"
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)
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type trans func(rw contentTransformer)
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type link trans
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type chain []link
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// NewChain creates a chained content transformer given the provided transforms.
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func NewChain(trs ...link) chain {
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return trs
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}
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// NewEmptyTransforms creates a new slice of transforms with a capacity of 20.
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func NewEmptyTransforms() []link {
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return make([]link, 0, 20)
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}
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// contentTransformer is an interface that enables rotation of pooled buffers
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// in the transformer chain.
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type contentTransformer interface {
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Path() []byte
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Content() []byte
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io.Writer
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}
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// Implements contentTransformer
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// Content is read from the from-buffer and rewritten to to the to-buffer.
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type fromToBuffer struct {
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path []byte
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from *bytes.Buffer
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to *bytes.Buffer
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}
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func (ft fromToBuffer) Path() []byte {
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return ft.path
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}
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func (ft fromToBuffer) Write(p []byte) (n int, err error) {
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return ft.to.Write(p)
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}
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func (ft fromToBuffer) Content() []byte {
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return ft.from.Bytes()
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}
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func (c *chain) Apply(w io.Writer, r io.Reader, p []byte) error {
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b1 := bp.GetBuffer()
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defer bp.PutBuffer(b1)
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if _, err := b1.ReadFrom(r); err != nil {
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return err
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}
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if len(*c) == 0 {
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_, err := b1.WriteTo(w)
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return err
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}
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b2 := bp.GetBuffer()
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defer bp.PutBuffer(b2)
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fb := &fromToBuffer{path: p, from: b1, to: b2}
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for i, tr := range *c {
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if i > 0 {
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if fb.from == b1 {
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fb.from = b2
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fb.to = b1
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fb.to.Reset()
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} else {
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fb.from = b1
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fb.to = b2
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fb.to.Reset()
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}
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}
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tr(fb)
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}
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_, err := fb.to.WriteTo(w)
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return err
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}
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