79 lines
1.6 KiB
Go
79 lines
1.6 KiB
Go
// Copyright 2021 The ebml-go authors.
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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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//
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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 ebml
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import (
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"bytes"
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"io"
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)
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type rollbackReader interface {
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Set(io.Reader)
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Get() io.Reader
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Read([]byte) (int, error)
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Reset()
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RollbackTo(int)
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}
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type rollbackReaderImpl struct {
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io.Reader
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buf []byte
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}
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func (r *rollbackReaderImpl) Set(v io.Reader) {
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r.Reader = v
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}
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func (r *rollbackReaderImpl) Get() io.Reader {
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return r.Reader
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}
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func (r *rollbackReaderImpl) Read(b []byte) (int, error) {
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n, err := r.Reader.Read(b)
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r.buf = append(r.buf, b[:n]...)
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return n, err
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}
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func (r *rollbackReaderImpl) Reset() {
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r.buf = r.buf[0:0]
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}
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func (r *rollbackReaderImpl) RollbackTo(i int) {
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buf := r.buf
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r.Reader = io.MultiReader(
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bytes.NewReader(buf[i:]),
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r.Reader,
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)
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r.buf = nil
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}
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type rollbackReaderNop struct {
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io.Reader
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}
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func (r *rollbackReaderNop) Set(v io.Reader) {
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r.Reader = v
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}
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func (r *rollbackReaderNop) Get() io.Reader {
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return r.Reader
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}
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func (*rollbackReaderNop) Reset() {
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}
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func (*rollbackReaderNop) RollbackTo(i int) {
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panic("can't rollback nop rollback reader")
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}
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