mirror of https://github.com/perkeep/perkeep.git
79 lines
1.5 KiB
Go
79 lines
1.5 KiB
Go
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/*
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Copyright 2011 Google Inc.
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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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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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*/
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package blob
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// TODO: use Generics if/when available
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type ChanPeeker struct {
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Ch <-chan SizedRef
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// A channel should either have a peek value or be closed:
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peek *SizedRef
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closed bool
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}
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func (cp *ChanPeeker) MustPeek() SizedRef {
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sr, ok := cp.Peek()
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if !ok {
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panic("No Peek value available")
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}
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return sr
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}
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func (cp *ChanPeeker) Peek() (sr SizedRef, ok bool) {
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if cp.closed {
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return
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}
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if cp.peek != nil {
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return *cp.peek, true
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}
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v, ok := <-cp.Ch
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if !ok {
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cp.closed = true
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return
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}
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cp.peek = &v
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return *cp.peek, true
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}
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func (cp *ChanPeeker) Closed() bool {
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cp.Peek()
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return cp.closed
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}
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func (cp *ChanPeeker) MustTake() SizedRef {
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sr, ok := cp.Take()
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if !ok {
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panic("MustTake called on empty channel")
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}
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return sr
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}
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func (cp *ChanPeeker) Take() (sr SizedRef, ok bool) {
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v, ok := cp.Peek()
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if !ok {
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return
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}
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cp.peek = nil
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return v, true
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}
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func (cp *ChanPeeker) ConsumeAll() {
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for !cp.Closed() {
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cp.Take()
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}
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}
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