contexts.go

import (
	"context"
	"sync/atomic"
	"time"
)

type Contexts struct {
	ReaderContext context.Context
	ReaderCancel  context.CancelFunc
	WriterContext context.Context
	WriterCancel  context.CancelFunc
	doneChan      chan struct{}
	readerDone    uintptr
	writerDone    uintptr
}

func NewContexts(rc context.Context, rcan context.CancelFunc, wc context.Context, wcan context.CancelFunc) *Contexts {
	ctxts := &Contexts{
		ReaderContext: rc,
		ReaderCancel:  rcan,
		WriterContext: wc,

errors.go

import (
	"context"
	"sync/atomic"
	"time"
)

type Contexts struct {
	ReaderContext context.Context
	ReaderCancel  context.CancelFunc
	WriterContext context.Context
	WriterCancel  context.CancelFunc
	doneChan      chan struct{}
	readerDone    uintptr
	writerDone    uintptr
}

func NewContexts(rc context.Context, rcan context.CancelFunc, wc context.Context, wcan context.CancelFunc) *Contexts {
	ctxts := &Contexts{
		ReaderContext: rc,
		ReaderCancel:  rcan,
		WriterContext: wc,

undoable_scanner.go

package main

import (
	"bufio"
	"io"
)

type UndoableScanner struct {
	inner *bufio.Scanner
	undo  [][]byte
	next  []byte
}

func (s *UndoableScanner) Buffer(buf []byte, max int) {
	s.inner.Buffer(buf, max)
}

func (s *UndoableScanner) Bytes() []byte {
	if len(s.undo) > 0 {
		return s.next
	} else {
		return s.inner.Bytes()
	}
}

func (s *UndoableScanner) Text() string {
	return string(s.Bytes())
}

func (s *UndoableScanner) Err() error {
	return s.inner.Err()
}

func (s *UndoableScanner) Scan() bool {
	if len(s.undo) > 0 {
		s.next = s.undo[0]
		s.undo = s.undo[1:]
		return true
	} else {
		return s.inner.Scan()
	}
}

func (s *UndoableScanner) Undo(b []byte) {
	s.undo = append(s.undo, b)
	s.next = nil
}

func NewUndoableScanner(r io.Reader, split bufio.SplitFunc) *UndoableScanner {
	s := bufio.NewScanner(r)
	s.Split(split)
	return &UndoableScanner{
		inner: s,
		undo:  make([][]byte, 0, 16),
		next:  nil,
	}
}