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238 lines
7.1 KiB
Go
238 lines
7.1 KiB
Go
/*
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Package liner implements a simple command line editor, inspired by linenoise
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(https://github.com/antirez/linenoise/). This package supports WIN32 in
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addition to the xterm codes supported by everything else.
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*/
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package liner
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import (
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"bufio"
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"container/ring"
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"errors"
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"fmt"
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"io"
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"strings"
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"sync"
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"unicode/utf8"
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)
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type commonState struct {
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terminalSupported bool
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outputRedirected bool
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inputRedirected bool
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history []string
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historyMutex sync.RWMutex
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completer WordCompleter
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columns int
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killRing *ring.Ring
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ctrlCAborts bool
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r *bufio.Reader
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tabStyle TabStyle
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multiLineMode bool
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cursorRows int
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maxRows int
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shouldRestart ShouldRestart
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}
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// TabStyle is used to select how tab completions are displayed.
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type TabStyle int
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// Two tab styles are currently available:
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//
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// TabCircular cycles through each completion item and displays it directly on
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// the prompt
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//
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// TabPrints prints the list of completion items to the screen after a second
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// tab key is pressed. This behaves similar to GNU readline and BASH (which
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// uses readline)
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const (
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TabCircular TabStyle = iota
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TabPrints
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)
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// ErrPromptAborted is returned from Prompt or PasswordPrompt when the user presses Ctrl-C
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// if SetCtrlCAborts(true) has been called on the State
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var ErrPromptAborted = errors.New("prompt aborted")
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// ErrNotTerminalOutput is returned from Prompt or PasswordPrompt if the
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// platform is normally supported, but stdout has been redirected
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var ErrNotTerminalOutput = errors.New("standard output is not a terminal")
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// Max elements to save on the killring
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const KillRingMax = 60
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// HistoryLimit is the maximum number of entries saved in the scrollback history.
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const HistoryLimit = 1000
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// ReadHistory reads scrollback history from r. Returns the number of lines
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// read, and any read error (except io.EOF).
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func (s *State) ReadHistory(r io.Reader) (num int, err error) {
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s.historyMutex.Lock()
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defer s.historyMutex.Unlock()
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in := bufio.NewReader(r)
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num = 0
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for {
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line, part, err := in.ReadLine()
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if err == io.EOF {
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break
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}
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if err != nil {
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return num, err
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}
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if part {
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return num, fmt.Errorf("line %d is too long", num+1)
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}
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if !utf8.Valid(line) {
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return num, fmt.Errorf("invalid string at line %d", num+1)
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}
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num++
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s.history = append(s.history, string(line))
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if len(s.history) > HistoryLimit {
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s.history = s.history[1:]
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}
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}
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return num, nil
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}
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// WriteHistory writes scrollback history to w. Returns the number of lines
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// successfully written, and any write error.
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//
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// Unlike the rest of liner's API, WriteHistory is safe to call
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// from another goroutine while Prompt is in progress.
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// This exception is to facilitate the saving of the history buffer
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// during an unexpected exit (for example, due to Ctrl-C being invoked)
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func (s *State) WriteHistory(w io.Writer) (num int, err error) {
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s.historyMutex.RLock()
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defer s.historyMutex.RUnlock()
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for _, item := range s.history {
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_, err := fmt.Fprintln(w, item)
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if err != nil {
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return num, err
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}
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num++
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}
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return num, nil
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}
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// AppendHistory appends an entry to the scrollback history. AppendHistory
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// should be called iff Prompt returns a valid command.
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func (s *State) AppendHistory(item string) {
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s.historyMutex.Lock()
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defer s.historyMutex.Unlock()
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if len(s.history) > 0 {
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if item == s.history[len(s.history)-1] {
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return
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}
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}
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s.history = append(s.history, item)
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if len(s.history) > HistoryLimit {
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s.history = s.history[1:]
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}
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}
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// Returns the history lines starting with prefix
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func (s *State) getHistoryByPrefix(prefix string) (ph []string) {
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for _, h := range s.history {
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if strings.HasPrefix(h, prefix) {
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ph = append(ph, h)
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}
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}
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return
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}
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// Returns the history lines matching the inteligent search
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func (s *State) getHistoryByPattern(pattern string) (ph []string, pos []int) {
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if pattern == "" {
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return
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}
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for _, h := range s.history {
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if i := strings.Index(h, pattern); i >= 0 {
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ph = append(ph, h)
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pos = append(pos, i)
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}
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}
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return
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}
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// Completer takes the currently edited line content at the left of the cursor
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// and returns a list of completion candidates.
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// If the line is "Hello, wo!!!" and the cursor is before the first '!', "Hello, wo" is passed
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// to the completer which may return {"Hello, world", "Hello, Word"} to have "Hello, world!!!".
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type Completer func(line string) []string
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// WordCompleter takes the currently edited line with the cursor position and
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// returns the completion candidates for the partial word to be completed.
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// If the line is "Hello, wo!!!" and the cursor is before the first '!', ("Hello, wo!!!", 9) is passed
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// to the completer which may returns ("Hello, ", {"world", "Word"}, "!!!") to have "Hello, world!!!".
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type WordCompleter func(line string, pos int) (head string, completions []string, tail string)
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// SetCompleter sets the completion function that Liner will call to
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// fetch completion candidates when the user presses tab.
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func (s *State) SetCompleter(f Completer) {
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if f == nil {
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s.completer = nil
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return
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}
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s.completer = func(line string, pos int) (string, []string, string) {
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return "", f(string([]rune(line)[:pos])), string([]rune(line)[pos:])
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}
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}
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// SetWordCompleter sets the completion function that Liner will call to
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// fetch completion candidates when the user presses tab.
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func (s *State) SetWordCompleter(f WordCompleter) {
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s.completer = f
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}
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// SetTabCompletionStyle sets the behvavior when the Tab key is pressed
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// for auto-completion. TabCircular is the default behavior and cycles
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// through the list of candidates at the prompt. TabPrints will print
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// the available completion candidates to the screen similar to BASH
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// and GNU Readline
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func (s *State) SetTabCompletionStyle(tabStyle TabStyle) {
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s.tabStyle = tabStyle
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}
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// ModeApplier is the interface that wraps a representation of the terminal
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// mode. ApplyMode sets the terminal to this mode.
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type ModeApplier interface {
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ApplyMode() error
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}
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// SetCtrlCAborts sets whether Prompt on a supported terminal will return an
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// ErrPromptAborted when Ctrl-C is pressed. The default is false (will not
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// return when Ctrl-C is pressed). Unsupported terminals typically raise SIGINT
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// (and Prompt does not return) regardless of the value passed to SetCtrlCAborts.
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func (s *State) SetCtrlCAborts(aborts bool) {
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s.ctrlCAborts = aborts
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}
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// SetMultiLineMode sets whether line is auto-wrapped. The default is false (single line).
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func (s *State) SetMultiLineMode(mlmode bool) {
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s.multiLineMode = mlmode
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}
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// ShouldRestart is passed the error generated by readNext and returns true if
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// the the read should be restarted or false if the error should be returned.
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type ShouldRestart func(err error) bool
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// SetShouldRestart sets the restart function that Liner will call to determine
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// whether to retry the call to, or return the error returned by, readNext.
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func (s *State) SetShouldRestart(f ShouldRestart) {
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s.shouldRestart = f
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}
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func (s *State) promptUnsupported(p string) (string, error) {
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if !s.inputRedirected || !s.terminalSupported {
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fmt.Print(p)
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}
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linebuf, _, err := s.r.ReadLine()
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if err != nil {
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return "", err
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}
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return string(linebuf), nil
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}
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