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