[llgo] cmd/llgoi: use line editor

[axw]

Summary

This diff adds line-editing to llgoi, by
vendoring and using github.com/peterh/liner.
I have only implemented the basics here;
follow-ups will come later to add persisted
history, and completion,

[pcc]

Thanks for working on this much-needed usability improvement.

I played around with your change locally, and it seems to break one of the tests (llgoi/panic.test).

cmd/llgoi/llgoi.go

522

It looks like liner doesn't do this for us, so we probably need to keep doing it ourselves.

539

It doesn't look like liner deals with multi-line history entries very well. (e.g. try typing "{<nl>}<nl><up>" and then editing the line). Can we maybe strip newlines and apply semicolon insertion where necessary instead of saving the literal newlines?

[axw]

In D9811#174002, @pcc wrote:

Thanks for working on this much-needed usability improvement.

I played around with your change locally, and it seems to break one of the tests (llgoi/panic.test).

Fixed. Prompt() doesn't return the newline, so we need to add one.

[axw]

Collapse history lines, add semicolons

Also, append newlines to lines passed
to readLine, and reinstate newline
written when in terminal mode.

[axw]

Sorry, just realised I hadn't submitted my replies. PTAL.

cmd/llgoi/llgoi.go

522

Reinstated.

539

I've done that now. Lines are collapsed, and semicolons (added by go/scanner) are written where necessary.

[pcc]

Please add liner to the list of third-party packages in LICENSE.TXT. Other than that, LGTM.

update_third_party.sh

104

Wouldn't this leave a .git directory in third_party/liner?

[axw]

Fix update_third_party.sh, update LICENSE.TXT

[axw]

Thanks, updated LICENSE.TXT.

update_third_party.sh

104

Yes, added && rm -fr .git.

CMakeLists.txt

 llvm_add_go_executable(cc-wrapper llvm.org/llgo/cmd/cc-wrapper DEPENDS
   cmd/cc-wrapper/main.go
 )
 
 llvm_add_go_executable(llgoi llvm.org/llgo/cmd/llgoi
   DEPENDS libgo ${CMAKE_BINARY_DIR}/bin/llgo${CMAKE_EXECUTABLE_SUFFIX}
           ${CMAKE_BINARY_DIR}/lib/go/llgo-${LLGO_VERSION}/cgo
           ${CMAKE_BINARY_DIR}/bin/llgo-go${CMAKE_EXECUTABLE_SUFFIX}
-          cmd/llgoi/isatty_posix.go
           cmd/llgoi/llgoi.go
   GOFLAGS "cc=${CMAKE_BINARY_DIR}/bin/clang"
           "cxx=${CMAKE_BINARY_DIR}/bin/clang++"
           "go=${CMAKE_BINARY_DIR}/bin/llgo-go"
 )
 
 install(FILES ${CMAKE_BINARY_DIR}/bin/llgo${CMAKE_EXECUTABLE_SUFFIX}
               ${CMAKE_BINARY_DIR}/bin/llgoi${CMAKE_EXECUTABLE_SUFFIX}

LICENSE.TXT

 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
 
 ==============================================================================
 The LLVM software contains code written by third parties.  Such software will
-have its own individual LICENSE.TXT file in the directory in which it appears.
-This file will describe the copyrights, license, and restrictions which apply
-to that code.
+have its own individual LICENSE or COPYING file in the directory in which it
+appears. This file will describe the copyrights, license, and restrictions
+which apply to that code.
 
 The disclaimer of warranty in the University of Illinois Open Source License
 applies to all code in the LLVM Distribution, and nothing in any of the
 other licenses gives permission to use the names of the LLVM Team or the
 University of Illinois to endorse or promote products derived from this
 Software.
 
 The following pieces of software have additional or alternate copyrights,
 licenses, and/or restrictions:
 
 Program             Directory
 -------             ---------
 go.tools            third_party/gotools
 gofrontend          third_party/gofrontend
+liner               third_party/liner
 

cmd/llgoi/isatty_posix.go

-//===- isatty_posix.go - isatty implementation for POSIX ------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// Implements isatty for POSIX systems.
-//
-//===----------------------------------------------------------------------===//
-
-package main
-
-// +build !windows
-
-/*
-#include <unistd.h>
-*/
-import "C"
-
-import (
-  "os"
-)
-
-func isatty(file *os.File) bool {
-  return C.isatty(C.int(file.Fd())) != 0
-}

cmd/llgoi/llgoi.go

 //===- llgoi.go - llgo-based Go REPL --------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This is llgoi, a Go REPL based on llgo and the LLVM JIT.
 //
 //===----------------------------------------------------------------------===//
 
 package main
 
 import (
-  "bufio"
   "bytes"
   "errors"
   "fmt"
   "go/ast"
   "go/build"
   "go/parser"
   "go/scanner"
   "go/token"
   "io"
   "os"
   "os/exec"
   "path/filepath"
   "runtime/debug"
   "strconv"
   "strings"
   "unsafe"
 
   "llvm.org/llgo/driver"
   "llvm.org/llgo/irgen"
   "llvm.org/llgo/third_party/gotools/go/types"
+  "llvm.org/llgo/third_party/liner"
   "llvm.org/llvm/bindings/go/llvm"
 )
 
 func getInstPrefix() (string, error) {
   path, err := exec.LookPath(os.Args[0])
   if err != nil {
     return "", err
   }
type line struct {
   assigns  []string
 
   parens, bracks, braces int
 }
 
 type interp struct {
   engine llvm.ExecutionEngine
 
+  liner       *liner.State
   pendingLine line
 
   copts irgen.CompilerOptions
 
   imports []*types.Package
   scope   map[string]types.Object
 
   pkgmap map[string]*types.Package
if pkg, ok := pkgmap[pkgpath]; ok && pkg.Complete() {
       return pkg, nil
     }
     return origImporter(pkgmap, pkgpath)
   }
   return nil
 }
 
 func (in *interp) init() error {
+  in.liner = liner.NewLiner()
   in.scope = make(map[string]types.Object)
   in.pkgmap = make(map[string]*types.Package)
 
   err := in.makeCompilerOptions()
   if err != nil {
     return err
   }
 
   return nil
 }
 
 func (in *interp) dispose() {
+  in.liner.Close()
   in.engine.Dispose()
 }
 
 func (in *interp) loadSourcePackageFromCode(pkgcode, pkgpath string, copts irgen.CompilerOptions) (*types.Package, error) {
   fset := token.NewFileSet()
   file, err := parser.ParseFile(fset, "<input>", pkgcode, parser.DeclarationErrors|parser.ParseComments)
   if err != nil {
     return nil, err
func (in *interp) loadPackage(pkgpath string) (*types.Package, error) {
   files, err := driver.ParseFiles(fset, inputs)
   if err != nil {
     return nil, err
   }
 
   return in.loadSourcePackage(fset, files, pkgpath, in.copts)
 }
 
+// readLine accumulates lines of input, including trailing newlines,
+// executing statements as they are completed.
 func (in *interp) readLine(line string) error {
   if !in.pendingLine.ready() {
     return in.readExprLine(line, nil)
   }
 
   var s scanner.Scanner
   fset := token.NewFileSet()
   file := fset.AddFile("", fset.Base(), len(line))
case token.IDENT:
 
     fallthrough
 
   default:
     return in.readExprLine(line, nil)
   }
 }
 
+// formatHistory reformats the provided Go source by collapsing all lines
+// and adding semicolons where required, suitable for adding to line history.
+func formatHistory(input []byte) string {
+  var buf bytes.Buffer
+  var s scanner.Scanner
+  fset := token.NewFileSet()
+  file := fset.AddFile("", fset.Base(), len(input))
+  s.Init(file, input, nil, 0)
+  pos, tok, lit := s.Scan()
+  for tok != token.EOF {
+    if int(pos)-1 > buf.Len() {
+      n := int(pos) - 1 - buf.Len()
+      buf.WriteString(strings.Repeat(" ", n))
+    }
+    var semicolon bool
+    if tok == token.SEMICOLON {
+      semicolon = true
+    } else if lit != "" {
+      buf.WriteString(lit)
+    } else {
+      buf.WriteString(tok.String())
+    }
+    pos, tok, lit = s.Scan()
+    if semicolon {
+      switch tok {
+      case token.RBRACE, token.RPAREN, token.EOF:
+      default:
+        buf.WriteRune(';')
+      }
+    }
+  }
+  return buf.String()
+}
+
 func main() {
   llvm.LinkInMCJIT()
   llvm.InitializeNativeTarget()
   llvm.InitializeNativeAsmPrinter()
 
   var in interp
   err := in.init()
   if err != nil {
     panic(err)
   }
   defer in.dispose()
 
-  tty := isatty(os.Stdin)
-
-  r := bufio.NewReader(os.Stdin)
+  var buf bytes.Buffer
   for {
-    if tty {
-      if in.pendingLine.ready() {
-        os.Stdout.WriteString("(llgo) ")
-      } else {
-        os.Stdout.WriteString("       ")
-      }
+    if in.pendingLine.ready() && buf.Len() > 0 {
+      history := formatHistory(buf.Bytes())
+      in.liner.AppendHistory(history)
+      buf.Reset()
+    prompt := "(llgo) "
+    if !in.pendingLine.ready() {
+      prompt = strings.Repeat(" ", len(prompt))
     }
-    line, err := r.ReadString('\n')
+    line, err := in.liner.Prompt(prompt)
     if err == io.EOF {
       break
     } else if err != nil {
       panic(err)
     }
-
-    err = in.readLine(line)
+    if line == "" {
+      continue
+    }
+    buf.WriteString(line + "\n")
+    err = in.readLine(line + "\n")
     if err != nil {
       fmt.Println(err)
     }
   }
 
-  if tty {
-    os.Stdout.WriteString("\n")
+  if liner.TerminalSupported() {
+    fmt.Println()
   }
 }

third_party/liner/COPYING

+Copyright © 2012 Peter Harris
+
+Permission is hereby granted, free of charge, to any person obtaining a
+copy of this software and associated documentation files (the "Software"),
+to deal in the Software without restriction, including without limitation
+the rights to use, copy, modify, merge, publish, distribute, sublicense,
+and/or sell copies of the Software, and to permit persons to whom the
+Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice (including the next
+paragraph) shall be included in all copies or substantial portions of the
+Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+

third_party/liner/README.md

+Liner
+=====
+
+Liner is a command line editor with history. It was inspired by linenoise;
+everything Unix-like is a VT100 (or is trying very hard to be). If your
+terminal is not pretending to be a VT100, change it. Liner also support
+Windows.
+
+Liner is released under the X11 license (which is similar to the new BSD
+license).
+
+Line Editing
+------------
+
+The following line editing commands are supported on platforms and terminals
+that Liner supports:
+
+Keystroke    | Action
+---------    | ------
+Ctrl-A, Home | Move cursor to beginning of line
+Ctrl-E, End  | Move cursor to end of line
+Ctrl-B, Left | Move cursor one character left
+Ctrl-F, Right| Move cursor one character right
+Ctrl-Left    | Move cursor to previous word
+Ctrl-Right   | Move cursor to next word
+Ctrl-D, Del  | (if line is *not* empty) Delete character under cursor
+Ctrl-D       | (if line *is* empty) End of File - usually quits application
+Ctrl-C       | Reset input (create new empty prompt)
+Ctrl-L       | Clear screen (line is unmodified)
+Ctrl-T       | Transpose previous character with current character
+Ctrl-H, BackSpace | Delete character before cursor
+Ctrl-W       | Delete word leading up to cursor
+Ctrl-K       | Delete from cursor to end of line
+Ctrl-U       | Delete from start of line to cursor
+Ctrl-P, Up   | Previous match from history
+Ctrl-N, Down | Next match from history
+Ctrl-R       | Reverse Search history (Ctrl-S forward, Ctrl-G cancel)
+Ctrl-Y       | Paste from Yank buffer (Alt-Y to paste next yank instead)
+Tab          | Next completion
+Shift-Tab    | (after Tab) Previous completion
+
+Getting started
+-----------------
+
+```go
+package main
+
+import (
+  "log"
+  "os"
+  "strings"
+
+  "github.com/peterh/liner"
+)
+
+var (
+  history_fn = "/tmp/.liner_history"
+  names      = []string{"john", "james", "mary", "nancy"}
+)
+
+func main() {
+  line := liner.NewLiner()
+  defer line.Close()
+
+  line.SetCompleter(func(line string) (c []string) {
+    for _, n := range names {
+      if strings.HasPrefix(n, strings.ToLower(line)) {
+        c = append(c, n)
+      }
+    }
+    return
+  })
+
+  if f, err := os.Open(history_fn); err == nil {
+    line.ReadHistory(f)
+    f.Close()
+  }
+
+  if name, err := line.Prompt("What is your name? "); err != nil {
+    log.Print("Error reading line: ", err)
+  } else {
+    log.Print("Got: ", name)
+    line.AppendHistory(name)
+  }
+
+  if f, err := os.Create(history_fn); err != nil {
+    log.Print("Error writing history file: ", err)
+  } else {
+    line.WriteHistory(f)
+    f.Close()
+  }
+}
+```
+
+For documentation, see http://godoc.org/github.com/peterh/liner

third_party/liner/bsdinput.go

+// +build openbsd freebsd netbsd
+
+package liner
+
+import "syscall"
+
+const (
+  getTermios = syscall.TIOCGETA
+  setTermios = syscall.TIOCSETA
+)
+
+const (
+  // Input flags
+  inpck  = 0x010
+  istrip = 0x020
+  icrnl  = 0x100
+  ixon   = 0x200
+
+  // Output flags
+  opost = 0x1
+
+  // Control flags
+  cs8 = 0x300
+
+  // Local flags
+  isig   = 0x080
+  icanon = 0x100
+  iexten = 0x400
+)
+
+type termios struct {
+  Iflag  uint32
+  Oflag  uint32
+  Cflag  uint32
+  Lflag  uint32
+  Cc     [20]byte
+  Ispeed int32
+  Ospeed int32
+}

third_party/liner/common.go

+/*
+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
+}
+
+// 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
+}
+
+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
+}

third_party/liner/fallbackinput.go

+// +build !windows,!linux,!darwin,!openbsd,!freebsd,!netbsd
+
+package liner
+
+import (
+  "bufio"
+  "errors"
+  "os"
+)
+
+// State represents an open terminal
+type State struct {
+  commonState
+}
+
+// Prompt displays p, and then waits for user input. Prompt does not support
+// line editing on this operating system.
+func (s *State) Prompt(p string) (string, error) {
+  return s.promptUnsupported(p)
+}
+
+// PasswordPrompt is not supported in this OS.
+func (s *State) PasswordPrompt(p string) (string, error) {
+  return "", errors.New("liner: function not supported in this terminal")
+}
+
+// NewLiner initializes a new *State
+//
+// Note that this operating system uses a fallback mode without line
+// editing. Patches welcome.
+func NewLiner() *State {
+  var s State
+  s.r = bufio.NewReader(os.Stdin)
+  return &s
+}
+
+// Close returns the terminal to its previous mode
+func (s *State) Close() error {
+  return nil
+}
+
+// TerminalSupported returns false because line editing is not
+// supported on this platform.
+func TerminalSupported() bool {
+  return false
+}
+
+type noopMode struct{}
+
+func (n noopMode) ApplyMode() error {
+  return nil
+}
+
+// TerminalMode returns a noop InputModeSetter on this platform.
+func TerminalMode() (ModeApplier, error) {
+  return noopMode{}, nil
+}

third_party/liner/input.go

+// +build linux darwin openbsd freebsd netbsd
+
+package liner
+
+import (
+  "bufio"
+  "errors"
+  "os"
+  "os/signal"
+  "strconv"
+  "strings"
+  "syscall"
+  "time"
+)
+
+type nexter struct {
+  r   rune
+  err error
+}
+
+// State represents an open terminal
+type State struct {
+  commonState
+  origMode    termios
+  defaultMode termios
+  next        <-chan nexter
+  winch       chan os.Signal
+  pending     []rune
+  useCHA      bool
+}
+
+// NewLiner initializes a new *State, and sets the terminal into raw mode. To
+// restore the terminal to its previous state, call State.Close().
+//
+// Note if you are still using Go 1.0: NewLiner handles SIGWINCH, so it will
+// leak a channel every time you call it. Therefore, it is recommened that you
+// upgrade to a newer release of Go, or ensure that NewLiner is only called
+// once.
+func NewLiner() *State {
+  var s State
+  s.r = bufio.NewReader(os.Stdin)
+
+  s.terminalSupported = TerminalSupported()
+  if m, err := TerminalMode(); err == nil {
+    s.origMode = *m.(*termios)
+  } else {
+    s.inputRedirected = true
+  }
+  if _, err := getMode(syscall.Stdout); err != 0 {
+    s.outputRedirected = true
+  }
+  if s.inputRedirected && s.outputRedirected {
+    s.terminalSupported = false
+  }
+  if s.terminalSupported && !s.inputRedirected && !s.outputRedirected {
+    mode := s.origMode
+    mode.Iflag &^= icrnl | inpck | istrip | ixon
+    mode.Cflag |= cs8
+    mode.Lflag &^= syscall.ECHO | icanon | iexten
+    mode.ApplyMode()
+
+    winch := make(chan os.Signal, 1)
+    signal.Notify(winch, syscall.SIGWINCH)
+    s.winch = winch
+
+    s.checkOutput()
+  }
+
+  if !s.outputRedirected {
+    s.getColumns()
+    s.outputRedirected = s.columns <= 0
+  }
+
+  return &s
+}
+
+var errTimedOut = errors.New("timeout")
+
+func (s *State) startPrompt() {
+  if s.terminalSupported {
+    if m, err := TerminalMode(); err == nil {
+      s.defaultMode = *m.(*termios)
+      mode := s.defaultMode
+      mode.Lflag &^= isig
+      mode.ApplyMode()
+    }
+  }
+  s.restartPrompt()
+}
+
+func (s *State) restartPrompt() {
+  next := make(chan nexter)
+  go func() {
+    for {
+      var n nexter
+      n.r, _, n.err = s.r.ReadRune()
+      next <- n
+      // Shut down nexter loop when an end condition has been reached
+      if n.err != nil || n.r == '\n' || n.r == '\r' || n.r == ctrlC || n.r == ctrlD {
+        close(next)
+        return
+      }
+    }
+  }()
+  s.next = next
+}
+
+func (s *State) stopPrompt() {
+  if s.terminalSupported {
+    s.defaultMode.ApplyMode()
+  }
+}
+
+func (s *State) nextPending(timeout <-chan time.Time) (rune, error) {
+  select {
+  case thing, ok := <-s.next:
+    if !ok {
+      return 0, errors.New("liner: internal error")
+    }
+    if thing.err != nil {
+      return 0, thing.err
+    }
+    s.pending = append(s.pending, thing.r)
+    return thing.r, nil
+  case <-timeout:
+    rv := s.pending[0]
+    s.pending = s.pending[1:]
+    return rv, errTimedOut
+  }
+  // not reached
+  return 0, nil
+}
+
+func (s *State) readNext() (interface{}, error) {
+  if len(s.pending) > 0 {
+    rv := s.pending[0]
+    s.pending = s.pending[1:]
+    return rv, nil
+  }
+  var r rune
+  select {
+  case thing, ok := <-s.next:
+    if !ok {
+      return 0, errors.New("liner: internal error")
+    }
+    if thing.err != nil {
+      return nil, thing.err
+    }
+    r = thing.r
+  case <-s.winch:
+    s.getColumns()
+    return winch, nil
+  }
+  if r != esc {
+    return r, nil
+  }
+  s.pending = append(s.pending, r)
+
+  // Wait at most 50 ms for the rest of the escape sequence
+  // If nothing else arrives, it was an actual press of the esc key
+  timeout := time.After(50 * time.Millisecond)
+  flag, err := s.nextPending(timeout)
+  if err != nil {
+    if err == errTimedOut {
+      return flag, nil
+    }
+    return unknown, err
+  }
+
+  switch flag {
+  case '[':
+    code, err := s.nextPending(timeout)
+    if err != nil {
+      if err == errTimedOut {
+        return code, nil
+      }
+      return unknown, err
+    }
+    switch code {
+    case 'A':
+      s.pending = s.pending[:0] // escape code complete
+      return up, nil
+    case 'B':
+      s.pending = s.pending[:0] // escape code complete
+      return down, nil
+    case 'C':
+      s.pending = s.pending[:0] // escape code complete
+      return right, nil
+    case 'D':
+      s.pending = s.pending[:0] // escape code complete
+      return left, nil
+    case 'F':
+      s.pending = s.pending[:0] // escape code complete
+      return end, nil
+    case 'H':
+      s.pending = s.pending[:0] // escape code complete
+      return home, nil
+    case 'Z':
+      s.pending = s.pending[:0] // escape code complete
+      return shiftTab, nil
+    case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+      num := []rune{code}
+      for {
+        code, err := s.nextPending(timeout)
+        if err != nil {
+          if err == errTimedOut {
+            return code, nil
+          }
+          return nil, err
+        }
+        switch code {
+        case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+          num = append(num, code)
+        case ';':
+          // Modifier code to follow
+          // This only supports Ctrl-left and Ctrl-right for now
+          x, _ := strconv.ParseInt(string(num), 10, 32)
+          if x != 1 {
+            // Can't be left or right
+            rv := s.pending[0]
+            s.pending = s.pending[1:]
+            return rv, nil
+          }
+          num = num[:0]
+          for {
+            code, err = s.nextPending(timeout)
+            if err != nil {
+              if err == errTimedOut {
+                rv := s.pending[0]
+                s.pending = s.pending[1:]
+                return rv, nil
+              }
+              return nil, err
+            }
+            switch code {
+            case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+              num = append(num, code)
+            case 'C', 'D':
+              // right, left
+              mod, _ := strconv.ParseInt(string(num), 10, 32)
+              if mod != 5 {
+                // Not bare Ctrl
+                rv := s.pending[0]
+                s.pending = s.pending[1:]
+                return rv, nil
+              }
+              s.pending = s.pending[:0] // escape code complete
+              if code == 'C' {
+                return wordRight, nil
+              }
+              return wordLeft, nil
+            default:
+              // Not left or right
+              rv := s.pending[0]
+              s.pending = s.pending[1:]
+              return rv, nil
+            }
+          }
+        case '~':
+          s.pending = s.pending[:0] // escape code complete
+          x, _ := strconv.ParseInt(string(num), 10, 32)
+          switch x {
+          case 2:
+            return insert, nil
+          case 3:
+            return del, nil
+          case 5:
+            return pageUp, nil
+          case 6:
+            return pageDown, nil
+          case 7:
+            return home, nil
+          case 8:
+            return end, nil
+          case 15:
+            return f5, nil
+          case 17:
+            return f6, nil
+          case 18:
+            return f7, nil
+          case 19:
+            return f8, nil
+          case 20:
+            return f9, nil
+          case 21:
+            return f10, nil
+          case 23:
+            return f11, nil
+          case 24:
+            return f12, nil
+          default:
+            return unknown, nil
+          }
+        default:
+          // unrecognized escape code
+          rv := s.pending[0]
+          s.pending = s.pending[1:]
+          return rv, nil
+        }
+      }
+    }
+
+  case 'O':
+    code, err := s.nextPending(timeout)
+    if err != nil {
+      if err == errTimedOut {
+        return code, nil
+      }
+      return nil, err
+    }
+    s.pending = s.pending[:0] // escape code complete
+    switch code {
+    case 'c':
+      return wordRight, nil
+    case 'd':
+      return wordLeft, nil
+    case 'H':
+      return home, nil
+    case 'F':
+      return end, nil
+    case 'P':
+      return f1, nil
+    case 'Q':
+      return f2, nil
+    case 'R':
+      return f3, nil
+    case 'S':
+      return f4, nil
+    default:
+      return unknown, nil
+    }
+  case 'y':
+    s.pending = s.pending[:0] // escape code complete
+    return altY, nil
+  default:
+    rv := s.pending[0]
+    s.pending = s.pending[1:]
+    return rv, nil
+  }
+
+  // not reached
+  return r, nil
+}
+
+// Close returns the terminal to its previous mode
+func (s *State) Close() error {
+  stopSignal(s.winch)
+  if !s.inputRedirected {
+    s.origMode.ApplyMode()
+  }
+  return nil
+}
+
+// TerminalSupported returns true if the current terminal supports
+// line editing features, and false if liner will use the 'dumb'
+// fallback for input.
+// Note that TerminalSupported does not check all factors that may
+// cause liner to not fully support the terminal (such as stdin redirection)
+func TerminalSupported() bool {
+  bad := map[string]bool{"": true, "dumb": true, "cons25": true}
+  return !bad[strings.ToLower(os.Getenv("TERM"))]
+}

third_party/liner/input_darwin.go

+// +build darwin
+
+package liner
+
+import "syscall"
+
+const (
+  getTermios = syscall.TIOCGETA
+  setTermios = syscall.TIOCSETA
+)
+
+const (
+  // Input flags
+  inpck  = 0x010
+  istrip = 0x020
+  icrnl  = 0x100
+  ixon   = 0x200
+
+  // Output flags
+  opost = 0x1
+
+  // Control flags
+  cs8 = 0x300
+
+  // Local flags
+  isig   = 0x080
+  icanon = 0x100
+  iexten = 0x400
+)
+
+type termios struct {
+  Iflag  uintptr
+  Oflag  uintptr
+  Cflag  uintptr
+  Lflag  uintptr
+  Cc     [20]byte
+  Ispeed uintptr
+  Ospeed uintptr
+}

third_party/liner/input_linux.go

+// +build linux
+
+package liner
+
+import "syscall"
+
+const (
+  getTermios = syscall.TCGETS
+  setTermios = syscall.TCSETS
+)
+
+const (
+  icrnl  = syscall.ICRNL
+  inpck  = syscall.INPCK
+  istrip = syscall.ISTRIP
+  ixon   = syscall.IXON
+  opost  = syscall.OPOST
+  cs8    = syscall.CS8
+  isig   = syscall.ISIG
+  icanon = syscall.ICANON
+  iexten = syscall.IEXTEN
+)
+
+type termios struct {
+  syscall.Termios
+}

third_party/liner/input_test.go

+// +build !windows
+
+package liner
+
+import (
+  "bufio"
+  "bytes"
+  "testing"
+)
+
+func (s *State) expectRune(t *testing.T, r rune) {
+  item, err := s.readNext()
+  if err != nil {
+    t.Fatalf("Expected rune '%c', got error %s\n", r, err)
+  }
+  if v, ok := item.(rune); !ok {
+    t.Fatalf("Expected rune '%c', got non-rune %v\n", r, v)
+  } else {
+    if v != r {
+      t.Fatalf("Expected rune '%c', got rune '%c'\n", r, v)
+    }
+  }
+}
+
+func (s *State) expectAction(t *testing.T, a action) {
+  item, err := s.readNext()
+  if err != nil {
+    t.Fatalf("Expected Action %d, got error %s\n", a, err)
+  }
+  if v, ok := item.(action); !ok {
+    t.Fatalf("Expected Action %d, got non-Action %v\n", a, v)
+  } else {
+    if v != a {
+      t.Fatalf("Expected Action %d, got Action %d\n", a, v)
+    }
+  }
+}
+
+func TestTypes(t *testing.T) {
+  input := []byte{'A', 27, 'B', 27, 91, 68, 27, '[', '1', ';', '5', 'D', 'e'}
+  var s State
+  s.r = bufio.NewReader(bytes.NewBuffer(input))
+
+  next := make(chan nexter)
+  go func() {
+    for {
+      var n nexter
+      n.r, _, n.err = s.r.ReadRune()
+      next <- n
+    }
+  }()
+  s.next = next
+
+  s.expectRune(t, 'A')
+  s.expectRune(t, 27)
+  s.expectRune(t, 'B')
+  s.expectAction(t, left)
+  s.expectAction(t, wordLeft)
+
+  s.expectRune(t, 'e')
+}

third_party/liner/input_windows.go

+package liner
+
+import (
+  "bufio"
+  "os"
+  "syscall"
+  "unsafe"
+)
+
+var (
+  kernel32 = syscall.NewLazyDLL("kernel32.dll")
+
+  procGetStdHandle               = kernel32.NewProc("GetStdHandle")
+  procReadConsoleInput           = kernel32.NewProc("ReadConsoleInputW")
+  procGetConsoleMode             = kernel32.NewProc("GetConsoleMode")
+  procSetConsoleMode             = kernel32.NewProc("SetConsoleMode")
+  procSetConsoleCursorPosition   = kernel32.NewProc("SetConsoleCursorPosition")
+  procGetConsoleScreenBufferInfo = kernel32.NewProc("GetConsoleScreenBufferInfo")
+  procFillConsoleOutputCharacter = kernel32.NewProc("FillConsoleOutputCharacterW")
+)
+
+// These names are from the Win32 api, so they use underscores (contrary to
+// what golint suggests)
+const (
+  std_input_handle     = uint32(-10 & 0xFFFFFFFF)
+  std_output_handle    = uint32(-11 & 0xFFFFFFFF)
+  std_error_handle     = uint32(-12 & 0xFFFFFFFF)
+  invalid_handle_value = ^uintptr(0)
+)
+
+type inputMode uint32
+
+// State represents an open terminal
+type State struct {
+  commonState
+  handle      syscall.Handle
+  hOut        syscall.Handle
+  origMode    inputMode
+  defaultMode inputMode
+  key         interface{}
+  repeat      uint16
+}
+
+const (
+  enableEchoInput      = 0x4
+  enableInsertMode     = 0x20
+  enableLineInput      = 0x2
+  enableMouseInput     = 0x10
+  enableProcessedInput = 0x1
+  enableQuickEditMode  = 0x40
+  enableWindowInput    = 0x8
+)
+
+// NewLiner initializes a new *State, and sets the terminal into raw mode. To
+// restore the terminal to its previous state, call State.Close().
+func NewLiner() *State {
+  var s State
+  hIn, _, _ := procGetStdHandle.Call(uintptr(std_input_handle))
+  s.handle = syscall.Handle(hIn)
+  hOut, _, _ := procGetStdHandle.Call(uintptr(std_output_handle))
+  s.hOut = syscall.Handle(hOut)
+
+  s.terminalSupported = true
+  if m, err := TerminalMode(); err == nil {
+    s.origMode = m.(inputMode)
+    mode := s.origMode
+    mode &^= enableEchoInput
+    mode &^= enableInsertMode
+    mode &^= enableLineInput
+    mode &^= enableMouseInput
+    mode |= enableWindowInput
+    mode.ApplyMode()
+  } else {
+    s.inputRedirected = true
+    s.r = bufio.NewReader(os.Stdin)
+  }
+
+  s.getColumns()
+  s.outputRedirected = s.columns <= 0
+
+  return &s
+}
+
+// These names are from the Win32 api, so they use underscores (contrary to
+// what golint suggests)
+const (
+  focus_event              = 0x0010
+  key_event                = 0x0001
+  menu_event               = 0x0008
+  mouse_event              = 0x0002
+  window_buffer_size_event = 0x0004
+)
+
+type input_record struct {
+  eventType uint16
+  pad       uint16
+  blob      [16]byte
+}
+
+type key_event_record struct {
+  KeyDown         int32
+  RepeatCount     uint16
+  VirtualKeyCode  uint16
+  VirtualScanCode uint16
+  Char            int16
+  ControlKeyState uint32
+}
+
+// These names are from the Win32 api, so they use underscores (contrary to
+// what golint suggests)
+const (
+  vk_tab    = 0x09
+  vk_prior  = 0x21
+  vk_next   = 0x22
+  vk_end    = 0x23
+  vk_home   = 0x24
+  vk_left   = 0x25
+  vk_up     = 0x26
+  vk_right  = 0x27
+  vk_down   = 0x28
+  vk_insert = 0x2d
+  vk_delete = 0x2e
+  vk_f1     = 0x70
+  vk_f2     = 0x71
+  vk_f3     = 0x72
+  vk_f4     = 0x73
+  vk_f5     = 0x74
+  vk_f6     = 0x75
+  vk_f7     = 0x76
+  vk_f8     = 0x77
+  vk_f9     = 0x78
+  vk_f10    = 0x79
+  vk_f11    = 0x7a
+  vk_f12    = 0x7b
+  yKey      = 0x59
+)
+
+const (
+  shiftPressed     = 0x0010
+  leftAltPressed   = 0x0002
+  leftCtrlPressed  = 0x0008
+  rightAltPressed  = 0x0001
+  rightCtrlPressed = 0x0004
+
+  modKeys = shiftPressed | leftAltPressed | rightAltPressed | leftCtrlPressed | rightCtrlPressed
+)
+
+func (s *State) readNext() (interface{}, error) {
+  if s.repeat > 0 {
+    s.repeat--
+    return s.key, nil
+  }
+
+  var input input_record
+  pbuf := uintptr(unsafe.Pointer(&input))
+  var rv uint32
+  prv := uintptr(unsafe.Pointer(&rv))
+
+  for {
+    ok, _, err := procReadConsoleInput.Call(uintptr(s.handle), pbuf, 1, prv)
+
+    if ok == 0 {
+      return nil, err
+    }
+
+    if input.eventType == window_buffer_size_event {
+      xy := (*coord)(unsafe.Pointer(&input.blob[0]))
+      s.columns = int(xy.x)
+      return winch, nil
+    }
+    if input.eventType != key_event {
+      continue
+    }
+    ke := (*key_event_record)(unsafe.Pointer(&input.blob[0]))
+    if ke.KeyDown == 0 {
+      continue
+    }
+
+    if ke.VirtualKeyCode == vk_tab && ke.ControlKeyState&modKeys == shiftPressed {
+      s.key = shiftTab
+    } else if ke.VirtualKeyCode == yKey && (ke.ControlKeyState&modKeys == leftAltPressed ||
+      ke.ControlKeyState&modKeys == rightAltPressed) {
+      s.key = altY
+    } else if ke.Char > 0 {
+      s.key = rune(ke.Char)
+    } else {
+      switch ke.VirtualKeyCode {
+      case vk_prior:
+        s.key = pageUp
+      case vk_next:
+        s.key = pageDown
+      case vk_end:
+        s.key = end
+      case vk_home:
+        s.key = home
+      case vk_left:
+        s.key = left
+        if ke.ControlKeyState&(leftCtrlPressed|rightCtrlPressed) != 0 {
+          if ke.ControlKeyState&modKeys == ke.ControlKeyState&(leftCtrlPressed|rightCtrlPressed) {
+            s.key = wordLeft
+          }
+        }
+      case vk_right:
+        s.key = right
+        if ke.ControlKeyState&(leftCtrlPressed|rightCtrlPressed) != 0 {
+          if ke.ControlKeyState&modKeys == ke.ControlKeyState&(leftCtrlPressed|rightCtrlPressed) {
+            s.key = wordRight
+          }
+        }
+      case vk_up:
+        s.key = up
+      case vk_down:
+        s.key = down
+      case vk_insert:
+        s.key = insert
+      case vk_delete:
+        s.key = del
+      case vk_f1:
+        s.key = f1
+      case vk_f2:
+        s.key = f2
+      case vk_f3:
+        s.key = f3
+      case vk_f4:
+        s.key = f4
+      case vk_f5:
+        s.key = f5
+      case vk_f6:
+        s.key = f6
+      case vk_f7:
+        s.key = f7
+      case vk_f8:
+        s.key = f8
+      case vk_f9:
+        s.key = f9
+      case vk_f10:
+        s.key = f10
+      case vk_f11:
+        s.key = f11
+      case vk_f12:
+        s.key = f12
+      default:
+        // Eat modifier keys
+        // TODO: return Action(Unknown) if the key isn't a
+        // modifier.
+        continue
+      }
+    }
+
+    if ke.RepeatCount > 1 {
+      s.repeat = ke.RepeatCount - 1
+    }
+    return s.key, nil
+  }
+  return unknown, nil
+}
+
+// Close returns the terminal to its previous mode
+func (s *State) Close() error {
+  s.origMode.ApplyMode()
+  return nil
+}
+
+func (s *State) startPrompt() {
+  if m, err := TerminalMode(); err == nil {
+    s.defaultMode = m.(inputMode)
+    mode := s.defaultMode
+    mode &^= enableProcessedInput
+    mode.ApplyMode()
+  }
+}
+
+func (s *State) restartPrompt() {
+}
+
+func (s *State) stopPrompt() {
+  s.defaultMode.ApplyMode()
+}
+
+// TerminalSupported returns true because line editing is always
+// supported on Windows.
+func TerminalSupported() bool {
+  return true
+}
+
+func (mode inputMode) ApplyMode() error {
+  hIn, _, err := procGetStdHandle.Call(uintptr(std_input_handle))
+  if hIn == invalid_handle_value || hIn == 0 {
+    return err
+  }
+  ok, _, err := procSetConsoleMode.Call(hIn, uintptr(mode))
+  if ok != 0 {
+    err = nil
+  }
+  return err
+}
+
+// TerminalMode returns the current terminal input mode as an InputModeSetter.
+//
+// This function is provided for convenience, and should
+// not be necessary for most users of liner.
+func TerminalMode() (ModeApplier, error) {
+  var mode inputMode
+  hIn, _, err := procGetStdHandle.Call(uintptr(std_input_handle))
+  if hIn == invalid_handle_value || hIn == 0 {
+    return nil, err
+  }
+  ok, _, err := procGetConsoleMode.Call(hIn, uintptr(unsafe.Pointer(&mode)))
+  if ok != 0 {
+    err = nil
+  }
+  return mode, err
+}

third_party/liner/line.go

+// +build windows linux darwin openbsd freebsd netbsd
+
+package liner
+
+import (
+  "container/ring"
+  "errors"
+  "fmt"
+  "io"
+  "strings"
+  "unicode"
+  "unicode/utf8"
+)
+
+type action int
+
+const (
+  left action = iota
+  right
+  up
+  down
+  home
+  end
+  insert
+  del
+  pageUp
+  pageDown
+  f1
+  f2
+  f3
+  f4
+  f5
+  f6
+  f7
+  f8
+  f9
+  f10
+  f11
+  f12
+  altY
+  shiftTab
+  wordLeft
+  wordRight
+  winch
+  unknown
+)
+
+const (
+  ctrlA = 1
+  ctrlB = 2
+  ctrlC = 3
+  ctrlD = 4
+  ctrlE = 5
+  ctrlF = 6
+  ctrlG = 7
+  ctrlH = 8
+  tab   = 9
+  lf    = 10
+  ctrlK = 11
+  ctrlL = 12
+  cr    = 13
+  ctrlN = 14
+  ctrlO = 15
+  ctrlP = 16
+  ctrlQ = 17
+  ctrlR = 18
+  ctrlS = 19
+  ctrlT = 20
+  ctrlU = 21
+  ctrlV = 22
+  ctrlW = 23
+  ctrlX = 24
+  ctrlY = 25
+  ctrlZ = 26
+  esc   = 27
+  bs    = 127
+)
+
+const (
+  beep = "\a"
+)
+
+type tabDirection int
+
+const (
+  tabForward tabDirection = iota
+  tabReverse
+)
+
+func (s *State) refresh(prompt []rune, buf []rune, pos int) error {
+  s.cursorPos(0)
+  _, err := fmt.Print(string(prompt))
+  if err != nil {
+    return err
+  }
+
+  pLen := countGlyphs(prompt)
+  bLen := countGlyphs(buf)
+  pos = countGlyphs(buf[:pos])
+  if pLen+bLen < s.columns {
+    _, err = fmt.Print(string(buf))
+    s.eraseLine()
+    s.cursorPos(pLen + pos)
+  } else {
+    // Find space available
+    space := s.columns - pLen
+    space-- // space for cursor
+    start := pos - space/2
+    end := start + space
+    if end > bLen {
+      end = bLen
+      start = end - space
+    }
+    if start < 0 {
+      start = 0
+      end = space
+    }
+    pos -= start
+
+    // Leave space for markers
+    if start > 0 {
+      start++
+    }
+    if end < bLen {
+      end--
+    }
+    startRune := len(getPrefixGlyphs(buf, start))
+    line := getPrefixGlyphs(buf[startRune:], end-start)
+
+    // Output
+    if start > 0 {
+      fmt.Print("{")
+    }
+    fmt.Print(string(line))
+    if end < bLen {
+      fmt.Print("}")
+    }
+
+    // Set cursor position
+    s.eraseLine()
+    s.cursorPos(pLen + pos)
+  }
+  return err
+}
+
+func longestCommonPrefix(strs []string) string {
+  if len(strs) == 0 {
+    return ""
+  }
+  longest := strs[0]
+
+  for _, str := range strs[1:] {
+    for !strings.HasPrefix(str, longest) {
+      longest = longest[:len(longest)-1]
+    }
+  }
+  // Remove trailing partial runes
+  longest = strings.TrimRight(longest, "\uFFFD")
+  return longest
+}
+
+func (s *State) circularTabs(items []string) func(tabDirection) (string, error) {
+  item := -1
+  return func(direction tabDirection) (string, error) {
+    if direction == tabForward {
+      if item < len(items)-1 {
+        item++
+      } else {
+        item = 0
+      }
+    } else if direction == tabReverse {
+      if item > 0 {
+        item--
+      } else {
+        item = len(items) - 1
+      }
+    }
+    return items[item], nil
+  }
+}
+
+func (s *State) printedTabs(items []string) func(tabDirection) (string, error) {
+  numTabs := 1
+  prefix := longestCommonPrefix(items)
+  return func(direction tabDirection) (string, error) {
+    if len(items) == 1 {
+      return items[0], nil
+    }
+
+    if numTabs == 2 {
+      if len(items) > 100 {
+        fmt.Printf("\nDisplay all %d possibilities? (y or n) ", len(items))
+        for {
+          next, err := s.readNext()
+          if err != nil {
+            return prefix, err
+          }
+
+          if key, ok := next.(rune); ok {
+            if unicode.ToLower(key) == 'n' {
+              return prefix, nil
+            } else if unicode.ToLower(key) == 'y' {
+              break
+            }
+          }
+        }
+      }
+      fmt.Println("")
+      maxWidth := 0
+      for _, item := range items {
+        if len(item) >= maxWidth {
+          maxWidth = len(item) + 1
+        }
+      }
+
+      numColumns := s.columns / maxWidth
+      numRows := len(items) / numColumns
+      if len(items)%numColumns > 0 {
+        numRows++
+      }
+
+      if len(items) <= numColumns {
+        maxWidth = 0
+      }
+      for i := 0; i < numRows; i++ {
+        for j := 0; j < numColumns*numRows; j += numRows {
+          if i+j < len(items) {
+            if maxWidth > 0 {
+              fmt.Printf("%-*s", maxWidth, items[i+j])
+            } else {
+              fmt.Printf("%v ", items[i+j])
+            }
+          }
+        }
+        fmt.Println("")
+      }
+    } else {
+      numTabs++
+    }
+    return prefix, nil
+  }
+}
+
+func (s *State) tabComplete(p []rune, line []rune, pos int) ([]rune, int, interface{}, error) {
+  if s.completer == nil {
+    return line, pos, rune(esc), nil
+  }
+  head, list, tail := s.completer(string(line), pos)
+  if len(list) <= 0 {
+    return line, pos, rune(esc), nil
+  }
+  hl := utf8.RuneCountInString(head)
+  if len(list) == 1 {
+    s.refresh(p, []rune(head+list[0]+tail), hl+utf8.RuneCountInString(list[0]))
+    return []rune(head + list[0] + tail), hl + utf8.RuneCountInString(list[0]), rune(esc), nil
+  }
+
+  direction := tabForward
+  tabPrinter := s.circularTabs(list)
+  if s.tabStyle == TabPrints {
+    tabPrinter = s.printedTabs(list)
+  }
+
+  for {
+    pick, err := tabPrinter(direction)
+    if err != nil {
+      return line, pos, rune(esc), err
+    }
+    s.refresh(p, []rune(head+pick+tail), hl+utf8.RuneCountInString(pick))
+
+    next, err := s.readNext()
+    if err != nil {
+      return line, pos, rune(esc), err
+    }
+    if key, ok := next.(rune); ok {
+      if key == tab {
+        direction = tabForward
+        continue
+      }
+      if key == esc {
+        return line, pos, rune(esc), nil
+      }
+    }
+    if a, ok := next.(action); ok && a == shiftTab {
+      direction = tabReverse
+      continue
+    }
+    return []rune(head + pick + tail), hl + utf8.RuneCountInString(pick), next, nil
+  }
+  // Not reached
+  return line, pos, rune(esc), nil
+}
+
+// reverse intelligent search, implements a bash-like history search.
+func (s *State) reverseISearch(origLine []rune, origPos int) ([]rune, int, interface{}, error) {
+  p := "(reverse-i-search)`': "
+  s.refresh([]rune(p), origLine, origPos)
+
+  line := []rune{}
+  pos := 0
+  foundLine := string(origLine)
+  foundPos := origPos
+
+  getLine := func() ([]rune, []rune, int) {
+    search := string(line)
+    prompt := "(reverse-i-search)`%s': "
+    return []rune(fmt.Sprintf(prompt, search)), []rune(foundLine), foundPos
+  }
+
+  history, positions := s.getHistoryByPattern(string(line))
+  historyPos := len(history) - 1
+
+  for {
+    next, err := s.readNext()
+    if err != nil {
+      return []rune(foundLine), foundPos, rune(esc), err
+    }
+
+    switch v := next.(type) {
+    case rune:
+      switch v {
+      case ctrlR: // Search backwards
+        if historyPos > 0 && historyPos < len(history) {
+          historyPos--
+          foundLine = history[historyPos]
+          foundPos = positions[historyPos]
+        } else {
+          fmt.Print(beep)
+        }
+      case ctrlS: // Search forward
+        if historyPos < len(history)-1 && historyPos >= 0 {
+          historyPos++
+          foundLine = history[historyPos]
+          foundPos = positions[historyPos]
+        } else {
+          fmt.Print(beep)
+        }
+      case ctrlH, bs: // Backspace
+        if pos <= 0 {
+          fmt.Print(beep)
+        } else {
+          n := len(getSuffixGlyphs(line[:pos], 1))
+          line = append(line[:pos-n], line[pos:]...)
+          pos -= n
+
+          // For each char deleted, display the last matching line of history
+          history, positions := s.getHistoryByPattern(string(line))
+          historyPos = len(history) - 1
+          if len(history) > 0 {
+            foundLine = history[historyPos]
+            foundPos = positions[historyPos]
+          } else {
+            foundLine = ""
+            foundPos = 0
+          }
+        }
+      case ctrlG: // Cancel
+        return origLine, origPos, rune(esc), err
+
+      case tab, cr, lf, ctrlA, ctrlB, ctrlD, ctrlE, ctrlF, ctrlK,
+        ctrlL, ctrlN, ctrlO, ctrlP, ctrlQ, ctrlT, ctrlU, ctrlV, ctrlW, ctrlX, ctrlY, ctrlZ:
+        fallthrough
+      case 0, ctrlC, esc, 28, 29, 30, 31:
+        return []rune(foundLine), foundPos, next, err
+      default:
+        line = append(line[:pos], append([]rune{v}, line[pos:]...)...)
+        pos++
+
+        // For each keystroke typed, display the last matching line of history
+        history, positions = s.getHistoryByPattern(string(line))
+        historyPos = len(history) - 1
+        if len(history) > 0 {
+          foundLine = history[historyPos]
+          foundPos = positions[historyPos]
+        } else {
+          foundLine = ""
+          foundPos = 0
+        }
+      }
+    case action:
+      return []rune(foundLine), foundPos, next, err
+    }
+    s.refresh(getLine())
+  }
+}
+
+// addToKillRing adds some text to the kill ring. If mode is 0 it adds it to a
+// new node in the end of the kill ring, and move the current pointer to the new
+// node. If mode is 1 or 2 it appends or prepends the text to the current entry
+// of the killRing.
+func (s *State) addToKillRing(text []rune, mode int) {
+  // Don't use the same underlying array as text
+  killLine := make([]rune, len(text))
+  copy(killLine, text)
+
+  // Point killRing to a newNode, procedure depends on the killring state and
+  // append mode.
+  if mode == 0 { // Add new node to killRing
+    if s.killRing == nil { // if killring is empty, create a new one
+      s.killRing = ring.New(1)
+    } else if s.killRing.Len() >= KillRingMax { // if killring is "full"
+      s.killRing = s.killRing.Next()
+    } else { // Normal case
+      s.killRing.Link(ring.New(1))
+      s.killRing = s.killRing.Next()
+    }
+  } else {
+    if s.killRing == nil { // if killring is empty, create a new one
+      s.killRing = ring.New(1)
+      s.killRing.Value = []rune{}
+    }
+    if mode == 1 { // Append to last entry
+      killLine = append(s.killRing.Value.([]rune), killLine...)
+    } else if mode == 2 { // Prepend to last entry
+      killLine = append(killLine, s.killRing.Value.([]rune)...)
+    }
+  }
+
+  // Save text in the current killring node
+  s.killRing.Value = killLine
+}
+
+func (s *State) yank(p []rune, text []rune, pos int) ([]rune, int, interface{}, error) {
+  if s.killRing == nil {
+    return text, pos, rune(esc), nil
+  }
+
+  lineStart := text[:pos]
+  lineEnd := text[pos:]
+  var line []rune
+
+  for {
+    value := s.killRing.Value.([]rune)
+    line = make([]rune, 0)
+    line = append(line, lineStart...)
+    line = append(line, value...)
+    line = append(line, lineEnd...)
+
+    pos = len(lineStart) + len(value)
+    s.refresh(p, line, pos)
+
+    next, err := s.readNext()
+    if err != nil {
+      return line, pos, next, err
+    }
+
+    switch v := next.(type) {
+    case rune:
+      return line, pos, next, nil
+    case action:
+      switch v {
+      case altY:
+        s.killRing = s.killRing.Prev()
+      default:
+        return line, pos, next, nil
+      }
+    }
+  }
+
+  return line, pos, esc, nil
+}
+
+// Prompt displays p and returns a line of user input, not including a trailing
+// newline character. An io.EOF error is returned if the user signals end-of-file
+// by pressing Ctrl-D. Prompt allows line editing if the terminal supports it.
+func (s *State) Prompt(prompt string) (string, error) {
+  if s.inputRedirected || !s.terminalSupported {
+    return s.promptUnsupported(prompt)
+  }
+  if s.outputRedirected {
+    return "", ErrNotTerminalOutput
+  }
+
+  s.historyMutex.RLock()
+  defer s.historyMutex.RUnlock()
+
+  s.startPrompt()
+  defer s.stopPrompt()
+  s.getColumns()
+
+  fmt.Print(prompt)
+  p := []rune(prompt)
+  var line []rune
+  pos := 0
+  historyEnd := ""
+  prefixHistory := s.getHistoryByPrefix(string(line))
+  historyPos := len(prefixHistory)
+  historyAction := false // used to mark history related actions
+  killAction := 0        // used to mark kill related actions
+mainLoop:
+  for {
+    next, err := s.readNext()
+  haveNext:
+    if err != nil {
+      return "", err
+    }
+
+    historyAction = false
+    switch v := next.(type) {
+    case rune:
+      switch v {
+      case cr, lf:
+        fmt.Println()
+        break mainLoop
+      case ctrlA: // Start of line
+        pos = 0
+        s.refresh(p, line, pos)
+      case ctrlE: // End of line
+        pos = len(line)
+        s.refresh(p, line, pos)
+      case ctrlB: // left
+        if pos > 0 {
+          pos -= len(getSuffixGlyphs(line[:pos], 1))
+          s.refresh(p, line, pos)
+        } else {
+          fmt.Print(beep)
+        }
+      case ctrlF: // right
+        if pos < len(line) {
+          pos += len(getPrefixGlyphs(line[pos:], 1))
+          s.refresh(p, line, pos)
+        } else {
+          fmt.Print(beep)
+        }
+      case ctrlD: // del
+        if pos == 0 && len(line) == 0 {
+          // exit
+          return "", io.EOF
+        }
+
+        // ctrlD is a potential EOF, so the rune reader shuts down.
+        // Therefore, if it isn't actually an EOF, we must re-startPrompt.
+        s.restartPrompt()
+
+        if pos >= len(line) {
+          fmt.Print(beep)
+        } else {
+          n := len(getPrefixGlyphs(line[pos:], 1))
+          line = append(line[:pos], line[pos+n:]...)
+          s.refresh(p, line, pos)
+        }
+      case ctrlK: // delete remainder of line
+        if pos >= len(line) {
+          fmt.Print(beep)
+        } else {
+          if killAction > 0 {
+            s.addToKillRing(line[pos:], 1) // Add in apend mode
+          } else {
+            s.addToKillRing(line[pos:], 0) // Add in normal mode
+          }
+
+          killAction = 2 // Mark that there was a kill action
+          line = line[:pos]
+          s.refresh(p, line, pos)
+        }
+      case ctrlP: // up
+        historyAction = true
+        if historyPos > 0 {
+          if historyPos == len(prefixHistory) {
+            historyEnd = string(line)
+          }
+          historyPos--
+          line = []rune(prefixHistory[historyPos])
+          pos = len(line)
+          s.refresh(p, line, pos)
+        } else {
+          fmt.Print(beep)
+        }
+      case ctrlN: // down
+        historyAction = true
+        if historyPos < len(prefixHistory) {
+          historyPos++
+          if historyPos == len(prefixHistory) {
+            line = []rune(historyEnd)
+          } else {
+            line = []rune(prefixHistory[historyPos])
+          }
+          pos = len(line)
+          s.refresh(p, line, pos)
+        } else {
+          fmt.Print(beep)
+        }
+      case ctrlT: // transpose prev glyph with glyph under cursor
+        if len(line) < 2 || pos < 1 {
+          fmt.Print(beep)
+        } else {
+          if pos == len(line) {
+            pos -= len(getSuffixGlyphs(line, 1))
+          }
+          prev := getSuffixGlyphs(line[:pos], 1)
+          next := getPrefixGlyphs(line[pos:], 1)
+          scratch := make([]rune, len(prev))
+          copy(scratch, prev)
+          copy(line[pos-len(prev):], next)
+          copy(line[pos-len(prev)+len(next):], scratch)
+          pos += len(next)
+          s.refresh(p, line, pos)
+        }
+      case ctrlL: // clear screen
+        s.eraseScreen()
+        s.refresh(p, line, pos)
+      case ctrlC: // reset
+        fmt.Println("^C")
+        if s.ctrlCAborts {
+          return "", ErrPromptAborted
+        }
+        line = line[:0]
+        pos = 0
+        fmt.Print(prompt)
+        s.restartPrompt()
+      case ctrlH, bs: // Backspace
+        if pos <= 0 {
+          fmt.Print(beep)
+        } else {
+          n := len(getSuffixGlyphs(line[:pos], 1))
+          line = append(line[:pos-n], line[pos:]...)
+          pos -= n
+          s.refresh(p, line, pos)
+        }
+      case ctrlU: // Erase line before cursor
+        if killAction > 0 {
+          s.addToKillRing(line[:pos], 2) // Add in prepend mode
+        } else {
+          s.addToKillRing(line[:pos], 0) // Add in normal mode
+        }
+
+        killAction = 2 // Mark that there was some killing
+        line = line[pos:]
+        pos = 0
+        s.refresh(p, line, pos)
+      case ctrlW: // Erase word
+        if pos == 0 {
+          fmt.Print(beep)
+          break
+        }
+        // Remove whitespace to the left
+        var buf []rune // Store the deleted chars in a buffer
+        for {
+          if pos == 0 || !unicode.IsSpace(line[pos-1]) {
+            break
+          }
+          buf = append(buf, line[pos-1])
+          line = append(line[:pos-1], line[pos:]...)
+          pos--
+        }
+        // Remove non-whitespace to the left
+        for {
+          if pos == 0 || unicode.IsSpace(line[pos-1]) {
+            break
+          }
+          buf = append(buf, line[pos-1])
+          line = append(line[:pos-1], line[pos:]...)
+          pos--
+        }
+        // Invert the buffer and save the result on the killRing
+        var newBuf []rune
+        for i := len(buf) - 1; i >= 0; i-- {
+          newBuf = append(newBuf, buf[i])
+        }
+        if killAction > 0 {
+          s.addToKillRing(newBuf, 2) // Add in prepend mode
+        } else {
+          s.addToKillRing(newBuf, 0) // Add in normal mode
+        }
+        killAction = 2 // Mark that there was some killing
+
+        s.refresh(p, line, pos)
+      case ctrlY: // Paste from Yank buffer
+        line, pos, next, err = s.yank(p, line, pos)
+        goto haveNext
+      case ctrlR: // Reverse Search
+        line, pos, next, err = s.reverseISearch(line, pos)
+        s.refresh(p, line, pos)
+        goto haveNext
+      case tab: // Tab completion
+        line, pos, next, err = s.tabComplete(p, line, pos)
+        goto haveNext
+      // Catch keys that do nothing, but you don't want them to beep
+      case esc:
+        // DO NOTHING
+      // Unused keys
+      case ctrlG, ctrlO, ctrlQ, ctrlS, ctrlV, ctrlX, ctrlZ:
+        fallthrough
+      // Catch unhandled control codes (anything <= 31)
+      case 0, 28, 29, 30, 31:
+        fmt.Print(beep)
+      default:
+        if pos == len(line) && len(p)+len(line) < s.columns-1 {
+          line = append(line, v)
+          fmt.Printf("%c", v)
+          pos++
+        } else {
+          line = append(line[:pos], append([]rune{v}, line[pos:]...)...)
+          pos++
+          s.refresh(p, line, pos)
+        }
+      }
+    case action:
+      switch v {
+      case del:
+        if pos >= len(line) {
+          fmt.Print(beep)
+        } else {
+          n := len(getPrefixGlyphs(line[pos:], 1))
+          line = append(line[:pos], line[pos+n:]...)
+        }
+      case left:
+        if pos > 0 {
+          pos -= len(getSuffixGlyphs(line[:pos], 1))
+        } else {
+          fmt.Print(beep)
+        }
+      case wordLeft:
+        if pos > 0 {
+          for {
+            pos--
+            if pos == 0 || unicode.IsSpace(line[pos-1]) {
+              break
+            }
+          }
+        } else {
+          fmt.Print(beep)
+        }
+      case right:
+        if pos < len(line) {
+          pos += len(getPrefixGlyphs(line[pos:], 1))
+        } else {
+          fmt.Print(beep)
+        }
+      case wordRight:
+        if pos < len(line) {
+          for {
+            pos++
+            if pos == len(line) || unicode.IsSpace(line[pos]) {
+              break
+            }
+          }
+        } else {
+          fmt.Print(beep)
+        }
+      case up:
+        historyAction = true
+        if historyPos > 0 {
+          if historyPos == len(prefixHistory) {
+            historyEnd = string(line)
+          }
+          historyPos--
+          line = []rune(prefixHistory[historyPos])
+          pos = len(line)
+        } else {
+          fmt.Print(beep)
+        }
+      case down:
+        historyAction = true
+        if historyPos < len(prefixHistory) {
+          historyPos++
+          if historyPos == len(prefixHistory) {
+            line = []rune(historyEnd)
+          } else {
+            line = []rune(prefixHistory[historyPos])
+          }
+          pos = len(line)
+        } else {
+          fmt.Print(beep)
+        }
+      case home: // Start of line
+        pos = 0
+      case end: // End of line
+        pos = len(line)
+      }
+      s.refresh(p, line, pos)
+    }
+    if !historyAction {
+      prefixHistory = s.getHistoryByPrefix(string(line))
+      historyPos = len(prefixHistory)
+    }
+    if killAction > 0 {
+      killAction--
+    }
+  }
+  return string(line), nil
+}
+
+// PasswordPrompt displays p, and then waits for user input. The input typed by
+// the user is not displayed in the terminal.
+func (s *State) PasswordPrompt(prompt string) (string, error) {
+  if !s.terminalSupported {
+    return "", errors.New("liner: function not supported in this terminal")
+  }
+  if s.inputRedirected {
+    return s.promptUnsupported(prompt)
+  }
+  if s.outputRedirected {
+    return "", ErrNotTerminalOutput
+  }
+
+  s.startPrompt()
+  defer s.stopPrompt()
+  s.getColumns()
+
+  fmt.Print(prompt)
+  p := []rune(prompt)
+  var line []rune
+  pos := 0
+
+mainLoop:
+  for {
+    next, err := s.readNext()
+    if err != nil {
+      return "", err
+    }
+
+    switch v := next.(type) {
+    case rune:
+      switch v {
+      case cr, lf:
+        fmt.Println()
+        break mainLoop
+      case ctrlD: // del
+        if pos == 0 && len(line) == 0 {
+          // exit
+          return "", io.EOF
+        }
+
+        // ctrlD is a potential EOF, so the rune reader shuts down.
+        // Therefore, if it isn't actually an EOF, we must re-startPrompt.
+        s.restartPrompt()
+      case ctrlL: // clear screen
+        s.eraseScreen()
+        s.refresh(p, []rune{}, 0)
+      case ctrlH, bs: // Backspace
+        if pos <= 0 {
+          fmt.Print(beep)
+        } else {
+          n := len(getSuffixGlyphs(line[:pos], 1))
+          line = append(line[:pos-n], line[pos:]...)
+          pos -= n
+        }
+      case ctrlC:
+        fmt.Println("^C")
+        if s.ctrlCAborts {
+          return "", ErrPromptAborted
+        }
+        line = line[:0]
+        pos = 0
+        fmt.Print(prompt)
+        s.restartPrompt()
+      // Unused keys
+      case esc, tab, ctrlA, ctrlB, ctrlE, ctrlF, ctrlG, ctrlK, ctrlN, ctrlO, ctrlP, ctrlQ, ctrlR, ctrlS,
+        ctrlT, ctrlU, ctrlV, ctrlW, ctrlX, ctrlY, ctrlZ:
+        fallthrough
+      // Catch unhandled control codes (anything <= 31)
+      case 0, 28, 29, 30, 31:
+        fmt.Print(beep)
+      default:
+        line = append(line[:pos], append([]rune{v}, line[pos:]...)...)
+        pos++
+      }
+    }
+  }
+  return string(line), nil
+}

third_party/liner/line_test.go

+package liner
+
+import (
+  "bytes"
+  "strings"
+  "testing"
+)
+
+func TestAppend(t *testing.T) {
+  var s State
+  s.AppendHistory("foo")
+  s.AppendHistory("bar")
+
+  var out bytes.Buffer
+  num, err := s.WriteHistory(&out)
+  if err != nil {
+    t.Fatal("Unexpected error writing history", err)
+  }
+  if num != 2 {
+    t.Fatalf("Expected 2 history entries, got %d", num)
+  }
+
+  s.AppendHistory("baz")
+  num, err = s.WriteHistory(&out)
+  if err != nil {
+    t.Fatal("Unexpected error writing history", err)
+  }
+  if num != 3 {
+    t.Fatalf("Expected 3 history entries, got %d", num)
+  }
+
+  s.AppendHistory("baz")
+  num, err = s.WriteHistory(&out)
+  if err != nil {
+    t.Fatal("Unexpected error writing history", err)
+  }
+  if num != 3 {
+    t.Fatalf("Expected 3 history entries after duplicate append, got %d", num)
+  }
+
+  s.AppendHistory("baz")
+
+}
+
+func TestHistory(t *testing.T) {
+  input := `foo
+bar
+baz
+quux
+dingle`
+
+  var s State
+  num, err := s.ReadHistory(strings.NewReader(input))
+  if err != nil {
+    t.Fatal("Unexpected error reading history", err)
+  }
+  if num != 5 {
+    t.Fatal("Wrong number of history entries read")
+  }
+
+  var out bytes.Buffer
+  num, err = s.WriteHistory(&out)
+  if err != nil {
+    t.Fatal("Unexpected error writing history", err)
+  }
+  if num != 5 {
+    t.Fatal("Wrong number of history entries written")
+  }
+  if strings.TrimSpace(out.String()) != input {
+    t.Fatal("Round-trip failure")
+  }
+
+  // Test reading with a trailing newline present
+  var s2 State
+  num, err = s2.ReadHistory(&out)
+  if err != nil {
+    t.Fatal("Unexpected error reading history the 2nd time", err)
+  }
+  if num != 5 {
+    t.Fatal("Wrong number of history entries read the 2nd time")
+  }
+
+  num, err = s.ReadHistory(strings.NewReader(input + "\n\xff"))
+  if err == nil {
+    t.Fatal("Unexpected success reading corrupted history", err)
+  }
+  if num != 5 {
+    t.Fatal("Wrong number of history entries read the 3rd time")
+  }
+}

third_party/liner/output.go

+// +build linux darwin openbsd freebsd netbsd
+
+package liner
+
+import (
+  "fmt"
+  "os"
+  "strings"
+  "syscall"
+  "unsafe"
+)
+
+func (s *State) cursorPos(x int) {
+  if s.useCHA {
+    // 'G' is "Cursor Character Absolute (CHA)"
+    fmt.Printf("\x1b[%dG", x+1)
+  } else {
+    // 'C' is "Cursor Forward (CUF)"
+    fmt.Print("\r")
+    if x > 0 {
+      fmt.Printf("\x1b[%dC", x)
+    }
+  }
+}
+
+func (s *State) eraseLine() {
+  fmt.Print("\x1b[0K")
+}
+
+func (s *State) eraseScreen() {
+  fmt.Print("\x1b[H\x1b[2J")
+}
+
+type winSize struct {
+  row, col       uint16
+  xpixel, ypixel uint16
+}
+
+func (s *State) getColumns() {
+  var ws winSize
+  ok, _, _ := syscall.Syscall(syscall.SYS_IOCTL, uintptr(syscall.Stdout),
+    syscall.TIOCGWINSZ, uintptr(unsafe.Pointer(&ws)))
+  if ok < 0 {
+    s.columns = 80
+  }
+  s.columns = int(ws.col)
+}
+
+func (s *State) checkOutput() {
+  // xterm is known to support CHA
+  if strings.Contains(strings.ToLower(os.Getenv("TERM")), "xterm") {
+    s.useCHA = true
+    return
+  }
+
+  // The test for functional ANSI CHA is unreliable (eg the Windows
+  // telnet command does not support reading the cursor position with
+  // an ANSI DSR request, despite setting TERM=ansi)
+
+  // Assume CHA isn't supported (which should be safe, although it
+  // does result in occasional visible cursor jitter)
+  s.useCHA = false
+}

third_party/liner/output_windows.go

+package liner
+
+import (
+  "unsafe"
+)
+
+type coord struct {
+  x, y int16
+}
+type smallRect struct {
+  left, top, right, bottom int16
+}
+
+type consoleScreenBufferInfo struct {
+  dwSize              coord
+  dwCursorPosition    coord
+  wAttributes         int16
+  srWindow            smallRect
+  dwMaximumWindowSize coord
+}
+
+func (s *State) cursorPos(x int) {
+  var sbi consoleScreenBufferInfo
+  procGetConsoleScreenBufferInfo.Call(uintptr(s.hOut), uintptr(unsafe.Pointer(&sbi)))
+  procSetConsoleCursorPosition.Call(uintptr(s.hOut),
+    uintptr(int(x)&0xFFFF|int(sbi.dwCursorPosition.y)<<16))
+}
+
+func (s *State) eraseLine() {
+  var sbi consoleScreenBufferInfo
+  procGetConsoleScreenBufferInfo.Call(uintptr(s.hOut), uintptr(unsafe.Pointer(&sbi)))
+  var numWritten uint32
+  procFillConsoleOutputCharacter.Call(uintptr(s.hOut), uintptr(' '),
+    uintptr(sbi.dwSize.x-sbi.dwCursorPosition.x),
+    uintptr(int(sbi.dwCursorPosition.x)&0xFFFF|int(sbi.dwCursorPosition.y)<<16),
+    uintptr(unsafe.Pointer(&numWritten)))
+}
+
+func (s *State) eraseScreen() {
+  var sbi consoleScreenBufferInfo
+  procGetConsoleScreenBufferInfo.Call(uintptr(s.hOut), uintptr(unsafe.Pointer(&sbi)))
+  var numWritten uint32
+  procFillConsoleOutputCharacter.Call(uintptr(s.hOut), uintptr(' '),
+    uintptr(sbi.dwSize.x)*uintptr(sbi.dwSize.y),
+    0,
+    uintptr(unsafe.Pointer(&numWritten)))
+  procSetConsoleCursorPosition.Call(uintptr(s.hOut), 0)
+}
+
+func (s *State) getColumns() {
+  var sbi consoleScreenBufferInfo
+  procGetConsoleScreenBufferInfo.Call(uintptr(s.hOut), uintptr(unsafe.Pointer(&sbi)))
+  s.columns = int(sbi.dwSize.x)
+}

third_party/liner/prefix_test.go

+// +build windows linux darwin openbsd freebsd netbsd
+
+package liner
+
+import "testing"
+
+type testItem struct {
+  list   []string
+  prefix string
+}
+
+func TestPrefix(t *testing.T) {
+  list := []testItem{
+    {[]string{"food", "foot"}, "foo"},
+    {[]string{"foo", "foot"}, "foo"},
+    {[]string{"food", "foo"}, "foo"},
+    {[]string{"food", "foe", "foot"}, "fo"},
+    {[]string{"food", "foot", "barbeque"}, ""},
+    {[]string{"cafeteria", "café"}, "caf"},
+    {[]string{"cafe", "café"}, "caf"},
+    {[]string{"cafè", "café"}, "caf"},
+    {[]string{"cafés", "café"}, "café"},
+    {[]string{"áéíóú", "áéíóú"}, "áéíóú"},
+    {[]string{"éclairs", "éclairs"}, "éclairs"},
+    {[]string{"éclairs are the best", "éclairs are great", "éclairs"}, "éclairs"},
+    {[]string{"éclair", "éclairs"}, "éclair"},
+    {[]string{"éclairs", "éclair"}, "éclair"},
+    {[]string{"éclair", "élan"}, "é"},
+  }
+
+  for _, test := range list {
+    lcp := longestCommonPrefix(test.list)
+    if lcp != test.prefix {
+      t.Errorf("%s != %s for %+v", lcp, test.prefix, test.list)
+    }
+  }
+}

third_party/liner/race_test.go

+// +build race
+
+package liner
+
+import (
+  "io/ioutil"
+  "os"
+  "sync"
+  "testing"
+)
+
+func TestWriteHistory(t *testing.T) {
+  oldout := os.Stdout
+  defer func() { os.Stdout = oldout }()
+  oldin := os.Stdout
+  defer func() { os.Stdin = oldin }()
+
+  newinr, newinw, err := os.Pipe()
+  if err != nil {
+    t.Fatal(err)
+  }
+  os.Stdin = newinr
+  newoutr, newoutw, err := os.Pipe()
+  if err != nil {
+    t.Fatal(err)
+  }
+  defer newoutr.Close()
+  os.Stdout = newoutw
+
+  var wait sync.WaitGroup
+  wait.Add(1)
+  s := NewLiner()
+  go func() {
+    s.AppendHistory("foo")
+    s.AppendHistory("bar")
+    s.Prompt("")
+    wait.Done()
+  }()
+
+  s.WriteHistory(ioutil.Discard)
+
+  newinw.Close()
+  wait.Wait()
+}

third_party/liner/signal.go

+// +build go1.1,!windows
+
+package liner
+
+import (
+  "os"
+  "os/signal"
+)
+
+func stopSignal(c chan<- os.Signal) {
+  signal.Stop(c)
+}

third_party/liner/signal_legacy.go

+// +build !go1.1,!windows
+
+package liner
+
+import (
+  "os"
+)
+
+func stopSignal(c chan<- os.Signal) {
+  // signal.Stop does not exist before Go 1.1
+}

third_party/liner/unixmode.go

+// +build linux darwin freebsd openbsd netbsd
+
+package liner
+
+import (
+  "syscall"
+  "unsafe"
+)
+
+func (mode *termios) ApplyMode() error {
+  _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, uintptr(syscall.Stdin), setTermios, uintptr(unsafe.Pointer(mode)))
+
+  if errno != 0 {
+    return errno
+  }
+  return nil
+}
+
+// TerminalMode returns the current terminal input mode as an InputModeSetter.
+//
+// This function is provided for convenience, and should
+// not be necessary for most users of liner.
+func TerminalMode() (ModeApplier, error) {
+  mode, errno := getMode(syscall.Stdin)
+
+  if errno != 0 {
+    return nil, errno
+  }
+  return mode, nil
+}
+
+func getMode(handle int) (*termios, syscall.Errno) {
+  var mode termios
+  _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, uintptr(handle), getTermios, uintptr(unsafe.Pointer(&mode)))
+
+  return &mode, errno
+}

third_party/liner/width.go

+package liner
+
+import "unicode"
+
+// These character classes are mostly zero width (when combined).
+// A few might not be, depending on the user's font. Fixing this
+// is non-trivial, given that some terminals don't support
+// ANSI DSR/CPR
+var zeroWidth = []*unicode.RangeTable{
+  unicode.Mn,
+  unicode.Me,
+  unicode.Cc,
+  unicode.Cf,
+}
+
+var doubleWidth = []*unicode.RangeTable{
+  unicode.Han,
+  unicode.Hangul,
+  unicode.Hiragana,
+  unicode.Katakana,
+}
+
+// countGlyphs considers zero-width characters to be zero glyphs wide,
+// and members of Chinese, Japanese, and Korean scripts to be 2 glyphs wide.
+func countGlyphs(s []rune) int {
+  n := 0
+  for _, r := range s {
+    switch {
+    case unicode.IsOneOf(zeroWidth, r):
+    case unicode.IsOneOf(doubleWidth, r):
+      n += 2
+    default:
+      n++
+    }
+  }
+  return n
+}
+
+func getPrefixGlyphs(s []rune, num int) []rune {
+  p := 0
+  for n := 0; n < num && p < len(s); p++ {
+    if !unicode.IsOneOf(zeroWidth, s[p]) {
+      n++
+    }
+  }
+  for p < len(s) && unicode.IsOneOf(zeroWidth, s[p]) {
+    p++
+  }
+  return s[:p]
+}
+
+func getSuffixGlyphs(s []rune, num int) []rune {
+  p := len(s)
+  for n := 0; n < num && p > 0; p-- {
+    if !unicode.IsOneOf(zeroWidth, s[p-1]) {
+      n++
+    }
+  }
+  return s[p:]
+}

third_party/liner/width_test.go

+package liner
+
+import (
+  "strconv"
+  "testing"
+)
+
+func accent(in []rune) []rune {
+  var out []rune
+  for _, r := range in {
+    out = append(out, r)
+    out = append(out, '\u0301')
+  }
+  return out
+}
+
+type testCase struct {
+  s      []rune
+  glyphs int
+}
+
+var testCases = []testCase{
+  {[]rune("query"), 5},
+  {[]rune("私"), 2},
+  {[]rune("hello世界"), 9},
+}
+
+func TestCountGlyphs(t *testing.T) {
+  for _, testCase := range testCases {
+    count := countGlyphs(testCase.s)
+    if count != testCase.glyphs {
+      t.Errorf("ASCII count incorrect. %d != %d", count, testCase.glyphs)
+    }
+    count = countGlyphs(accent(testCase.s))
+    if count != testCase.glyphs {
+      t.Errorf("Accent count incorrect. %d != %d", count, testCase.glyphs)
+    }
+  }
+}
+
+func compare(a, b []rune, name string, t *testing.T) {
+  if len(a) != len(b) {
+    t.Errorf(`"%s" != "%s" in %s"`, string(a), string(b), name)
+    return
+  }
+  for i := range a {
+    if a[i] != b[i] {
+      t.Errorf(`"%s" != "%s" in %s"`, string(a), string(b), name)
+      return
+    }
+  }
+}
+
+func TestPrefixGlyphs(t *testing.T) {
+  for _, testCase := range testCases {
+    for i := 0; i <= len(testCase.s); i++ {
+      iter := strconv.Itoa(i)
+      out := getPrefixGlyphs(testCase.s, i)
+      compare(out, testCase.s[:i], "ascii prefix "+iter, t)
+      out = getPrefixGlyphs(accent(testCase.s), i)
+      compare(out, accent(testCase.s[:i]), "accent prefix "+iter, t)
+    }
+    out := getPrefixGlyphs(testCase.s, 999)
+    compare(out, testCase.s, "ascii prefix overflow", t)
+    out = getPrefixGlyphs(accent(testCase.s), 999)
+    compare(out, accent(testCase.s), "accent prefix overflow", t)
+
+    out = getPrefixGlyphs(testCase.s, -3)
+    if len(out) != 0 {
+      t.Error("ascii prefix negative")
+    }
+    out = getPrefixGlyphs(accent(testCase.s), -3)
+    if len(out) != 0 {
+      t.Error("accent prefix negative")
+    }
+  }
+}
+
+func TestSuffixGlyphs(t *testing.T) {
+  for _, testCase := range testCases {
+    for i := 0; i <= len(testCase.s); i++ {
+      iter := strconv.Itoa(i)
+      out := getSuffixGlyphs(testCase.s, i)
+      compare(out, testCase.s[len(testCase.s)-i:], "ascii suffix "+iter, t)
+      out = getSuffixGlyphs(accent(testCase.s), i)
+      compare(out, accent(testCase.s[len(testCase.s)-i:]), "accent suffix "+iter, t)
+    }
+    out := getSuffixGlyphs(testCase.s, 999)
+    compare(out, testCase.s, "ascii suffix overflow", t)
+    out = getSuffixGlyphs(accent(testCase.s), 999)
+    compare(out, accent(testCase.s), "accent suffix overflow", t)
+
+    out = getSuffixGlyphs(testCase.s, -3)
+    if len(out) != 0 {
+      t.Error("ascii suffix negative")
+    }
+    out = getSuffixGlyphs(accent(testCase.s), -3)
+    if len(out) != 0 {
+      t.Error("accent suffix negative")
+    }
+  }
+}

update_third_party.sh

 #!/bin/sh -e
 
+scriptpath=$(readlink -f "$0")
+llgosrcdir=$(dirname "$scriptpath")
+cd $llgosrcdir
+
 gofrontendrepo=https://code.google.com/p/gofrontend
 gofrontendrev=15a24202fa42
 
 gccrepo=svn://gcc.gnu.org/svn/gcc/trunk
 gccrev=219477
 
 gotoolsrepo=https://go.googlesource.com/tools
 gotoolsrev=d4e70101500b43ffe705d4c45e50dd4f1c8e3b2e
 
+linerrepo=https://github.com/peterh/liner.git
+linerrev=1bb0d1c1a25ed393d8feb09bab039b2b1b1fbced
+
 tempdir=$(mktemp -d /tmp/update_third_party.XXXXXX)
 gofrontenddir=$tempdir/gofrontend
 gotoolsdir=$tempdir/go.tools
+linerdir=third_party/liner
 
 rm -rf third_party
 mkdir -p third_party/gofrontend third_party/gotools
 
 # --------------------- gofrontend ---------------------
 
 hg clone -r $gofrontendrev $gofrontendrepo $gofrontenddir
 

 
 mkdir -p third_party/gofrontend/include third_party/gofrontend/libgcc
 
 # Copy in our versions of GCC files.
 cp include/dwarf2.h third_party/gofrontend/include/
 cp include/filenames.h third_party/gofrontend/include/
 cp include/unwind-pe.h third_party/gofrontend/libgcc/
 
+# Note: this expects the llgo source tree to be located at llvm/tools/llgo.
 cp ../../autoconf/config.guess third_party/gofrontend/
 cp ../../autoconf/config.sub third_party/gofrontend/
 
 for d in libbacktrace libffi ; do
   svn export -r $gccrev $gccrepo/$d third_party/gofrontend/$d
 done
 
 # Remove GPL licensed files, and files that confuse our license check.

 (cd $gotoolsdir && git checkout $gotoolsrev)
 
 cp -r $gotoolsdir/LICENSE $gotoolsdir/go third_party/gotools
 
 # Vendor the go.tools repository.
 find third_party/gotools -name '*.go' | xargs sed -i -e \
   's,"golang.org/x/tools/,"llvm.org/llgo/third_party/gotools/,g'
 
+# --------------------- peterh/liner -----------------
+
+git clone $linerrepo $linerdir
+(cd $linerdir && git checkout $linerrev && rm -rf .git)
+
 # --------------------- license check ---------------------
 
 # We don't want any GPL licensed code without an autoconf/libtool
 # exception, or any GPLv3 licensed code.
 
 for i in `grep -lr 'General Public License' third_party` ; do
   if grep -q 'configuration script generated by Autoconf, you may include it under' $i || \
      grep -q 'is built using GNU Libtool, you may include this file under the' $i ; then