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codearea.go
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codearea.go
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package cli
import (
"bytes"
"strings"
"sync"
"unicode"
"unicode/utf8"
"github.com/elves/elvish/pkg/cli/term"
"github.com/elves/elvish/pkg/parse"
"github.com/elves/elvish/pkg/ui"
)
// CodeArea is a Widget for displaying and editing code.
type CodeArea interface {
Widget
// CopyState returns a copy of the state.
CopyState() CodeAreaState
// MutateState calls the given the function while locking StateMutex.
MutateState(f func(*CodeAreaState))
// Submit triggers the OnSubmit callback.
Submit()
}
// CodeAreaSpec specifies the configuration and initial state for CodeArea.
type CodeAreaSpec struct {
// A Handler that takes precedence over the default handling of events.
OverlayHandler Handler
// A function that highlights the given code and returns any errors it has
// found when highlighting. If this function is not given, the Widget does
// not highlight the code nor show any errors.
Highlighter func(code string) (ui.Text, []error)
// Prompt callback.
Prompt func() ui.Text
// Right-prompt callback.
RPrompt func() ui.Text
// A function that calls the callback with string pairs for abbreviations
// and their expansions. If this function is not given, the Widget does not
// expand any abbreviations.
Abbreviations func(f func(abbr, full string))
// A function that returns whether pasted texts (from bracketed pastes)
// should be quoted. If this function is not given, the Widget defaults to
// not quoting pasted texts.
QuotePaste func() bool
// A function that is called on the submit event.
OnSubmit func()
// State. When used in New, this field specifies the initial state.
State CodeAreaState
}
// CodeAreaState keeps the mutable state of the CodeArea widget.
type CodeAreaState struct {
Buffer CodeBuffer
Pending PendingCode
HideRPrompt bool
}
// CodeBuffer represents the buffer of the CodeArea widget.
type CodeBuffer struct {
// Content of the buffer.
Content string
// Position of the dot (more commonly known as the cursor), as a byte index
// into Content.
Dot int
}
// PendingCode represents pending code, such as during completion.
type PendingCode struct {
// Beginning index of the text area that the pending code replaces, as a
// byte index into RawState.Code.
From int
// End index of the text area that the pending code replaces, as a byte
// index into RawState.Code.
To int
// The content of the pending code.
Content string
}
// ApplyPending applies pending code to the code buffer, and resets pending code.
func (s *CodeAreaState) ApplyPending() {
s.Buffer, _, _ = patchPending(s.Buffer, s.Pending)
s.Pending = PendingCode{}
}
func (c *CodeBuffer) InsertAtDot(text string) {
*c = CodeBuffer{
Content: c.Content[:c.Dot] + text + c.Content[c.Dot:],
Dot: c.Dot + len(text),
}
}
type codeArea struct {
// Mutex for synchronizing access to State.
StateMutex sync.RWMutex
// Configuration and state.
CodeAreaSpec
// Consecutively inserted text. Used for expanding abbreviations.
inserts string
// Value of State.CodeBuffer when handleKeyEvent was last called. Used for
// detecting whether insertion has been interrupted.
lastCodeBuffer CodeBuffer
// Whether the widget is in the middle of bracketed pasting.
pasting bool
// Buffer for keeping Pasted text during bracketed pasting.
pasteBuffer bytes.Buffer
}
// NewCodeArea creates a new CodeArea from the given spec.
func NewCodeArea(spec CodeAreaSpec) CodeArea {
if spec.OverlayHandler == nil {
spec.OverlayHandler = DummyHandler{}
}
if spec.Highlighter == nil {
spec.Highlighter = func(s string) (ui.Text, []error) { return ui.T(s), nil }
}
if spec.Prompt == nil {
spec.Prompt = func() ui.Text { return nil }
}
if spec.RPrompt == nil {
spec.RPrompt = func() ui.Text { return nil }
}
if spec.Abbreviations == nil {
spec.Abbreviations = func(func(a, f string)) {}
}
if spec.QuotePaste == nil {
spec.QuotePaste = func() bool { return false }
}
if spec.OnSubmit == nil {
spec.OnSubmit = func() {}
}
return &codeArea{CodeAreaSpec: spec}
}
// Submit emits a submit event with the current code content.
func (w *codeArea) Submit() {
w.OnSubmit()
}
// Render renders the code area, including the prompt and rprompt, highlighted
// code, the cursor, and compilation errors in the code content.
func (w *codeArea) Render(width, height int) *term.Buffer {
view := getView(w)
bb := term.NewBufferBuilder(width)
renderView(view, bb)
b := bb.Buffer()
truncateToHeight(b, height)
return b
}
// Handle handles KeyEvent's of non-function keys, as well as PasteSetting
// events.
func (w *codeArea) Handle(event term.Event) bool {
switch event := event.(type) {
case term.PasteSetting:
return w.handlePasteSetting(bool(event))
case term.KeyEvent:
return w.handleKeyEvent(ui.Key(event))
}
return false
}
func (w *codeArea) MutateState(f func(*CodeAreaState)) {
w.StateMutex.Lock()
defer w.StateMutex.Unlock()
f(&w.State)
}
func (w *codeArea) CopyState() CodeAreaState {
w.StateMutex.RLock()
defer w.StateMutex.RUnlock()
return w.State
}
func (w *codeArea) resetInserts() {
w.inserts = ""
w.lastCodeBuffer = CodeBuffer{}
}
func (w *codeArea) handlePasteSetting(start bool) bool {
w.resetInserts()
if start {
w.pasting = true
} else {
text := w.pasteBuffer.String()
if w.QuotePaste() {
text = parse.Quote(text)
}
w.MutateState(func(s *CodeAreaState) { s.Buffer.InsertAtDot(text) })
w.pasting = false
w.pasteBuffer = bytes.Buffer{}
}
return true
}
func (w *codeArea) handleKeyEvent(key ui.Key) bool {
isFuncKey := key.Mod != 0 || key.Rune < 0
if w.pasting {
if isFuncKey {
// TODO: Notify the user of the error, or insert the original
// character as is.
} else {
w.pasteBuffer.WriteRune(key.Rune)
}
return true
}
if w.OverlayHandler.Handle(term.KeyEvent(key)) {
return true
}
// We only implement essential keybindings here. Other keybindings can be
// added via handler overlays.
switch key {
case ui.K('\n'):
w.resetInserts()
w.Submit()
return true
case ui.K(ui.Backspace):
w.resetInserts()
w.MutateState(func(s *CodeAreaState) {
c := &s.Buffer
// Remove the last rune.
_, chop := utf8.DecodeLastRuneInString(c.Content[:c.Dot])
*c = CodeBuffer{
Content: c.Content[:c.Dot-chop] + c.Content[c.Dot:],
Dot: c.Dot - chop,
}
})
return true
default:
if isFuncKey || !unicode.IsGraphic(key.Rune) {
w.resetInserts()
return false
}
w.StateMutex.Lock()
defer w.StateMutex.Unlock()
if w.lastCodeBuffer != w.State.Buffer {
// Something has happened between the last insert and this one;
// reset the state.
w.resetInserts()
}
s := string(key.Rune)
w.State.Buffer.InsertAtDot(s)
w.inserts += s
w.lastCodeBuffer = w.State.Buffer
var abbr, full string
// Try to expand an abbreviation, preferring the longest one
w.Abbreviations(func(a, f string) {
if strings.HasSuffix(w.inserts, a) && len(a) > len(abbr) {
abbr, full = a, f
}
})
if len(abbr) > 0 {
c := &w.State.Buffer
*c = CodeBuffer{
Content: c.Content[:c.Dot-len(abbr)] + full + c.Content[c.Dot:],
Dot: c.Dot - len(abbr) + len(full),
}
w.resetInserts()
}
return true
}
}