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editor.go
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editor.go
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package main
import (
"fmt"
"os"
"golang.org/x/sys/unix"
)
type Cmd rune
const STATUS_BAR = 1
const (
// Must be higher than 128 to avoid clashing with ASCII
UP Cmd = 1000
DOWN = 1001
LEFT = 1002
RIGHT = 1003
PAGE_UP = 1004
PAGE_DOWN = 1005
HOME_KEY = 1006
END_KEY = 1007
DELETE = 1008
SHIFT_RIGHT = 1009
SHIFT_LEFT = 1010
// Specific ANSI mappings
BACKSPACE = 127
ENTER = 13
SEARCH = 6 // Ctrl-F on Mac OS
UNDO = 26 // Ctrl-X on Mac OS
COPY = 3 // Ctrl-C on Mac OS
PASTE = 22 // Ctrl-V on Mac OS
DELETE_ROW = 4 // Ctrl-D on Mac OS
SAVE = 19 // Ctrl-S on Mac OS
SAVE_AND_EXIT = 17 // Ctrl-Q on Mac OS
EXIT = 23 // Ctrl-W on Mac OS
)
type Editor struct {
originalTermios *unix.Termios
wRows, wCols uint // size of Editor
cx, cy uint // Position in file of cursor
rows []Row // Rows in file
rowOffset, colOffset uint // Position in file of top left corner of editor
filename string
charHistory byteRing
cmdHistory *CommandHistory
syntax *Syntax
paste string
}
func ConstructEditor(filename string) (Editor, error) {
rows, err := OpenOrCreate(filename)
if err != nil {
return Editor{}, err
}
e := Editor{
cx: 0,
cy: 0,
rowOffset: 0,
colOffset: 0,
wRows: 0,
wCols: 0,
filename: filename,
rows: rows,
charHistory: *NewbyteRing(10),
cmdHistory: CreateCommandHistory(),
syntax: CreateSyntax(filename),
paste: "",
}
e.GetWindowSize()
return e, nil
}
func (e *Editor) ShowCursor() {
e.MoveCursor(e.cx, e.cy)
}
func (e *Editor) HideCursor() {
fmt.Printf("\x1b[%d;%dL", (e.cy-e.rowOffset)+1, (e.cx-e.colOffset)+1)
}
// MoveCursor to document coordinates (x, y).
func (e *Editor) MoveCursor(x, y uint) {
e.SetScroll()
fmt.Printf("\x1b[%d;%dH", (y-e.rowOffset)+1, (x-e.colOffset)+1)
}
func (e *Editor) MoveCursorToStatusBar() {
e.MoveCursor(0, e.wRows-1)
}
func (e *Editor) ClearLine() {
fmt.Printf("\x1b[K")
}
func (e *Editor) GetWindowSize() (uint, uint) {
if e.wRows != 0 && e.wCols != 0 {
return e.wRows, e.wCols
}
e.wRows, e.wCols = GetWindowSize()
return e.wRows, e.wCols
}
func (e *Editor) GetRow(y uint) *Row {
return &e.rows[y]
}
func (e *Editor) GetCurrentRow() *Row {
return e.GetRow(e.cy)
}
func (e *Editor) GetRowLength() uint {
return e.GetCurrentRow().RenderLen()
}
func (e *Editor) GetEditorRows() uint {
return uint(e.wRows) - STATUS_BAR
}
func (e *Editor) GetDocumentRows() uint {
return uint(len(e.rows))
}
func (e *Editor) DrawRows() {
e.ClearLine()
r := e.GetEditorRows()
// Leave room for status bar
nRows := e.GetDocumentRows()
if nRows > e.wRows {
nRows = e.GetEditorRows()
}
for _, r := range e.rows[e.rowOffset : e.rowOffset+nRows] {
l := r.RenderWithin(e.colOffset, e.wCols-e.colOffset)
fmt.Printf("%s\r\n", e.syntax.Highlight(l))
}
// TODO: Temporary fix to address unaddressed, overflow error.
e.DrawEmptyRows(Min(r-nRows, r-1))
e.DrawStatusBar()
}
func (e *Editor) DrawEmptyRows(r uint) {
for i := uint(1); i < r; i++ {
fmt.Printf("~\r\n")
}
fmt.Printf("~\r")
}
func (e *Editor) RefreshScreen() {
e.SetScroll()
fmt.Printf("\x1b[2J") // Clear the screen
e.HideCursor()
fmt.Printf("\x1b[H") // Reposition Cursor
e.DrawRows()
e.ShowCursor()
}
func (e *Editor) ReadChar() byte {
c := make([]byte, 1)
cs, _ := os.Stdin.Read(c)
if cs == 0 {
return 0x00
}
e.charHistory.Insert(c[0])
return c[0]
}
func (e *Editor) ReadCharBlock() byte {
c := make([]byte, 1)
cs, _ := os.Stdin.Read(c)
for cs == 0 && c[0] == 0x00 {
cs, _ = os.Stdin.Read(c)
}
e.charHistory.Insert(c[0])
return c[0]
}
func (e *Editor) KeyPress() bool {
x := e.ReadChar()
switch x {
case SAVE_AND_EXIT:
e.Save()
return true
case EXIT:
return true
case '\x1b':
c := e.HandleEscapeCode()
e.HandleMoveCursor(c)
e.HandleOtherEscapedCmds(c)
break
case BACKSPACE:
if e.GetRowLength() == 0 {
e.RemoveCurrentRow()
} else if e.cx == 0 && e.cy > 0 {
l := e.GetCurrentRow().RenderLen()
e.JoinRows(e.cy-1, e.cy)
// Point cursor where it was prior.
e.cy--
e.cx = e.GetCurrentRow().RenderLen() - l
} else {
e.GetCurrentRow().RemoveCharAt(e.cx)
e.HandleMoveCursor(LEFT)
}
case ENTER:
e.SplitCurrentRow()
y := e.cy // So that AddCmd had value of current y, not future e.cy
e.cmdHistory.AddCmd(
func(e *Editor) error { e.JoinRows(y, y+1); return nil },
func(e *Editor) error { return fmt.Errorf("REDO unimplemented") },
)
e.HandleMoveCursor(RIGHT) // Jumps to start of next (newly-created) line.
case SEARCH:
e.cx, e.cy = e.RunSearch()
case UNDO:
e.cmdHistory.Undo(e)
case COPY:
e.paste = e.RunCopy()
case PASTE:
if len(e.paste) > 0 {
e.GetCurrentRow().AddCharsAt(e.cx, e.paste)
}
case DELETE_ROW:
e.RemoveCurrentRow()
case SAVE:
e.Save()
}
if !isControlChar(x) {
e.GetCurrentRow().AddCharAt(e.cx, x)
e.HandleMoveCursor(RIGHT)
}
return false
}
// TODO: This does more than RemoveCurrentRow
func (e *Editor) RemoveCurrentRow() {
if (e.cy+1) == e.GetDocumentRows() && e.GetDocumentRows() > 0 {
// Last row, just remove
e.rows = e.rows[:]
} else if e.GetDocumentRows() > 0 {
e.rows = append(e.rows[:e.cy], e.rows[e.cy+1:]...)
}
}
func (e *Editor) HandleMoveCursor(x Cmd) {
switch x {
case LEFT:
if e.cx != 0 {
e.cx -= 1
// Move left at start of line, go to end of previous line
} else if e.cy != 0 {
e.cy--
e.cx = e.GetRowLength()
}
break
case RIGHT:
// Move right at EOL, go to start of next line.
if (e.cx + 1) > e.GetRowLength() {
if (e.cy + 1) < e.GetDocumentRows() {
e.cy++
e.cx = 0
}
} else {
e.cx += 1
}
break
case UP:
if e.cy > 0 {
e.cy--
}
break
case DOWN:
if (e.cy + 1) < e.GetDocumentRows() {
e.cy++
}
break
case PAGE_UP:
for i := uint(0); i < e.wRows; i++ {
e.HandleMoveCursor(UP)
}
break
case PAGE_DOWN:
for i := uint(0); i < e.wRows; i++ {
e.HandleMoveCursor(DOWN)
}
break
case HOME_KEY:
e.cx = 0
break
case END_KEY:
e.cx = e.GetRowLength()
if e.cx > e.wCols {
e.colOffset = e.cx - e.wCols
}
break
case SHIFT_RIGHT:
e.cx = e.GetCurrentRow().GetNextWordFrom(e.cx, true)
case SHIFT_LEFT:
e.cx = e.GetCurrentRow().GetNextWordFrom(e.cx, false)
}
if e.cy >= uint(len(e.rows)) {
e.cy = uint(len(e.rows)) - 1
}
rowL := e.GetRowLength()
if rowL == 0 {
e.cx = 0
} else if e.cx > rowL {
e.cx = rowL
}
}
func (e *Editor) SetScroll() {
if e.cy < e.rowOffset {
e.rowOffset = e.cy
} else if e.cy >= (e.rowOffset + e.GetEditorRows()) {
e.rowOffset = e.cy - e.GetEditorRows() + 1
}
if e.cx < e.colOffset {
e.colOffset = e.cx
} else if e.cx >= (e.colOffset + e.wCols) {
e.colOffset = e.cx - e.wCols + 1
}
}
func (e *Editor) HandleEscapeCode() Cmd {
a := e.ReadChar()
if a == '\x1b' {
return '\x1b'
}
b := e.ReadChar()
if b == '\x1b' {
return '\x1b'
}
if a == '[' {
// Page up/down
if b >= '0' && b <= '9' {
c := e.ReadChar()
if c == '\x1b' {
return '\x1b'
}
if c == 0x7E {
switch b {
case '1':
return HOME_KEY
case '3':
return DELETE
case '4':
return END_KEY
case '5':
return PAGE_UP
case '6':
return PAGE_DOWN
case '7':
return HOME_KEY
case '8':
return END_KEY
}
}
if c == 0x3B {
d := e.ReadChar()
if d == '\x1b' {
return '\x1b'
}
e := e.ReadChar()
if e == '\x1b' {
return '\x1b'
}
if d == 0x32 {
switch e {
case 0x43:
return SHIFT_RIGHT
case 0x44:
return SHIFT_LEFT
}
}
}
}
// Arrow keys
switch b {
case 'A':
return UP
case 'B':
return DOWN
case 'C':
return RIGHT
case 'D':
return LEFT
case 'F':
return END_KEY
case 'H':
return HOME_KEY
}
}
if a == 'O' {
switch b {
case 'H':
return HOME_KEY
case 'F':
return END_KEY
}
}
return '\x1b'
}
func (e *Editor) DrawStatusBar() {
y, x := e.GetWindowSize()
r := e.GetCurrentRow()
h := e.cmdHistory.Depth()
Cprintf("%DarkBlue%STATUS BAR --% (%Blue.d, %Blue.d) of (%Magenta.d, %Magenta.d) %v. Row: %d. History: %d. Copy: %s", e.cx, e.cy, x, y, e.charHistory.GetHistory(), r.RenderLen(), h, e.paste)
}
func (e *Editor) Close() error {
err := RevertTerminalMode(e.originalTermios)
if err != nil {
fmt.Println(fmt.Errorf(
"Error on terminal close when disabling raw mode. Error: %w\n", err,
).Error())
}
e.filename = ""
return err
}
func (e *Editor) Save() error {
f, err := os.Create(e.filename)
if err != nil {
return err
}
noOfRows := len(e.rows)
for i, row := range e.rows {
_, err := f.Write(row.Export())
if err != nil {
return err
}
if i+1 < noOfRows {
f.Write([]byte{'\n'})
}
}
return nil
}
// HandleOtherEscapedCmds is responsible for handling other ANSI escape keys that don't simply move the cursor
// (i.e. they can move the cursor, but only through e.HandleMoveCursor()).
func (e *Editor) HandleOtherEscapedCmds(c Cmd) {
switch c {
case DELETE:
row := e.GetCurrentRow()
rowL := uint(len(row.Render()))
safeToJoinRow := e.cy+1 < e.GetDocumentRows()
if e.cx+1 < rowL {
row.RemoveCharAt(e.cx + 1)
} else if rowL == 1 {
row.RemoveCharAt(0)
} else if (e.cx == rowL || rowL == 0) && safeToJoinRow {
// TODO: need to generalise this for BACKSPACE
// TODO: Also is this why
e.JoinRows(e.cy, e.cy+1)
}
}
}
// SplitCurrentRow based on the current cursor position.
func (e *Editor) SplitCurrentRow() {
a, b := e.GetCurrentRow().SplitAt(e.cx)
newRows := []Row{*a, *b}
if (e.cy + 1) >= e.GetDocumentRows() {
// Last line in file, must make a new row
e.rows = append(e.rows[:e.GetDocumentRows()-1], newRows...)
} else {
end := make([]Row, e.GetDocumentRows()-e.cy-1)
copy(end, e.rows[e.cy+1:])
e.rows = append(e.rows[:e.cy], newRows...)
e.rows = append(e.rows, end...)
}
}
// Run Search across file. Return co-ordinate, (x, y) of first result.
// Will read inputs until an enter is pressed, and will be used as search term.
func (e *Editor) RunSearch() (uint, uint) {
q := make([]byte, 0)
b := e.ReadChar()
for b != ENTER {
e.MoveCursorToStatusBar()
e.ClearLine()
fmt.Printf("SEARCH: %s", string(q))
if !isControlChar(b) {
q = append(q, b)
} else if b == BACKSPACE && len(q) > 0 {
q = q[:len(q)-1]
}
b = e.ReadChar()
}
// Read search results and let user go through results.
for r := range SearchRows(e.rows, string(q)) {
// TODO: handle move cursor on page scrolling.
e.cx = r.startI
e.cy = r.rowI
e.RefreshScreen()
// Blocking read on input.
b = e.ReadChar()
for b == 0x00 {
b = e.ReadChar()
}
if b == SEARCH {
return r.startI, r.rowI // Exit search mode
} else if b == ENTER {
continue // Go to next search term
} else {
break // Leave search, back to original cursor.
}
}
// Default back to current position
e.MoveCursor(e.cx, e.cy)
return e.cx, e.cy
}
// JoinRows from b into row a. If a or b index out of range, no action applied.
func (e *Editor) JoinRows(a, b uint) {
if a >= e.GetDocumentRows() || b >= e.GetDocumentRows() {
return
}
e.rows[a].Append(&e.rows[b])
// Remove row b
if (b + 1) < e.GetDocumentRows() {
e.rows = append(e.rows[:b], e.rows[b+1:]...)
} else {
e.rows = e.rows[:b]
}
}
func (e *Editor) RunCopy() string {
sx, sy := e.cx, e.cy
ex, ey := e.GetCopyEndCoordinates()
return e.GetStringBetween(sx, sy, ex, ey)
}
func (e *Editor) GetCopyEndCoordinates() (uint, uint) {
x := e.ReadCharBlock()
cmd := e.HandleEscapeCode()
// TODO: Use copy-specific equaivalent of HandleEscapeCode to avoid side effects/ changes. And below
if x != '\x1b' || cmd == DELETE { // DELETE is only none-move Cmd from HandleEscapeCode
return e.cx, e.cy
}
for true {
e.HandleMoveCursor(cmd)
e.ShowCursor()
x = e.ReadCharBlock()
cmd = e.HandleEscapeCode()
if x != '\x1b' || cmd == DELETE {
break
}
}
return e.cx, e.cy
}
func (e *Editor) GetStringBetween(sx uint, sy uint, ex uint, ey uint) string {
// Invalid start, end cursors.
if sy > ey || (sy == ey && sx > ex) {
return ""
}
if sy == ey {
return e.GetRow(sy).Render()[sx:ex]
}
result := e.GetRow(sy).Render()[sx:]
for i := sy + 1; i+1 < ey; i++ {
result += e.GetRow(sy).Render()
}
result += e.GetRow(ey).Render()[:ex]
return result
}