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editor.go
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editor.go
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package main
import (
"fmt"
"github.com/srinathh/gokilo/runes"
)
// ERow represents a line of text in a file
type ERow []rune
// Text expands tabs in an eRow to spaces
func (row ERow) Text() ERow {
dest := []rune{}
for _, r := range row {
switch r {
case '\t':
dest = append(dest, tabSpaces...)
default:
dest = append(dest, r)
}
}
return dest
}
// CxToRx transforms cursor positions to account for tab stops
func (row ERow) CxToRx(cx int) int {
rx := 0
for j := 0; j < cx; j++ {
if row[j] == '\t' {
rx = (rx + kiloTabStop - 1) - (rx % kiloTabStop)
}
rx++
}
return rx
}
// Editor represents the data in the being edited in memory
type Editor struct {
//Cx, Cy int // Cx and Cy represent current cursor position
Cursor Point
Rows []ERow // Rows represent the textual data
Dirty bool // has the file been edited
FileName string // the path to the file being edited. Could be empty string
}
// NewEditor returns a new blank editor
func NewEditor() *Editor {
return &Editor{
FileName: "",
Dirty: false,
Cursor: Point{0, 0},
//Cx: 0,
//Cy: 0,
Rows: []ERow{},
}
}
// NewEditorFromFile creates an editor from a file system file
func NewEditorFromFile(filename string) (*Editor, error) {
rows := []ERow{}
if filename != "" {
var err error
if rows, err = Open(filename); err != nil {
return nil, fmt.Errorf("Error opening file %s: %v", filename, err)
}
}
return &Editor{
FileName: filename,
Dirty: false,
Cursor: Point{0, 0},
Rows: rows,
}, nil
}
// CursorUp moves the cursor up as long as row number is non zero
func (e *Editor) CursorUp() {
if e.Cursor.Row > 0 {
e.Cursor.Row--
}
e.ResetX()
}
// CursorDown moves the cursor down till one line past the last line
func (e *Editor) CursorDown() {
if e.Cursor.Row < len(e.Rows) {
e.Cursor.Row++
}
e.ResetX()
}
// CursorLeft moves the cursor left. If at col 0 & any line other thant
// the first line, it moves to the previous line
func (e *Editor) CursorLeft() {
if e.Cursor.Col > 0 {
e.Cursor.Col--
} else if e.Cursor.Row > 0 {
e.Cursor.Row--
e.Cursor.Col = len(e.Rows[e.Cursor.Row])
}
}
// CursorRight moves the cursor right & wraps past EOL to col 0
func (e *Editor) CursorRight() {
// right moves only if we're within a valid line.
// for past EOF, there's no movement
if e.Cursor.Row >= len(e.Rows) {
return
}
if e.Cursor.Col < len(e.Rows[e.Cursor.Row]) {
e.Cursor.Col++
} else if e.Cursor.Col == len(e.Rows[e.Cursor.Row]) {
e.Cursor.Row++
e.Cursor.Col = 0
}
}
// CursorEnd moves the cursor to end of line
func (e *Editor) CursorEnd() {
if e.Cursor.Row < len(e.Rows) {
e.Cursor.Col = len(e.Rows[e.Cursor.Row])
}
}
// CursorPageUp moves the cursor one screen up
func (e *Editor) CursorPageUp(screenRows int, rowOffset int) {
e.Cursor.Row = rowOffset
for j := 0; j < screenRows; j++ {
e.CursorUp()
}
}
// CursorPageDown moves the cursor one screen down
func (e *Editor) CursorPageDown(screenRows int, rowOffset int) {
e.Cursor.Row = rowOffset + screenRows - 1
if e.Cursor.Row > len(e.Rows) {
e.Cursor.Row = len(e.Rows)
}
for j := 0; j < screenRows; j++ {
e.CursorDown()
}
}
// CursorHome moves the cursor to col 0
func (e *Editor) CursorHome() {
e.Cursor.Col = 0
}
// ResetX sets the cursor X position to a valid position after moving y
func (e *Editor) ResetX() {
// if we moved past last row, set cursor to 0
if e.Cursor.Row >= len(e.Rows) {
e.Cursor.Col = 0
return
}
// we allow moving to 1 pos past the last character
rowLen := len(e.Rows[e.Cursor.Row])
if e.Cursor.Col > rowLen {
e.Cursor.Col = len(e.Rows[e.Cursor.Row])
}
}
// InsertChar inserts a character at a given location
func (e *Editor) InsertChar(c rune) {
// if we're at the last line, insert a new row
if e.Cursor.Row == len(e.Rows) {
e.InsertRow(len(e.Rows), "")
}
// store a reference to the working row to improve readability
src := e.Rows[e.Cursor.Row]
dest := make([]rune, len(src)+1)
copy(dest, src[:e.Cursor.Col])
copy(dest[e.Cursor.Col+1:], src[e.Cursor.Col:])
dest[e.Cursor.Col] = c
e.Rows[e.Cursor.Row] = dest
e.Dirty = true
e.Cursor.Col++
}
// InsertRow inserts a row at a given index
func (e *Editor) InsertRow(rowidx int, s string) {
if rowidx < 0 || rowidx > len(e.Rows) {
return
}
row := []rune(s)
e.Rows = append(e.Rows, ERow{})
copy(e.Rows[rowidx+1:], e.Rows[rowidx:])
e.Rows[rowidx] = row
e.Dirty = true
}
// InsertNewline inserts a new line at the cursor position
func (e *Editor) InsertNewline() {
if e.Cursor.Col == 0 {
e.InsertRow(e.Cursor.Row, "")
e.Dirty = true
return
}
moveChars := string(e.Rows[e.Cursor.Row][e.Cursor.Col:])
e.Rows[e.Cursor.Row] = e.Rows[e.Cursor.Row][:e.Cursor.Col]
e.InsertRow(e.Cursor.Row+1, moveChars)
e.Dirty = true
e.Cursor.Row++
e.Cursor.Col = 0
}
// DelChar deletes a character at current cursor location
func (e *Editor) DelChar() {
// if the cursor is at the line beyond the end of text
// then move it to the last line
if e.Cursor.Row == len(e.Rows) {
if len(e.Rows) == 0 {
return
}
e.Cursor.Row = len(e.Rows) - 1
e.Cursor.Col = len(e.Rows[e.Cursor.Row])
}
// if at the beginning of the text, then do nothing
if e.Cursor.Col == 0 && e.Cursor.Row == 0 {
return
}
// different handling for at the beginning of the line or middle of line
if e.Cursor.Col > 0 {
row := e.Rows[e.Cursor.Row]
copy(row[e.Cursor.Col-1:], row[e.Cursor.Col:])
row = row[:len(row)-1]
e.Rows[e.Cursor.Row] = row
e.Cursor.Col--
} else {
e.Cursor.Col = len(e.Rows[e.Cursor.Row-1])
e.Rows[e.Cursor.Row-1] = append(e.Rows[e.Cursor.Row-1], e.Rows[e.Cursor.Row]...)
e.DelRow(e.Cursor.Row)
e.Cursor.Row--
}
e.Dirty = true
}
// DelRow deletes a given row
func (e *Editor) DelRow(rowidx int) {
if rowidx < 0 || rowidx >= len(e.Rows) {
return
}
copy(e.Rows[rowidx:], e.Rows[rowidx+1:])
e.Rows = e.Rows[:len(e.Rows)-1]
e.Dirty = true
}
// Find searches the whole editor for a text
func (e *Editor) Find(search ERow) []Point {
ret := []Point{}
for i := 0; i < len(e.Rows); i++ {
if idx := runes.Index(runes.ToLower(e.Rows[i]), runes.ToLower(search)); idx != -1 {
ret = append(ret, Point{Col: idx, Row: i})
}
}
return ret
}
// SetCursor sets the cursor to a specific point
func (e *Editor) SetCursor(p Point) {
e.Cursor.Col = p.Col
e.Cursor.Row = p.Row
}