-
Notifications
You must be signed in to change notification settings - Fork 2
/
lineeditor.go
71 lines (58 loc) · 1.49 KB
/
lineeditor.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
package main
// LineEditor represents the a line being edited
type LineEditor struct {
Cx int // Cx and Cy represent current cursor position
Row ERow // Rows represent the textual data
}
// NewLineEditor returns a new blank editor
func NewLineEditor() *LineEditor {
return &LineEditor{
Cx: 0,
Row: ERow{},
}
}
// CursorLeft moves the cursor left. If at col 0 & any line other thant
// the first line, it moves to the previous line
func (e *LineEditor) CursorLeft() {
if e.Cx > 0 {
e.Cx--
}
}
// CursorRight moves the cursor right & wraps past EOL to col 0
func (e *LineEditor) CursorRight() {
// right moves only if we're within a valid line.
// for past EOF, there's no movement
if e.Cx < len(e.Row) {
e.Cx++
}
}
// CursorEnd moves the cursor to end of line
func (e *LineEditor) CursorEnd() {
e.Cx = len(e.Row)
}
// CursorHome moves the cursor to col 0
func (e *LineEditor) CursorHome() {
e.Cx = 0
}
// InsertChar inserts a character at a given location
func (e *LineEditor) InsertChar(c rune) {
// store a reference to the working row to improve readability
src := e.Row
dest := make([]rune, len(src)+1)
copy(dest, src[:e.Cx])
copy(dest[e.Cx+1:], src[e.Cx:])
dest[e.Cx] = c
e.Row = dest
e.Cx++
}
// DelChar deletes a character at current cursor location
func (e *LineEditor) DelChar() {
// different handling for at the beginning of the line or middle of line
if e.Cx > 0 {
row := e.Row
copy(row[e.Cx-1:], row[e.Cx:])
row = row[:len(row)-1]
e.Row = row
e.Cx--
}
}