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package femto
// FromCharPos converts from a character position to an x, y position
func FromCharPos(loc int, buf *Buffer) Loc {
charNum := 0
x, y := 0, 0
lineLen := Count(buf.Line(y)) + 1
for charNum+lineLen <= loc {
charNum += lineLen
y++
lineLen = Count(buf.Line(y)) + 1
}
x = loc - charNum
return Loc{x, y}
}
// ToCharPos converts from an x, y position to a character position
func ToCharPos(start Loc, buf *Buffer) int {
x, y := start.X, start.Y
loc := 0
for i := 0; i < y; i++ {
// + 1 for the newline
loc += Count(buf.Line(i)) + 1
}
loc += x
return loc
}
// InBounds returns whether the given location is a valid character position in the given buffer
func InBounds(pos Loc, buf *Buffer) bool {
if pos.Y < 0 || pos.Y >= buf.NumLines || pos.X < 0 || pos.X > Count(buf.Line(pos.Y)) {
return false
}
return true
}
// ByteOffset is just like ToCharPos except it counts bytes instead of runes
func ByteOffset(pos Loc, buf *Buffer) int {
x, y := pos.X, pos.Y
loc := 0
for i := 0; i < y; i++ {
// + 1 for the newline
loc += len(buf.Line(i)) + 1
}
loc += len(buf.Line(y)[:x])
return loc
}
// Loc stores a location
type Loc struct {
X, Y int
}
// Diff returns the distance between two locations
func Diff(a, b Loc, buf *Buffer) int {
if a.Y == b.Y {
if a.X > b.X {
return a.X - b.X
}
return b.X - a.X
}
// Make sure a is guaranteed to be less than b
if b.LessThan(a) {
a, b = b, a
}
loc := 0
for i := a.Y + 1; i < b.Y; i++ {
// + 1 for the newline
loc += Count(buf.Line(i)) + 1
}
loc += Count(buf.Line(a.Y)) - a.X + b.X + 1
return loc
}
// LessThan returns true if b is smaller
func (l Loc) LessThan(b Loc) bool {
if l.Y < b.Y {
return true
}
if l.Y == b.Y && l.X < b.X {
return true
}
return false
}
// GreaterThan returns true if b is bigger
func (l Loc) GreaterThan(b Loc) bool {
if l.Y > b.Y {
return true
}
if l.Y == b.Y && l.X > b.X {
return true
}
return false
}
// GreaterEqual returns true if b is greater than or equal to b
func (l Loc) GreaterEqual(b Loc) bool {
if l.Y > b.Y {
return true
}
if l.Y == b.Y && l.X > b.X {
return true
}
if l == b {
return true
}
return false
}
// LessEqual returns true if b is less than or equal to b
func (l Loc) LessEqual(b Loc) bool {
if l.Y < b.Y {
return true
}
if l.Y == b.Y && l.X < b.X {
return true
}
if l == b {
return true
}
return false
}
// This moves the location one character to the right
func (l Loc) right(buf *Buffer) Loc {
if l == buf.End() {
return Loc{l.X + 1, l.Y}
}
var res Loc
if l.X < Count(buf.Line(l.Y)) {
res = Loc{l.X + 1, l.Y}
} else {
res = Loc{0, l.Y + 1}
}
return res
}
// This moves the given location one character to the left
func (l Loc) left(buf *Buffer) Loc {
if l == buf.Start() {
return Loc{l.X - 1, l.Y}
}
var res Loc
if l.X > 0 {
res = Loc{l.X - 1, l.Y}
} else {
res = Loc{Count(buf.Line(l.Y - 1)), l.Y - 1}
}
return res
}
// Move moves the cursor n characters to the left or right
// It moves the cursor left if n is negative
func (l Loc) Move(n int, buf *Buffer) Loc {
if n > 0 {
for i := 0; i < n; i++ {
l = l.right(buf)
}
return l
}
for i := 0; i < Abs(n); i++ {
l = l.left(buf)
}
return l
}