Add ByteOffset and ToCharPos to plugin API

cmd/micro/loc.go

@@ -28,6 +28,18 @@ func ToCharPos(start Loc, buf *Buffer) int {
 	return loc
 }
 
+// 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

cmd/micro/micro.go

@@ -335,6 +335,8 @@ func main() {
 	L.SetGlobal("JoinPaths", luar.New(L, filepath.Join))
 	L.SetGlobal("configDir", luar.New(L, configDir))
 	L.SetGlobal("Reload", luar.New(L, LoadAll))
+	L.SetGlobal("ByteOffset", luar.New(L, ByteOffset))
+	L.SetGlobal("ToCharPos", luar.New(L, ToCharPos))
 
 	// Used for asynchronous jobs
 	L.SetGlobal("JobStart", luar.New(L, JobStart))

runtime/help/plugins.md

@@ -86,6 +86,10 @@ as Go's GOOS variable, so `darwin`, `windows`, `linux`, `freebsd`...)
    `waitToClose` bool only applies if `interactive` is true and means that it should wait before
    returning to the editor.
 
+* `ToCharPos(loc Loc, buf *Buffer) int`: returns the character position of a given x, y location.
+
+* `ByteOffset(loc Loc, buf *Buffer) int`: exactly like `ToCharPos` except it it counts bytes instead of runes.
+
 * `JobStart(cmd string, onStdout, onStderr, onExit string, userargs ...string)`:
    Starts running the given shell command in the background. `onStdout` `onStderr` and `onExit`
    are callbacks to lua functions which will be called when the given actions happen