text.go

package nyne

import (
	"log"
	"unicode/utf8"
)

// WinFunc retrieves the Win by its ID
type WinFunc func(int) (*Win, error)

// TabwidthFunc returns the tabwidth based on properties of the Event
type TabwidthFunc func(Event) int

// Tab constructs a tab character or the equivalent width of spaces
// depending on if expand is set
func Tab(width int, expand bool) []byte {
	if expand {
		var tab []byte
		for i := 0; i < width; i++ {
			tab = append(tab, ' ')
		}
		return tab
	}
	return []byte{0x09}
}

// Tabexpand expands tabs to spaces
func Tabexpand(condition Condition, win WinFunc, tabwidth TabwidthFunc) (rune, Handler) {
	return '\t', func(e Event) (Event, bool) {
		ok := true
		if !condition(e) {
			return e, ok
		}

		w, err := win(e.ID)
		if err != nil {
			log.Println(err)
			return e, ok
		}

		tab := Tab(tabwidth(e), true)

		// select current character
		err = w.SetAddr("#%d;+#1", e.SelBegin)
		if err != nil {
			log.Println(err)
			w.WriteEvent(e)
		}

		// replace character with tab
		w.SetData(tab)

		// update the event to reflect the change
		rc := utf8.RuneCount(tab)
		selEnd := e.SelBegin + rc
		e.Origin = WindowFiles
		e.Action = BodyInsert
		e.SelEnd = selEnd
		e.OrigSelEnd = selEnd
		e.NumRunes = rc
		e.Text = Text(tab)

		return e, ok
	}
}