wiki/list-editor/cursor.js

function createCursor(start) {
    let cursor = start;
    let lastMovement = 0;

    return {
        get() {
            return cursor;
        },
        set(newPosition) {
            cursor = newPosition;
        },
        getId(store) {
            return store.currentID(cursor)
        },
        atFirst() {
            return cursor === 0;
        },
        atPosition(other) {
            return cursor === other;
        },
        atEnd(store) {
            return cursor === store.length()
        },
        hasMoved(saved) {
            return cursor !== saved.get()
        },
        getCurrent(store) {
            let id = store.currentID(cursor)
            return store.value(id)
        },
        getCurrentElement(elements) {
            return elements.slice(cursor, cursor + 1);
        },
        save() {
            return createCursor(cursor);
        },
        moveUp(store) {
            cursor = store.prevCursorPosition(cursor)
            lastMovement = -1
        },
        moveDown(store) {
            cursor = store.nextCursorPosition(cursor, true)
            lastMovement = 1
        },
        remove(store) {
            let id = store.currentID(cursor)
            let item = store.value(id)
            store.remove(cursor)
            if (cursor >= store.length()) {
                cursor = store.length() - 1
            }
            cursor = store.firstSameIndented(cursor, item.indented)
        },
        insertAbove(store, item) {
            store.insertBefore(store.currentID(cursor), item)
        },
        insertBelow(store, item) {
            let currentID = store.currentID(cursor)
            let currentItem = store.value(currentID)
            if (currentItem.fold !== 'open') {
                cursor = store.lastHigherIndented(cursor)
                item.indented = currentItem.indented
                cursor--
            }
            let id = store.insertAfter(store.currentID(cursor), item)
            cursor = store.index(id)
        },
        forwardToNextVisible(store) {
            cursor = store.nextCursorPosition(cursor, false)
        },
        lastDir() {
            return lastMovement
        },
        resetLastMove() {
            lastMovement = 0
        }
    };
}

export default createCursor;