pivot-editor/index.html

<script>
var N = {
    Create:(inMeta, ...inChildren)=>
    {
        var output = {
            Meta:inMeta,

            Children:[],
            Parents:[],
            WalkID:0,

            edited:[],
            editing:[]
        };
        inChildren.forEach( inChild => N.ConnectChild(output, inChild) );
        return output;
    },
    ConnectChild:(inParent, inChild)=>
    {
        inParent.Children.push(inChild);
        inChild.Parents.push(inParent);
    },
    Walk:(inNode, inKey, inIterator, inWalkID) =>
    {
        let array = inNode[inKey];
        for(let i=0; i<array.length; i++)
        {
            let next = array[i];
            if(next.WalkID !== inWalkID)
            {
                next.WalkID = inWalkID;
                let results = inIterator(next);
                if(results !== false)
                {
                    N.Walk(next, inKey, inIterator, inWalkID);
                }
            }
        }
    },
    WalkChildren:(inNode, inIterator, inWalkID) => N.Walk(inNode, "Children", inIterator, inWalkID),
    WalkParents :(inNode, inIterator, inWalkID) => N.Walk(inNode, "Parents",  inIterator, inWalkID)
};
</script>
<script>
let tree1 = N.Create("root1",
    N.Create("branch1", 
        N.Create("leaf1"),
        N.Create("leaf2"),
        N.Create("leaf3"),
    ),
    N.Create("branch2",
        N.Create("leaft3"),
        N.Create("leaft4")
    )
);

let leaves = [];
let leavesCollect = n=>
{
    if(n.Children.length == 0)
    {
        leaves.push(n);
    }
};
N.WalkChildren(tree1, leavesCollect, 1);

let tree2 = N.Create("root2", 
    N.Create("branch3",
        N.Create("leaf5"),
        N.Create("leaf6")
    ),
    N.Create("branch4", ...leaves)
);

let orchard = N.Create("orchard", tree1, tree2);


/*************************************************************/

// phase 0, start node
let modified = tree1;

// phase 1, walk up and flag additions
let additionNodes = [];
let additionGather = n =>
{
    additionNodes.push(n);
};

// phase 2 walk down and flag multiply, also collect leaves
let multiplyNodes = [];
let multiplyLeaves = [];
let multiplyGather = n =>
{
    multiplyNodes.push(n)
    n.Children.length == 0 ?  multiplyLeaves.push(n) : null;
};

// phase 3 walk up from leaves and flag additions
// (re-uses phase 1)

///////////////////////

// phase 0
modified.WalkID = "add-1";

//phase 1
N.Walk(modified, "Parents", additionGather, modified.WalkID);

//phase 2
N.Walk(modified, "Children", multiplyGather, modified.WalkID);

//phase 3
multiplyLeaves.forEach(leaf=>{
    N.Walk(leaf, "Parents", additionGather, modified.WalkID);
});

console.log(additionNodes);
console.log(multiplyNodes);
</script>