Makes a Zipper factory that uses the implementation provided in the parameters.

Gets the value of the current location.

Moves location to the root, constructing any changes made.

Moves location to the parent, constructing a new parent if the children have changed.

If already at the top, returns null.

Moves location to the leftmost child. If the current item is a leaf, returns null.

Moves location to the left sibling. If the current location is already the leftmost, returns null.

Moves location to the right sibling. If the current location is already the rightmost, returns null.

Moves location to the leftmost sibling. If the current location is already the leftmost, returns itself.

Moves location to the rightmost sibling. If the current location is already the rightmost, returns itself.

Moves location to the next element in depth-first order.

Moves location to the previous element in depth-first order.

Returns a boolean indicating if the zipper has been exhausted by calls to next.

Returns a boolean indicating if the zipper is at the top.

Returns a boolean indicating if the zipper is not at the top.

Returns a boolean indicating if the current location is not a leaf.

Returns a boolean indicating if the current location is a leaf.

Returns a boolean indicating if the item at the current location is the leftmost sibling.

Returns a boolean indicating if the item at the current location is the rightmost sibling.

Returns a boolean indicating if the zipper is not at the top.

Alias for isNotTop

Returns a boolean indicating if the item at the current location is the leftmost sibling.

Alias for isLeftmost

Returns a boolean indicating if the item at the current location is the rightmost sibling.

Alias for isRightmost

Alias for isBranch

Replaces the current item with the given value.

Replaces the current item with value returned by calling fn with the current item.

Inserts a new item as the left sibling.

Inserts a new item as the right sibling.

Inserts a new item as the leftmost child.

Inserts a new item as the rightmost child.

Removes item at the current location. Returns location that would be previous in depth first search.

The Zipper class.

Keeps track of the current item, path, and metadata (implementation functions).

Don't use this constructor directly. Create your own Zipper factory with makeZipper, and use it to create instances of Zipper.

Zipper for nested Arrays.

Don't use with new keyword - use the function plainly or with ArrayZipper.from([1, 2, 3]).

Visits the data structure in depth-first order, calling one or more visitors on each node, on pre and post events.

The visitor functions are called with three arguments:

• event - PRE or POST
• item - the item currently being visited
• state - the state of the visit

If you're visiting for side-effects, you don't have to return anything from your visitor function. To edit items, visit state, or stop the visit, you must return an object which can have zero or more of the following keys:

• item: if supplied, will replace the item at the current location with the supplied value. The data structure won't change if the value has the same reference as the current value.
• state: if supplied, will update the state of the visit with the value. State is shared with all visitors.
• stop: if truthy, will stop the visit
• cut: if truthy, will skip the subtree of the current node.

Returns a new data structure of modified items, or the original zipper if the structure wasn't modified.

Takes a visitor function that takes an item and state argument, and returns a visitor function that is only invoked on the pre-event.

Equal to:

const myVisitor = (item, state) => console.log('visited item', item);
function visitor(event, item, state) {
    if (event === PRE) return myVisitor(item, state);
}

Takes a visitor function that takes an item and state argument, and returns a visitor function that is only invoked on the post-event.

Equal to:

const myVisitor = (item, state) => console.log('visited item', item);
function visitor(event, item, state) {
    if (event === POST) return myVisitor(item, state);
}

Pre-event identifier.

Post-event identifier.

Walks the data structure in depth-first order, applying inner and outer functions before and after (respectively) each item's subtree is walked.

Returns a new data structure from modified items, or the original zipper if the structure wasn't modified.

Walks the data structure in depth-first order, applying the function before the item's subtree has been walked.

Returns a new data structure of modified items, or the original zipper if the structure wasn't modified.

Walks the data structure in depth-first order, applying the function after the item's subtree has been walked.

Returns a new data structure of modified items, or the original zipper if the structure wasn't modified.