Returns the current cursor.

Returns the CoordState at the given point.

Navigates up to the parent node, fires a navigationEvent, then returns true. If already at the root of the tree, then none of this happens and false is returned.

Navigates down the tree to the child with the given index, fires a navigationEvent, then returns true. If the requested child doesn't exist, then none of this happens and false is returned.

If possible, moves to the sibling node immediately to the left of the current one. Returns whether a move was made (i.e. whether there was a left sibling). Fires navigationEvents while moving.

If possible, moves to the sibling node immediately to the right of the current one. Returns whether a move was made (i.e. whether there was a right sibling). Fires navigationEvents while moving.

Navigates up to the root of the tree. Fires navigationEvents for each step.

Navigates up the tree to the node containing game info properties, if any. Returns true if a game info node was found.

Pushes the current location in the game tree onto an internal position stack, such that popPosition is capable of navigating back to the same position, even if the game tree has been modified (though the old position must still exist in the tree to return to it).

Returns to the last position pushed onto the internal position stack via pushPosition, if there is one. Returns a code indicating the result of the action.

Drops the last position pushed onto the internal stack by pushPosition off of the stack, if there is one. Returns a code indicating the result of the action.

Returns the set of properties on the current node.

Modifies the set of properties on the current node. Fires propertiesModifiedEvent after modifying if the new property set is different from the old property set (order is irrelevant).

Searches for a property on the current node, returning it if found.

Searches for a valued property on the current node, returning its value if found.

Sets a property on the current node, replacing an existing property with the same name, if one exists. Fires propertiesModifiedEvent if the property has changed.

Deletes a property from the current node, if it's set, and fires propertiesModifiedEvent.

Note that although a Property is a Descriptor, giving a valued Property here will not cause deletion to match on the value of the property. That is, the following code will result in Nothing, because the deletion only cares about the name of the property.

do putProperty $ PL Black
   deleteProperty $ PL White
   getPropertyValue propertyPL

Calls the given function to modify the state of the given property (descriptor) on the current node. Nothing represents the property not existing on the node, and a Just marks the property's presence. Fires propertiesModifiedEvent if the property changed. This function does not do any validation to check that the resulting tree state is valid.

The given function is not allowed to change the property into a different property. Instead, the old property should be removed and the new property should be inserted separately. If the function does this, ModifyPropertyCannotChangeType is returned and no modification takes place.

Calls the given function to modify the state of the given valued property (descriptor) on the current node. Nothing represents the property not existing on the node, and a Just with the property's value marks the property's presence. Fires propertiesModifiedEvent if the property changed. This function does not do any validation to check that the resulting tree state is valid.

Mutates the string-valued property attached to the current node according to the given function. The input string will be empty if the current node either has the property with an empty value, or doesn't have the property. Returning an empty string removes the property from the node, if it was set. Fires propertiesModifiedEvent if the property changed.

Mutates the list-valued property attached to the current node according to the given function. The input list will be empty if the current node either has the property with an empty value, or doesn't have the property. Returning an empty list removes the property from the node, if it was set.

Fires propertiesModifiedEvent if the property changed.

See also modifyPropertyCoords.

Mutates the CoordList-valued property attached to the current node according to the given function. Conversion between CoordList and [Coord] is performed automatically. The input list will be empty if the current node either has the property with an empty value, or doesn't have the property. Returning an empty list removes the property from the node, if it was set.

Importantly, this might not be specific enough for properties such as DD and VW where a present, empty list has different semantics from the property not being present. In that case, modifyPropertyValue is better.

Fires propertiesModifiedEvent if the property changed.

Mutates the game info for the current path, returning the new info. If the current node or one of its ancestors has game info properties, then that node is modified. Otherwise, properties are inserted on the root node. The return value on success is (oldGameInfo, newGameInfo).

The given function is not allowed to modify the RootInfo within the GameInfo. If this happens, an error code is returned and no modifications are made.

Sets the game's VariationMode via the ST property on the root node, then fires a variationModeChangedEvent if the variation mode has changed.

Retrieves the stone assigned in the current node to a point by AB, AE, or AW. The possible results are:

• Nothing: No stone has been assigned to the point. The point could still be in any state, e.g. from a play on the current node or some property in an ancestor node.
• Just Nothing: The point has been assigned to be empty.
• Just (Just Color): The point has been assigned to have a stone of the given color.

Looks up all stones that are assigned by AB, AE, or AW properties on the current node. Returns a map from each point to the stone that is assigned to the point.

Modifies the state of currently assigned stones, keeping in mind that it is invalid to mix MoveProperty and SetupProperty properties in a single node. This function has the behaviour of a user changing stone assignments in a UI. How this function works is:

• Pick a node to work with. If there is a move property on the current node and there is not already a setup property on the current node, then we'll create and modify a new child node. Otherwise, either there are no move properties on the node (so we can add setup properties at will), or there are both move and setup properties on the node (the node is already invalid), so we'll just modify the current node.
• If we're modifying the current node, then apply the modification function to the state of stone assignment for each coordinate. See getAssignedStone for the meaning of Maybe (Maybe Color). Modify the properties in the node as necessary to apply the result (propertiesModifiedEvent). (NOTE: Currently one event is fired for each property modified; this may change in the future.)
• If we need to create a child node, then apply the modification function to Nothing to determine if we're actually adding assignments. If the function returns a Just, then we create a child node with the necessary assignment properties, insert it (childAddedEvent), then navigate to it (navigationEvent). If the function returns Nothing, then modifyAssignedStones does nothing.

Returns the Mark at a point on the current node.

Calls the given function to modify the presence of a Mark on the current node.

Adds a child node to the current node at the end of the current node's child list. Fires a childAddedEvent after the child is added.

Adds a child node to the current node at the given index, shifting all existing children at and after the index to the right. The index must be in the range [0, numberOfChildren]; if it is not, it will be capped to this range. Fires a childAddedEvent after the child is added.

Tries to remove the child node at the given index below the current node. Returns a status code indicating whether the deletion succeeded, or why not.

Registers a new event handler for a given event type.

Registers a new event handler for a given event type. Unlike on, whose handler may receive arguments, the handler given here doesn't receive any arguments.