Struct Visitor

pub struct Visitor {
    pub blackboard: Blackboard,
    pub flags: VisitorFlags,
    /* private fields */
}

A collection of nodes that stores data that can be read or write values of types with the Visit trait.

Instead of calling methods of the visitor in order to read or write the visitor’s data, reading and writing happens in the Visit::visit method of a variable that will either store the read value or holds the value to be written.

For example, x.visit("MyValue", &mut visitor) will do one of:

1. Take the value of x and store it in visitor under the name “MyValue”, if visitor.is_reading() is false.
2. Read a value named “MyValue” from visitor and store it in x, if visitor.is_reading() is true.

Whether the value of x gets written into visitor or overwitten with a value from visitor is determined by whether Visitor::is_reading() returns true or false.

Fields

blackboard: Blackboard

A place to store whatever objects may be needed to assist with reading and writing values.

flags: VisitorFlags

Flags that can activate special behaviour in some Visit values, such as crate::variable::InheritableVariable.

Implementations

impl Visitor

pub const MAGIC: &'static str = "RG3D"

Sequence of bytes that is automatically written at the start when a visitor is encoded into bytes. It is written by Visitor::save_binary, Visitor::save_binary_to_memory, and Visitor::save_binary_to_vec.

Visitor::load_binary will return an error if this sequence of bytes is not present at the beginning of the file, and Visitor::load_from_memory will return an error of these bytes are not at the beginning of the given slice.

pub fn new() -> Visitor

Creates a Visitor containing only a single node called “__ROOT__” which will be the current region of the visitor.

pub fn is_reading(&self) -> bool

True if this Visitor is changing the values that it visits. In other words x.visit("MyValue", &mut visitor) will result in x being mutated to match whatever value is stored in visitor.

False if this visitor is copying and storing the values that it visits. In other words x.visit("MyValue", &mut visitor) will result in x being unchanged, but visitor will be mutated to store the value of x under the name “MyValue”.

pub fn enter_region( &mut self, name: &str, ) -> Result<RegionGuard<'_>, VisitError>

If Visitor::is_reading, find a node with the given name that is a child of the current node, and return a Visitor for the found node. Return an error if no node with that name exists.

If not reading, create a node with the given name as a chld of the current node, and return a visitor for the new node. Return an error if a node with that name already exists.

pub fn current_region(&self) -> Option<&str>

The name of the current region. This should never be None if the Visitor is operating normally, because there should be no way to leave the initial __ROOT__ region.

pub fn save_text(&self) -> String

Create a String containing all the data of this Visitor. The String is formatted to be human-readable with each node on its own line and tabs to indent child nodes.

pub fn save_binary_to_memory<W>(&self, writer: W) -> Result<(), VisitError>

where W: Write,

Write the data of this Visitor to the given writer. Begin by writing Visitor::MAGIC.

pub fn save_binary_to_vec(&self) -> Result<Vec<u8>, VisitError>

Encode the data of this visitor into bytes and push the bytes into the given Vec<u8>. Begin by writing Visitor::MAGIC.

pub fn save_binary<P>(&self, path: P) -> Result<(), VisitError>

where P: AsRef<Path>,

Create a file at the given path and write the data of this visitor into that file in a non-human-readable binary format so that the data can be reconstructed using Visitor::load_binary. Begin by writing Visitor::MAGIC.

pub async fn load_binary<P>(path: P) -> Result<Visitor, VisitError>

where P: AsRef<Path>,

Create a visitor by reading data from the file at the given path, assuming that the file was created using Visitor::save_binary. Return a VisitError::NotSupportedFormat if Visitor::MAGIC is not the first bytes read from the file.

pub fn load_from_memory(data: &[u8]) -> Result<Visitor, VisitError>

Create a visitor by decoding data from the given byte slice, assuming that the bytes are in the format that would be produced by Visitor::save_binary_to_vec. Return a VisitError::NotSupportedFormat if Visitor::MAGIC is not the first bytes read from the slice.

Trait Implementations

impl Default for Visitor

fn default() -> Visitor

Returns the “default value” for a type.