Struct Graph 

pub struct Graph { /* private fields */ }

A graph.

Cheap to clone and cheap to keep around, the same way crate::Docs is: the handle is a pointer and an index, and every clone is the same graph.

Implementations

impl Graph

pub fn name(&self) -> Result<String>

The name this graph was opened under.

Errors

Code::Invalid if called from inside a callback that is already holding this database.

pub fn add<N: Node>(&self, node: &N) -> Result<Id<N>>

Put a node in, replacing whatever was under its id.

The Id that comes back is this graph’s handle on the node and is the same one every time for the same struct id, so adding a node twice updates it rather than making a second one.

Errors

Code::ShapeMismatch when another type already uses this label, and Code::Invalid for an id that cannot be a key.

pub fn id_of<N: Node>( &self, id: &<N::Id as Asked>::Ask, ) -> Result<Option<Id<N>>>

This graph’s handle on the node with the id you wrote, if it has one.

The one call that pays the lookup from a struct id to a dense id, which is what the module docs are about.

Errors

Code::Invalid for an id that cannot be a key.

pub fn get<N: Node>(&self, id: Id<N>) -> Result<Option<N>>

Read a node back.

Errors

Code::Corrupt if the stored node is not an N, which is a graph that disagrees with its own labels.

pub fn has<N: Node>(&self, id: Id<N>) -> Result<bool>

Whether this graph still has that node.

Errors

Code::Invalid if called from inside a callback holding this database.

pub fn remove<N: Node>(&self, id: Id<N>) -> Result<bool>

Take a node out, along with every edge at either end of it.

Answers whether the node was there.

Errors

Code::Corrupt if the stored node is not an N.

pub fn count<N: Node>(&self) -> Result<usize>

How many nodes of this type the graph holds.

Errors

Code::Invalid if called from inside a callback holding this database.

pub fn nodes(&self) -> Result<usize>

How many nodes of every type the graph holds.

Errors

Code::Invalid if called from inside a callback holding this database.

pub fn edges(&self) -> Result<usize>

How many edges of every type the graph holds, counting two edges between the same pair as two.

Errors

Code::Invalid if called from inside a callback holding this database.

pub fn link<E: Edge>( &self, from: Id<E::From>, to: Id<E::To>, edge: &E, ) -> Result<EdgeId<E>>

Put an edge between two nodes.

Linking the same pair twice leaves two edges, each with its own fields, because that is what a property graph means by a multigraph and because two ratings of the same film on two dates is the case rather than the corner case.

Errors

Code::NotFound if either end is not in the graph, because an edge hanging off an id that was never added is a dangling reference that every later read would have to guard against.

pub fn unlink<E: Edge>(&self, from: Id<E::From>, to: Id<E::To>) -> Result<bool>

Take one edge of this kind out from between two nodes.

Answers whether there was one. With two edges between the same pair it takes one of them, and which one is whatever the run’s order left.

Errors

Code::Invalid if called from inside a callback holding this database.

pub fn edge<E: Edge>(&self, id: EdgeId<E>) -> Result<Option<E>>

Read an edge’s fields.

Errors

Code::Corrupt if the stored edge is not an E.

pub fn out<E: Edge>(&self, from: Id<E::From>) -> Result<Vec<Id<E::To>>>

Where an edge of this kind goes from this node.

Errors

Code::Invalid if called from inside a callback holding this database.

pub fn incoming<E: Edge>(&self, to: Id<E::To>) -> Result<Vec<Id<E::From>>>

Where an edge of this kind comes into this node from.

Errors

Code::Invalid if called from inside a callback holding this database.

pub fn out_edges<E: Edge>(&self, from: Id<E::From>) -> Result<Vec<Hop<E>>>

The same as Graph::out, with the edge that got to each one.

Errors

Code::Invalid if called from inside a callback holding this database.

pub fn degree<E: Edge>(&self, from: Id<E::From>) -> Result<usize>

How many edges of this kind leave this node.

Read off the run header, so it does not touch the run.

Errors

Code::Invalid if called from inside a callback holding this database.

pub fn walk<N: Node>(&self, from: Id<N>) -> Walk<'_, N>

Start a walk at a node.

pub fn walk_from<N: Node, V: Asked>( &self, path: impl Into<Path<N, V>>, value: &V::Ask, ) -> Result<Walk<'_, N>>

Start a walk at everything a path index answers.

Errors

The same as Graph::find.

pub fn find<N: Node, V: Asked>( &self, path: impl Into<Path<N, V>>, value: &V::Ask, ) -> Result<Vec<N>>

Every node of this type with value at path.

Errors

Code::Invalid if the path is not indexed, and Code::Corrupt if a stored node is not an N.

pub fn count_at<N: Node, V: Asked>( &self, path: impl Into<Path<N, V>>, value: &V::Ask, ) -> Result<usize>

How many nodes of this type have value at path.

Errors

The same as Graph::find, without the decode.

pub fn memory_bytes(&self) -> Result<usize>

What this graph weighs.

Errors

Code::Invalid if called from inside a callback holding this database.

Trait Implementations

impl Clone for Graph

fn clone(&self) -> Graph

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Graph

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.