Struct Dag 

pub struct Dag { /* private fields */ }

A directed acyclic graph of tasks.

Nodes are task ids; an edge dep -> task means task depends on dep (so a topological sort yields dependencies before the tasks that need them). Dependency nodes may be referenced before the dependency task itself is added; Dag::validate catches any that are never registered.

Implementations

impl Dag

pub fn new() -> Self

Create an empty DAG.

pub fn add_task(&mut self, task: Arc<dyn Task>) -> Result<()>

Register a task and wire up edges from its declared dependencies.

Returns an error on a duplicate id or a self-dependency. Missing dependency tasks and cycles are reported later by Dag::validate.

pub fn len(&self) -> usize

Number of registered tasks.

pub fn is_empty(&self) -> bool

Whether the DAG has no tasks.

pub fn task(&self, id: &str) -> Option<Arc<dyn Task>>

Look up a task by id.

pub fn task_ids(&self) -> Vec<String>

All registered task ids (unordered).

pub fn dependencies_of(&self, id: &str) -> Vec<String>

Direct dependencies of id (incoming edges).

pub fn dependents_of(&self, id: &str) -> Vec<String>

Direct dependents of id (outgoing edges).

pub fn validate(&self) -> Result<()>

Validate the graph: every dependency must be a registered task and the graph must be acyclic.

pub fn topological_order(&self) -> Result<Vec<String>>

Return task ids in dependency order (dependencies first).

Errors if the graph contains a cycle.

Trait Implementations

impl Default for Dag

fn default() -> Dag

Returns the “default value” for a type.