Struct FeatureQuery 

pub struct FeatureQuery<'g> { /* private fields */ }

A query over a feature graph.

A FeatureQuery is the entry point for Cargo resolution, and also provides iterators over feature IDs and links. This struct is constructed through the query_ methods on FeatureGraph, or through PackageQuery::to_feature_query.

Implementations

impl<'g> FeatureQuery<'g>

pub fn graph(&self) -> &FeatureGraph<'g>

Returns the feature graph the query is going to be executed on.

pub fn direction(&self) -> DependencyDirection

Returns the direction the query is happening in.

pub fn initials(&self) -> &FeatureSet<'g>

Returns the set of initial features specified in the query.

pub fn initial_packages<'a>( &'a self, ) -> impl Iterator<Item = PackageMetadata<'g>> + 'a

Returns the list of initial packages specified in the query.

The order of packages is unspecified.

pub fn starts_from_package(&self, package_id: &PackageId) -> Result<bool, Error>

Returns true if the query starts from the given package.

Returns an error if the package ID is unknown.

pub fn resolve(self) -> FeatureSet<'g>

Resolves this query into a set of known feature IDs.

This is the entry point for iterators.

The result is every feature reachable from the initials, ignoring any conditions attached to it (such as whether it is a dev-dependency or a weak dependency). This does not determine which features Cargo would enable in a particular build.

To simulate a Cargo build, pass a set of workspace features to FeatureSet::into_cargo_set, then inspect CargoSet::target_features and CargoSet::host_features.

pub fn resolve_with( self, visitor: impl FeatureLinkVisitor<'g>, ) -> FeatureSet<'g>

Resolves this query into a set of known feature IDs, using the provided visitor to determine which links are followed.

The visitor can be called twice for a weak dependency feature (dep?/feature). See FeatureLinkVisitor::visit_link for details.

With a visitor that accepts every link, a reverse query returns the same set as resolve. Note that (unlike with resolve), a forward query can return a smaller set of features because of weak links not being activated.

pub fn resolve_with_fn( self, visitor_fn: impl FnMut(&FeatureLinkContext<'g>, ConditionalLink<'g>) -> bool, ) -> FeatureSet<'g>

Resolves this query into a set of known feature IDs, using the provided visitor function to determine which links are followed.

The visitor function can be called twice for a weak dependency feature (dep?/feature). See FeatureLinkVisitor::visit_link for details.

Trait Implementations

impl<'g> Clone for FeatureQuery<'g>

fn clone(&self) -> FeatureQuery<'g>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<'g> Debug for FeatureQuery<'g>

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

Formats the value using the given formatter.