Trait Query

pub trait Query:
    QueryClone
    + Send
    + Sync
    + Downcast
    + Debug {
    // Required method
    fn weight(
        &self,
        enable_scoring: EnableScoring<'_>,
    ) -> Result<Box<dyn Weight>>;

    // Provided methods
    fn explain(
        &self,
        searcher: &Searcher,
        doc_address: DocAddress,
    ) -> Result<Explanation> { ... }
    fn count(&self, searcher: &Searcher) -> Result<usize> { ... }
    fn query_terms<'a>(&'a self, _visitor: &mut dyn FnMut(&'a Term, bool)) { ... }
}

The Query trait defines a set of documents and a scoring method for those documents.

The Query trait is in charge of defining :

• a set of documents
• a way to score these documents

When performing a search, these documents will then be pushed to a Collector, which will in turn be in charge of deciding what to do with them.

Concretely, this scored docset is represented by the Scorer trait.

Because our index is actually split into segments, the query does not actually directly creates DocSet object. Instead, the query creates a Weight object for a given searcher.

The weight object, in turn, makes it possible to create a scorer for a specific SegmentReader.

So to sum it up :

• a Query is a recipe to define a set of documents as well the way to score them.
• a Weight is this recipe tied to a specific Searcher. It may for instance hold statistics about the different term of the query. It is created by the query.
• a Scorer is a cursor over the set of matching documents, for a specific SegmentReader. It is created by the Weight.

When implementing a new type of Query, it is normal to implement a dedicated Query, Weight and Scorer.

Required Methods

fn weight(&self, enable_scoring: EnableScoring<'_>) -> Result<Box<dyn Weight>>

Create the weight associated with a query.

If scoring is not required, setting scoring_enabled to false can increase performances.

See Weight.

Provided Methods

fn explain( &self, searcher: &Searcher, doc_address: DocAddress, ) -> Result<Explanation>

Returns an Explanation for the score of the document.

fn count(&self, searcher: &Searcher) -> Result<usize>

Returns the number of documents matching the query.

fn query_terms<'a>(&'a self, _visitor: &mut dyn FnMut(&'a Term, bool))

Extract all of the terms associated with the query and pass them to the given closure.

Each term is associated with a boolean indicating whether positions are required or not.

Note that there can be multiple instances of any given term in a query and deduplication must be handled by the visitor.

Implementations

impl dyn Query

pub fn is<__T: Query>(&self) -> bool

Returns true if the trait object wraps an object of type __T.

pub fn downcast<__T: Query>(self: Box<Self>) -> Result<Box<__T>, Box<Self>>

Returns a boxed object from a boxed trait object if the underlying object is of type __T. Returns the original boxed trait if it isn’t.

pub fn downcast_rc<__T: Query>(self: Rc<Self>) -> Result<Rc<__T>, Rc<Self>>

Returns an Rc-ed object from an Rc-ed trait object if the underlying object is of type __T. Returns the original Rc-ed trait if it isn’t.

pub fn downcast_ref<__T: Query>(&self) -> Option<&__T>

Returns a reference to the object within the trait object if it is of type __T, or None if it isn’t.

pub fn downcast_mut<__T: Query>(&mut self) -> Option<&mut __T>

Returns a mutable reference to the object within the trait object if it is of type __T, or None if it isn’t.

Trait Implementations

impl Query for Box<dyn Query>

fn weight(&self, enabled_scoring: EnableScoring<'_>) -> Result<Box<dyn Weight>>

Create the weight associated with a query.

fn count(&self, searcher: &Searcher) -> Result<usize>

Returns the number of documents matching the query.

fn query_terms<'a>(&'a self, visitor: &mut dyn FnMut(&'a Term, bool))

Extract all of the terms associated with the query and pass them to the given closure.

fn explain( &self, searcher: &Searcher, doc_address: DocAddress, ) -> Result<Explanation>

Returns an Explanation for the score of the document.

impl QueryClone for Box<dyn Query>

fn box_clone(&self) -> Box<dyn Query>

Returns a boxed clone of self.

Implementations on Foreign Types

impl Query for Box<dyn Query>

fn weight(&self, enabled_scoring: EnableScoring<'_>) -> Result<Box<dyn Weight>>

fn count(&self, searcher: &Searcher) -> Result<usize>

fn query_terms<'a>(&'a self, visitor: &mut dyn FnMut(&'a Term, bool))

Implementors

impl Query for AllQuery

impl Query for BooleanQuery

impl Query for BoostQuery

impl Query for ConstScoreQuery

impl Query for DisjunctionMaxQuery

impl Query for EmptyQuery

impl Query for ExistsQuery

impl Query for FastFieldRangeQuery

impl Query for FuzzyTermQuery

impl Query for InvertedIndexRangeQuery

impl Query for MoreLikeThisQuery

impl Query for PhrasePrefixQuery

impl Query for PhraseQuery

impl Query for RangeQuery

impl Query for RegexPhraseQuery

impl Query for RegexQuery

impl Query for TermQuery

impl Query for TermSetQuery