Class QuerySourceRdfJs

A lazy query source.

Implements

IQuerySource

Constructors

constructor

new QuerySourceRdfJs(
    source: Source<Quad> | DatasetCore<Quad, Quad>,
    dataFactory: ComunicaDataFactory,
    bindingsFactory: BindingsFactory,
): QuerySourceRdfJs
Parameters
- source: Source<Quad> | DatasetCore<Quad, Quad>
- dataFactory: ComunicaDataFactory
- bindingsFactory: BindingsFactory
Returns QuerySourceRdfJs
- Defined in packages/actor-query-source-identify-rdfjs/lib/QuerySourceRdfJs.ts:87

Properties

referenceValue

referenceValue: QuerySourceReference

The URL of RDF source of this source.

`Protected` `Readonly`selectorShape

selectorShape: FragmentSelectorShape

`Protected` `Readonly`source

source: IRdfJsSourceExtended | DatasetCore<Quad, Quad>

Methods

canContainBlankNodes

canContainBlankNodes(): boolean
If this source may currently return blank nodes. Sources that do not implement this, or that can not know it, must be assumed to return blank nodes.

Returns boolean
False if the source certainly returns no blank nodes, true otherwise.
Implementation of IQuerySource.canContainBlankNodes
- Defined in packages/actor-query-source-identify-rdfjs/lib/QuerySourceRdfJs.ts:339

`Protected`getCardinalityCache

getCardinalityCache(context: IActionContext): Map<string, number> | undefined
Obtain the cardinality cache for the query execution that the given context belongs to. Returns undefined if the context carries no query execution scope, in which case nothing is cached.
Parameters
- context: IActionContext
  The action context.
Returns Map<string, number> | undefined
- Defined in packages/actor-query-source-identify-rdfjs/lib/QuerySourceRdfJs.ts:411

`Protected`getDistinctValues

getDistinctValues(
    operation: Pattern,
    variable: Variable,
    cardinality: number,
    quotedTripleFiltering: boolean,
): number | undefined
Determine how many distinct values the given variable of the given pattern takes. Only counted when the source can answer it with an index lookup, and left undefined otherwise.
Parameters
- operation: Pattern
  The pattern being evaluated.
- variable: Variable
  A variable of that pattern.
- cardinality: number
  The cardinality of that pattern.
- quotedTripleFiltering: boolean
  If the source supports quoted triple filtering.
Returns number | undefined
- Defined in packages/actor-query-source-identify-rdfjs/lib/QuerySourceRdfJs.ts:432

getFilterFactor

getFilterFactor(): Promise<number>
Returns Promise<number>
A value from 0 to 1 indicating to what respect a source type is able to pre-filter the source based on the pattern. 1 indicates that the source can apply the whole pattern, and 0 indicates that the source can not apply the pattern at all (and local filtering must happen). Plain RDF documents for example have a filter factor of 0, while SPARQL endpoints have a filter factor of 1.
Implementation of IQuerySource.getFilterFactor
- Defined in packages/actor-query-source-identify-rdfjs/lib/QuerySourceRdfJs.ts:162

getSelectorShape

getSelectorShape(): Promise<FragmentSelectorShape>
Get the selector type that is supported by this source.

Returns Promise<FragmentSelectorShape>
Implementation of IQuerySource.getSelectorShape
- Defined in packages/actor-query-source-identify-rdfjs/lib/QuerySourceRdfJs.ts:158

queryBindings

queryBindings(operation: BaseOperation, context: IActionContext): BindingsStream
Returns a (possibly lazy) stream that returns all bindings matching the operation.

Passed operations MUST conform to the query shape exposed by the selector type returned from getSelectorShape. The given operation represents a Linked Data Fragments selector.

The returned stream MUST expose the property 'metadata' of type MetadataBindings. The implementor is reponsible for handling cases where 'metadata' is being called without the stream being in flow-mode. This metadata object can become invalidated (see metadata.state), in which case the 'metadata' property must and will be updated.
Parameters
- operation: BaseOperation
  The query operation to execute.
- context: IActionContext
  The query context.
Returns BindingsStream
The resulting bindings stream.

See
https://linkeddatafragments.org/specification/linked-data-fragments/#selectors
Implementation of IQuerySource.queryBindings
- Defined in packages/actor-query-source-identify-rdfjs/lib/QuerySourceRdfJs.ts:166

queryBindingsSynchronous

queryBindingsSynchronous(
operation: BaseOperation,
context: IActionContext,
): Bindings[] | undefined
Synchronously returns all bindings of the given operation.

This is optional, and only meant for sources that can answer lookups without I/O. When present, synchronous should be true in the selector shape, for the operations that can be passed here.
Parameters
- operation: BaseOperation
  The operation to evaluate.
- context: IActionContext
  The query context.
Returns Bindings[] | undefined
The resulting bindings, or undefined if the operation can not be evaluated synchronously, in which case queryBindings must be used instead.
Implementation of IQuerySource.queryBindingsSynchronous
- Defined in packages/actor-query-source-identify-rdfjs/lib/QuerySourceRdfJs.ts:343

queryBoolean

queryBoolean(_operation: Ask, _context: IActionContext): Promise<boolean>
Returns a promise resolving to the ask response of the given operation.

This method should only be supported if the selector type returned from getSelectorShape supports ask queries.
Parameters
- _operation: Ask
- _context: IActionContext
Returns Promise<boolean>
The resulting ask reply.
Implementation of IQuerySource.queryBoolean
- Defined in packages/actor-query-source-identify-rdfjs/lib/QuerySourceRdfJs.ts:610

queryQuads

queryQuads(
operation: BaseOperation,
_context: IActionContext,
): AsyncIterator<Quad>
Returns a (possibly lazy) stream that returns all quads matching the operation.

This method should only be supported if the selector type returned from getSelectorShape supports construct queries.
Parameters
- operation: BaseOperation
  The query operation to execute.
- _context: IActionContext
Returns AsyncIterator<Quad>
The resulting quads stream.
Implementation of IQuerySource.queryQuads
- Defined in packages/actor-query-source-identify-rdfjs/lib/QuerySourceRdfJs.ts:597

queryVoid

queryVoid(_operation: BaseOperation, _context: IActionContext): Promise<void>
Returns a promise resolving when the given update operation succeeds.

This method should only be supported if the selector type returned from getSelectorShape supports update queries.
Parameters
- _operation: BaseOperation
- _context: IActionContext
Returns Promise<void>
The void response.
Implementation of IQuerySource.queryVoid
- Defined in packages/actor-query-source-identify-rdfjs/lib/QuerySourceRdfJs.ts:617

`Protected`setMetadata

setMetadata(
    it: AsyncIterator<any>,
    operation: Pattern,
    context: IActionContext,
    forceEstimateCardinality?: boolean,
    extraMetadata?: Record<string, any>,
): Promise<void>
Parameters
- it: AsyncIterator<any>
- operation: Pattern
- context: IActionContext
- forceEstimateCardinality: boolean = false
- extraMetadata: Record<string, any> = {}
Returns Promise<void>
- Defined in packages/actor-query-source-identify-rdfjs/lib/QuerySourceRdfJs.ts:508

toString

toString(): string
Returns a string representation of this source.

Returns string
Implementation of IQuerySource.toString
- Defined in packages/actor-query-source-identify-rdfjs/lib/QuerySourceRdfJs.ts:624

`Protected`toUnionDefaultGraph

toUnionDefaultGraph(operation: Pattern, unionDefaultGraph: boolean): Pattern
In union default graph mode, the pattern to match for a pattern over the default graph, with a variable graph so that it also matches named graphs.
Parameters
- operation: Pattern
  A quad pattern.
- unionDefaultGraph: boolean
  If union default graph mode is enabled.
Returns Pattern
The given pattern, or a new one with a variable graph and the same metadata.
- Defined in packages/actor-query-source-identify-rdfjs/lib/QuerySourceRdfJs.ts:328

`Static`getCardinalityCacheKey

getCardinalityCacheKey(...terms: (Term | undefined)[]): string | undefined
Determine a cardinality cache key for the given (already nullified) quad pattern terms. Returns undefined for patterns that must not be cached, i.e. those containing quoted triples, as those are matched structurally rather than by value.
Parameters
- ...terms: (Term | undefined)[]
  The quad pattern terms, where undefined represents a wildcard.
Returns string | undefined
- Defined in packages/actor-query-source-identify-rdfjs/lib/QuerySourceRdfJs.ts:477

`Static`hasDuplicateVariables

hasDuplicateVariables(pattern: BaseQuad): boolean
Parameters
- pattern: BaseQuad
Returns boolean
- Defined in packages/actor-query-source-identify-rdfjs/lib/QuerySourceRdfJs.ts:153

`Static`hasQuotedVariables

hasQuotedVariables(operation: Pattern): boolean
Check if the given pattern contains quoted triples with variables, which require post-filtering that sync lookups do not do.
Parameters
- operation: Pattern
  A quad pattern.
Returns boolean
- Defined in packages/actor-query-source-identify-rdfjs/lib/QuerySourceRdfJs.ts:378

`Static`isCardinalityCacheable

isCardinalityCacheable(...terms: (Term | undefined)[]): boolean
Check whether counting the given (already nullified) quad pattern is expensive enough to be worth caching.

Patterns with at most one wildcard are answered by a direct index lookup, so counting them is cheap. In bind joins those are the materialized patterns, which differ for every binding, so caching them would only add lookup and storage cost. Patterns with more wildcards require an index walk proportional to their cardinality, and are exactly the patterns that a bind join re-evaluates unchanged once per binding.
Parameters
- ...terms: (Term | undefined)[]
  The quad pattern terms, where undefined represents a wildcard.
Returns boolean
- Defined in packages/actor-query-source-identify-rdfjs/lib/QuerySourceRdfJs.ts:393

`Static`nullifyVariables

nullifyVariables(
term: Term | undefined,
quotedTripleFiltering: boolean,
): Term | undefined
Parameters
- term: Term | undefined
- quotedTripleFiltering: boolean
Returns Term | undefined
- Defined in packages/actor-query-source-identify-rdfjs/lib/QuerySourceRdfJs.ts:146

Class QuerySourceRdfJs

Implements

Index

Constructors

Properties

Methods

Constructors

constructor

Parameters

Returns QuerySourceRdfJs

Properties

referenceValue

Protected ReadonlyselectorShape

Protected Readonlysource

Methods

canContainBlankNodes

Returns boolean

ProtectedgetCardinalityCache

Parameters

Returns Map<string, number> | undefined

ProtectedgetDistinctValues

Parameters

Returns number | undefined

getFilterFactor

Returns Promise<number>

getSelectorShape

Returns Promise<FragmentSelectorShape>

queryBindings

Parameters

Returns BindingsStream

See

queryBindingsSynchronous

Parameters

Returns Bindings[] | undefined

queryBoolean

Parameters

Returns Promise<boolean>

queryQuads

Parameters

Returns AsyncIterator<Quad>

queryVoid

Parameters

Returns Promise<void>

ProtectedsetMetadata

Parameters

Returns Promise<void>

toString

Returns string

ProtectedtoUnionDefaultGraph

Parameters

Returns Pattern

StaticgetCardinalityCacheKey

Parameters

Returns string | undefined

StatichasDuplicateVariables

Parameters

Returns boolean

StatichasQuotedVariables

Parameters

Returns boolean

StaticisCardinalityCacheable

Parameters

Returns boolean

StaticnullifyVariables

Parameters

Returns Term | undefined

Settings

On This Page

`Protected` `Readonly`selectorShape

`Protected` `Readonly`source

`Protected`getCardinalityCache

`Protected`getDistinctValues

`Protected`setMetadata

`Protected`toUnionDefaultGraph

`Static`getCardinalityCacheKey

`Static`hasDuplicateVariables

`Static`hasQuotedVariables

`Static`isCardinalityCacheable

`Static`nullifyVariables