Capabilities

Qlue-s provides SPARQL support to your editor (or tool). These are structured in Capabilities.

✨ Completion

Completion provides suggestions how the query could continue.

Completions are invoked automatically by your editor or by the user (usually by the key combination ctrl + space). They are also triggered when the user types ?.

Qlue-ls provides different types of completions:

Variable completion

When a user types a word beginning with ?, all variables in scope will be returned.

Warning

Variable completion should work everywhere where variables are allowed. However, note that collecting variables after the cursor is harder then before the cursor and might not work as expected.

SPO completion

Warning

For SPO completions a backend has to be configured

Subject, Predicate, Object completions are triggered when the cursor is in a GraphPattern.

Qlue-ls sends 2 queries to the backend, retrieving possible continuations. One with constraining context, one without. If the context-sensitive query failed, the context-free one is used as a fallback.

Note that the quality of the result depends on the query, while the speed depends on the triple store.

To get really good SPO completions, custom completion queries are required.

📐 Formatting

Format SPARQL queries to ensure consistent and readable syntax. Customizable options to align with preferred query styles are also implemented.

🩺 Diagnostics

Diagnostics provide feadback on the query. Diagnostics come in severity: ❌ error, ⚠️ warning and ℹ️ info.

Here is a complete list of diagnostics qlue-ls can provide:

Type	Name	Description
❌ error	undefined prefix	a used prefix is not declared
❌ error	ungrouped select variable	a selected variable is not in the group by clause
❌ error	invalid projection variable	projection variable is already defined
⚠️ warning	unused prefix	a declared prefix is not used
ℹ️ info	uncompacted uri	a raw uncompacted uri is used
ℹ️ info	same subject	multiple triples have the same subject

ℹ️ Hover

For example when the user hovers a FILTER the server returns a explanation about what a Filter is

and how to use it.

When a backend is configured, the server will access to knowledge-graph to get information about the token. For example if the user hovers osmrel:62768 and a hover request is send, Qlue-ls will respond with "Freiburg im Breisgau" as this is the label of osmrel:62768.

Note

The query used to retrieve information about a iri, can be configured.

🛠️ Code Actions

Code action suggest complex changes to your input. Often in the form of a quickfix, to fix a diagnostic.

name	description	diagnostic
shorten uri	shorten uri into compacted form	uncompacted uri
declare prefix	declares undeclared prefix (if known)	undeclared prefix
contract triples	contract triples with same subject	same subject
shorten all uri's	shorten all uri's into compacted form
add to result	add variable to selected result
filter variable	add filter for this variable
lang-filter	add language filter for object variable
transform into subselect	make a select into a subselect

Custom Capabilities

Qlue-ls also introduces custom capabilities. That means your lsp-client will not have support for it. You will have to hack your lsp-client to use this.

🕳 Jump

This capability enables "tab navigation". The server provides the next, or previous relevant position in the query. The LSP-client has to move the cursor to this position. This enables the user to quickly jump to relevalt positions in the query.

Request:

• method: 'qlueLs/jump'
• params: JumpParams defined as follows:

export interface JumpParams extends TextDocumentPositionParams {
    previous?: boolean;
}

Response:

• result: JumpResult | null defined as follows:

export interface JumpResult {
    position: Position;
    insert_before: string | null;
    insert_after: string | null;
}

❓ operation identification

Determine if a operation is a query or update.

Request:

• method: 'qlueLs/identifyOperationType'
• params: IdentifyOperationTypeParams defined as follows:

export interface IdentifyOperationTypeParams {
    textDocument: TextDocumentIdentifier;
}

Response:

• result: IdentifyOperationTypeResult defined as follows:

export interface IdentifyOperationTypeResult {
    OperationType: OperationType
}

export enum OperationType {
  Query = "Query",
  Update = "Update",
  Unknown = "Unknown"
}