Documentation query

[voodoos]

In the objective of restoring classic Merlin workflows in text-based editors we need a custom query to get a symbol's documentation.

Proposed interface:

Client capability:

export interface GetDocClientCapabilities {
	/**
	 * Client supports the follow content formats if the content
	 * property refers to a `literal of type MarkupContent`.
	 * The order describes the preferred format of the client.
	 */
	contentFormat?: MarkupKind[];
}

Query:

export interface GetDocParams extends TextDocumentPositionParams
{
    /**
     * An optional identifier. If provided, documentation for this ident 
     * is looked up from the environment at the given position. Else the 
     * server will look for the documentation of the identifier under 
     * the cursor if used.
     */
    identifier?:string;

    /**
     * Optionally override the result's format. 
     */
    contentFormat?:MarkupKind;
}

Response:

result: GetDoc | null
export interface GetDoc {
    /**
     * The documentation
     */
    doc: MarkupContent;

}

We could also have the format choice be made a part of t capability, but I am not sure this is worth the added complexity ?

A response with null result is returned of the identifier doesn't have documentation. An error is returned if the identifier is invalid.