V4.0 Facet Drill Down and Drill Sideways support

[nzdev]

Adds support for Facet Drill Down and Drill Sideways
Adds tests for Facet Drill Down and Drill Sideways
See GivenTaxonomyIndexFacetDrillDownSubquery_Returns_ExpectedTotals_Facet test for usage.
Add examples to docs

DrillDown Query

DrillDown query is used to drill down and sideways on facets.

Basic MatchAll Query example

// Setup
// Create a config
var facetsConfig = new FacetsConfig();
facetConfigs.SetHierarchical("publishDate", true);

services.AddExamineLuceneIndex("MyIndex",
    // Set the indexing of your fields to use the facet type
    fieldDefinitions: new FieldDefinitionCollection(
        new FieldDefinition("publishDate", FieldDefinitionTypes.FacetTaxonomyFullText),
        new FieldDefinition("Author", FieldDefinitionTypes.FacetTaxonomyFullText)
        ),
    // Pass your config
    facetsConfig: facetsConfig,
    // Enable the Taxonomy sidecar index, required for Heirachy facets
    useTaxonomyIndex: true
    );


var searcher = myIndex.Searcher;
var results = searcher.CreateQuery()
    .DrillDownQuery(
        dims =>
        {
            // Specify the dimensions to drill down on
            dims.AddDimension("Author", "Lisa");
        },
        null // Optional base query to drill down over
        ,
        sideways =>
        {
            // Drill Sideways for the top 10 facets
            sideways.SetTopN(10);
        },
        BooleanOperation.Or // Default operation for boolean subqueries
        )
        .WithFacets((Action<IFacetOperations>)(facets =>
        {
            //Fetch the facets
            facets.FacetString("publishDate", x => x.MaxCount(10));
            facets.FacetString("Author", x => x.MaxCount(10));
        }));
    .Execute();

var publishDateResults = results.GetFacet("publishDate"); // Returns the facets for the specific field publishDate
var AuthorFacetResults = results.GetFacet("Author"); // Returns the facets for the specific field publishDate

Basic BaseQuery example

// Setup
// Create a config
var facetsConfig = new FacetsConfig();
facetConfigs.SetHierarchical("publishDate", true);

services.AddExamineLuceneIndex("MyIndex",
    // Set the indexing of your fields to use the facet type
    fieldDefinitions: new FieldDefinitionCollection(
        new FieldDefinition("publishDate", FieldDefinitionTypes.FacetTaxonomyFullText),
        new FieldDefinition("Author", FieldDefinitionTypes.FacetTaxonomyFullText)
        ),
    // Pass your config
    facetsConfig: facetsConfig,
    // Enable the Taxonomy sidecar index, required for Heirachy facets
    useTaxonomyIndex: true
    );


var searcher = myIndex.Searcher;
var results = searcher.CreateQuery()
    .DrillDownQuery(
        dims =>
        {
            // Specify the dimensions to drill down on
            dims.AddDimension("Author", "Lisa");
        },
         baseQuery => // Optional base query to drill down over
        {
            return baseQuery.Field(ExamineFieldNames.CategoryFieldName, "content");
        } 
        ,
        sideways =>
        {
            // Drill Sideways for the top 10 facets
            sideways.SetTopN(10);
        },
        BooleanOperation.Or // Default operation for boolean subqueries
        )
        .WithFacets((Action<IFacetOperations>)(facets =>
        {
            //Fetch the facets
            facets.FacetString("publishDate", x => x.MaxCount(10));
            facets.FacetString("Author", x => x.MaxCount(10));
        }));
    .Execute();

var publishDateResults = results.GetFacet("publishDate"); // Returns the facets for the specific field publishDate
var AuthorFacetResults = results.GetFacet("Author"); // Returns the facets for the specific field publishDate