Package org.terracotta.context.query

Class QueryBuilder

java.lang.Object
org.terracotta.context.query.QueryBuilder
public class QueryBuilder extends Object
A QueryBuilder allows for modular assembly of context graph queries.

Query assembly is performed by chaining a sequence of graph traversal and filtering operations together in order to select a particular set of the input node set's descendants.

  • Field Details

    • current

      private Query current

  • Constructor Details

    • QueryBuilder

      private QueryBuilder()

  • Method Details

    • queryBuilder

      public static QueryBuilder queryBuilder()
      Creates a new query builder instance.

      A newly constructed query builder represents the identity query. It simply returns the input node set as the output node set.

      Returns:
      a new query builder

    • filter

      public QueryBuilder filter(Matcher<? super TreeNode> filter)
      Filters the current node set using the supplied Matcher.

      Nodes in the current node set that are not selected by the supplied matcher are removed.

      Parameters:
      filter - matcher to apply
      Returns:
      this query builder

    • children

      public QueryBuilder children()
      Selects the union of the current node sets child nodes.
      Returns:
      this query builder

    • parent

      public QueryBuilder parent()
      Selects the parent of the current node.
      Returns:
      this query builder

    • descendants

      public QueryBuilder descendants()
      Selects the merged descendant set of the current node set.

      More precisely this recursively merges the children of each member of the node-set in to the output node set until the set ceases to grow.

      Returns:
      this query builder

    • chain

      public QueryBuilder chain(Query query)
      Applies the given query on the currently selected node set.
      Parameters:
      query - query to apply
      Returns:
      this query builder

    • ensureUnique

      public QueryBuilder ensureUnique()
      Asserts that the current node set is a singleton.

      If the current node set is not of size 1 then the query will terminate with an IllegalStateException.

      Returns:
      this query builder

    • empty

      public QueryBuilder empty()
      Selects an empty node set.
      Returns:
      this query builder

    • build

      public Query build()
      Returns a query that represents the currently assembled transformation.
      Returns:
      a newly constructed query