Package org.eclipse.rdf4j.federated.util

Class QueryStringUtil

java.lang.Object
org.eclipse.rdf4j.federated.util.QueryStringUtil
public class QueryStringUtil extends Object
Various static functions for query handling and parsing.
Author:
Andreas Schwarte

  • Field Details

  • Constructor Details

    • QueryStringUtil

      public QueryStringUtil()

  • Method Details

    • hasFreeVars

      public static boolean hasFreeVars(StatementPattern stmt, BindingSet bindings)
      returns true iff there is at least one free variable, i.e. there is no binding for any variable
      Parameters:
      stmt -
      bindings -
      Returns:
      whether free vars are available

    • toString

      public static String toString(StatementPattern stmt)
      Return a string representation of this statement using the following pattern, where variables are indicated using ?var and values are represented as strings. Pattern: {s; p; o}
      Parameters:
      stmt -
      Returns:
      a string representation of the statement

    • toString

      public static String toString(ArbitraryLengthPath node, Set<String> varNames, BindingSet bindings)
      Converts an ArbitraryLengthPath node to a sub query string and makes sure to insert any bindings.

      This method assumes that the ArbitraryLengthPath.getPathExpression() is a StatementPattern.

      Parameters:
      node -
      varNames -
      bindings -
      Returns:
      the query string

    • toString

      public static String toString(Var var)

    • toString

      public static String toString(Resource subj, IRI pred, Value obj)
      Return a string representation of this statement using the following pattern, where variables are indicated using ?var and values are represented as strings. Pattern: {s; p; o}
      Parameters:
      subj - the subject
      pred - the predicate
      obj - the object
      Returns:
      a string representation

    • selectQueryString

      public static String selectQueryString(StatementPattern stmt, BindingSet bindings, FilterValueExpr filterExpr, AtomicBoolean evaluated, Dataset dataset) throws IllegalQueryException
      Construct a SELECT query for the provided statement.
      Parameters:
      stmt -
      bindings -
      filterExpr -
      evaluated - parameter can be used outside this method to check whether FILTER has been evaluated, false in beginning
      Returns:
      the SELECT query
      Throws:
      IllegalQueryException - if the query does not have any free variables

    • selectQueryString

      public static String selectQueryString(ExclusiveTupleExprRenderer expr, BindingSet bindings, FilterValueExpr filterExpr, AtomicBoolean evaluated, Dataset dataset) throws IllegalQueryException
      Construct a SELECT query for the provided ExclusiveTupleExprRenderer
      Parameters:
      stmt -
      bindings -
      filterExpr -
      evaluated - parameter can be used outside this method to check whether FILTER has been evaluated, false in beginning
      Returns:
      the SELECT query
      Throws:
      IllegalQueryException - if the query does not have any free variables

    • selectQueryString

      public static String selectQueryString(ExclusiveGroup group, BindingSet bindings, FilterValueExpr filterExpr, AtomicBoolean evaluated, Dataset dataset) throws IllegalQueryException
      Construct a SELECT query for the provided ExclusiveGroup. Note that bindings and filterExpr are applied whenever possible.
      Parameters:
      group - the expression for the query
      bindings - the bindings to be applied
      filterExpr - a filter expression or null
      evaluated - parameter can be used outside this method to check whether FILTER has been evaluated, false in beginning
      Returns:
      the SELECT query string
      Throws:
      IllegalQueryException

    • askQueryString

      public static String askQueryString(ExclusiveTupleExpr expr, BindingSet bindings, Dataset dataset)
      Transform the ExclusiveTupleExpr into a ASK query string
      Parameters:
      expr -
      bindings -
      Returns:
      the ASK query string
      Throws:
      IllegalQueryException

    • selectQueryStringBoundUnion

      @Deprecated public static String selectQueryStringBoundUnion(StatementPattern stmt, List<BindingSet> unionBindings, FilterValueExpr filterExpr, Boolean evaluated, Dataset dataset)
      Deprecated.
      replaced with
      invalid @link 
      #selectQueryStringBoundJoinVALUES(StatementPattern, List, FilterValueExpr, AtomicBoolean)
      Construct a SELECT query string for a bound union. Pattern: SELECT ?v_1 ?v_2 ?v_N WHERE { { ?v_1 p o } UNION { ?v_2 p o } UNION ... } Note that the filterExpr is not evaluated at the moment.
      Parameters:
      stmt -
      unionBindings -
      filterExpr -
      evaluated - parameter can be used outside this method to check whether FILTER has been evaluated, false in beginning
      Returns:
      the SELECT query string

    • selectQueryStringBoundJoinVALUES

      public static String selectQueryStringBoundJoinVALUES(StatementPattern stmt, List<BindingSet> unionBindings, FilterValueExpr filterExpr, AtomicBoolean evaluated, Dataset dataset)
      Creates a bound join subquery using the SPARQL 1.1 VALUES operator.

      Example subquery: 

       SELECT ?v ?__index WHERE {
    VALUES (?s ?__index) {
      (:s1 1) (:s2 2)
      ...
      (:sN N)
    }
    ?s name ?v.
 }
      Parameters:
      stmt -
      unionBindings -
      filterExpr -
      evaluated - parameter can be used outside this method to check whether FILTER has been evaluated, false in beginning
      Returns:
      the SELECT query string
      Since:
      3.0
      See Also:

    • selectQueryStringBoundCheck

      public static String selectQueryStringBoundCheck(StatementPattern stmt, List<BindingSet> unionBindings, Dataset dataset)
      Construct a SELECT query for a grouped bound check. Pattern: SELECT ?o_1 .. ?o_N WHERE { { s1 p1 ?o_1 FILTER ?o_1=o1 } UNION ... UNION { sN pN ?o_N FILTER ?o_N=oN }}
      Parameters:
      stmt -
      unionBindings -
      Returns:
      the SELECT query string

    • constructInnerUnion

      protected static String constructInnerUnion(StatementPattern stmt, int outerID, Set<String> varNames, List<BindingSet> bindings)

    • constructJoinArg

      protected static String constructJoinArg(ExclusiveTupleExpr exclusiveExpr, Set<String> varNames, BindingSet bindings)
      Construct a query substring from the ExclusiveTupleExpr that can be used as an argument to a Join.

      This method can only be used for ExclusiveTupleExpr that additionally provide ExclusiveTupleExprRenderer capabilities. An exception to this is if the given expression is a StatementPattern, e.g. an ExclusiveStatement or ExclusiveGroup.

      Parameters:
      exclusiveExpr -
      varNames -
      bindings -
      Returns:
      the query string with bindings inserted

    • askQueryString

      public static String askQueryString(StatementPattern stmt, BindingSet bindings, Dataset dataset)
      Construct a boolean ASK query for the provided statement.
      Parameters:
      stmt -
      bindings -
      Returns:
      the ASK query string

    • selectQueryStringLimit1

      public static String selectQueryStringLimit1(StatementPattern stmt, BindingSet bindings, Dataset dataset)
      Construct a SELECT query for the provided statement with LIMIT 1. Such query can be used for source selection instead of ASK queries.
      Parameters:
      stmt -
      bindings -
      Returns:
      the SELECT query string

    • selectQueryStringLimit1

      public static String selectQueryStringLimit1(ExclusiveTupleExpr expr, BindingSet bindings, Dataset dataset)
      Construct a SELECT query for the provided expr with LIMIT 1. Such query can be used for source selection instead of ASK queries.
      Parameters:
      stmt -
      bindings -
      Returns:
      the SELECT query string

    • selectQueryStringLimit1

      public static String selectQueryStringLimit1(ExclusiveGroup group, BindingSet bindings, Dataset dataset)
      Construct a SELECT query for the provided ExclusiveGroup with LIMIT 1. Such query can be used for source selection instead of ASK queries.
      Parameters:
      group -
      bindings -
      Returns:
      the SELECT query string

    • constructStatement

      protected static String constructStatement(StatementPattern stmt, Set<String> varNames, BindingSet bindings)
      Construct the statement string, i.e. "s p o . " with bindings inserted wherever possible. Note that the relevant free variables are added to the varNames set for further evaluation.
      Parameters:
      stmt -
      varNames -
      bindings -
      Returns:
      the constructed statement pattern

    • constructStatementId

      protected static String constructStatementId(StatementPattern stmt, String varID, Set<String> varNames, BindingSet bindings)
      Construct the statement string, i.e. "s p o . " with bindings inserted wherever possible. Variables are renamed to "var_"+varId to identify query results in bound queries. Note that the free variables are also added to the varNames set for further evaluation.
      Parameters:
      stmt -
      varNames -
      bindings -
      Returns:
      the constructed statement pattern

    • constructStatementCheckId

      protected static String constructStatementCheckId(StatementPattern stmt, int varID, Set<String> varNames, BindingSet bindings)
      Construct the statement string, i.e. "s p ?o_varID FILTER ?o_N=o ". This kind of statement pattern is necessary to later on identify available results.
      Parameters:
      stmt -
      varID -
      varNames -
      bindings -
      Returns:
      the statement pattern string

    • appendVar

      protected static StringBuilder appendVar(StringBuilder sb, Var var, Set<String> varNames, BindingSet bindings)
      Append the variable to the provided StringBuilder. Cases: 1) unbound: check provided bindingset for possible match a) match found: append matching value b) no match: append ?varName and add to varNames 2) bound: append value
      Parameters:
      sb -
      var -
      varNames -
      bindings -
      Returns:
      the stringbuilder

    • appendVarId

      protected static StringBuilder appendVarId(StringBuilder sb, Var var, String varID, Set<String> varNames, BindingSet bindings)
      Append the variable to the provided StringBuilder, however change name of variable by appending "_varId" to it. Cases: 1) unbound: check provided bindingset for possible match a) match found: append matching value b) no match: append ?varName_varId and add to varNames 2) bound: append value
      Parameters:
      sb -
      var -
      varNames -
      bindings -
      Returns:
      the complemented string builder

    • getValueString

      protected static String getValueString(Value value)
      Return the string representation of this value, see appendValue(StringBuilder, Value) for details.
      Parameters:
      value -
      Returns:
      the string representation

    • appendValue

      protected static StringBuilder appendValue(StringBuilder sb, Value value)
      Append a string representation of the value to the string builder. 1. URI: invalid input: '<'http://myUri> 2. Literal: "myLiteral"^^
      Parameters:
      sb -
      value -
      Returns:
      the string builder

    • appendURI

      protected static StringBuilder appendURI(StringBuilder sb, IRI uri)
      Append the uri to the stringbuilder, i.e. invalid input: '<'uri.stringValue>.
      Parameters:
      sb -
      uri -
      Returns:
      the string builder

    • appendBNode

      protected static StringBuilder appendBNode(StringBuilder sb, BNode bNode)
      Append a dummy string (see BNODE_URI) to represent the BNode. Note: currently it is not possible to retrieve values for a BNode via SPARQL, hence we use a dummy BNode which does not produce any results. A warning is printed to debug.
      Parameters:
      sb -
      bNode -
      Returns:
      the string builder

    • appendLiteral

      protected static StringBuilder appendLiteral(StringBuilder sb, Literal lit)
      Append the literal to the stringbuilder.
      Parameters:
      sb -
      lit -
      Returns:
      the string builder

    • loadQueries

      public static List<String> loadQueries(String queryFile) throws FileNotFoundException, IOException
      load the queries from a queries file located at the specified path. Expected format: - Queries are SPARQL queries in String format - queries are allowed to span several lines - a query is interpreted to be finished if an empty line occurs Ex: QUERY1 ... Q1 cntd QUERY2
      Parameters:
      queryFile -
      Returns:
      a list of queries for the query type
      Throws:
      FileNotFoundException
      IOException