GH-5447 improve group by and value factory

Author: hmottestad

core/common/iterator/src/main/java/org/eclipse/rdf4j/common/iteration/CloseableIteration.java

@@ -14,6 +14,8 @@
 import java.util.Iterator;
 import java.util.stream.Stream;
 
+import org.eclipse.rdf4j.model.Statement;
+
 /**
  * An {@link CloseableIteration} that can be closed to free resources that it is holding. CloseableIterations
  * automatically free their resources when exhausted. If not read until exhaustion or if you want to make sure the
@@ -33,6 +35,8 @@
  */
 public interface CloseableIteration<E> extends Iterator<E>, AutoCloseable {
 
+	EmptyIteration<Statement> EMPTY_STATEMENT_ITERATION = new EmptyIteration<>();
+
 	/**
 	 * Convert the results to a Java 8 Stream.
 	 *

core/common/iterator/src/main/java/org/eclipse/rdf4j/common/iteration/DualUnionIteration.java

@@ -50,7 +50,11 @@ public DualUnionIteration(Comparator<E> cmp,
 	public static <E> CloseableIteration<? extends E> getWildcardInstance(
 			CloseableIteration<? extends E> leftIteration, CloseableIteration<? extends E> rightIteration) {
 
-		if (rightIteration instanceof EmptyIteration) {
+		if (leftIteration == EMPTY_STATEMENT_ITERATION) {
+			return rightIteration;
+		} else if (rightIteration == EMPTY_STATEMENT_ITERATION) {
+			return leftIteration;
+		} else if (rightIteration instanceof EmptyIteration) {
 			return leftIteration;
 		} else if (leftIteration instanceof EmptyIteration) {
 			return rightIteration;
@@ -63,7 +67,11 @@ public static <E> CloseableIteration<? extends E> getWildcardInstance(
 	public static <E> CloseableIteration<? extends E> getWildcardInstance(Comparator<E> cmp,
 			CloseableIteration<? extends E> leftIteration, CloseableIteration<? extends E> rightIteration) {
 
-		if (rightIteration instanceof EmptyIteration) {
+		if (leftIteration == EMPTY_STATEMENT_ITERATION) {
+			return rightIteration;
+		} else if (rightIteration == EMPTY_STATEMENT_ITERATION) {
+			return leftIteration;
+		} else if (rightIteration instanceof EmptyIteration) {
 			return leftIteration;
 		} else if (leftIteration instanceof EmptyIteration) {
 			return rightIteration;
@@ -75,7 +83,11 @@ public static <E> CloseableIteration<? extends E> getWildcardInstance(Comparator
 	public static <E> CloseableIteration<E> getInstance(CloseableIteration<E> leftIteration,
 			CloseableIteration<E> rightIteration) {
 
-		if (rightIteration instanceof EmptyIteration) {
+		if (leftIteration == EMPTY_STATEMENT_ITERATION) {
+			return rightIteration;
+		} else if (rightIteration == EMPTY_STATEMENT_ITERATION) {
+			return leftIteration;
+		} else if (rightIteration instanceof EmptyIteration) {
 			return leftIteration;
 		} else if (leftIteration instanceof EmptyIteration) {
 			return rightIteration;

core/model-api/src/main/java/org/eclipse/rdf4j/model/ValueFactory.java

@@ -155,6 +155,16 @@ public interface ValueFactory {
 	 */
 	Literal createLiteral(long value);
 
+	/**
+	 * Creates a new typed numerical literal representing the specified value.
+	 *
+	 * @param value The value for the literal.
+	 * @param xsd   The XSD datatype to use.
+	 */
+	default Literal createLiteral(long value, CoreDatatype.XSD xsd) {
+		return createLiteral(Long.toString(value), xsd);
+	}
+
 	/**
 	 * Creates a new <var>xsd:float</var>-typed literal representing the specified value.
 	 *

core/model-api/src/main/java/org/eclipse/rdf4j/model/base/AbstractLiteral.java

@@ -402,6 +402,10 @@ private static String toString(double value) {
 			this(value, Long.toString(value), CoreDatatype.XSD.LONG);
 		}
 
+		NumberLiteral(long value, CoreDatatype.XSD datatype) {
+			this(value, Long.toString(value), datatype);
+		}
+
 		NumberLiteral(float value) {
 			this(value, toString(value), CoreDatatype.XSD.FLOAT);
 		}

core/model-api/src/main/java/org/eclipse/rdf4j/model/base/AbstractValueFactory.java

@@ -128,9 +128,36 @@ public Literal createLiteral(String label, CoreDatatype datatype) {
 			throw new IllegalArgumentException("reserved datatype <" + datatype + ">");
 		}
 
+		if (datatype == CoreDatatype.XSD.INTEGER) {
+			if (label.length() <= 3 && !label.startsWith("+") && !label.startsWith("-")) {
+				try {
+					int v = Integer.parseInt(label);
+					if (v >= 0 && v <= 999) {
+						return smallIntLiterals[v];
+					}
+				} catch (NumberFormatException e) {
+					// ignore
+				}
+			}
+		} else if (datatype == CoreDatatype.XSD.BOOLEAN) {
+			if ("true".equals(label) || "1".equals(label)) {
+				return TRUE;
+			} else if ("false".equals(label) || "0".equals(label)) {
+				return FALSE;
+			}
+		}
+
 		return new TypedLiteral(label, datatype);
 	}
 
+	static TypedLiteral[] smallIntLiterals = new TypedLiteral[1000];
+
+	static {
+		for (int i = 0; i <= 999; i++) {
+			smallIntLiterals[i] = new TypedLiteral(i + "", CoreDatatype.XSD.INTEGER);
+		}
+	}
+
 	@Override
 	public Literal createLiteral(String label, IRI datatype, CoreDatatype coreDatatype) {
 		Objects.requireNonNull(label, "Label may not be null");
@@ -182,6 +209,11 @@ public Literal createLiteral(long value) {
 		return new NumberLiteral(value);
 	}
 
+	@Override
+	public Literal createLiteral(long value, CoreDatatype.XSD datatype) {
+		return new NumberLiteral(value, datatype);
+	}
+
 	@Override
 	public Literal createLiteral(float value) {
 		return new NumberLiteral(value);

core/model/src/main/java/org/eclipse/rdf4j/model/impl/SimpleValueFactory.java

@@ -165,6 +165,12 @@ public Literal createLiteral(long value) {
 		return createIntegerLiteral(value, CoreDatatype.XSD.LONG);
 	}
 
+	@Override
+	public Literal createLiteral(long value, CoreDatatype.XSD xsd) {
+		assert xsd.isIntegerDatatype();
+		return createIntegerLiteral(value, xsd);
+	}
+
 	/**
 	 * Calls {@link #createNumericLiteral(Number, IRI)} with the supplied value and datatype as parameters.
 	 */

core/model/src/main/java/org/eclipse/rdf4j/model/impl/ValidatingValueFactory.java

@@ -175,6 +175,11 @@ public Literal createLiteral(long value) {
 		return delegate.createLiteral(value);
 	}
 
+	@Override
+	public Literal createLiteral(long value, CoreDatatype.XSD xsd) {
+		return delegate.createLiteral(value, xsd);
+	}
+
 	@Override
 	public Literal createLiteral(float value) {
 		return delegate.createLiteral(value);

core/queryalgebra/evaluation/src/main/java/org/eclipse/rdf4j/query/algebra/evaluation/iterator/GroupIterator.java

@@ -505,7 +505,7 @@ public CountCollector(ValueFactory vf) {
 
 		@Override
 		public Value getFinalValue() {
-			return vf.createLiteral(Long.toString(value), CoreDatatype.XSD.INTEGER);
+			return vf.createLiteral(value, CoreDatatype.XSD.INTEGER);
 		}
 	}
 

core/sail/base/src/main/java/org/eclipse/rdf4j/sail/base/SailDatasetImpl.java

@@ -46,7 +46,6 @@ class SailDatasetImpl implements SailDataset {
 
 	private static final EmptyIteration<Triple> TRIPLE_EMPTY_ITERATION = new EmptyIteration<>();
 	private static final EmptyIteration<Namespace> NAMESPACES_EMPTY_ITERATION = new EmptyIteration<>();
-	private static final EmptyIteration<Statement> STATEMENT_EMPTY_ITERATION = new EmptyIteration<>();
 
 	/**
 	 * {@link SailDataset} of the backing {@link SailSource}.
@@ -286,7 +285,7 @@ public CloseableIteration<? extends Statement> getStatements(Resource subj, IRI
 		} else if (iter != null) {
 			return iter;
 		} else {
-			return STATEMENT_EMPTY_ITERATION;
+			return CloseableIteration.EMPTY_STATEMENT_ITERATION;
 		}
 	}