Implement casting/mapping towards datatype xsd:dateTime and xsd:date.

src/engine/sparqlExpressions/CMakeLists.txt

@@ -16,7 +16,7 @@ add_library(sparqlExpressions
         ConditionalExpressions.cpp
         SparqlExpressionTypes.cpp
         SparqlExpression.cpp
-        ConvertToNumericExpression.cpp
+        ConvertToDtypeConstructor.cpp
         RdfTermExpressions.cpp
         LangExpression.cpp
         CountStarExpression.cpp

src/engine/sparqlExpressions/ConvertToNumericExpression.cpp → src/engine/sparqlExpressions/ConvertToDtypeConstructor.cpp

@@ -1,4 +1,4 @@
-//  Copyright 2024, University of Freiburg,
+//  Copyright 2024 - 2025, University of Freiburg,
 //                  Chair of Algorithms and Data Structures
 //  Author: Hannes Baumann <[email protected]>
 
@@ -7,7 +7,26 @@
 
 #include "engine/sparqlExpressions/NaryExpressionImpl.h"
 
+/*
+  The SparqlExpressions specified in the following namespace sections
+  enable datatype casting/mapping for XML-schema-datatype values.
+
+  For more details regarding the casting/mapping definition see:
+  https://www.w3.org/TR/sparql11-query/#FunctionMapping
+
+  EXAMPLES
+  (1) `xsd:dateTime(?var)` attempts to convert the date-time provided in form of
+  a xsd:string value, which is bound to ?var, into an actual xsd:dateTime
+  datatype value. If the conversion fails, the result is `undefined`.
+
+  (2) `xsd:integer(?var)` attempts to convert the value bound to ?var into an
+  xsd:integer. If the conversion fails, the result is `undefined`.
+*/
+
 namespace sparqlExpression {
+
+//______________________________________________________________________________
+// CONVERT TO NUMERIC
 namespace detail::to_numeric {
 
 // class that converts an input `int64_t`, `double` or `std::string`
@@ -16,7 +35,7 @@ CPP_template(typename T, bool AllowExponentialNotation = true)(
     requires(concepts::same_as<int64_t, T> ||
              concepts::same_as<double, T>)) class ToNumericImpl {
  private:
-  Id getFromString(const std::string& input) const {
+  ValueId getFromString(const std::string& input) const {
     auto str = absl::StripAsciiWhitespace(input);
     // Abseil and the standard library don't match leading + signs, so we skip
     // them.
@@ -57,7 +76,7 @@ CPP_template(typename T, bool AllowExponentialNotation = true)(
   };
 
  public:
-  Id operator()(IntDoubleStr value) const {
+  ValueId operator()(IntDoubleStr value) const {
     if (std::holds_alternative<std::string>(value)) {
       return getFromString(std::get<std::string>(value));
     } else if (std::holds_alternative<int64_t>(value)) {
@@ -77,6 +96,8 @@ using ToDecimal =
     NARY<1, FV<ToNumericImpl<double, false>, ToNumericValueGetter>>;
 }  // namespace detail::to_numeric
 
+//______________________________________________________________________________
+// CONVERT TO BOOLEAN
 namespace detail::to_boolean {
 class ToBooleanImpl {
  public:
@@ -103,8 +124,55 @@ class ToBooleanImpl {
 using ToBoolean = NARY<1, FV<ToBooleanImpl, ToNumericValueGetter>>;
 }  // namespace detail::to_boolean
 
+//______________________________________________________________________________
+// CONVERT TO DATE(TIME)
+namespace detail::to_datetime {
+
+// Cast to xsd:dateTime or xsd:date (ValueId)
+template <bool ToJustXsdDate>
+inline auto convertStringToDateTimeValueId =
+    [](OptIdOrString input) -> ValueId {
+  if (!input.has_value()) {
+    return Id::makeUndefined();
+  }
+  const auto& inputValue = input.value();
+
+  // Remark: If the parsing procedure for datetime/date string values with
+  // parseXsdDatetimeGetOptDate/parseXsdDateGetOptDate fails,
+  // return Id::makeUndefined().
+  const auto retrieveValueId = [](std::optional<DateYearOrDuration> optValue) {
+    if (optValue.has_value()) {
+      return Id::makeFromDate(optValue.value());
+    }
+    return Id::makeUndefined();
+  };
+
+  if (auto* valueId = std::get_if<ValueId>(&inputValue)) {
+    return *valueId;
+  }
+
+  auto* str = std::get_if<std::string>(&inputValue);
+  AD_CORRECTNESS_CHECK(str != nullptr);
+  if constexpr (ToJustXsdDate) {
+    return retrieveValueId(DateYearOrDuration::parseXsdDateGetOptDate(*str));
+  } else {
+    return retrieveValueId(
+        DateYearOrDuration::parseXsdDatetimeGetOptDate(*str));
+  }
+};
+
+NARY_EXPRESSION(ToXsdDateTime, 1,
+                FV<decltype(convertStringToDateTimeValueId<false>),
+                   DateIdOrLiteralValueGetter>);
+NARY_EXPRESSION(ToXsdDate, 1,
+                FV<decltype(convertStringToDateTimeValueId<true>),
+                   DateIdOrLiteralValueGetter>);
+
+}  // namespace detail::to_datetime
+
 using namespace detail::to_numeric;
 using namespace detail::to_boolean;
+using namespace detail::to_datetime;
 using Expr = SparqlExpression::Ptr;
 
 Expr makeConvertToIntExpression(Expr child) {
@@ -122,4 +190,13 @@ Expr makeConvertToDecimalExpression(Expr child) {
 Expr makeConvertToBooleanExpression(Expr child) {
   return std::make_unique<ToBoolean>(std::move(child));
 }
+
+Expr makeConvertToDateTimeExpression(Expr child) {
+  return std::make_unique<ToXsdDateTime>(std::move(child));
+}
+
+Expr makeConvertToDateExpression(Expr child) {
+  return std::make_unique<ToXsdDate>(std::move(child));
+}
+
 }  // namespace sparqlExpression

src/engine/sparqlExpressions/NaryExpression.h

@@ -104,14 +104,17 @@ SparqlExpression::Ptr makeIfExpression(SparqlExpression::Ptr child1,
                                        SparqlExpression::Ptr child2,
                                        SparqlExpression::Ptr child3);
 
-// Implemented in ConvertToNumeric.cpp
+// Implemented in ConvertToDtypeConstructor.cpp
 SparqlExpression::Ptr makeConvertToIntExpression(SparqlExpression::Ptr child);
 SparqlExpression::Ptr makeConvertToDoubleExpression(
     SparqlExpression::Ptr child);
 SparqlExpression::Ptr makeConvertToDecimalExpression(
     SparqlExpression::Ptr child);
 SparqlExpression::Ptr makeConvertToBooleanExpression(
     SparqlExpression::Ptr child);
+SparqlExpression::Ptr makeConvertToDateTimeExpression(
+    SparqlExpression::Ptr child);
+SparqlExpression::Ptr makeConvertToDateExpression(SparqlExpression::Ptr child);
 
 // Implemented in RdfTermExpressions.cpp
 SparqlExpression::Ptr makeDatatypeExpression(SparqlExpression::Ptr child);

src/engine/sparqlExpressions/SparqlExpressionValueGetters.h

@@ -350,4 +350,30 @@
                               const EvaluationContext* context) const;
 };
 
+// Defines the return type for value-getter `DateIdOrLiteralValueGetter`.
+using OptIdOrString = std::optional<std::variant<ValueId, std::string>>;
+
+// This value-getter returns a `Date` related `ValueId` or `std::string` (from
+// literal).
+struct DateIdOrLiteralValueGetter : Mixin<DateIdOrLiteralValueGetter> {
+  using Mixin<DateIdOrLiteralValueGetter>::operator();
+  // Remark: We use only LiteralFromIdGetter because Iri values should never
+  // contain date-related string values.
+  OptIdOrString operator()(ValueId id, const EvaluationContext* context) const {
+    if (id.getDatatype() == Datatype::Date) {
+      // Additionally check that `DateYearOrDuration` doesn't hold a
+      // `DayTimeDuration` value.
+      if (id.getDate().isDate()) {
+        return id;
+      }
+      return std::nullopt;
+    }
+    return LiteralFromIdGetter{}(id, context);
+  }
+  OptIdOrString operator()(const LiteralOrIri& litOrIri,
+                           const EvaluationContext* context) const {
+    return LiteralFromIdGetter{}(litOrIri, context);
+  }
+};
+
 }  // namespace sparqlExpression::detail

src/parser/sparqlParser/SparqlQleverVisitor.cpp

@@ -179,6 +179,16 @@ ExpressionPtr Visitor::processIriFunctionCall(
       return sparqlExpression::makeConvertToStringExpression(
           std::move(argList[0]));
     }
+    if (functionName == "dateTime") {
+      checkNumArgs(1);
+      return sparqlExpression::makeConvertToDateTimeExpression(
+          std::move(argList[0]));
+    }
+    if (functionName == "date") {
+      checkNumArgs(1);
+      return sparqlExpression::makeConvertToDateExpression(
+          std::move(argList[0]));
+    }
   }
 
   // QLever-internal functions.

src/util/DateYearDuration.cpp

@@ -130,14 +130,13 @@ static DateYearOrDuration makeDateOrLargeYear(std::string_view fullInput,
 }
 
 // _____________________________________________________________________________
-DateYearOrDuration DateYearOrDuration::parseXsdDatetime(
+static std::optional<DateYearOrDuration> parseXsdDatetimeImpl(
     std::string_view dateString) {
   constexpr static ctll::fixed_string dateTime =
       dateRegex + "T" + timeRegex + grp(timeZoneRegex) + "?";
   auto match = ctre::match<dateTime>(dateString);
   if (!match) {
-    throw DateParseException{absl::StrCat(
-        "The value ", dateString, " cannot be parsed as an `xsd:dateTime`.")};
+    return std::nullopt;
   }
   int64_t year = match.template get<"year">().to_number<int64_t>();
   int month = match.template get<"month">().to_number();
@@ -150,14 +149,29 @@ DateYearOrDuration DateYearOrDuration::parseXsdDatetime(
 }
 
 // _____________________________________________________________________________
-DateYearOrDuration DateYearOrDuration::parseXsdDate(
+DateYearOrDuration DateYearOrDuration::parseXsdDatetime(
+    std::string_view dateString) {
+  if (auto optDate = parseXsdDatetimeImpl(dateString); optDate) {
+    return optDate.value();
+  }
+  throw DateParseException{absl::StrCat(
+      "The value ", dateString, " cannot be parsed as an `xsd:dateTime`.")};
+}
+
+// _____________________________________________________________________________
+std::optional<DateYearOrDuration>
+DateYearOrDuration::parseXsdDatetimeGetOptDate(std::string_view dateString) {
+  return parseXsdDatetimeImpl(dateString);
+}
+
+// _____________________________________________________________________________
+static std::optional<DateYearOrDuration> parseXsdDateImpl(
     std::string_view dateString) {
   constexpr static ctll::fixed_string dateTime =
       dateRegex + grp(timeZoneRegex) + "?";
   auto match = ctre::match<dateTime>(dateString);
   if (!match) {
-    throw DateParseException{absl::StrCat(
-        "The value ", dateString, " cannot be parsed as an `xsd:date`.")};
+    return std::nullopt;
   }
   int64_t year = match.template get<"year">().to_number<int64_t>();
   int month = match.template get<"month">().to_number();
@@ -166,6 +180,22 @@ DateYearOrDuration DateYearOrDuration::parseXsdDate(
                              parseTimeZone(match));
 }
 
+// _____________________________________________________________________________
+DateYearOrDuration DateYearOrDuration::parseXsdDate(
+    std::string_view dateString) {
+  if (auto optDate = parseXsdDateImpl(dateString); optDate) {
+    return optDate.value();
+  }
+  throw DateParseException{absl::StrCat("The value ", dateString,
+                                        " cannot be parsed as an `xsd:date`.")};
+}
+
+// _____________________________________________________________________________
+std::optional<DateYearOrDuration> DateYearOrDuration::parseXsdDateGetOptDate(
+    std::string_view dateString) {
+  return parseXsdDateImpl(dateString);
+}
+
 // _____________________________________________________________________________
 DateYearOrDuration DateYearOrDuration::parseGYear(std::string_view dateString) {
   constexpr static ctll::fixed_string yearRegex = "(?<year>-?\\d{4,})";

src/util/DateYearDuration.h

@@ -154,19 +154,31 @@ class DateYearOrDuration {
   // 2. If the year is outside the range [-9999, 9999], then the date must be
   // January 1, 00:00 hours.
 
-  // Parse from xsd:dateTime (e.g. 1900-12-13T03:12:00.33Z)
+  // Parse from `xsd:dateTime` (e.g. `1900-12-13T03:12:00.33Z`)
   static DateYearOrDuration parseXsdDatetime(std::string_view dateString);
-
-  // Parse from xsd:date (e.g. 1900-12-13)
+  // Parse from `xsd:dateTime` (e.g. `1900-12-13T03:12:00.33Z`). Returns a
+  // `DateYearOrDuration` value under the condition that `dateString` adheres to
+  // the correct datetime string format (is parsable). If the parsing procedure
+  // fails `std::nullopt` is returned.
+  static std::optional<DateYearOrDuration> parseXsdDatetimeGetOptDate(
+      std::string_view dateString);
+
+  // Parse from `xsd:date` (e.g. `1900-12-13`)
   static DateYearOrDuration parseXsdDate(std::string_view dateString);
-
-  // Parse from xsd:gYearMonth (e.g. 1900-03)
+  // Parse from `xsd:date` (e.g. `1900-12-13`). Returns a `DateYearOrDuration`
+  // value under the condition that `dateString` adheres to the correct date
+  // string format (is parsable). If the parsing procedure fails `std::nullopt`
+  // is returned.
+  static std::optional<DateYearOrDuration> parseXsdDateGetOptDate(
+      std::string_view dateString);
+
+  // Parse from `xsd:gYearMonth` (e.g. `1900-03`)
   static DateYearOrDuration parseGYearMonth(std::string_view dateString);
 
-  // Parse from xsd:gYear (e.g. 1900)
+  // Parse from `xsd:gYear` (e.g. `1900`)
   static DateYearOrDuration parseGYear(std::string_view dateString);
 
-  // Parse from xsd:dayTimeDuration (e.g. P2DT3H59M59.99S)
+  // Parse from `xsd:dayTimeDuration` (e.g. `P2DT3H59M59.99S`)
   static DateYearOrDuration parseXsdDayTimeDuration(
       std::string_view dayTimeDurationString);
 

test/SparqlAntlrParserTest.cpp

@@ -1862,13 +1862,19 @@ TEST(SparqlParser, FunctionCall) {
                      matchUnary(&makeConvertToDecimalExpression));
   expectFunctionCall(absl::StrCat(xsd, "boolean>(?x)"),
                      matchUnary(&makeConvertToBooleanExpression));
+  expectFunctionCall(absl::StrCat(xsd, "date>(?x)"),
+                     matchUnary(&makeConvertToDateExpression));
+  expectFunctionCall(absl::StrCat(xsd, "dateTime>(?x)"),
+                     matchUnary(&makeConvertToDateTimeExpression));
 
   expectFunctionCall(absl::StrCat(xsd, "string>(?x)"),
                      matchUnary(&makeConvertToStringExpression));
 
   // Wrong number of arguments.
   expectFunctionCallFails(absl::StrCat(geof, "distance>(?a)"));
   expectFunctionCallFails(absl::StrCat(geof, "distance>(?a, ?b, ?c)"));
+  expectFunctionCallFails(absl::StrCat(xsd, "date>(?varYear, ?varMonth)"));
+  expectFunctionCallFails(absl::StrCat(xsd, "dateTime>(?varYear, ?varMonth)"));
 
   // Unknown function with `geof:`, `math:`, `xsd:`, or `ql` prefix.
   expectFunctionCallFails(absl::StrCat(geof, "nada>(?x)"));

test/SparqlExpressionTest.cpp

@@ -1158,6 +1158,36 @@ TEST(SparqlExpression, testToNumericExpression) {
               Ids{U, U, I(1), I(0), U, I(1), I(-33)});
 }
 
+// ____________________________________________________________________________
+TEST(SparqlExpression, testToDateOrDateTimeExpression) {
+  using namespace ad_utility::testing;
+  Id T = Id::makeFromBool(true);
+  Id F = Id::makeFromBool(false);
+  Id G = Id::makeFromGeoPoint(GeoPoint(50.0, 50.0));
+  auto parserDate = DateYearOrDuration::parseXsdDate;
+  auto parserDateTime = DateYearOrDuration::parseXsdDatetime;
+  auto checkGetDate = testUnaryExpression<&makeConvertToDateExpression>;
+  auto checkGetDateTime = testUnaryExpression<&makeConvertToDateTimeExpression>;
+
+  checkGetDate(idOrLitOrStringVec({"---", T, F, G, "2025-02", I(10), D(0.01),
+                                   "-2025-02-20", "2025-02-20", "2025-1-1",
+                                   DateId(parserDate, "0000-01-01")}),
+               Ids{U, U, U, U, U, U, U, DateId(parserDate, "-2025-02-20"),
+                   DateId(parserDate, "2025-02-20"), U,
+                   DateId(parserDate, "0000-01-01")});
+  checkGetDateTime(
+      idOrLitOrStringVec({"---", T, F, G, "2025-02", I(10), D(0.01),
+                          "-2025-02-20", "2025-02-20", "2025-1-1",
+                          "1900-12-13T03:12:00.33Z", "-1900-12-13T03:12:00.33Z",
+                          "2025-02-20T17:12:00.01-05:00",
+                          DateId(parserDateTime, "2025-02-20T17:12:00.01Z")}),
+      Ids{U, U, U, U, U, U, U, U, U, U,
+          DateId(parserDateTime, "1900-12-13T03:12:00.33Z"),
+          DateId(parserDateTime, "-1900-12-13T03:12:00.33Z"),
+          DateId(parserDateTime, "2025-02-20T17:12:00.01-05:00"),
+          DateId(parserDateTime, "2025-02-20T17:12:00.01Z")});
+}
+
 // ____________________________________________________________________________
 TEST(SparqlExpression, testToBooleanExpression) {
   Id T = Id::makeFromBool(true);