1 files changed, 95 insertions, 0 deletions

diff --git a/subprojects/store-query/src/main/java/tools/refinery/store/query/literal/CheckLiteral.java b/subprojects/store-query/src/main/java/tools/refinery/store/query/literal/CheckLiteral.java
new file mode 100644
index 00000000..dfedd2cb
--- /dev/null
+++ b/subprojects/store-query/src/main/java/tools/refinery/store/query/literal/CheckLiteral.java
@@ -0,0 +1,95 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package tools.refinery.store.query.literal;
+
+import tools.refinery.store.query.InvalidQueryException;
+import tools.refinery.store.query.equality.LiteralEqualityHelper;
+import tools.refinery.store.query.equality.LiteralHashCodeHelper;
+import tools.refinery.store.query.substitution.Substitution;
+import tools.refinery.store.query.term.ConstantTerm;
+import tools.refinery.store.query.term.Term;
+import tools.refinery.store.query.term.Variable;
+import tools.refinery.store.query.term.bool.BoolNotTerm;
+import tools.refinery.store.query.term.bool.BoolTerms;
+
+import java.util.Collections;
+import java.util.Objects;
+import java.util.Set;
+
+// {@link Object#equals(Object)} is implemented by {@link AbstractLiteral}.
+@SuppressWarnings("squid:S2160")
+public class CheckLiteral extends AbstractLiteral implements CanNegate<CheckLiteral> {
+        private final Term<Boolean> term;
+
+        public CheckLiteral(Term<Boolean> term) {
+                if (!term.getType().equals(Boolean.class)) {
+                        throw new InvalidQueryException("Term %s must be of type %s, got %s instead".formatted(
+                                        term, Boolean.class.getName(), term.getType().getName()));
+                }
+                this.term = term;
+        }
+
+        public Term<Boolean> getTerm() {
+                return term;
+        }
+
+        @Override
+        public Set<Variable> getOutputVariables() {
+                return Set.of();
+        }
+
+        @Override
+        public Set<Variable> getInputVariables(Set<? extends Variable> positiveVariablesInClause) {
+                return Collections.unmodifiableSet(term.getInputVariables());
+        }
+
+        @Override
+        public Set<Variable> getPrivateVariables(Set<? extends Variable> positiveVariablesInClause) {
+                return Set.of();
+        }
+
+        @Override
+        public Literal substitute(Substitution substitution) {
+                return new CheckLiteral(term.substitute(substitution));
+        }
+
+        @Override
+        public CheckLiteral negate() {
+                if (term instanceof BoolNotTerm notTerm) {
+                        return new CheckLiteral(notTerm.getBody());
+                }
+                return new CheckLiteral(BoolTerms.not(term));
+        }
+
+        @Override
+        public boolean equalsWithSubstitution(LiteralEqualityHelper helper, Literal other) {
+                if (other == null || getClass() != other.getClass()) {
+                        return false;
+                }
+                var otherAssumeLiteral = (CheckLiteral) other;
+                return term.equalsWithSubstitution(helper, otherAssumeLiteral.term);
+        }
+
+        @Override
+        public int hashCodeWithSubstitution(LiteralHashCodeHelper helper) {
+                return Objects.hash(super.hashCodeWithSubstitution(helper), term.hashCodeWithSubstitution(helper));
+        }
+
+        @Override
+        public Literal reduce() {
+                if (term instanceof ConstantTerm<Boolean> constantTerm) {
+                        // Return {@link BooleanLiteral#FALSE} for {@code false} or {@code null} literals.
+                        return Boolean.TRUE.equals(constantTerm.getValue()) ? BooleanLiteral.TRUE :
+                                        BooleanLiteral.FALSE;
+                }
+                return this;
+        }
+
+        @Override
+        public String toString() {
+                return "(%s)".formatted(term);
+        }
+}