1 files changed, 64 insertions, 0 deletions

diff --git a/subprojects/store-query/src/main/java/tools/refinery/store/query/literal/VariableBinder.java b/subprojects/store-query/src/main/java/tools/refinery/store/query/literal/VariableBinder.java
new file mode 100644
index 00000000..5f43d07d
--- /dev/null
+++ b/subprojects/store-query/src/main/java/tools/refinery/store/query/literal/VariableBinder.java
@@ -0,0 +1,64 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package tools.refinery.store.query.literal;
+
+import tools.refinery.store.query.term.Variable;
+
+import java.util.Map;
+import java.util.Set;
+import java.util.stream.Stream;
+
+public final class VariableBinder {
+        public static final VariableBinder EMPTY = new VariableBinder(Map.of());
+
+        private final Map<Variable, VariableDirection> directionMap;
+
+        VariableBinder(Map<Variable, VariableDirection> directionMap) {
+                this.directionMap = directionMap;
+        }
+
+        public VariableDirection getDirection(Variable variable) {
+                var direction = directionMap.get(variable);
+                if (direction == null) {
+                        throw new IllegalArgumentException("No such variable " + variable);
+                }
+                return direction;
+        }
+
+        public VariableDirection getDirection(Variable variable, Set<? extends Variable> positiveVariables) {
+                var direction = getDirection(variable);
+                return disambiguateDirection(direction, variable, positiveVariables);
+        }
+
+        public Stream<Variable> getVariablesWithDirection(VariableDirection direction) {
+                return directionMap.entrySet().stream()
+                                .filter(pair -> pair.getValue() == direction)
+                                .map(Map.Entry::getKey);
+        }
+
+        public Stream<Variable> getVariablesWithDirection(VariableDirection direction,
+                                                                                                          Set<? extends Variable> positiveVariables) {
+                if (direction == VariableDirection.NEGATIVE) {
+                        throw new IllegalArgumentException("Use #getVariablesWithDirection(VariableDirection) if disambiguation " +
+                                        "of VariableDirection#NEGATIVE variables according to the containing DnfClose is not desired");
+                }
+                return directionMap.entrySet().stream()
+                                .filter(pair -> disambiguateDirection(pair.getValue(), pair.getKey(), positiveVariables) == direction)
+                                .map(Map.Entry::getKey);
+        }
+
+        private VariableDirection disambiguateDirection(VariableDirection direction, Variable variable,
+                                                                                                        Set<? extends Variable> positiveVariables) {
+                if (direction != VariableDirection.NEGATIVE) {
+                        return direction;
+                }
+                return positiveVariables.contains(variable) ? VariableDirection.IN : VariableDirection.CLOSURE;
+        }
+
+        public static VariableBinderBuilder builder() {
+                return new VariableBinderBuilder();
+        }
+}