refactor(language): assignment and cast expression

Also reorganizes operator names for easier future extension.

4 files changed, 50 insertions, 48 deletions

diff --git a/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext b/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext
index a2fea627..43351d3e 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext
+++ b/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext
@@ -103,7 +103,10 @@ Parameter:
 //      name=Identifier;
 
 Expr:
-        ComparisonExpr;
+        AssignmentExpr;
+
+AssignmentExpr returns Expr:
+        ComparisonExpr ({AssignmentExpr.left=current}"is" right=ComparisonExpr)*;
 
 enum ComparisonOp:
         LESS="<" | LESS_EQ="<=" | GREATER=">" | GREATER_EQ=">=" | EQ="==" | NOT_EQ="!=" |
@@ -113,15 +116,16 @@ ComparisonExpr returns Expr:
         LatticeExpr ({ComparisonExpr.left=current}
         op=ComparisonOp right=LatticeExpr)*;
 
-enum LatticeOp returns BinaryOp:
+enum LatticeBinaryOp:
         MEET="/\\" | JOIN="\\/";
 
 LatticeExpr returns Expr:
-        RangeExpr ({ArithmeticBinaryExpr.left=current}
-        op=LatticeOp right=RangeExpr)*;
+        RangeExpr ({LatticeBinaryExpr.left=current}
+        op=LatticeBinaryOp right=RangeExpr)*;
 
 RangeExpr returns Expr:
-        AdditiveExpr ({RangeExpr.left=current} ".." right=AdditiveExpr)*;
+        AdditiveExpr ({RangeExpr.left=current} ".." ("*" | right=AdditiveExpr))* |
+        {RangeExpr} "*" ".." ("*" | right=AdditiveExpr);
 
 enum AdditiveOp returns BinaryOp:
         ADD="+" | SUB="-";
@@ -145,8 +149,8 @@ ExponentialExpr returns Expr:
         op=ExponentialOp right=ExponentialExpr)?;
 
 UnaryExpr returns Expr:
-        ArithmeticUnaryExpr | ModalExpr | NegationExpr | CountExpr | AggregationExpr |
-        Atom | VariableOrNodeExpr | Constant | "(" Expr ")";
+        ArithmeticUnaryExpr | ModalExpr | NegationExpr |
+        CountExpr | AggregationExpr | CastExpr;
 
 enum UnaryOp:
         PLUS="+" | MINUS="-";
@@ -170,7 +174,13 @@ enum AggregationOp:
         SUM="sum" | PROD="prod" | MIN="min" | MAX="max";
 
 AggregationExpr:
-        op=AggregationOp "{" value=Expr "|" condition=Expr "}";
+        op=AggregationOp "{" value=Expr "|" condition=ComparisonExpr "}";
+
+CastExpr returns Expr:
+        CastExprBody ({CastExpr.body=current} "as" targetType=[Relation|QualifiedName])?;
+
+CastExprBody returns Expr:
+        Atom | VariableOrNodeExpr | Constant | "(" Expr ")";
 
 Atom:
         relation=[Relation|QualifiedName]
@@ -181,7 +191,7 @@ VariableOrNodeExpr:
         variableOrNode=[VariableOrNode|QualifiedName];
 
 Constant:
-        RealConstant | IntConstant | InfConstant | StringConstant | LogicConstant;
+        RealConstant | IntConstant | StringConstant | LogicConstant;
 
 IntConstant:
         intValue=INT;
@@ -189,9 +199,6 @@ IntConstant:
 RealConstant:
         realValue=Real;
 
-InfConstant:
-        {InfConstant} "*";
-
 StringConstant:
         stringValue=STRING;
 
diff --git a/subprojects/language/src/main/java/tools/refinery/language/resource/state/DerivedVariableComputer.java b/subprojects/language/src/main/java/tools/refinery/language/resource/state/DerivedVariableComputer.java
index f0baf35f..f096264b 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/resource/state/DerivedVariableComputer.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/resource/state/DerivedVariableComputer.java
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ * SPDX-FileCopyrightText: 2021-2024 The Refinery Authors <https://refinery.tools/>
  *
  * SPDX-License-Identifier: EPL-2.0
  */
@@ -44,15 +44,14 @@ public class DerivedVariableComputer {
                                 knownVariables.add(name);
                         }
                 }
-                if (definition instanceof PredicateDefinition predicateDefinition) {
-                        installDerivedPredicateDefinitionState(predicateDefinition, knownVariables);
-                } else if (definition instanceof FunctionDefinition functionDefinition) {
-                        installDerivedFunctionDefinitionState(functionDefinition, knownVariables);
-                } else if (definition instanceof RuleDefinition ruleDefinition) {
-                        installDerivedRuleDefinitionState(ruleDefinition, knownVariables);
-                } else {
-                        throw new IllegalArgumentException("Unknown ParametricDefinition: " + definition);
-                }
+        switch (definition) {
+            case PredicateDefinition predicateDefinition ->
+                    installDerivedPredicateDefinitionState(predicateDefinition, knownVariables);
+            case FunctionDefinition functionDefinition ->
+                    installDerivedFunctionDefinitionState(functionDefinition, knownVariables);
+            case RuleDefinition ruleDefinition -> installDerivedRuleDefinitionState(ruleDefinition, knownVariables);
+            default -> throw new IllegalArgumentException("Unknown ParametricDefinition: " + definition);
+        }
         }
 
         protected void installDerivedPredicateDefinitionState(PredicateDefinition definition, Set<String> knownVariables) {
diff --git a/subprojects/language/src/main/java/tools/refinery/language/resource/state/ImplicitVariableScope.java b/subprojects/language/src/main/java/tools/refinery/language/resource/state/ImplicitVariableScope.java
index e25887ad..c8e01724 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/resource/state/ImplicitVariableScope.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/resource/state/ImplicitVariableScope.java
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ * SPDX-FileCopyrightText: 2021-2024 The Refinery Authors <https://refinery.tools/>
  *
  * SPDX-License-Identifier: EPL-2.0
  */
@@ -16,10 +16,7 @@ import org.eclipse.xtext.scoping.IScopeProvider;
 import tools.refinery.language.model.problem.*;
 import tools.refinery.language.naming.NamingUtil;
 
-import java.util.Deque;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Set;
+import java.util.*;
 
 public class ImplicitVariableScope {
         private final EObject root;
@@ -71,13 +68,12 @@ public class ImplicitVariableScope {
                 if ((hasKnownVariables && hasParent) || (!hasKnownVariables && !hasParent)) {
                         throw new IllegalStateException("Either known variables or parent must be provided, but not both");
                 }
-                if (hasKnownVariables) {
-                        return;
-                }
-                if (parent.knownVariables == null) {
-                        throw new IllegalStateException("Parent scope must be processed before current scope");
+                if (!hasKnownVariables) {
+                        if (parent.knownVariables == null) {
+                                throw new IllegalStateException("Parent scope must be processed before current scope");
+                        }
+                        knownVariables = new HashSet<>(parent.knownVariables);
                 }
-                knownVariables = new HashSet<>(parent.knownVariables);
         }
 
         private void processEObject(EObject eObject, IScopeProvider scopeProvider, LinkingHelper linkingHelper,
diff --git a/subprojects/language/src/main/java/tools/refinery/language/scoping/ProblemScopeProvider.java b/subprojects/language/src/main/java/tools/refinery/language/scoping/ProblemScopeProvider.java
index a4437ba6..f83a7ebd 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/scoping/ProblemScopeProvider.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/scoping/ProblemScopeProvider.java
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ * SPDX-FileCopyrightText: 2021-2024 The Refinery Authors <https://refinery.tools/>
  *
  * SPDX-License-Identifier: EPL-2.0
  */
@@ -18,8 +18,8 @@ import org.eclipse.xtext.scoping.Scopes;
 import tools.refinery.language.model.problem.*;
 import tools.refinery.language.utils.ProblemDesugarer;
 
-import java.util.ArrayList;
-import java.util.List;
+import java.util.Collection;
+import java.util.LinkedHashSet;
 
 /**
  * This class contains custom scoping description.
@@ -58,7 +58,7 @@ public class ProblemScopeProvider extends AbstractProblemScopeProvider {
         }
 
         protected IScope getVariableScope(EObject context, IScope delegateScope) {
-                List<Variable> variables = new ArrayList<>();
+                Collection<Variable> variables = new LinkedHashSet<>();
                 addSingletonVariableToScope(context, variables);
                 EObject currentContext = context;
                 while (currentContext != null && !(currentContext instanceof ParametricDefinition)) {
@@ -73,7 +73,7 @@ public class ProblemScopeProvider extends AbstractProblemScopeProvider {
                 return Scopes.scopeFor(variables, parentScope);
         }
 
-        protected void addSingletonVariableToScope(EObject context, List<Variable> variables) {
+        protected void addSingletonVariableToScope(EObject context, Collection<Variable> variables) {
                 if (context instanceof VariableOrNodeExpr expr) {
                         Variable singletonVariable = expr.getSingletonVariable();
                         if (singletonVariable != null) {
@@ -82,18 +82,21 @@ public class ProblemScopeProvider extends AbstractProblemScopeProvider {
                 }
         }
 
-        protected void addExistentiallyQualifiedVariableToScope(EObject currentContext, List<Variable> variables) {
-                if (currentContext instanceof ExistentialQuantifier quantifier) {
-                        variables.addAll(quantifier.getImplicitVariables());
-                } else if (currentContext instanceof Match match) {
-                        variables.addAll(match.getCondition().getImplicitVariables());
-                } else if (currentContext instanceof Consequent consequent) {
+        protected void addExistentiallyQualifiedVariableToScope(EObject currentContext, Collection<Variable> variables) {
+                switch (currentContext) {
+                case ExistentialQuantifier quantifier -> variables.addAll(quantifier.getImplicitVariables());
+                case Match match -> variables.addAll(match.getCondition().getImplicitVariables());
+                case Consequent consequent -> {
                         for (var literal : consequent.getActions()) {
                                 if (literal instanceof NewAction newAction && newAction.getVariable() != null) {
                                         variables.add(newAction.getVariable());
                                 }
                         }
                 }
+                default -> {
+                        // Nothing to add.
+                }
+                }
         }
 
         protected IScope getOppositeScope(EObject context) {
@@ -105,10 +108,7 @@ public class ProblemScopeProvider extends AbstractProblemScopeProvider {
                 if (!(relation instanceof ClassDeclaration classDeclaration)) {
                         return IScope.NULLSCOPE;
                 }
-                var referenceDeclarations = classDeclaration.getFeatureDeclarations()
-                                .stream()
-                                .filter(ReferenceDeclaration.class::isInstance)
-                                .toList();
+                var referenceDeclarations = classDeclaration.getFeatureDeclarations();
                 return Scopes.scopeFor(referenceDeclarations);
         }
 }