Parallel dynamic function calls

src/main/java/org/rumbledb/api/Item.java

@@ -439,6 +439,15 @@ default public RuntimeIterator getBodyIterator() {
         throw new UnsupportedOperationException("Operation not defined for type " + this.getDynamicType());
     }
 
+    /**
+     * Returns the body iterator, if it is a function item.
+     * 
+     * @return the function signature.
+     */
+    default public Map<Long, RuntimeIterator> getBodyIterators() {
+        throw new UnsupportedOperationException("Operation not defined for type " + this.getDynamicType());
+    }
+
     /**
      * Returns the local variable bindings, if it is a function item.
      * 

src/main/java/org/rumbledb/compiler/RuntimeIteratorVisitor.java

@@ -142,6 +142,7 @@
 import org.rumbledb.types.SequenceType;
 
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
@@ -497,12 +498,15 @@ public RuntimeIterator visitInlineFunctionExpr(InlineFunctionExpression expressi
             paramNameToSequenceTypes.put(paramEntry.getKey(), paramEntry.getValue());
         }
         SequenceType returnType = expression.getReturnType();
-        RuntimeIterator bodyIterator = this.visit(expression.getBody(), argument);
+        Map<Long, RuntimeIterator> bodyIterators = new HashMap<>();
+        for (long l : expression.getBodies().keySet()) {
+            bodyIterators.put(l, this.visit(expression.getBodies().get(l), argument));
+        }
         RuntimeIterator runtimeIterator = new FunctionRuntimeIterator(
                 expression.getName(),
                 paramNameToSequenceTypes,
                 returnType,
-                bodyIterator,
+                bodyIterators,
                 expression.getHighestExecutionMode(this.visitorConfig),
                 expression.getMetadata()
         );

src/main/java/org/rumbledb/compiler/StaticContextVisitor.java

@@ -24,6 +24,7 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Map.Entry;
 
 import org.rumbledb.context.BuiltinFunctionCatalogue;
 import org.rumbledb.context.FunctionIdentifier;
@@ -191,23 +192,45 @@ public StaticContext visitFunctionDeclaration(FunctionDeclaration declaration, S
     @Override
     public StaticContext visitInlineFunctionExpr(InlineFunctionExpression expression, StaticContext argument) {
         // define a static context for the function body, add params to the context and visit the body expression
-        StaticContext functionDeclarationContext = new StaticContext(argument);
-        expression.getParams()
-            .forEach(
-                (paramName, sequenceType) -> functionDeclarationContext.addVariable(
-                    paramName,
-                    sequenceType,
-                    expression.getMetadata(),
-                    ExecutionMode.LOCAL
-                )
+        StaticContext functionDeclarationContextLocal = new StaticContext(argument);
+        for (Entry<Name, SequenceType> entry : expression.getParams().entrySet()) {
+            functionDeclarationContextLocal.addVariable(
+                entry.getKey(),
+                entry.getValue(),
+                expression.getMetadata(),
+                ExecutionMode.LOCAL
             );
+        }
         // visit the body first to make its execution mode available while adding the function to the catalog
-        this.visit(expression.getBody(), functionDeclarationContext);
+        this.visit(expression.getBodies().get(0L), functionDeclarationContextLocal);
+
+        StaticContext functionDeclarationContextRDD = new StaticContext(argument);
+        boolean first = true;
+        for (Entry<Name, SequenceType> entry : expression.getParams().entrySet()) {
+            if (first) {
+                functionDeclarationContextRDD.addVariable(
+                    entry.getKey(),
+                    entry.getValue(),
+                    expression.getMetadata(),
+                    ExecutionMode.DATAFRAME
+                );
+                first = false;
+            } else {
+                functionDeclarationContextRDD.addVariable(
+                    entry.getKey(),
+                    entry.getValue(),
+                    expression.getMetadata(),
+                    ExecutionMode.LOCAL
+                );
+            }
+        }
+        StaticContext functionDeclarationContextDF = new StaticContext(argument);
+        this.visit(expression.getBodies().get(1L), functionDeclarationContextDF);
         expression.initHighestExecutionMode(this.visitorConfig);
         expression.registerUserDefinedFunctionExecutionMode(
             this.visitorConfig
         );
-        return functionDeclarationContext;
+        return argument;
     }
 
     @Override

src/main/java/org/rumbledb/compiler/TranslationVisitor.java

@@ -396,7 +396,7 @@ public Name parseName(JsoniqParser.QnameContext ctx, boolean isFunction, boolean
     @Override
     public Node visitFunctionDecl(JsoniqParser.FunctionDeclContext ctx) {
         Name name = parseName(ctx.qname(), true, false);
-        Map<Name, SequenceType> fnParams = new LinkedHashMap<>();
+        LinkedHashMap<Name, SequenceType> fnParams = new LinkedHashMap<>();
         SequenceType fnReturnType = null;
         Name paramName;
         SequenceType paramType;
@@ -1371,7 +1371,7 @@ public Node visitNamedFunctionRef(JsoniqParser.NamedFunctionRefContext ctx) {
 
     @Override
     public Node visitInlineFunctionExpr(JsoniqParser.InlineFunctionExprContext ctx) {
-        Map<Name, SequenceType> fnParams = new LinkedHashMap<>();
+        LinkedHashMap<Name, SequenceType> fnParams = new LinkedHashMap<>();
         SequenceType fnReturnType = SequenceType.MOST_GENERAL_SEQUENCE_TYPE;
         Name paramName;
         SequenceType paramType;

src/main/java/org/rumbledb/compiler/VariableDependenciesVisitor.java

@@ -352,7 +352,9 @@ public Void visitContextExpr(ContextItemExpression expression, Void argument) {
 
     @Override
     public Void visitInlineFunctionExpr(InlineFunctionExpression expression, Void argument) {
-        visit(expression.getBody(), null);
+        for (long l : expression.getBodies().keySet()) {
+            visit(expression.getBodies().get(l), null);
+        }
         addInputVariableDependencies(expression, getInputVariableDependencies(expression.getBody()));
         removeInputVariableDependencies(expression, expression.getParams().keySet());
         return null;

src/main/java/org/rumbledb/compiler/XQueryTranslationVisitor.java

@@ -371,7 +371,7 @@ private void processAnnotations(XQueryParser.AnnotationsContext annotations) {
     @Override
     public Node visitFunctionDecl(XQueryParser.FunctionDeclContext ctx) {
         Name name = parseName(ctx.eqName(), true, false);
-        Map<Name, SequenceType> fnParams = new LinkedHashMap<>();
+        LinkedHashMap<Name, SequenceType> fnParams = new LinkedHashMap<>();
         SequenceType fnReturnType = MOST_GENERAL_SEQUENCE_TYPE;
         Name paramName;
         SequenceType paramType;
@@ -1279,7 +1279,7 @@ public Node visitNamedFunctionRef(XQueryParser.NamedFunctionRefContext ctx) {
 
     @Override
     public Node visitInlineFunctionRef(XQueryParser.InlineFunctionRefContext ctx) {
-        Map<Name, SequenceType> fnParams = new LinkedHashMap<>();
+        LinkedHashMap<Name, SequenceType> fnParams = new LinkedHashMap<>();
         SequenceType fnReturnType = SequenceType.MOST_GENERAL_SEQUENCE_TYPE;
         Name paramName;
         SequenceType paramType;

src/main/java/org/rumbledb/expressions/CommaExpression.java

@@ -29,6 +29,8 @@
 
 public class CommaExpression extends Expression {
 
+    private static final long serialVersionUID = 1L;
+
     private final List<Expression> expressions;
 
     public CommaExpression(List<Expression> expressions, ExceptionMetadata metadata) {

src/main/java/org/rumbledb/expressions/Expression.java

@@ -36,7 +36,8 @@
  */
 public abstract class Expression extends Node {
 
-    protected StaticContext staticContext;
+    private static final long serialVersionUID = 1L;
+    protected transient StaticContext staticContext;
 
     protected SequenceType inferredSequenceType;
 

src/main/java/org/rumbledb/expressions/Node.java

@@ -24,6 +24,7 @@
 import org.rumbledb.exceptions.ExceptionMetadata;
 import org.rumbledb.exceptions.OurBadException;
 
+import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.function.Predicate;
@@ -32,8 +33,9 @@
  * This is the top-level class for nodes in the intermediate representation of a
  * JSONiq query. Nodes include expressions, clauses, function declarations, etc.
  */
-public abstract class Node {
+public abstract class Node implements Serializable {
 
+    private static final long serialVersionUID = 1L;
     private ExceptionMetadata metadata;
 
     protected ExecutionMode highestExecutionMode = ExecutionMode.UNSET;

src/main/java/org/rumbledb/expressions/arithmetic/AdditiveExpression.java

@@ -30,6 +30,8 @@
 import java.util.List;
 
 public class AdditiveExpression extends Expression {
+    private static final long serialVersionUID = 1L;
+
     private Expression leftExpression;
     private Expression rightExpression;
     private boolean isMinus;

src/main/java/org/rumbledb/expressions/arithmetic/MultiplicativeExpression.java

@@ -31,6 +31,7 @@
 import java.util.List;
 
 public class MultiplicativeExpression extends Expression {
+    private static final long serialVersionUID = 1L;
 
     public static enum MultiplicativeOperator {
         MUL("*"),

src/main/java/org/rumbledb/expressions/comparison/ComparisonExpression.java

@@ -31,6 +31,8 @@
 
 public class ComparisonExpression extends Expression {
 
+    private static final long serialVersionUID = 1L;
+
     public static enum ComparisonOperator {
         VC_EQ("eq"),
         VC_NE("ne"),

src/main/java/org/rumbledb/expressions/control/ConditionalExpression.java

@@ -33,6 +33,7 @@
 
 public class ConditionalExpression extends Expression {
 
+    private static final long serialVersionUID = 1L;
     private final Expression conditionExpression;
     private final Expression thenExpression;
     private final Expression elseExpression;

src/main/java/org/rumbledb/expressions/flowr/Clause.java

@@ -34,6 +34,8 @@
 public abstract class Clause extends Node {
 
     /* Clauses are organized in doubly-linked lists */
+    private static final long serialVersionUID = 1L;
+
     protected Clause previousClause;
     protected Clause nextClause;
     protected FLWOR_CLAUSES clauseType;

src/main/java/org/rumbledb/expressions/flowr/CountClause.java

@@ -30,6 +30,7 @@
 
 
 public class CountClause extends Clause {
+    private static final long serialVersionUID = 1L;
     private VariableReferenceExpression countClauseVar;
 
     public CountClause(VariableReferenceExpression countClauseVar, ExceptionMetadata metadata) {

src/main/java/org/rumbledb/expressions/flowr/FlworExpression.java

@@ -32,6 +32,7 @@
 
 public class FlworExpression extends Expression {
 
+    private static final long serialVersionUID = 1L;
     private ReturnClause returnClause;
 
     public FlworExpression(

src/main/java/org/rumbledb/expressions/flowr/ForClause.java

@@ -36,6 +36,7 @@
 
 public class ForClause extends Clause {
 
+    private static final long serialVersionUID = 1L;
     private final Name variableName;
     private final boolean allowingEmpty;
     private final Name positionalVariableName;

src/main/java/org/rumbledb/expressions/flowr/GroupByClause.java

@@ -32,6 +32,7 @@
 
 public class GroupByClause extends Clause {
 
+    private static final long serialVersionUID = 1L;
     private final List<GroupByVariableDeclaration> variables;
 
     public GroupByClause(List<GroupByVariableDeclaration> variables, ExceptionMetadata metadata) {

src/main/java/org/rumbledb/expressions/flowr/LetClause.java

@@ -36,6 +36,7 @@
 
 public class LetClause extends Clause {
 
+    private static final long serialVersionUID = 1L;
     private final Name variableName;
     protected SequenceType sequenceType;
     protected Expression expression;

src/main/java/org/rumbledb/expressions/flowr/OrderByClause.java

@@ -31,6 +31,7 @@
 
 public class OrderByClause extends Clause {
 
+    private static final long serialVersionUID = 1L;
 
     private final List<OrderByClauseSortingKey> sortingKeys;
     private final boolean isStable;

src/main/java/org/rumbledb/expressions/flowr/ReturnClause.java

@@ -32,6 +32,7 @@
 
 public class ReturnClause extends Clause {
 
+    private static final long serialVersionUID = 1L;
 
     private final Expression returnExpr;
 

src/main/java/org/rumbledb/expressions/flowr/SimpleMapExpression.java

@@ -31,6 +31,7 @@
 import java.util.List;
 
 public class SimpleMapExpression extends Expression {
+    private static final long serialVersionUID = 1L;
     private Expression leftExpression;
     private Expression rightExpression;
 

src/main/java/org/rumbledb/expressions/logic/AndExpression.java

@@ -29,6 +29,8 @@
 import java.util.List;
 
 public class AndExpression extends Expression {
+    private static final long serialVersionUID = 1L;
+
     private Expression leftExpression;
     private Expression rightExpression;
 

src/main/java/org/rumbledb/expressions/logic/NotExpression.java

@@ -32,6 +32,7 @@
 
 public class NotExpression extends Expression {
 
+    private static final long serialVersionUID = 1L;
     private Expression mainExpression;
 
     public NotExpression(Expression mainExpression, ExceptionMetadata metadata) {

src/main/java/org/rumbledb/expressions/logic/OrExpression.java

@@ -29,6 +29,7 @@
 import java.util.List;
 
 public class OrExpression extends Expression {
+    private static final long serialVersionUID = 1L;
     private Expression leftExpression;
     private Expression rightExpression;
 

src/main/java/org/rumbledb/expressions/miscellaneous/RangeExpression.java

@@ -31,6 +31,7 @@
 
 public class RangeExpression extends Expression {
 
+    private static final long serialVersionUID = 1L;
     private Expression leftExpression;
     private Expression rightExpression;
 

src/main/java/org/rumbledb/expressions/miscellaneous/StringConcatExpression.java

@@ -30,6 +30,7 @@
 import java.util.List;
 
 public class StringConcatExpression extends Expression {
+    private static final long serialVersionUID = 1L;
     private Expression leftExpression;
     private Expression rightExpression;
 

src/main/java/org/rumbledb/expressions/module/FunctionDeclaration.java

@@ -34,6 +34,7 @@
 
 public class FunctionDeclaration extends Node {
 
+    private static final long serialVersionUID = 1L;
     private final InlineFunctionExpression functionExpression;
 
     public FunctionDeclaration(

src/main/java/org/rumbledb/expressions/module/LibraryModule.java

@@ -31,6 +31,7 @@
 
 public class LibraryModule extends Module {
 
+    private static final long serialVersionUID = 1L;
     protected StaticContext staticContext;
     private String namespace;
     private final Prolog prolog;

src/main/java/org/rumbledb/expressions/module/MainModule.java

@@ -33,6 +33,7 @@
 
 public class MainModule extends Module {
 
+    private static final long serialVersionUID = 1L;
     protected StaticContext staticContext;
     private final Prolog prolog;
     private final Expression expression;

src/main/java/org/rumbledb/expressions/module/Module.java

@@ -5,6 +5,8 @@
 import org.rumbledb.expressions.Node;
 
 public abstract class Module extends Node {
+    private static final long serialVersionUID = 1L;
+
     public Module(ExceptionMetadata metadata) {
         super(metadata);
     }

src/main/java/org/rumbledb/expressions/module/Prolog.java

@@ -31,6 +31,7 @@
 
 public class Prolog extends Node {
 
+    private static final long serialVersionUID = 1L;
     private List<Node> declarations;
     private List<LibraryModule> importedModules;
 

src/main/java/org/rumbledb/expressions/postfix/ArrayLookupExpression.java

@@ -33,6 +33,8 @@
 
 public class ArrayLookupExpression extends Expression {
 
+    private static final long serialVersionUID = 1L;
+
     private Expression mainExpression;
     private Expression lookupExpression;
 

src/main/java/org/rumbledb/expressions/postfix/ArrayUnboxingExpression.java

@@ -33,6 +33,8 @@
 
 public class ArrayUnboxingExpression extends Expression {
 
+    private static final long serialVersionUID = 1L;
+
     private Expression mainExpression;
 
     public ArrayUnboxingExpression(Expression mainExpression, ExceptionMetadata metadata) {