Merge pull request #763 from wolfgangmm/bugfix/groupby-fix

Fixes for FLWOR expressions

src/org/exist/xquery/AbstractFLWORClause.java

@@ -0,0 +1,90 @@
+package org.exist.xquery;
+
+import org.exist.dom.QName;
+import org.exist.xquery.value.Sequence;
+import org.exist.xquery.value.Type;
+
+/**
+ * Abstract base class for clauses in a FLWOR expressions, for/let/group by ...
+ */
+public abstract class AbstractFLWORClause extends AbstractExpression implements FLWORClause {
+
+    protected LocalVariable firstVar = null;
+    private FLWORClause previousClause  = null;
+    protected Expression returnExpr;
+    private int actualReturnType = Type.ITEM;
+
+    public AbstractFLWORClause(XQueryContext context) {
+        super(context);
+    }
+
+    public LocalVariable createVariable(String name) throws XPathException {
+        final LocalVariable var = new LocalVariable(QName.parse(context, name, null));
+        if (firstVar == null) {
+            firstVar = var;
+        }
+        return var;
+    }
+
+    @Override
+    public Sequence preEval(Sequence seq) throws XPathException {
+        // just return the input sequence by default
+        if (returnExpr instanceof FLWORClause) {
+            return ((FLWORClause)returnExpr).preEval(seq);
+        }
+        return seq;
+    }
+
+    @Override
+    public Sequence postEval(Sequence seq) throws XPathException {
+        // reset variable after evaluation has completed
+        firstVar = null;
+        return seq;
+    }
+
+    @Override
+    public void setReturnExpression(Expression expr) {
+        this.returnExpr = expr;
+    }
+
+    @Override
+    public Expression getReturnExpression() {
+        return returnExpr;
+    }
+
+    @Override
+    public LocalVariable getStartVariable() {
+        return firstVar;
+    }
+
+    @Override
+    public void setPreviousClause(FLWORClause clause) {
+        previousClause = clause;
+    }
+
+    @Override
+    public FLWORClause getPreviousClause() {
+        return previousClause;
+    }
+
+    protected void setActualReturnType(int type) {
+        this.actualReturnType = type;
+    }
+
+    @Override
+    public int returnsType() {
+        //Type.ITEM by default : this may change *after* evaluation
+        return actualReturnType;
+    }
+
+    @Override
+    public void resetState(boolean postOptimization) {
+        super.resetState(postOptimization);
+        firstVar = null;
+    }
+
+    @Override
+    public int getDependencies() {
+        return returnExpr.getDependencies();
+    }
+}

src/org/exist/xquery/BasicExpressionVisitor.java

@@ -171,6 +171,21 @@ public void visitLetExpression(LetExpr letExpr) {
         //Nothing to do
     }
 
+    @Override
+    public void visitOrderByClause(OrderByClause orderBy) {
+        // Nothing to do
+    }
+
+    @Override
+    public void visitGroupByClause(GroupByClause groupBy) {
+        // Nothing to do
+    }
+
+    @Override
+    public void visitWhereClause(WhereClause where) {
+        // Nothing to do
+    }
+
     @Override
     public void visitBuiltinFunction(Function function) {
         //Nothing to do