Check validity of window frame in Parser

h2/src/main/org/h2/command/Parser.java

@@ -3112,6 +3112,7 @@ public class Parser {
             starting = readWindowFrameStarting();
             following = null;
         }
+        int idx = lastParseIndex;
         WindowFrameExclusion exclusion = WindowFrameExclusion.EXCLUDE_NO_OTHERS;
         if (readIf("EXCLUDE")) {
             if (readIf("CURRENT")) {
@@ -3126,7 +3127,11 @@ public class Parser {
                 read("OTHERS");
             }
         }
-        return new WindowFrame(units, starting, following, exclusion);
+        WindowFrame frame = new WindowFrame(units, starting, following, exclusion);
+        if (!frame.isValid()) {
+            throw DbException.getSyntaxError(sqlCommand, idx);
+        }
+        return frame;
     }
 
     private WindowFrameBound readWindowFrameStarting() {

h2/src/main/org/h2/expression/aggregate/WindowFrame.java

@@ -11,7 +11,6 @@ import java.util.Collections;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 
-import org.h2.api.ErrorCode;
 import org.h2.engine.Session;
 import org.h2.expression.BinaryOperation;
 import org.h2.expression.BinaryOperation.OpType;
@@ -225,6 +224,18 @@ public final class WindowFrame {
         this.exclusion = exclusion;
     }
 
+    /**
+     * Checks validity of this frame.
+     *
+     * @return whether bounds of this frame valid
+     */
+    public boolean isValid() {
+        WindowFrameBoundType s = starting.getType(),
+                f = following != null ? following.getType() : WindowFrameBoundType.CURRENT_ROW;
+        return s != WindowFrameBoundType.UNBOUNDED_FOLLOWING && f != WindowFrameBoundType.UNBOUNDED_PRECEDING
+                && s.compareTo(f) <= 0;
+    }
+
     /**
      * Returns whether window frame specification can be omitted.
      *
@@ -269,10 +280,7 @@ public final class WindowFrame {
         int endIndex = following != null ? getIndex(session, orderedRows, sortOrder, currentRow, following, true)
                 : currentRow;
         if (endIndex < startIndex) {
-            startIndex = getIndex(session, orderedRows, sortOrder, currentRow, starting, false);
-            endIndex = following != null ? getIndex(session, orderedRows, sortOrder, currentRow, following, true)
-                    : currentRow;
-            throw DbException.get(ErrorCode.SYNTAX_ERROR_1, getSQL());
+            return Collections.emptyIterator();
         }
         int size = orderedRows.size();
         if (startIndex >= size || endIndex < 0) {