oracle sql parser support keep

src/main/java/com/alibaba/druid/sql/ast/SQLKeep.java

@@ -0,0 +1,42 @@
+package com.alibaba.druid.sql.ast;
+
+import com.alibaba.druid.sql.visitor.SQLASTVisitor;
+
+public class SQLKeep extends SQLObjectImpl {
+
+    protected DenseRank  denseRank;
+
+    protected SQLOrderBy orderBy;
+
+    @Override
+    protected void accept0(SQLASTVisitor visitor) {
+        if (visitor.visit(this)) {
+            acceptChild(visitor, this.orderBy);
+        }
+        visitor.endVisit(this);
+    }
+
+    public DenseRank getDenseRank() {
+        return denseRank;
+    }
+
+    public void setDenseRank(DenseRank denseRank) {
+        this.denseRank = denseRank;
+    }
+
+    public SQLOrderBy getOrderBy() {
+        return orderBy;
+    }
+
+    public void setOrderBy(SQLOrderBy orderBy) {
+        if (orderBy != null) {
+            orderBy.setParent(this);
+        }
+        this.orderBy = orderBy;
+    }
+
+    public static enum DenseRank {
+                                  FIRST, //
+                                  LAST
+    }
+}

src/main/java/com/alibaba/druid/sql/ast/expr/SQLAggregateExpr.java

@@ -21,6 +21,7 @@ import java.util.List;
 
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.SQLExprImpl;
+import com.alibaba.druid.sql.ast.SQLKeep;
 import com.alibaba.druid.sql.ast.SQLOrderBy;
 import com.alibaba.druid.sql.ast.SQLOver;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
@@ -31,6 +32,7 @@ public class SQLAggregateExpr extends SQLExprImpl implements Serializable {
     protected String              methodName;
     protected SQLAggregateOption  option;
     protected final List<SQLExpr> arguments        = new ArrayList<SQLExpr>();
+    protected SQLKeep             keep;
     protected SQLOver             over;
     protected SQLOrderBy          withinGroup;
     protected boolean             ignoreNulls      = false;
@@ -88,9 +90,23 @@ public class SQLAggregateExpr extends SQLExprImpl implements Serializable {
     }
 
     public void setOver(SQLOver over) {
+        if (over != null) {
+            over.setParent(this);
+        }
         this.over = over;
     }
     
+    public SQLKeep getKeep() {
+        return keep;
+    }
+
+    public void setKeep(SQLKeep keep) {
+        if (keep != null) {
+            keep.setParent(this);
+        }
+        this.keep = keep;
+    }
+    
     public boolean isIgnoreNulls() {
         return this.ignoreNulls;
     }