Support cast varchar to bitmap (StarRocks#1941)

be/src/exprs/vectorized/cast_expr.cpp

@@ -15,6 +15,7 @@
 #include "gutil/strings/substitute.h"
 #include "runtime/runtime_state.h"
 #include "storage/hll.h"
+#include "util/bitmap_value.h"
 #include "util/date_func.h"
 
 namespace starrocks {
@@ -157,6 +158,30 @@ ColumnPtr cast_fn<TYPE_VARCHAR, TYPE_HLL>(ColumnPtr& column) {
 
     return builder.build(column->is_constant());
 }
+
+template <>
+ColumnPtr cast_fn<TYPE_VARCHAR, TYPE_OBJECT>(ColumnPtr& column) {
+    ColumnBuilder<TYPE_OBJECT> builder;
+    ColumnViewer<TYPE_VARCHAR> viewer(column);
+    for (int row = 0; row < viewer.size(); ++row) {
+        if (viewer.is_null(row)) {
+            builder.append_null();
+            continue;
+        }
+
+        auto value = viewer.value(row);
+        BitmapValue bitmap;
+        // TODO(kks): check value.data is valid bitmap firstly
+        if (bitmap.deserialize(value.data)) {
+            builder.append(&bitmap);
+        } else {
+            builder.append_null();
+        }
+    }
+
+    return builder.build(column->is_constant());
+}
+
 // all int(tinyint, smallint, int, bigint, largeint) cast implements
 DEFINE_UNARY_FN_WITH_IMPL(ImplicitToNumber, value) {
     return value;
@@ -1033,6 +1058,10 @@ Expr* VectorizedCastExprFactory::from_thrift(const TExprNode& node) {
         return new VectorizedCastExpr<TYPE_VARCHAR, TYPE_HLL>(node);
     }
 
+    if (from_type == TYPE_VARCHAR && to_type == TYPE_OBJECT) {
+        return new VectorizedCastExpr<TYPE_VARCHAR, TYPE_OBJECT>(node);
+    }
+
     if (to_type == TYPE_VARCHAR) {
         switch (from_type) {
             CASE_TO_STRING_FROM(TYPE_BOOLEAN);