feat(api): add ops.StructColumn operation

Author: cpcloud

ibis/expr/operations/generic.py

@@ -373,6 +373,23 @@ def has_resolved_name(self):
         return True
 
 
+@public
+class StructColumn(Value):
+    names = rlz.tuple_of(rlz.instance_of(str), min_length=1)
+    values = rlz.tuple_of(rlz.any, min_length=1)
+
+    output_shape = rlz.Shape.COLUMNAR
+
+    @immutable_property
+    def output_dtype(self):
+        return dt.Struct.from_tuples(
+            zip(self.names, (value.type() for value in self.values))
+        )
+
+    def root_tables(self):
+        return distinct_roots(*self.values)
+
+
 @public
 class DecimalPrecision(Unary):
     arg = rlz.decimal

ibis/expr/types/structs.py

@@ -46,7 +46,15 @@ def struct(
     Create a struct literal from a [`dict`][dict] with a specified type
     >>> t = ibis.struct(dict(a=1, b='foo'), type='struct<a: float, b: string>')
     """
-    return literal(collections.OrderedDict(value), type=type)
+    import ibis.expr.operations as ops
+
+    items = dict(value)
+    values = items.values()
+    if any(isinstance(value, Value) for value in values):
+        return ops.StructColumn(
+            names=tuple(items.keys()), values=tuple(values)
+        ).to_expr()
+    return literal(collections.OrderedDict(items), type=type)
 
 
 @public