chore: Migrate strconcat_op operator to SQLGlot (#2166)

* chore: Migrate strconcat_op operator to SQLGlot

Migrated the `strconcat_op` operator from the Ibis compiler to the new SQLGlot compiler. This includes the implementation of the compiler logic and a corresponding unit test with a snapshot.

* fix

Author: jialuoo

bigframes/core/compile/sqlglot/expressions/string_ops.py

@@ -23,6 +23,7 @@
 import bigframes.core.compile.sqlglot.scalar_compiler as scalar_compiler
 
 register_unary_op = scalar_compiler.scalar_op_compiler.register_unary_op
+register_binary_op = scalar_compiler.scalar_op_compiler.register_binary_op
 
 
 @register_unary_op(ops.capitalize_op)
@@ -276,6 +277,11 @@ def _(expr: TypedExpr) -> sge.Expression:
     return sge.Upper(this=expr.expr)
 
 
+@register_binary_op(ops.strconcat_op)
+def _(left: TypedExpr, right: TypedExpr) -> sge.Expression:
+    return sge.Concat(expressions=[left.expr, right.expr])
+
+
 @register_unary_op(ops.ZfillOp, pass_op=True)
 def _(expr: TypedExpr, op: ops.ZfillOp) -> sge.Expression:
     return sge.Case(

tests/unit/core/compile/sqlglot/expressions/snapshots/test_string_ops/test_strconcat/out.sql

@@ -0,0 +1,13 @@
+WITH `bfcte_0` AS (
+  SELECT
+    `string_col` AS `bfcol_0`
+  FROM `bigframes-dev`.`sqlglot_test`.`scalar_types`
+), `bfcte_1` AS (
+  SELECT
+    *,
+    CONCAT(`bfcol_0`, 'a') AS `bfcol_1`
+  FROM `bfcte_0`
+)
+SELECT
+  `bfcol_1` AS `string_col`
+FROM `bfcte_1`

tests/unit/core/compile/sqlglot/expressions/test_string_ops.py

@@ -311,3 +311,10 @@ def test_add_string(scalar_types_df: bpd.DataFrame, snapshot):
     sql = utils._apply_binary_op(bf_df, ops.add_op, "string_col", ex.const("a"))
 
     snapshot.assert_match(sql, "out.sql")
+
+
+def test_strconcat(scalar_types_df: bpd.DataFrame, snapshot):
+    bf_df = scalar_types_df[["string_col"]]
+    sql = utils._apply_binary_op(bf_df, ops.strconcat_op, "string_col", ex.const("a"))
+
+    snapshot.assert_match(sql, "out.sql")