From 0cba1f6401957d597dbd58e0d69a0d7f46190bf9 Mon Sep 17 00:00:00 2001
From: go-jet <zer0.sub@protonmail.com>
Date: Fri, 16 Oct 2020 13:26:53 +0200
Subject: [PATCH] Lateral - initial commit.

---
 internal/jet/select_table.go  | 22 ++++++++++++++++++++--
 postgres/lateral.go           | 13 +++++++++++++
 postgres/lateral_test.go      |  9 +++++++++
 tests/postgres/select_test.go | 31 +++++++++++++++++++++++++++++++
 4 files changed, 73 insertions(+), 2 deletions(-)
 create mode 100644 postgres/lateral.go
 create mode 100644 postgres/lateral_test.go

diff --git a/internal/jet/select_table.go b/internal/jet/select_table.go
index 52689d4..1421b14 100644
--- a/internal/jet/select_table.go
+++ b/internal/jet/select_table.go
@@ -13,8 +13,8 @@ type selectTableImpl struct {
 }
 
 // NewSelectTable func
-func NewSelectTable(selectStmt SerializerStatement, alias string) SelectTable {
-	selectTable := &selectTableImpl{selectStmt: selectStmt, alias: alias}
+func NewSelectTable(selectStmt SerializerStatement, alias string) selectTableImpl {
+	selectTable := selectTableImpl{selectStmt: selectStmt, alias: alias}
 	return selectTable
 }
 
@@ -38,3 +38,21 @@ func (s selectTableImpl) serialize(statement StatementType, out *SQLBuilder, opt
 	out.WriteString("AS")
 	out.WriteIdentifier(s.alias)
 }
+
+// --------------------------------------
+
+type lateralImpl struct {
+	selectTableImpl
+}
+
+func NewLateral(selectStmt SerializerStatement, alias string) SelectTable {
+	return lateralImpl{selectTableImpl: NewSelectTable(selectStmt, alias)}
+}
+
+func (s lateralImpl) serialize(statement StatementType, out *SQLBuilder, options ...SerializeOption) {
+	out.WriteString("LATERAL")
+	s.selectStmt.serialize(statement, out)
+
+	out.WriteString("AS")
+	out.WriteIdentifier(s.alias)
+}
diff --git a/postgres/lateral.go b/postgres/lateral.go
new file mode 100644
index 0000000..fbbe953
--- /dev/null
+++ b/postgres/lateral.go
@@ -0,0 +1,13 @@
+package postgres
+
+import "github.com/go-jet/jet/v2/internal/jet"
+
+func LATERAL(selectStmt SelectStatement, alias string) SelectTable {
+	subQuery := &selectTableImpl{
+		SelectTable: jet.NewLateral(selectStmt, alias),
+	}
+
+	subQuery.readableTableInterfaceImpl.parent = subQuery
+
+	return subQuery
+}
diff --git a/postgres/lateral_test.go b/postgres/lateral_test.go
new file mode 100644
index 0000000..a401a1e
--- /dev/null
+++ b/postgres/lateral_test.go
@@ -0,0 +1,9 @@
+package postgres
+
+import "testing"
+
+func TestLATERAL(t *testing.T) {
+	assertSerialize(t, LATERAL(SELECT(Int(1)), "lat1"), `LATERAL (
+     SELECT $1
+) AS lat1`)
+}
diff --git a/tests/postgres/select_test.go b/tests/postgres/select_test.go
index 8bd6f53..afa7230 100644
--- a/tests/postgres/select_test.go
+++ b/tests/postgres/select_test.go
@@ -1893,3 +1893,34 @@ WHERE ($1 AND (customer.customer_id = $2)) AND (customer.activebool = $3);
 	require.Len(t, dest, 1)
 	testutils.AssertDeepEqual(t, dest[0], customer0)
 }
+
+func TestLateral(t *testing.T) {
+
+	languages := LATERAL(
+		SELECT(
+			Language.AllColumns,
+		).FROM(
+			Language,
+		).WHERE(
+			Language.Name.NOT_IN(String("spanish")).
+				AND(Film.LanguageID.EQ(Language.LanguageID)),
+		),
+		"films")
+
+	stmt := SELECT(
+		Film.AllColumns,
+		languages.AllColumns(),
+	).FROM(
+		Film.CROSS_JOIN(languages),
+	).WHERE(
+		Film.FilmID.EQ(Int(1)),
+	)
+
+	var dest []struct {
+		model.Film
+		model.Language
+	}
+
+	err := stmt.Query(db, &dest)
+	require.NoError(t, err)
+}