feat(sql/ast): Early support for rendering SQL AST

Author: kyleconroy

internal/engine/postgresql/convert.go

@@ -2982,6 +2982,7 @@ func convertXmlSerialize(n *pg.XmlSerialize) *ast.XmlSerialize {
 
 func convertNode(node *pg.Node) ast.Node {
 	if node == nil || node.Node == nil {
+		// TODO: WHY
 		return &ast.TODO{}
 	}
 

internal/engine/postgresql/print_test.go

@@ -0,0 +1,39 @@
+package postgresql
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+
+	"github.com/sqlc-dev/sqlc/internal/sql/ast"
+)
+
+func TestPrintAst(t *testing.T) {
+	p := NewParser()
+
+	queries := []string{
+		`SELECT * FROM foo;`,
+		`SELECT * FROM foo,bar;`,
+		`SELECT * FROM foo WHERE EXISTS (SELECT * FROM foo);`,
+		`WITH bar AS (SELECT * FROM foo), bat AS (SELECT 1) SELECT * FROM foo;`,
+	}
+
+	for i, q := range queries {
+		q := q
+		t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {
+			stmts, err := p.Parse(strings.NewReader(q))
+			if err != nil {
+				t.Fatal(err)
+			}
+			for _, stmt := range stmts {
+				out := ast.Format(stmt.Raw)
+				if diff := cmp.Diff(q, out); diff != "" {
+					t.Errorf("- %s", q)
+					t.Errorf("+ %s", out)
+				}
+			}
+		})
+	}
+}

internal/sql/ast/a_const.go

@@ -8,3 +8,10 @@ type A_Const struct {
 func (n *A_Const) Pos() int {
 	return n.Location
 }
+
+func (n *A_Const) Format(buf *TrackedBuffer) {
+	if n == nil {
+		return
+	}
+	buf.astFormat(n.Val)
+}

internal/sql/ast/a_star.go

@@ -6,3 +6,10 @@ type A_Star struct {
 func (n *A_Star) Pos() int {
 	return 0
 }
+
+func (n *A_Star) Format(buf *TrackedBuffer) {
+	if n == nil {
+		return
+	}
+	buf.WriteRune('*')
+}

internal/sql/ast/column_ref.go

@@ -11,3 +11,10 @@ type ColumnRef struct {
 func (n *ColumnRef) Pos() int {
 	return n.Location
 }
+
+func (n *ColumnRef) Format(buf *TrackedBuffer) {
+	if n == nil {
+		return
+	}
+	buf.astFormat(n.Fields)
+}

internal/sql/ast/common_table_expr.go

@@ -1,5 +1,7 @@
 package ast
 
+import "fmt"
+
 type CommonTableExpr struct {
 	Ctename          *string
 	Aliascolnames    *List
@@ -16,3 +18,14 @@ type CommonTableExpr struct {
 func (n *CommonTableExpr) Pos() int {
 	return n.Location
 }
+
+func (n *CommonTableExpr) Format(buf *TrackedBuffer) {
+	if n == nil {
+		return
+	}
+	if n.Ctename != nil {
+		fmt.Fprintf(buf, " %s AS (", *n.Ctename)
+	}
+	buf.astFormat(n.Ctequery)
+	buf.WriteString(")")
+}

internal/sql/ast/integer.go

@@ -1,9 +1,18 @@
 package ast
 
+import "strconv"
+
 type Integer struct {
 	Ival int64
 }
 
 func (n *Integer) Pos() int {
 	return 0
 }
+
+func (n *Integer) Format(buf *TrackedBuffer) {
+	if n == nil {
+		return
+	}
+	buf.WriteString(strconv.FormatInt(n.Ival, 10))
+}

internal/sql/ast/list.go

@@ -7,3 +7,15 @@ type List struct {
 func (n *List) Pos() int {
 	return 0
 }
+
+func (n *List) Format(buf *TrackedBuffer) {
+	if n == nil {
+		return
+	}
+	for i, item := range n.Items {
+		if i > 0 {
+			buf.WriteRune(',')
+		}
+		buf.astFormat(item)
+	}
+}

internal/sql/ast/print.go

@@ -0,0 +1,39 @@
+package ast
+
+import (
+	"strings"
+
+	"github.com/sqlc-dev/sqlc/internal/debug"
+)
+
+type formatter interface {
+	Format(*TrackedBuffer)
+}
+
+type TrackedBuffer struct {
+	*strings.Builder
+}
+
+// NewTrackedBuffer creates a new TrackedBuffer.
+func NewTrackedBuffer() *TrackedBuffer {
+	buf := &TrackedBuffer{
+		Builder: new(strings.Builder),
+	}
+	return buf
+}
+
+func (t *TrackedBuffer) astFormat(n Node) {
+	if ft, ok := n.(formatter); ok {
+		ft.Format(t)
+	} else {
+		debug.Dump(n)
+	}
+}
+
+func Format(n Node) string {
+	tb := NewTrackedBuffer()
+	if ft, ok := n.(formatter); ok {
+		ft.Format(tb)
+	}
+	return tb.String()
+}

internal/sql/ast/range_var.go

@@ -13,3 +13,12 @@ type RangeVar struct {
 func (n *RangeVar) Pos() int {
 	return n.Location
 }
+
+func (n *RangeVar) Format(buf *TrackedBuffer) {
+	if n == nil {
+		return
+	}
+	if n.Relname != nil {
+		buf.WriteString(*n.Relname)
+	}
+}