Added from_base64 and to_base64

Signed-off-by: Juanjo Alvarez <[email protected]>

Author: Juanjo Alvarez

sql/expression/function/registry.go

@@ -74,4 +74,6 @@ var Defaults = []sql.Function{
 	sql.Function2{Name: "ifnull", Fn: NewIfNull},
 	sql.Function2{Name: "nullif", Fn: NewNullIf},
 	sql.Function0{Name: "now", Fn: NewNow},
+	sql.Function1{Name: "to_base64", Fn: NewToBase64},
+	sql.Function1{Name: "from_base64", Fn: NewFromBase64},
 }

sql/expression/function/tobase64_frombase64.go

@@ -0,0 +1,148 @@
+package function
+
+import (
+	"encoding/base64"
+	"fmt"
+	"reflect"
+	"strings"
+
+	"gopkg.in/src-d/go-mysql-server.v0/sql"
+	"gopkg.in/src-d/go-mysql-server.v0/sql/expression"
+)
+
+// ToBase64 is a function to encode a string to the Base64 format
+// using the same dialect that MySQL's TO_BASE64 uses
+type ToBase64 struct {
+	expression.UnaryExpression
+}
+
+// NewToBase64 creates a new ToBase64 expression.
+func NewToBase64(e sql.Expression) sql.Expression {
+	return &ToBase64{expression.UnaryExpression{Child: e}}
+}
+
+// Eval implements the Expression interface.
+func (t *ToBase64) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
+	str, err := t.Child.Eval(ctx, row)
+
+	if err != nil {
+		return nil, err
+	}
+
+	if str == nil {
+		return nil, nil
+	}
+
+	str, err = sql.Text.Convert(str)
+	if err != nil {
+		return nil, sql.ErrInvalidType.New(reflect.TypeOf(str))
+	}
+
+	encoded := base64.StdEncoding.EncodeToString([]byte(str.(string)))
+
+	lenEncoded := len(encoded)
+	if lenEncoded <= 76 {
+		return encoded, nil
+	}
+
+	// Split into max 76 chars lines
+	var out strings.Builder
+	start := 0
+	end := 76
+	for {
+		out.WriteString(encoded[start:end] + "\n")
+		start += 76
+		end += 76
+		if end >= lenEncoded {
+			out.WriteString(encoded[start:lenEncoded])
+			break
+		}
+	}
+
+	return out.String(), nil
+}
+
+// String implements the Stringer interface.
+func (t *ToBase64) String() string {
+	return fmt.Sprintf("TO_BASE64(%s)", t.Child)
+}
+
+// IsNullable implements the Expression interface.
+func (t *ToBase64) IsNullable() bool {
+	return t.Child.IsNullable()
+}
+
+// TransformUp implements the Expression interface.
+func (t *ToBase64) TransformUp(f sql.TransformExprFunc) (sql.Expression, error) {
+	child, err := t.Child.TransformUp(f)
+	if err != nil {
+		return nil, err
+	}
+	return f(NewToBase64(child))
+}
+
+// Type implements the Expression interface.
+func (t *ToBase64) Type() sql.Type {
+	return sql.Text
+}
+
+
+// FromBase64 is a function to decode a Base64-formatted string
+// using the same dialect that MySQL's FROM_BASE64 uses
+type FromBase64 struct {
+	expression.UnaryExpression
+}
+
+// NewFromBase64 creates a new FromBase64 expression.
+func NewFromBase64(e sql.Expression) sql.Expression {
+	return &FromBase64{expression.UnaryExpression{Child: e}}
+}
+
+// Eval implements the Expression interface.
+func (t *FromBase64) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
+	str, err := t.Child.Eval(ctx, row)
+
+	if err != nil {
+		return nil, err
+	}
+
+	if str == nil {
+		return nil, nil
+	}
+
+	str, err = sql.Text.Convert(str)
+	if err != nil {
+		return nil, sql.ErrInvalidType.New(reflect.TypeOf(str))
+	}
+
+	decoded, err := base64.StdEncoding.DecodeString(str.(string))
+	if err != nil {
+		return nil, err
+	}
+
+	return string(decoded), nil
+}
+
+// String implements the Stringer interface.
+func (t *FromBase64) String() string {
+	return fmt.Sprintf("FROM_BASE64(%s)", t.Child)
+}
+
+// IsNullable implements the Expression interface.
+func (t *FromBase64) IsNullable() bool {
+	return t.Child.IsNullable()
+}
+
+// TransformUp implements the Expression interface.
+func (t *FromBase64) TransformUp(f sql.TransformExprFunc) (sql.Expression, error) {
+	child, err := t.Child.TransformUp(f)
+	if err != nil {
+		return nil, err
+	}
+	return f(NewFromBase64(child))
+}
+
+// Type implements the Expression interface.
+func (t *FromBase64) Type() sql.Type {
+	return sql.Text
+}

sql/expression/function/tobase64_frombase64_test.go

@@ -0,0 +1,56 @@
+package function
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"gopkg.in/src-d/go-mysql-server.v0/sql"
+	"gopkg.in/src-d/go-mysql-server.v0/sql/expression"
+)
+
+func TestBase64(t *testing.T) {
+	fTo := NewToBase64(expression.NewGetField(0, sql.Text, "", false))
+	fFrom := NewFromBase64(expression.NewGetField(0, sql.Text, "", false))
+
+	testCases := []struct {
+		name     string
+		row      sql.Row
+		expected interface{}
+		err      bool
+	}{
+		// Use a MySQL server to get expected values if updating/adding to this!
+		{"null input", sql.NewRow(nil), nil, false},
+		{"single_line", sql.NewRow("foo"), string("Zm9v"), false},
+		{"multi_line", sql.NewRow(
+			"Gallia est omnis divisa in partes tres, quarum unam " +
+				"incolunt Belgae, aliam Aquitani, tertiam qui ipsorum lingua Celtae, " +
+				"nostra Galli appellantur"),
+			"R2FsbGlhIGVzdCBvbW5pcyBkaXZpc2EgaW4gcGFydGVzIHRyZXMsIHF1YXJ1bSB1bmFtIGluY29s\n" +
+				"dW50IEJlbGdhZSwgYWxpYW0gQXF1aXRhbmksIHRlcnRpYW0gcXVpIGlwc29ydW0gbGluZ3VhIENl\n" +
+				"bHRhZSwgbm9zdHJhIEdhbGxpIGFwcGVsbGFudHVy", false},
+		{"empty_input", sql.NewRow(""), string(""), false},
+		{"symbols", sql.NewRow("!@#$% %^&*()_+\r\n\t{};"), string("IUAjJCUgJV4mKigpXysNCgl7fTs="),
+			false},
+	}
+
+	for _, tt := range testCases {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Helper()
+			require := require.New(t)
+			ctx := sql.NewEmptyContext()
+			v, err := fTo.Eval(ctx, tt.row)
+
+			if tt.err {
+				require.Error(err)
+			} else {
+				require.NoError(err)
+				require.Equal(tt.expected, v)
+
+				ctx = sql.NewEmptyContext()
+				v2, err := fFrom.Eval(ctx, sql.NewRow(v))
+				require.NoError(err)
+				require.Equal(sql.NewRow(v2), tt.row)
+			}
+		})
+	}
+}