forked from dolthub/go-mysql-server
/
tobase64_frombase64.go
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/
tobase64_frombase64.go
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// Copyright 2020-2021 Dolthub, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package function
import (
"encoding/base64"
"fmt"
"reflect"
"strings"
"github.com/gabereiser/go-mysql-server/sql/encodings"
"github.com/gabereiser/go-mysql-server/sql/types"
"github.com/gabereiser/go-mysql-server/sql"
"github.com/gabereiser/go-mysql-server/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
}
var _ sql.FunctionExpression = (*ToBase64)(nil)
// NewToBase64 creates a new ToBase64 expression.
func NewToBase64(e sql.Expression) sql.Expression {
return &ToBase64{expression.UnaryExpression{Child: e}}
}
// FunctionName implements sql.FunctionExpression
func (t *ToBase64) FunctionName() string {
return "to_base64"
}
// Description implements sql.FunctionExpression
func (t *ToBase64) Description() string {
return "encodes the string str in base64 format."
}
// Eval implements the Expression interface.
func (t *ToBase64) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
val, err := t.Child.Eval(ctx, row)
if err != nil {
return nil, err
}
if val == nil {
return nil, nil
}
var strBytes []byte
if types.IsTextOnly(t.Child.Type()) {
val, err = t.Child.Type().Convert(val)
if err != nil {
return nil, sql.ErrInvalidType.New(reflect.TypeOf(val))
}
// For string types we need to re-encode the internal string so that we get the correct base64 output
encoder := t.Child.Type().(sql.StringType).Collation().CharacterSet().Encoder()
encodedBytes, ok := encoder.Encode(encodings.StringToBytes(val.(string)))
if !ok {
return nil, fmt.Errorf("unable to re-encode string for TO_BASE64 function")
}
strBytes = encodedBytes
} else {
val, err = types.LongText.Convert(val)
if err != nil {
return nil, sql.ErrInvalidType.New(reflect.TypeOf(val))
}
strBytes = []byte(val.(string))
}
encoded := base64.StdEncoding.EncodeToString(strBytes)
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 fmt.Stringer interface.
func (t *ToBase64) String() string {
return fmt.Sprintf("%s(%s)", t.FunctionName(), t.Child)
}
// IsNullable implements the Expression interface.
func (t *ToBase64) IsNullable() bool {
return t.Child.IsNullable()
}
// WithChildren implements the Expression interface.
func (t *ToBase64) WithChildren(children ...sql.Expression) (sql.Expression, error) {
if len(children) != 1 {
return nil, sql.ErrInvalidChildrenNumber.New(t, len(children), 1)
}
return NewToBase64(children[0]), nil
}
// Type implements the Expression interface.
func (t *ToBase64) Type() sql.Type {
return types.LongText
}
// 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
}
var _ sql.FunctionExpression = (*FromBase64)(nil)
// NewFromBase64 creates a new FromBase64 expression.
func NewFromBase64(e sql.Expression) sql.Expression {
return &FromBase64{expression.UnaryExpression{Child: e}}
}
// FunctionName implements sql.FunctionExpression
func (t *FromBase64) FunctionName() string {
return "from_base64"
}
// Description implements sql.FunctionExpression
func (t *FromBase64) Description() string {
return "decodes the base64-encoded string str."
}
// 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 = types.LongText.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 decoded, nil
}
// String implements the fmt.Stringer interface.
func (t *FromBase64) String() string {
return fmt.Sprintf("%s(%s)", t.FunctionName(), t.Child)
}
// IsNullable implements the Expression interface.
func (t *FromBase64) IsNullable() bool {
return t.Child.IsNullable()
}
// WithChildren implements the Expression interface.
func (t *FromBase64) WithChildren(children ...sql.Expression) (sql.Expression, error) {
if len(children) != 1 {
return nil, sql.ErrInvalidChildrenNumber.New(t, len(children), 1)
}
return NewFromBase64(children[0]), nil
}
// Type implements the Expression interface.
func (t *FromBase64) Type() sql.Type {
return types.LongBlob
}