/
convert.go
83 lines (74 loc) · 2.2 KB
/
convert.go
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//
//
// 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,
// See the License for the specific language governing permissions and
// limitations under the License.
package expressions
import (
"fmt"
"strings"
iconv "github.com/djimenez/iconv-go"
"github.com/juju/errors"
"github.com/ngaut/log"
"github.com/Dong-Chan/alloydb/context"
"github.com/Dong-Chan/alloydb/expression"
)
// FunctionConvert provides a way to convert data between different character sets.
// See: https://dev.mysql.com/doc/refman/5.7/en/cast-functions.html#function_convert
type FunctionConvert struct {
Expr expression.Expression
Charset string
}
// Clone implements the Expression Clone interface.
func (f *FunctionConvert) Clone() (expression.Expression, error) {
expr, err := f.Expr.Clone()
if err != nil {
return nil, err
}
nf := &FunctionConvert{
Expr: expr,
Charset: f.Charset,
}
return nf, nil
}
// IsStatic implements the Expression IsStatic interface.
func (f *FunctionConvert) IsStatic() bool {
return f.Expr.IsStatic()
}
// String implements the Expression String interface.
func (f *FunctionConvert) String() string {
return fmt.Sprintf("CONVERT(%s AS %s)", f.Expr.String(), f.Charset)
}
// Eval implements the Expression Eval interface.
func (f *FunctionConvert) Eval(ctx context.Context, args map[interface{}]interface{}) (interface{}, error) {
value, err := f.Expr.Eval(ctx, args)
if err != nil {
return nil, err
}
// Casting nil to any type returns nil
if value == nil {
return nil, nil
}
str, ok := value.(string)
if !ok {
return nil, nil
}
if strings.ToLower(f.Charset) == "ascii" {
return value, nil
} else if strings.ToLower(f.Charset) == "utf8mb4" {
return value, nil
}
target, err := iconv.ConvertString(str, "utf-8", f.Charset)
if err != nil {
log.Errorf("Convert %s to %s with error: %v", str, f.Charset, err)
return nil, errors.Trace(err)
}
return target, nil
}