forked from pingcap/tidb
/
value.go
58 lines (49 loc) · 1.44 KB
/
value.go
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// Copyright 2015 PingCAP, 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,
// See the License for the specific language governing permissions and
// limitations under the License.
package expressions
import (
"fmt"
"github.com/pingcap/tidb/context"
"github.com/pingcap/tidb/expression"
)
var (
_ expression.Expression = (*Value)(nil)
)
// Value is the expression holding simple value.
type Value struct {
// Val holds simple value.
Val interface{}
}
// Clone implements the Expression Clone interface.
func (l Value) Clone() (expression.Expression, error) {
return Value{Val: l.Val}, nil
}
// IsStatic implements the Expression IsStatic interface, always returns true.
func (l Value) IsStatic() bool {
return true
}
// String implements the Expression String interface.
func (l Value) String() string {
switch x := l.Val.(type) {
case nil:
return "NULL"
case string:
return fmt.Sprintf("%q", x)
default:
return fmt.Sprintf("%v", l.Val)
}
}
// Eval implements the Expression Eval interface.
func (l Value) Eval(ctx context.Context, args map[interface{}]interface{}) (interface{}, error) {
return l.Val, nil
}