github.com/dolthub/go-mysql-server@v0.18.0/sql/expression/bindvar.go (about)

     1  // Copyright 2020-2022 DoltHub, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package expression
    16  
    17  import (
    18  	"github.com/dolthub/go-mysql-server/sql"
    19  	"github.com/dolthub/go-mysql-server/sql/types"
    20  )
    21  
    22  type BindVar struct {
    23  	Name string
    24  	Typ  sql.Type
    25  }
    26  
    27  var _ sql.Expression = (*BindVar)(nil)
    28  var _ sql.CollationCoercible = (*BindVar)(nil)
    29  
    30  func NewBindVar(name string) *BindVar {
    31  	return &BindVar{Name: name, Typ: types.NewDeferredType(name)}
    32  }
    33  
    34  func (bv *BindVar) Resolved() bool {
    35  	return true
    36  }
    37  
    38  func (bv *BindVar) String() string {
    39  	return "BindVar(" + bv.Name + ")"
    40  }
    41  
    42  func (bv *BindVar) Type() sql.Type {
    43  	return bv.Typ
    44  }
    45  
    46  // CollationCoercibility implements the interface sql.CollationCoercible.
    47  func (bv *BindVar) CollationCoercibility(ctx *sql.Context) (collation sql.CollationID, coercibility byte) {
    48  	return bv.Typ.CollationCoercibility(ctx)
    49  }
    50  
    51  func (bv *BindVar) IsNullable() bool {
    52  	return true
    53  }
    54  
    55  func (bv *BindVar) Eval(*sql.Context, sql.Row) (interface{}, error) {
    56  	return nil, sql.ErrUnboundPreparedStatementVariable.New(bv.Name)
    57  }
    58  
    59  func (bv *BindVar) Children() []sql.Expression {
    60  	return nil
    61  }
    62  
    63  func (bv *BindVar) WithChildren(children ...sql.Expression) (sql.Expression, error) {
    64  	if len(children) != 0 {
    65  		return nil, sql.ErrInvalidChildrenNumber.New(bv, len(children), 0)
    66  
    67  	}
    68  	return bv, nil
    69  }
    70  
    71  func IsBindVar(e sql.Expression) bool {
    72  	_, ok := e.(*BindVar)
    73  	return ok
    74  }