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

     1  // Copyright 2020-2021 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  	"fmt"
    19  
    20  	"github.com/dolthub/go-mysql-server/sql"
    21  	"github.com/dolthub/go-mysql-server/sql/types"
    22  )
    23  
    24  // Between checks a value is between two given values.
    25  type Between struct {
    26  	Val   sql.Expression
    27  	Lower sql.Expression
    28  	Upper sql.Expression
    29  }
    30  
    31  var _ sql.Expression = (*Between)(nil)
    32  var _ sql.CollationCoercible = (*Between)(nil)
    33  
    34  // NewBetween creates a new Between expression.
    35  func NewBetween(val, lower, upper sql.Expression) *Between {
    36  	return &Between{val, lower, upper}
    37  }
    38  
    39  func (b *Between) String() string {
    40  	return fmt.Sprintf("(%s BETWEEN %s AND %s)", b.Val, b.Lower, b.Upper)
    41  }
    42  
    43  func (b *Between) DebugString() string {
    44  	return fmt.Sprintf("(%s BETWEEN %s AND %s)", sql.DebugString(b.Val), sql.DebugString(b.Lower), sql.DebugString(b.Upper))
    45  }
    46  
    47  // Children implements the Expression interface.
    48  func (b *Between) Children() []sql.Expression {
    49  	return []sql.Expression{b.Val, b.Lower, b.Upper}
    50  }
    51  
    52  // Type implements the Expression interface.
    53  func (*Between) Type() sql.Type { return types.Boolean }
    54  
    55  // CollationCoercibility implements the interface sql.CollationCoercible.
    56  func (b *Between) CollationCoercibility(ctx *sql.Context) (collation sql.CollationID, coercibility byte) {
    57  	return sql.GetCoercibility(ctx, b.Val)
    58  }
    59  
    60  // IsNullable implements the Expression interface.
    61  func (b *Between) IsNullable() bool {
    62  	return b.Val.IsNullable() || b.Lower.IsNullable() || b.Upper.IsNullable()
    63  }
    64  
    65  // Resolved implements the Expression interface.
    66  func (b *Between) Resolved() bool {
    67  	return b.Val.Resolved() && b.Lower.Resolved() && b.Upper.Resolved()
    68  }
    69  
    70  // Eval implements the Expression interface.
    71  func (b *Between) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
    72  	// TODO: Delete Between expression entirely?
    73  	// Reuse type conversion logic in comparison expressions by creating a logically equivalent expression
    74  	return NewAnd(NewLessThanOrEqual(b.Lower, b.Val), NewGreaterThanOrEqual(b.Upper, b.Val)).Eval(ctx, row)
    75  }
    76  
    77  // WithChildren implements the Expression interface.
    78  func (b *Between) WithChildren(children ...sql.Expression) (sql.Expression, error) {
    79  	if len(children) != 3 {
    80  		return nil, sql.ErrInvalidChildrenNumber.New(b, len(children), 3)
    81  	}
    82  	return NewBetween(children[0], children[1], children[2]), nil
    83  }