github.com/dolthub/dolt/go@v0.40.5-0.20240520175717-68db7794bea6/libraries/doltcore/sqle/dfunctions/version.go (about)

     1  // Copyright 2020 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 dfunctions
    16  
    17  import (
    18  	"github.com/dolthub/go-mysql-server/sql"
    19  	"github.com/dolthub/go-mysql-server/sql/types"
    20  )
    21  
    22  const VersionFuncName = "dolt_version"
    23  
    24  var VersionString = "SET_BY_INIT"
    25  
    26  type Version struct{}
    27  
    28  // NewVersion creates a new Version expression.
    29  func NewVersion() sql.Expression {
    30  	return &Version{}
    31  }
    32  
    33  // Children implements the Expression interface.
    34  func (*Version) Children() []sql.Expression {
    35  	return nil
    36  }
    37  
    38  // Eval implements the Expression interface.
    39  func (*Version) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
    40  	return VersionString, nil
    41  }
    42  
    43  // IsNullable implements the Expression interface.
    44  func (*Version) IsNullable() bool {
    45  	return false
    46  }
    47  
    48  // Resolved implements the Expression interface.
    49  func (*Version) Resolved() bool {
    50  	return true
    51  }
    52  
    53  // String implements the Stringer interface.
    54  func (*Version) String() string {
    55  	return "DOLT_VERSION"
    56  }
    57  
    58  // Type implements the Expression interface.
    59  func (*Version) Type() sql.Type {
    60  	return types.Text
    61  }
    62  
    63  // WithChildren implements the Expression interface.
    64  func (v *Version) WithChildren(children ...sql.Expression) (sql.Expression, error) {
    65  	if len(children) != 0 {
    66  		return nil, sql.ErrInvalidChildrenNumber.New(v, len(children), 0)
    67  	}
    68  	return NewVersion(), nil
    69  }