github.com/dolthub/go-mysql-server@v0.18.0/enginetest/mysqlshim/iter.go (about)

     1  // Copyright 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 mysqlshim
    16  
    17  import (
    18  	dsql "database/sql"
    19  	"io"
    20  	"reflect"
    21  	"time"
    22  
    23  	"github.com/dolthub/go-mysql-server/sql"
    24  )
    25  
    26  // mysqlIter wraps an iterator returned by the MySQL connection.
    27  type mysqlIter struct {
    28  	rows  *dsql.Rows
    29  	types []reflect.Type
    30  }
    31  
    32  var _ sql.RowIter = mysqlIter{}
    33  
    34  // newMySQLIter returns a new mysqlIter.
    35  func newMySQLIter(rows *dsql.Rows) mysqlIter {
    36  	columnTypes, err := rows.ColumnTypes()
    37  	if err != nil {
    38  		panic(err)
    39  	}
    40  	types := make([]reflect.Type, len(columnTypes))
    41  	for i, columnType := range columnTypes {
    42  		scanType := columnType.ScanType()
    43  		switch scanType {
    44  		case reflect.TypeOf(dsql.RawBytes{}):
    45  			scanType = reflect.TypeOf("")
    46  		case reflect.TypeOf(dsql.NullBool{}):
    47  			scanType = reflect.TypeOf(true)
    48  		case reflect.TypeOf(dsql.NullByte{}):
    49  			scanType = reflect.TypeOf(byte(0))
    50  		case reflect.TypeOf(dsql.NullFloat64{}):
    51  			scanType = reflect.TypeOf(float64(0))
    52  		case reflect.TypeOf(dsql.NullInt16{}):
    53  			scanType = reflect.TypeOf(int16(0))
    54  		case reflect.TypeOf(dsql.NullInt32{}):
    55  			scanType = reflect.TypeOf(int32(0))
    56  		case reflect.TypeOf(dsql.NullInt64{}):
    57  			scanType = reflect.TypeOf(int64(0))
    58  		case reflect.TypeOf(dsql.NullString{}):
    59  			scanType = reflect.TypeOf("")
    60  		case reflect.TypeOf(dsql.NullTime{}):
    61  			scanType = reflect.TypeOf(time.Time{})
    62  		}
    63  		types[i] = scanType
    64  	}
    65  	return mysqlIter{rows, types}
    66  }
    67  
    68  // Next implements the interface sql.RowIter.
    69  func (m mysqlIter) Next(ctx *sql.Context) (sql.Row, error) {
    70  	if m.rows.Next() {
    71  		output := make(sql.Row, len(m.types))
    72  		for i, typ := range m.types {
    73  			output[i] = reflect.New(typ).Interface()
    74  		}
    75  		err := m.rows.Scan(output...)
    76  		if err != nil {
    77  			return nil, err
    78  		}
    79  		for i, val := range output {
    80  			reflectVal := reflect.ValueOf(val)
    81  			if reflectVal.IsNil() {
    82  				output[i] = nil
    83  			} else {
    84  				output[i] = reflectVal.Elem().Interface()
    85  				if byteSlice, ok := val.([]byte); ok {
    86  					output[i] = string(byteSlice)
    87  				}
    88  			}
    89  		}
    90  		return output, nil
    91  	}
    92  	return nil, io.EOF
    93  }
    94  
    95  // Close implements the interface sql.RowIter.
    96  func (m mysqlIter) Close(ctx *sql.Context) error {
    97  	return m.rows.Close()
    98  }