328 lines
7.8 KiB
Go
328 lines
7.8 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Type conversions for Scan.
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package sql
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import (
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"database/sql/driver"
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"errors"
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"fmt"
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"reflect"
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"strconv"
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"time"
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)
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var errNilPtr = errors.New("destination pointer is nil") // embedded in descriptive error
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// driverArgs converts arguments from callers of Stmt.Exec and
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// Stmt.Query into driver Values.
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//
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// The statement ds may be nil, if no statement is available.
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func driverArgs(ds *driverStmt, args []interface{}) ([]driver.Value, error) {
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dargs := make([]driver.Value, len(args))
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var si driver.Stmt
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if ds != nil {
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si = ds.si
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}
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cc, ok := si.(driver.ColumnConverter)
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// Normal path, for a driver.Stmt that is not a ColumnConverter.
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if !ok {
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for n, arg := range args {
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var err error
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dargs[n], err = driver.DefaultParameterConverter.ConvertValue(arg)
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if err != nil {
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return nil, fmt.Errorf("sql: converting Exec argument #%d's type: %v", n, err)
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}
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}
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return dargs, nil
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}
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// Let the Stmt convert its own arguments.
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for n, arg := range args {
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// First, see if the value itself knows how to convert
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// itself to a driver type. For example, a NullString
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// struct changing into a string or nil.
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if svi, ok := arg.(driver.Valuer); ok {
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sv, err := svi.Value()
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if err != nil {
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return nil, fmt.Errorf("sql: argument index %d from Value: %v", n, err)
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}
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if !driver.IsValue(sv) {
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return nil, fmt.Errorf("sql: argument index %d: non-subset type %T returned from Value", n, sv)
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}
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arg = sv
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}
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// Second, ask the column to sanity check itself. For
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// example, drivers might use this to make sure that
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// an int64 values being inserted into a 16-bit
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// integer field is in range (before getting
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// truncated), or that a nil can't go into a NOT NULL
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// column before going across the network to get the
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// same error.
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var err error
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ds.Lock()
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dargs[n], err = cc.ColumnConverter(n).ConvertValue(arg)
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ds.Unlock()
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if err != nil {
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return nil, fmt.Errorf("sql: converting argument #%d's type: %v", n, err)
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}
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if !driver.IsValue(dargs[n]) {
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return nil, fmt.Errorf("sql: driver ColumnConverter error converted %T to unsupported type %T",
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arg, dargs[n])
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}
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}
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return dargs, nil
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}
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// convertAssign copies to dest the value in src, converting it if possible.
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// An error is returned if the copy would result in loss of information.
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// dest should be a pointer type.
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func convertAssign(dest, src interface{}) error {
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// Common cases, without reflect.
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switch s := src.(type) {
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case string:
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switch d := dest.(type) {
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case *string:
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if d == nil {
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return errNilPtr
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}
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*d = s
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return nil
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case *[]byte:
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if d == nil {
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return errNilPtr
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}
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*d = []byte(s)
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return nil
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}
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case []byte:
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switch d := dest.(type) {
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case *string:
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if d == nil {
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return errNilPtr
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}
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*d = string(s)
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return nil
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case *interface{}:
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if d == nil {
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return errNilPtr
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}
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*d = cloneBytes(s)
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return nil
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case *[]byte:
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if d == nil {
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return errNilPtr
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}
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*d = cloneBytes(s)
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return nil
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case *RawBytes:
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if d == nil {
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return errNilPtr
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}
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*d = s
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return nil
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}
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case time.Time:
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switch d := dest.(type) {
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case *string:
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*d = s.Format(time.RFC3339Nano)
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return nil
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case *[]byte:
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if d == nil {
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return errNilPtr
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}
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*d = []byte(s.Format(time.RFC3339Nano))
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return nil
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}
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case nil:
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switch d := dest.(type) {
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case *interface{}:
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if d == nil {
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return errNilPtr
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}
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*d = nil
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return nil
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case *[]byte:
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if d == nil {
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return errNilPtr
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}
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*d = nil
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return nil
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case *RawBytes:
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if d == nil {
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return errNilPtr
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}
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*d = nil
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return nil
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}
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}
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var sv reflect.Value
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switch d := dest.(type) {
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case *string:
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sv = reflect.ValueOf(src)
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switch sv.Kind() {
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case reflect.Bool,
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reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
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reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
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reflect.Float32, reflect.Float64:
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*d = asString(src)
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return nil
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}
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case *[]byte:
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sv = reflect.ValueOf(src)
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if b, ok := asBytes(nil, sv); ok {
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*d = b
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return nil
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}
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case *RawBytes:
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sv = reflect.ValueOf(src)
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if b, ok := asBytes([]byte(*d)[:0], sv); ok {
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*d = RawBytes(b)
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return nil
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}
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case *bool:
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bv, err := driver.Bool.ConvertValue(src)
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if err == nil {
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*d = bv.(bool)
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}
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return err
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case *interface{}:
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*d = src
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return nil
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}
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if scanner, ok := dest.(Scanner); ok {
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return scanner.Scan(src)
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}
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dpv := reflect.ValueOf(dest)
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if dpv.Kind() != reflect.Ptr {
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return errors.New("destination not a pointer")
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}
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if dpv.IsNil() {
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return errNilPtr
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}
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if !sv.IsValid() {
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sv = reflect.ValueOf(src)
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}
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dv := reflect.Indirect(dpv)
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if sv.IsValid() && sv.Type().AssignableTo(dv.Type()) {
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dv.Set(sv)
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return nil
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}
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if dv.Kind() == sv.Kind() && sv.Type().ConvertibleTo(dv.Type()) {
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dv.Set(sv.Convert(dv.Type()))
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return nil
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}
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switch dv.Kind() {
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case reflect.Ptr:
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if src == nil {
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dv.Set(reflect.Zero(dv.Type()))
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return nil
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} else {
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dv.Set(reflect.New(dv.Type().Elem()))
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return convertAssign(dv.Interface(), src)
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}
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case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
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s := asString(src)
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i64, err := strconv.ParseInt(s, 10, dv.Type().Bits())
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if err != nil {
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err = strconvErr(err)
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return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
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}
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dv.SetInt(i64)
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return nil
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case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
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s := asString(src)
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u64, err := strconv.ParseUint(s, 10, dv.Type().Bits())
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if err != nil {
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err = strconvErr(err)
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return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
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}
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dv.SetUint(u64)
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return nil
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case reflect.Float32, reflect.Float64:
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s := asString(src)
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f64, err := strconv.ParseFloat(s, dv.Type().Bits())
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if err != nil {
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err = strconvErr(err)
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return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
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}
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dv.SetFloat(f64)
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return nil
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}
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return fmt.Errorf("unsupported Scan, storing driver.Value type %T into type %T", src, dest)
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}
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func strconvErr(err error) error {
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if ne, ok := err.(*strconv.NumError); ok {
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return ne.Err
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}
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return err
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}
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func cloneBytes(b []byte) []byte {
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if b == nil {
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return nil
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} else {
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c := make([]byte, len(b))
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copy(c, b)
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return c
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}
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}
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func asString(src interface{}) string {
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switch v := src.(type) {
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case string:
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return v
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case []byte:
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return string(v)
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}
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rv := reflect.ValueOf(src)
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switch rv.Kind() {
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case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
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return strconv.FormatInt(rv.Int(), 10)
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case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
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return strconv.FormatUint(rv.Uint(), 10)
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case reflect.Float64:
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return strconv.FormatFloat(rv.Float(), 'g', -1, 64)
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case reflect.Float32:
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return strconv.FormatFloat(rv.Float(), 'g', -1, 32)
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case reflect.Bool:
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return strconv.FormatBool(rv.Bool())
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}
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return fmt.Sprintf("%v", src)
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}
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func asBytes(buf []byte, rv reflect.Value) (b []byte, ok bool) {
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switch rv.Kind() {
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case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
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return strconv.AppendInt(buf, rv.Int(), 10), true
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case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
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return strconv.AppendUint(buf, rv.Uint(), 10), true
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case reflect.Float32:
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return strconv.AppendFloat(buf, rv.Float(), 'g', -1, 32), true
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case reflect.Float64:
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return strconv.AppendFloat(buf, rv.Float(), 'g', -1, 64), true
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case reflect.Bool:
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return strconv.AppendBool(buf, rv.Bool()), true
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case reflect.String:
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s := rv.String()
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return append(buf, s...), true
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}
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return
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}
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