mirror of
https://github.com/autc04/Retro68.git
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283 lines
8.0 KiB
Go
283 lines
8.0 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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package driver
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import (
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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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// ValueConverter is the interface providing the ConvertValue method.
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//
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// Various implementations of ValueConverter are provided by the
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// driver package to provide consistent implementations of conversions
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// between drivers. The ValueConverters have several uses:
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//
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// * converting from the Value types as provided by the sql package
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// into a database table's specific column type and making sure it
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// fits, such as making sure a particular int64 fits in a
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// table's uint16 column.
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//
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// * converting a value as given from the database into one of the
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// driver Value types.
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//
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// * by the sql package, for converting from a driver's Value type
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// to a user's type in a scan.
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type ValueConverter interface {
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// ConvertValue converts a value to a driver Value.
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ConvertValue(v interface{}) (Value, error)
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}
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// Valuer is the interface providing the Value method.
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//
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// Types implementing Valuer interface are able to convert
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// themselves to a driver Value.
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type Valuer interface {
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// Value returns a driver Value.
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Value() (Value, error)
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}
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// Bool is a ValueConverter that converts input values to bools.
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//
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// The conversion rules are:
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// - booleans are returned unchanged
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// - for integer types,
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// 1 is true
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// 0 is false,
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// other integers are an error
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// - for strings and []byte, same rules as strconv.ParseBool
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// - all other types are an error
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var Bool boolType
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type boolType struct{}
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var _ ValueConverter = boolType{}
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func (boolType) String() string { return "Bool" }
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func (boolType) ConvertValue(src interface{}) (Value, error) {
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switch s := src.(type) {
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case bool:
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return s, nil
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case string:
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b, err := strconv.ParseBool(s)
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if err != nil {
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return nil, fmt.Errorf("sql/driver: couldn't convert %q into type bool", s)
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}
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return b, nil
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case []byte:
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b, err := strconv.ParseBool(string(s))
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if err != nil {
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return nil, fmt.Errorf("sql/driver: couldn't convert %q into type bool", s)
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}
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return b, nil
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}
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sv := reflect.ValueOf(src)
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switch sv.Kind() {
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case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
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iv := sv.Int()
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if iv == 1 || iv == 0 {
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return iv == 1, nil
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}
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return nil, fmt.Errorf("sql/driver: couldn't convert %d into type bool", iv)
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case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
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uv := sv.Uint()
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if uv == 1 || uv == 0 {
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return uv == 1, nil
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}
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return nil, fmt.Errorf("sql/driver: couldn't convert %d into type bool", uv)
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}
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return nil, fmt.Errorf("sql/driver: couldn't convert %v (%T) into type bool", src, src)
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}
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// Int32 is a ValueConverter that converts input values to int64,
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// respecting the limits of an int32 value.
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var Int32 int32Type
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type int32Type struct{}
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var _ ValueConverter = int32Type{}
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func (int32Type) ConvertValue(v interface{}) (Value, error) {
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rv := reflect.ValueOf(v)
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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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i64 := rv.Int()
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if i64 > (1<<31)-1 || i64 < -(1<<31) {
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return nil, fmt.Errorf("sql/driver: value %d overflows int32", v)
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}
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return i64, nil
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case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
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u64 := rv.Uint()
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if u64 > (1<<31)-1 {
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return nil, fmt.Errorf("sql/driver: value %d overflows int32", v)
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}
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return int64(u64), nil
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case reflect.String:
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i, err := strconv.Atoi(rv.String())
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if err != nil {
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return nil, fmt.Errorf("sql/driver: value %q can't be converted to int32", v)
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}
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return int64(i), nil
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}
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return nil, fmt.Errorf("sql/driver: unsupported value %v (type %T) converting to int32", v, v)
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}
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// String is a ValueConverter that converts its input to a string.
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// If the value is already a string or []byte, it's unchanged.
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// If the value is of another type, conversion to string is done
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// with fmt.Sprintf("%v", v).
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var String stringType
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type stringType struct{}
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func (stringType) ConvertValue(v interface{}) (Value, error) {
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switch v.(type) {
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case string, []byte:
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return v, nil
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}
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return fmt.Sprintf("%v", v), nil
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}
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// Null is a type that implements ValueConverter by allowing nil
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// values but otherwise delegating to another ValueConverter.
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type Null struct {
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Converter ValueConverter
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}
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func (n Null) ConvertValue(v interface{}) (Value, error) {
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if v == nil {
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return nil, nil
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}
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return n.Converter.ConvertValue(v)
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}
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// NotNull is a type that implements ValueConverter by disallowing nil
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// values but otherwise delegating to another ValueConverter.
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type NotNull struct {
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Converter ValueConverter
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}
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func (n NotNull) ConvertValue(v interface{}) (Value, error) {
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if v == nil {
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return nil, fmt.Errorf("nil value not allowed")
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}
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return n.Converter.ConvertValue(v)
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}
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// IsValue reports whether v is a valid Value parameter type.
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func IsValue(v interface{}) bool {
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if v == nil {
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return true
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}
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switch v.(type) {
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case []byte, bool, float64, int64, string, time.Time:
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return true
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}
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return false
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}
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// IsScanValue is equivalent to IsValue.
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// It exists for compatibility.
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func IsScanValue(v interface{}) bool {
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return IsValue(v)
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}
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// DefaultParameterConverter is the default implementation of
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// ValueConverter that's used when a Stmt doesn't implement
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// ColumnConverter.
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//
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// DefaultParameterConverter returns its argument directly if
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// IsValue(arg). Otherwise, if the argument implements Valuer, its
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// Value method is used to return a Value. As a fallback, the provided
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// argument's underlying type is used to convert it to a Value:
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// underlying integer types are converted to int64, floats to float64,
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// bool, string, and []byte to themselves. If the argument is a nil
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// pointer, ConvertValue returns a nil Value. If the argument is a
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// non-nil pointer, it is dereferenced and ConvertValue is called
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// recursively. Other types are an error.
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var DefaultParameterConverter defaultConverter
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type defaultConverter struct{}
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var _ ValueConverter = defaultConverter{}
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var valuerReflectType = reflect.TypeOf((*Valuer)(nil)).Elem()
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// callValuerValue returns vr.Value(), with one exception:
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// If vr.Value is an auto-generated method on a pointer type and the
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// pointer is nil, it would panic at runtime in the panicwrap
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// method. Treat it like nil instead.
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// Issue 8415.
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//
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// This is so people can implement driver.Value on value types and
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// still use nil pointers to those types to mean nil/NULL, just like
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// string/*string.
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//
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// This function is mirrored in the database/sql package.
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func callValuerValue(vr Valuer) (v Value, err error) {
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if rv := reflect.ValueOf(vr); rv.Kind() == reflect.Ptr &&
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rv.IsNil() &&
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rv.Type().Elem().Implements(valuerReflectType) {
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return nil, nil
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}
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return vr.Value()
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}
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func (defaultConverter) ConvertValue(v interface{}) (Value, error) {
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if IsValue(v) {
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return v, nil
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}
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if vr, ok := v.(Valuer); ok {
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sv, err := callValuerValue(vr)
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if err != nil {
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return nil, err
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}
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if !IsValue(sv) {
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return nil, fmt.Errorf("non-Value type %T returned from Value", sv)
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}
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return sv, nil
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}
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rv := reflect.ValueOf(v)
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switch rv.Kind() {
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case reflect.Ptr:
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// indirect pointers
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if rv.IsNil() {
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return nil, nil
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} else {
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return defaultConverter{}.ConvertValue(rv.Elem().Interface())
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}
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case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
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return rv.Int(), nil
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case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32:
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return int64(rv.Uint()), nil
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case reflect.Uint64:
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u64 := rv.Uint()
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if u64 >= 1<<63 {
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return nil, fmt.Errorf("uint64 values with high bit set are not supported")
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}
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return int64(u64), nil
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case reflect.Float32, reflect.Float64:
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return rv.Float(), nil
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case reflect.Bool:
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return rv.Bool(), nil
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case reflect.Slice:
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ek := rv.Type().Elem().Kind()
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if ek == reflect.Uint8 {
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return rv.Bytes(), nil
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}
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return nil, fmt.Errorf("unsupported type %T, a slice of %s", v, ek)
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case reflect.String:
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return rv.String(), nil
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}
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return nil, fmt.Errorf("unsupported type %T, a %s", v, rv.Kind())
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}
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