1 files changed, 252 insertions, 0 deletions
diff --git a/src/database/sql/driver/types.go b/src/database/sql/driver/types.go
new file mode 100644
index 000000000..3305354df
--- /dev/null
+++ b/src/database/sql/driver/types.go
@@ -0,0 +1,252 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package driver
+
+import (
+	"fmt"
+	"reflect"
+	"strconv"
+	"time"
+)
+
+// ValueConverter is the interface providing the ConvertValue method.
+//
+// Various implementations of ValueConverter are provided by the
+// driver package to provide consistent implementations of conversions
+// between drivers.  The ValueConverters have several uses:
+//
+//  * converting from the Value types as provided by the sql package
+//    into a database table's specific column type and making sure it
+//    fits, such as making sure a particular int64 fits in a
+//    table's uint16 column.
+//
+//  * converting a value as given from the database into one of the
+//    driver Value types.
+//
+//  * by the sql package, for converting from a driver's Value type
+//    to a user's type in a scan.
+type ValueConverter interface {
+	// ConvertValue converts a value to a driver Value.
+	ConvertValue(v interface{}) (Value, error)
+}
+
+// Valuer is the interface providing the Value method.
+//
+// Types implementing Valuer interface are able to convert
+// themselves to a driver Value.
+type Valuer interface {
+	// Value returns a driver Value.
+	Value() (Value, error)
+}
+
+// Bool is a ValueConverter that converts input values to bools.
+//
+// The conversion rules are:
+//  - booleans are returned unchanged
+//  - for integer types,
+//       1 is true
+//       0 is false,
+//       other integers are an error
+//  - for strings and []byte, same rules as strconv.ParseBool
+//  - all other types are an error
+var Bool boolType
+
+type boolType struct{}
+
+var _ ValueConverter = boolType{}
+
+func (boolType) String() string { return "Bool" }
+
+func (boolType) ConvertValue(src interface{}) (Value, error) {
+	switch s := src.(type) {
+	case bool:
+		return s, nil
+	case string:
+		b, err := strconv.ParseBool(s)
+		if err != nil {
+			return nil, fmt.Errorf("sql/driver: couldn't convert %q into type bool", s)
+		}
+		return b, nil
+	case []byte:
+		b, err := strconv.ParseBool(string(s))
+		if err != nil {
+			return nil, fmt.Errorf("sql/driver: couldn't convert %q into type bool", s)
+		}
+		return b, nil
+	}
+
+	sv := reflect.ValueOf(src)
+	switch sv.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		iv := sv.Int()
+		if iv == 1 || iv == 0 {
+			return iv == 1, nil
+		}
+		return nil, fmt.Errorf("sql/driver: couldn't convert %d into type bool", iv)
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		uv := sv.Uint()
+		if uv == 1 || uv == 0 {
+			return uv == 1, nil
+		}
+		return nil, fmt.Errorf("sql/driver: couldn't convert %d into type bool", uv)
+	}
+
+	return nil, fmt.Errorf("sql/driver: couldn't convert %v (%T) into type bool", src, src)
+}
+
+// Int32 is a ValueConverter that converts input values to int64,
+// respecting the limits of an int32 value.
+var Int32 int32Type
+
+type int32Type struct{}
+
+var _ ValueConverter = int32Type{}
+
+func (int32Type) ConvertValue(v interface{}) (Value, error) {
+	rv := reflect.ValueOf(v)
+	switch rv.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		i64 := rv.Int()
+		if i64 > (1<<31)-1 || i64 < -(1<<31) {
+			return nil, fmt.Errorf("sql/driver: value %d overflows int32", v)
+		}
+		return i64, nil
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		u64 := rv.Uint()
+		if u64 > (1<<31)-1 {
+			return nil, fmt.Errorf("sql/driver: value %d overflows int32", v)
+		}
+		return int64(u64), nil
+	case reflect.String:
+		i, err := strconv.Atoi(rv.String())
+		if err != nil {
+			return nil, fmt.Errorf("sql/driver: value %q can't be converted to int32", v)
+		}
+		return int64(i), nil
+	}
+	return nil, fmt.Errorf("sql/driver: unsupported value %v (type %T) converting to int32", v, v)
+}
+
+// String is a ValueConverter that converts its input to a string.
+// If the value is already a string or []byte, it's unchanged.
+// If the value is of another type, conversion to string is done
+// with fmt.Sprintf("%v", v).
+var String stringType
+
+type stringType struct{}
+
+func (stringType) ConvertValue(v interface{}) (Value, error) {
+	switch v.(type) {
+	case string, []byte:
+		return v, nil
+	}
+	return fmt.Sprintf("%v", v), nil
+}
+
+// Null is a type that implements ValueConverter by allowing nil
+// values but otherwise delegating to another ValueConverter.
+type Null struct {
+	Converter ValueConverter
+}
+
+func (n Null) ConvertValue(v interface{}) (Value, error) {
+	if v == nil {
+		return nil, nil
+	}
+	return n.Converter.ConvertValue(v)
+}
+
+// NotNull is a type that implements ValueConverter by disallowing nil
+// values but otherwise delegating to another ValueConverter.
+type NotNull struct {
+	Converter ValueConverter
+}
+
+func (n NotNull) ConvertValue(v interface{}) (Value, error) {
+	if v == nil {
+		return nil, fmt.Errorf("nil value not allowed")
+	}
+	return n.Converter.ConvertValue(v)
+}
+
+// IsValue reports whether v is a valid Value parameter type.
+// Unlike IsScanValue, IsValue permits the string type.
+func IsValue(v interface{}) bool {
+	if IsScanValue(v) {
+		return true
+	}
+	if _, ok := v.(string); ok {
+		return true
+	}
+	return false
+}
+
+// IsScanValue reports whether v is a valid Value scan type.
+// Unlike IsValue, IsScanValue does not permit the string type.
+func IsScanValue(v interface{}) bool {
+	if v == nil {
+		return true
+	}
+	switch v.(type) {
+	case int64, float64, []byte, bool, time.Time:
+		return true
+	}
+	return false
+}
+
+// DefaultParameterConverter is the default implementation of
+// ValueConverter that's used when a Stmt doesn't implement
+// ColumnConverter.
+//
+// DefaultParameterConverter returns the given value directly if
+// IsValue(value).  Otherwise integer type are converted to
+// int64, floats to float64, and strings to []byte.  Other types are
+// an error.
+var DefaultParameterConverter defaultConverter
+
+type defaultConverter struct{}
+
+var _ ValueConverter = defaultConverter{}
+
+func (defaultConverter) ConvertValue(v interface{}) (Value, error) {
+	if IsValue(v) {
+		return v, nil
+	}
+
+	if svi, ok := v.(Valuer); ok {
+		sv, err := svi.Value()
+		if err != nil {
+			return nil, err
+		}
+		if !IsValue(sv) {
+			return nil, fmt.Errorf("non-Value type %T returned from Value", sv)
+		}
+		return sv, nil
+	}
+
+	rv := reflect.ValueOf(v)
+	switch rv.Kind() {
+	case reflect.Ptr:
+		// indirect pointers
+		if rv.IsNil() {
+			return nil, nil
+		} else {
+			return defaultConverter{}.ConvertValue(rv.Elem().Interface())
+		}
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return rv.Int(), nil
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32:
+		return int64(rv.Uint()), nil
+	case reflect.Uint64:
+		u64 := rv.Uint()
+		if u64 >= 1<<63 {
+			return nil, fmt.Errorf("uint64 values with high bit set are not supported")
+		}
+		return int64(u64), nil
+	case reflect.Float32, reflect.Float64:
+		return rv.Float(), nil
+	}
+	return nil, fmt.Errorf("unsupported type %T, a %s", v, rv.Kind())
+}