mirror of
https://github.com/go-gitea/gitea
synced 2024-12-24 12:14:29 +01:00
62 lines
3.6 KiB
Go
62 lines
3.6 KiB
Go
|
// Package bsoncodec provides a system for encoding values to BSON representations and decoding
|
||
|
|
// values from BSON representations. This package considers both binary BSON and ExtendedJSON as
|
||
|
|
// BSON representations. The types in this package enable a flexible system for handling this
|
||
|
|
// encoding and decoding.
|
||
|
|
//
|
||
|
|
// The codec system is composed of two parts:
|
||
|
|
//
|
||
|
|
// 1) ValueEncoders and ValueDecoders that handle encoding and decoding Go values to and from BSON
|
||
|
|
// representations.
|
||
|
|
//
|
||
|
|
// 2) A Registry that holds these ValueEncoders and ValueDecoders and provides methods for
|
||
|
|
// retrieving them.
|
||
|
|
//
|
||
|
|
// ValueEncoders and ValueDecoders
|
||
|
|
//
|
||
|
|
// The ValueEncoder interface is implemented by types that can encode a provided Go type to BSON.
|
||
|
|
// The value to encode is provided as a reflect.Value and a bsonrw.ValueWriter is used within the
|
||
|
|
// EncodeValue method to actually create the BSON representation. For convenience, ValueEncoderFunc
|
||
|
|
// is provided to allow use of a function with the correct signature as a ValueEncoder. An
|
||
|
|
// EncodeContext instance is provided to allow implementations to lookup further ValueEncoders and
|
||
|
|
// to provide configuration information.
|
||
|
|
//
|
||
|
|
// The ValueDecoder interface is the inverse of the ValueEncoder. Implementations should ensure that
|
||
|
|
// the value they receive is settable. Similar to ValueEncoderFunc, ValueDecoderFunc is provided to
|
||
|
|
// allow the use of a function with the correct signature as a ValueDecoder. A DecodeContext
|
||
|
|
// instance is provided and serves similar functionality to the EncodeContext.
|
||
|
|
//
|
||
|
|
// Registry and RegistryBuilder
|
||
|
|
//
|
||
|
|
// A Registry is an immutable store for ValueEncoders, ValueDecoders, and a type map. For looking up
|
||
|
|
// ValueEncoders and Decoders the Registry first attempts to find a ValueEncoder or ValueDecoder for
|
||
|
|
// the type provided; if one cannot be found it then checks to see if a registered ValueEncoder or
|
||
|
|
// ValueDecoder exists for an interface the type implements. Finally, the reflect.Kind of the type
|
||
|
|
// is used to lookup a default ValueEncoder or ValueDecoder for that kind. If no ValueEncoder or
|
||
|
|
// ValueDecoder can be found, an error is returned.
|
||
|
|
//
|
||
|
|
// The Registry also holds a type map. This allows users to retrieve the Go type that should be used
|
||
|
|
// when decoding a BSON value into an empty interface. This is primarily only used for the empty
|
||
|
|
// interface ValueDecoder.
|
||
|
|
//
|
||
|
|
// A RegistryBuilder is used to construct a Registry. The Register methods are used to associate
|
||
|
|
// either a reflect.Type or a reflect.Kind with a ValueEncoder or ValueDecoder. A RegistryBuilder
|
||
|
|
// returned from NewRegistryBuilder contains no registered ValueEncoders nor ValueDecoders and
|
||
|
|
// contains an empty type map.
|
||
|
|
//
|
||
|
|
// The RegisterTypeMapEntry method handles associating a BSON type with a Go type. For example, if
|
||
|
|
// you want to decode BSON int64 and int32 values into Go int instances, you would do the following:
|
||
|
|
//
|
||
|
|
// var regbuilder *RegistryBuilder = ... intType := reflect.TypeOf(int(0))
|
||
|
|
// regbuilder.RegisterTypeMapEntry(bsontype.Int64, intType).RegisterTypeMapEntry(bsontype.Int32,
|
||
|
|
// intType)
|
||
|
|
//
|
||
|
|
// DefaultValueEncoders and DefaultValueDecoders
|
||
|
|
//
|
||
|
|
// The DefaultValueEncoders and DefaultValueDecoders types provide a full set of ValueEncoders and
|
||
|
|
// ValueDecoders for handling a wide range of Go types, including all of the types within the
|
||
|
|
// primitive package. To make registering these codecs easier, a helper method on each type is
|
||
|
|
// provided. For the DefaultValueEncoders type the method is called RegisterDefaultEncoders and for
|
||
|
|
// the DefaultValueDecoders type the method is called RegisterDefaultDecoders, this method also
|
||
|
|
// handles registering type map entries for each BSON type.
|
||
|
|
package bsoncodec
|