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Diffstat (limited to 'cli/vendor/github.com/ethereum/go-ethereum/rlp/doc.go')
| -rw-r--r-- | cli/vendor/github.com/ethereum/go-ethereum/rlp/doc.go | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/cli/vendor/github.com/ethereum/go-ethereum/rlp/doc.go b/cli/vendor/github.com/ethereum/go-ethereum/rlp/doc.go new file mode 100644 index 0000000..e4404c9 --- /dev/null +++ b/cli/vendor/github.com/ethereum/go-ethereum/rlp/doc.go @@ -0,0 +1,161 @@ +// Copyright 2014 The go-ethereum Authors +// This file is part of the go-ethereum library. +// +// The go-ethereum library is free software: you can redistribute it and/or modify +// it under the terms of the GNU Lesser General Public License as published by +// the Free Software Foundation, either version 3 of the License, or +// (at your option) any later version. +// +// The go-ethereum library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU Lesser General Public License for more details. +// +// You should have received a copy of the GNU Lesser General Public License +// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. + +/* +Package rlp implements the RLP serialization format. + +The purpose of RLP (Recursive Linear Prefix) is to encode arbitrarily nested arrays of +binary data, and RLP is the main encoding method used to serialize objects in Ethereum. +The only purpose of RLP is to encode structure; encoding specific atomic data types (eg. +strings, ints, floats) is left up to higher-order protocols. In Ethereum integers must be +represented in big endian binary form with no leading zeroes (thus making the integer +value zero equivalent to the empty string). + +RLP values are distinguished by a type tag. The type tag precedes the value in the input +stream and defines the size and kind of the bytes that follow. + + +Encoding Rules + +Package rlp uses reflection and encodes RLP based on the Go type of the value. + +If the type implements the Encoder interface, Encode calls EncodeRLP. It does not +call EncodeRLP on nil pointer values. + +To encode a pointer, the value being pointed to is encoded. A nil pointer to a struct +type, slice or array always encodes as an empty RLP list unless the slice or array has +element type byte. A nil pointer to any other value encodes as the empty string. + +Struct values are encoded as an RLP list of all their encoded public fields. Recursive +struct types are supported. + +To encode slices and arrays, the elements are encoded as an RLP list of the value's +elements. Note that arrays and slices with element type uint8 or byte are always encoded +as an RLP string. + +A Go string is encoded as an RLP string. + +An unsigned integer value is encoded as an RLP string. Zero always encodes as an empty RLP +string. big.Int values are treated as integers. Signed integers (int, int8, int16, ...) +are not supported and will return an error when encoding. + +Boolean values are encoded as the unsigned integers zero (false) and one (true). + +An interface value encodes as the value contained in the interface. + +Floating point numbers, maps, channels and functions are not supported. + + +Decoding Rules + +Decoding uses the following type-dependent rules: + +If the type implements the Decoder interface, DecodeRLP is called. + +To decode into a pointer, the value will be decoded as the element type of the pointer. If +the pointer is nil, a new value of the pointer's element type is allocated. If the pointer +is non-nil, the existing value will be reused. Note that package rlp never leaves a +pointer-type struct field as nil unless one of the "nil" struct tags is present. + +To decode into a struct, decoding expects the input to be an RLP list. The decoded +elements of the list are assigned to each public field in the order given by the struct's +definition. The input list must contain an element for each decoded field. Decoding +returns an error if there are too few or too many elements for the struct. + +To decode into a slice, the input must be a list and the resulting slice will contain the +input elements in order. For byte slices, the input must be an RLP string. Array types +decode similarly, with the additional restriction that the number of input elements (or +bytes) must match the array's defined length. + +To decode into a Go string, the input must be an RLP string. The input bytes are taken +as-is and will not necessarily be valid UTF-8. + +To decode into an unsigned integer type, the input must also be an RLP string. The bytes +are interpreted as a big endian representation of the integer. If the RLP string is larger +than the bit size of the type, decoding will return an error. Decode also supports +*big.Int. There is no size limit for big integers. + +To decode into a boolean, the input must contain an unsigned integer of value zero (false) +or one (true). + +To decode into an interface value, one of these types is stored in the value: + + []interface{}, for RLP lists + []byte, for RLP strings + +Non-empty interface types are not supported when decoding. +Signed integers, floating point numbers, maps, channels and functions cannot be decoded into. + + +Struct Tags + +As with other encoding packages, the "-" tag ignores fields. + + type StructWithIgnoredField struct{ + Ignored uint `rlp:"-"` + Field uint + } + +Go struct values encode/decode as RLP lists. There are two ways of influencing the mapping +of fields to list elements. The "tail" tag, which may only be used on the last exported +struct field, allows slurping up any excess list elements into a slice. + + type StructWithTail struct{ + Field uint + Tail []string `rlp:"tail"` + } + +The "optional" tag says that the field may be omitted if it is zero-valued. If this tag is +used on a struct field, all subsequent public fields must also be declared optional. + +When encoding a struct with optional fields, the output RLP list contains all values up to +the last non-zero optional field. + +When decoding into a struct, optional fields may be omitted from the end of the input +list. For the example below, this means input lists of one, two, or three elements are +accepted. + + type StructWithOptionalFields struct{ + Required uint + Optional1 uint `rlp:"optional"` + Optional2 uint `rlp:"optional"` + } + +The "nil", "nilList" and "nilString" tags apply to pointer-typed fields only, and change +the decoding rules for the field type. For regular pointer fields without the "nil" tag, +input values must always match the required input length exactly and the decoder does not +produce nil values. When the "nil" tag is set, input values of size zero decode as a nil +pointer. This is especially useful for recursive types. + + type StructWithNilField struct { + Field *[3]byte `rlp:"nil"` + } + +In the example above, Field allows two possible input sizes. For input 0xC180 (a list +containing an empty string) Field is set to nil after decoding. For input 0xC483000000 (a +list containing a 3-byte string), Field is set to a non-nil array pointer. + +RLP supports two kinds of empty values: empty lists and empty strings. When using the +"nil" tag, the kind of empty value allowed for a type is chosen automatically. A field +whose Go type is a pointer to an unsigned integer, string, boolean or byte array/slice +expects an empty RLP string. Any other pointer field type encodes/decodes as an empty RLP +list. + +The choice of null value can be made explicit with the "nilList" and "nilString" struct +tags. Using these tags encodes/decodes a Go nil pointer value as the empty RLP value kind +defined by the tag. +*/ +package rlp |
