Struct NoteMetadata 

pub struct NoteMetadata { /* private fields */ }

The metadata associated with a note.

Note metadata consists of two parts:

• The header of the metadata, which consists of:
  • the sender of the note
  • the NoteType
  • the NoteTag
  • type information about the NoteAttachment.
• The optional NoteAttachment.

Word layout & validity

NoteMetadata can be encoded into two words, a header and an attachment word.

The header word has the following layout:

0th felt: [sender_id_suffix (56 bits) | 6 zero bits | note_type (2 bit)]
1st felt: [sender_id_prefix (64 bits)]
2nd felt: [32 zero bits | note_tag (32 bits)]
3rd felt: [30 zero bits | attachment_kind (2 bits) | attachment_scheme (32 bits)]

The felt validity of each part of the layout is guaranteed:

• 1st felt: The lower 8 bits of the account ID suffix are 0 by construction, so that they can be overwritten with other data. The suffix’ most significant bit must be zero such that the entire felt retains its validity even if all of its lower 8 bits are be set to 1. So the note type can be comfortably encoded.
• 2nd felt: Is equivalent to the prefix of the account ID so it inherits its validity.
• 3rd felt: The upper 32 bits are always zero.
• 4th felt: The upper 30 bits are always zero.

The value of the attachment word depends on the NoteAttachmentKind:

• NoteAttachmentKind::None: Empty word.
• NoteAttachmentKind::Word: The raw word itself.
• NoteAttachmentKind::Array: The commitment to the elements.

Implementations

impl NoteMetadata

pub fn new(sender: AccountId, note_type: NoteType, tag: NoteTag) -> Self

Returns a new NoteMetadata instantiated with the specified parameters.

pub fn sender(&self) -> AccountId

Returns the account which created the note.

pub fn note_type(&self) -> NoteType

Returns the note’s type.

pub fn tag(&self) -> NoteTag

Returns the tag associated with the note.

pub fn attachment(&self) -> &NoteAttachment

Returns the attachment of the note.

pub fn is_private(&self) -> bool

Returns true if the note is private.

pub fn to_header_word(&self) -> Word

Returns the Word that represents the header of a NoteMetadata.

See NoteMetadata docs for more details.

pub fn to_attachment_word(&self) -> Word

Returns the Word that represents the attachment of a NoteMetadata.

See NoteMetadata docs for more details.

pub fn to_commitment(&self) -> Word

Returns the commitment to the note metadata, which is defined as:

hash(NOTE_METADATA_HEADER || NOTE_METADATA_ATTACHMENT)

pub fn set_attachment(&mut self, attachment: NoteAttachment)

Overwrites the note’s attachment with the provided one.

pub fn with_attachment(self, attachment: NoteAttachment) -> Self

Overwrites the note’s attachment with the provided one.

Trait Implementations

impl Clone for NoteMetadata

fn clone(&self) -> NoteMetadata

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for NoteMetadata

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Deserializable for NoteMetadata

fn read_from<R: ByteReader>( source: &mut R, ) -> Result<Self, DeserializationError>

Reads a sequence of bytes from the provided source, attempts to deserialize these bytes into Self, and returns the result.

fn read_from_bytes(bytes: &[u8]) -> Result<Self, DeserializationError>

Attempts to deserialize the provided bytes into Self and returns the result.

impl PartialEq for NoteMetadata

fn eq(&self, other: &NoteMetadata) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serializable for NoteMetadata

fn write_into<W: ByteWriter>(&self, target: &mut W)

Serializes self into bytes and writes these bytes into the target.

fn to_bytes(&self) -> Vec<u8>

Serializes self into a vector of bytes.

fn get_size_hint(&self) -> usize

Returns an estimate of how many bytes are needed to represent self.

impl Eq for NoteMetadata

impl StructuralPartialEq for NoteMetadata