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use std::io::{Read, Write};
use crate::{
common::traits::private::Sealed,
v0::{
config::Config,
raw::VariableLengthEnum,
tokens::{error::MetadataTokenError, MetadataToken},
traits::{ReadFrom, WriteTo},
},
};
use super::{
error::{MetadataRecordReadError, MetadataRecordWriteError},
traits::MetadataRecordObj,
NameMetadataRecordObj, ReservedMetadataRecord, UnknownMetadataRecordObj,
VariableNameMetadataRecordObj,
};
/// A [metadata record](https://github.com/jiricekcz/fef-specification/blob/main/metadata/Metadata.md#metadata-keys).
///
/// All library-defined metadata records are represented by this enum. There are also catch all variants for unknown metadata records and reserved metadata records.
#[derive(Debug, Clone, PartialEq)]
#[non_exhaustive]
pub enum MetadataRecord {
Name(NameMetadataRecordObj),
VariableName(VariableNameMetadataRecordObj),
Reserved(ReservedMetadataRecord),
Unknown(UnknownMetadataRecordObj),
}
impl Sealed for MetadataRecord {}
impl<R: Read + ?Sized> ReadFrom<R> for MetadataRecord {
type ReadError = MetadataRecordReadError;
/// Reads a metadata record from a reader.
///
/// It reads the metadata token and then reads the metadata record based on the token.
///
/// # Example
///
/// Reading a known and unknown metadata record:
/// ```rust
/// # use fef::v0::metadata::MetadataRecord;
/// # use fef::v0::metadata::NameMetadataRecordObj;
/// # use fef::v0::config::DEFAULT_CONFIG;
/// # use fef::v0::raw::VariableLengthEnum;
/// # use fef::v0::metadata::UnknownMetadataRecordObj;
/// # use fef::v0::metadata::ReservedMetadataRecord;
/// # use fef::v0::traits::ReadFrom;
/// # fn main() -> Result<(), Box<dyn std::error::Error>> {
/// let data = vec![
/// // Known metadata record - Name
/// 0x01, // Metadata token
/// 0x08, // Length of the name record
/// 0x07, // Length of the name string
/// b'F', b'o', b'r', b'm', b'u', b'l', b'a', // Name string
/// // Unknown reserved metadata record
/// 0x1F, // Metadata token
/// 0x08, // Length of the record
/// 0x57, 0x6F, 0x72, 0x6C, 0x64, 0x21, 0x21, 0x21, // Record data
/// // Unknown not reserved metadata record
/// 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, // Metadata token
/// 0x02, // Length of the record
/// 0x57, 0x6F // Record data
/// ];
/// let mut reader = &mut data.as_slice();
///
/// let record1 = MetadataRecord::read_from(&mut reader, &DEFAULT_CONFIG)?;
/// assert_eq!(record1, MetadataRecord::Name(NameMetadataRecordObj::new("Formula".to_string())));
///
/// let record2 = MetadataRecord::read_from(&mut reader, &DEFAULT_CONFIG)?;
/// assert!(matches!(record2, MetadataRecord::Reserved(ReservedMetadataRecord::Official(_))));
///
/// let record3 = MetadataRecord::read_from(&mut reader, &DEFAULT_CONFIG)?;
/// assert!(matches!(record3, MetadataRecord::Unknown(_)));
/// # Ok(())
/// # }
/// ```
fn read_from<C: ?Sized + Config>(
reader: &mut R,
configuration: &C,
) -> Result<Self, Self::ReadError> {
let identifier = VariableLengthEnum::read_from(reader, configuration)?;
let token = match MetadataToken::try_from(identifier) {
Ok(token) => token,
Err(error) => match error {
MetadataTokenError::IdentifierNotRecognized { identifier } => {
let record =
UnknownMetadataRecordObj::read_from(reader, configuration, identifier)?;
return Ok(MetadataRecord::Unknown(record));
}
_ => return Err(error.into()),
},
};
match token {
MetadataToken::Name => {
let record = NameMetadataRecordObj::read_from(reader, configuration)?;
Ok(MetadataRecord::Name(record))
}
MetadataToken::VariableName => {
let record = VariableNameMetadataRecordObj::read_from(reader, configuration)?;
Ok(MetadataRecord::VariableName(record))
}
MetadataToken::ReservedOfficial(_) => {
let record: ReservedMetadataRecord =
ReservedMetadataRecord::read_from(reader, configuration, token)?;
Ok(MetadataRecord::Reserved(record))
}
MetadataToken::ReservedThirdParty(_) => {
let record = ReservedMetadataRecord::read_from(reader, configuration, token)?;
Ok(MetadataRecord::Reserved(record))
}
MetadataToken::ReservedCustom(_) => {
let record = ReservedMetadataRecord::read_from(reader, configuration, token)?;
Ok(MetadataRecord::Reserved(record))
}
}
}
}
macro_rules! write_metadata_record {
($record:ident, $writer:ident, $configuration:ident) => {{
let identifier: VariableLengthEnum = match $record.token() {
Err(err) => match err {
MetadataTokenError::IdentifierTooLarge { identifier } => identifier,
MetadataTokenError::IdentifierNotRecognized { identifier } => identifier,
},
Ok(token) => <MetadataToken as Into<usize>>::into(token).into(),
};
identifier.write_to($writer, $configuration)?;
$record.write_to($writer, $configuration)?;
}};
}
impl<W: ?Sized + Write> WriteTo<W> for MetadataRecord {
type WriteError = MetadataRecordWriteError;
/// Writes the metadata record to a writer.
///
/// # Example
///
/// ```rust
/// # use fef::v0::metadata::MetadataRecord;
/// # use fef::v0::metadata::NameMetadataRecordObj;
/// # use fef::v0::metadata::VariableNameMetadataRecordObj;
/// # use fef::v0::metadata::ReservedMetadataRecord;
/// # use fef::v0::metadata::CustomReservedMetadataRecordObj;
/// # use fef::v0::config::DEFAULT_CONFIG;
/// # use fef::v0::traits::WriteTo;
/// # fn main() -> Result<(), Box<dyn std::error::Error>> {
/// let record1 = MetadataRecord::Name(NameMetadataRecordObj::new("Formula".to_string()));
/// let record2 = MetadataRecord::VariableName(VariableNameMetadataRecordObj::new("x".to_string(), 1.into()));
///
/// let record3_inner = CustomReservedMetadataRecordObj::new(0x100100, vec![0x12, 0x34])?;
/// let record3 = MetadataRecord::Reserved(ReservedMetadataRecord::Custom(record3_inner));
///
/// let mut writer: Vec<u8> = Vec::new();
///
/// record1.write_to(&mut writer, &DEFAULT_CONFIG)?;
/// record2.write_to(&mut writer, &DEFAULT_CONFIG)?;
/// record3.write_to(&mut writer, &DEFAULT_CONFIG)?;
///
/// assert_eq!(writer, vec![
/// // Record 1
/// 0x01, // Metadata token
/// 0x08, // Length of the name record
/// 0x07, // Length of the name string
/// b'F', b'o', b'r', b'm', b'u', b'l', b'a', // Name string
/// // Record 2
/// 0x02, // Metadata token
/// 0x03, // Length of the record
/// 0x01, // Variable identifier
/// 0x01, // Length of the string
/// b'x', // Name
/// // Record 3
/// 0xC0, 0x82, 0x00, // Metadata token
/// 0x02, // Length of the record
/// 0x12, 0x34, // Record data
/// ]);
/// # Ok(())
/// # }
/// ```
fn write_to<C: ?Sized + Config>(
&self,
writer: &mut W,
configuration: &C,
) -> Result<(), Self::WriteError> {
match self {
MetadataRecord::Name(record) => write_metadata_record!(record, writer, configuration),
MetadataRecord::VariableName(record) => {
write_metadata_record!(record, writer, configuration)
}
MetadataRecord::Reserved(record) => {
write_metadata_record!(record, writer, configuration)
}
MetadataRecord::Unknown(record) => {
write_metadata_record!(record, writer, configuration)
}
};
Ok(())
}
}
impl MetadataRecord {
pub(crate) fn byte_length(&self) -> usize {
let inner_length = match self {
MetadataRecord::Name(record) => record.byte_length(),
MetadataRecord::VariableName(record) => record.byte_length(),
MetadataRecord::Reserved(record) => record.byte_length(),
MetadataRecord::Unknown(record) => record.byte_length(),
};
let identifier: VariableLengthEnum = match self {
MetadataRecord::Name(_) => {
VariableLengthEnum::from(Into::<usize>::into(MetadataToken::Name))
}
MetadataRecord::VariableName(_) => {
VariableLengthEnum::from(Into::<usize>::into(MetadataToken::VariableName))
}
MetadataRecord::Reserved(record) => {
VariableLengthEnum::from(record.identifier() as usize)
}
MetadataRecord::Unknown(record) => record.identifier.to_owned(),
};
identifier.min_byte_length()
+ inner_length
+ VariableLengthEnum::min_byte_length_of_usize(inner_length)
}
}