Beginnings of a Rust Preserves decoder
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02e0eae396
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1be54a2b8f
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@ -172,3 +172,21 @@ mod value_tests {
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assert_eq!(r, s);
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}
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}
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#[cfg(test)]
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mod decoder_tests {
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use crate::value::codec::Decoder;
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#[test] fn read_123() {
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let mut d = Decoder::new(&b"abc"[..], None);
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assert_eq!(d.read().ok(), Some(97));
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assert_eq!(d.read().ok(), Some(98));
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assert_eq!(d.read().ok(), Some(99));
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assert!(d.read().err().unwrap().is_eof())
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}
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#[test] fn read_samples() {
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let mut d = Decoder::new(std::fs::File::open("../../tests/samples.bin").unwrap(), None);
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println!("{:?}", d.next().ok().unwrap());
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}
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}
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@ -0,0 +1,267 @@
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use std::io::Read;
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use std::convert::TryInto;
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use crate::value::value::{Value, AValue, Set, Dictionary};
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use num::bigint::BigInt;
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pub type Result<V> = std::result::Result<V, Error>;
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#[derive(Debug)]
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pub enum Error {
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Io(std::io::Error),
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Syntax(&'static str),
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Eof,
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}
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impl From<std::io::Error> for Error {
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fn from(v: std::io::Error) -> Self {
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Error::Io(v)
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}
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}
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impl From<std::str::Utf8Error> for Error {
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fn from(_v: std::str::Utf8Error) -> Self {
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Error::Syntax("Invalid UTF-8")
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}
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}
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impl Error {
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pub fn is_io(&self) -> bool { if let Error::Io(_) = *self { true } else { false } }
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pub fn is_syntax(&self) -> bool { if let Error::Syntax(_) = *self { true } else { false } }
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pub fn is_eof(&self) -> bool { if let Error::Eof = *self { true } else { false } }
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}
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pub type PlaceholderMap = std::collections::BTreeMap<usize, Value>;
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pub struct Decoder<R: Read> {
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read: R,
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index: usize,
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buf: Box<Option<Option<u8>>>,
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placeholders: PlaceholderMap,
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}
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impl<R: Read> Decoder<R> {
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pub fn new(read: R, placeholders: Option<PlaceholderMap>) -> Self {
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Decoder{
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read,
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index: 0,
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buf: Box::new(None),
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placeholders: placeholders.unwrap_or(PlaceholderMap::new())
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}
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}
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fn prime_if_possible(&mut self) -> Result<()> {
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match *self.buf {
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None => {
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let bs = &mut [0];
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*self.buf = Some(match self.read.read(bs)? {
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0 => None,
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1 => {
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self.index = self.index + 1;
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Some(bs[0])
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},
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_ => panic!("buffer overrun")
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})
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}
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Some(_) => ()
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}
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Ok(())
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}
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pub fn skip(&mut self) -> Result<()> {
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self.prime_if_possible()?;
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*self.buf = None;
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Ok(())
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}
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pub fn peek(&mut self) -> Result<u8> {
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self.prime_if_possible()?;
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match *self.buf {
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Some(Some(v)) => Ok(v),
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Some(None) => Err(Error::Eof),
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None => panic!()
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}
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}
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pub fn read(&mut self) -> Result<u8> {
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let v = self.peek()?;
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self.skip()?;
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Ok(v)
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}
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pub fn readbytes(&mut self, n: usize) -> Result<Vec<u8>> {
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if (*self.buf).is_some() {
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panic!();
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}
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let mut bs = vec![0; n];
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match self.read.read_exact(&mut bs) {
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Ok(()) => Ok(bs),
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Err(e) =>
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if e.kind() == std::io::ErrorKind::UnexpectedEof {
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Err(Error::Eof)
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} else {
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Err(Error::from(e))
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}
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}
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}
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pub fn readvalues(&mut self, mut count: usize) -> Result<Vec<AValue>> {
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let mut pieces: Vec<AValue> = Vec::new();
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while count > 0 {
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pieces.push(self.next()?);
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count = count - 1;
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}
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Ok(pieces)
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}
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pub fn nextop(&mut self) -> Result<(u8, u8, u8)> {
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let b = self.read()?;
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let major = b >> 6;
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let minor = (b >> 4) & 3;
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let arg = b & 15;
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Ok((major, minor, arg))
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}
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pub fn varint(&mut self) -> Result<usize> {
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let v = self.read()?;
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if v < 128 {
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Ok(usize::from(v))
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} else {
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Ok(self.varint()? * 128 + usize::from(v - 128))
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}
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}
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pub fn wirelength(&mut self, arg: u8) -> Result<usize> {
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if arg < 15 {
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Ok(usize::from(arg))
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} else {
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self.varint()
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}
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}
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pub fn peekend(&mut self) -> Result<bool> {
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if self.peek()? == 4 {
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self.skip()?;
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Ok(true)
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} else {
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Ok(false)
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}
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}
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pub fn decodeint(bs: &[u8]) -> BigInt {
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BigInt::from_signed_bytes_be(bs)
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}
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pub fn decodebinary(minor: u8, bs: Vec<u8>) -> Result<AValue> {
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Ok(match minor {
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0 => Value::from(Self::decodeint(&bs)).wrap(),
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1 => Value::from(std::str::from_utf8(&bs)?).wrap(),
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2 => Value::from(bs).wrap(),
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3 => Value::symbol(std::str::from_utf8(&bs)?).wrap(),
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_ => panic!()
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})
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}
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pub fn decodecompound(minor: u8, mut pieces: Vec<AValue>) -> Result<AValue> {
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match minor {
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0 =>
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if pieces.len() == 0 {
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Err(Error::Syntax("Too few elements in encoded record"))
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} else {
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let label = pieces.remove(0).rc();
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Ok(Value::record(&label, pieces).wrap())
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},
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1 => Ok(Value::from(pieces).wrap()),
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2 => {
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let mut s = Set::new();
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while let Some(v) = pieces.pop() {
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s.insert(v);
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}
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Ok(Value::Set(s).wrap())
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}
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3 =>
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if pieces.len() % 2 != 0 {
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Err(Error::Syntax("Missing dictionary value"))
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} else {
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let mut d = Dictionary::new();
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while let Some(v) = pieces.pop() {
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let k = pieces.pop().unwrap();
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d.insert(k, v);
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}
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Ok(Value::Dictionary(d).wrap())
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},
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_ => panic!()
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}
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}
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pub fn binarystream(&mut self, minor: u8) -> Result<AValue> {
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let mut bs: Vec<u8> = Vec::new();
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while !self.peekend()? {
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match self.next()?.1.as_bytestring() {
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Some(chunk) => bs.extend_from_slice(chunk),
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None => return Err(Error::Syntax("Unexpected non-binary chunk")),
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}
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}
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Self::decodebinary(minor, bs)
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}
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pub fn valuestream(&mut self, minor: u8) -> Result<AValue> {
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let mut pieces: Vec<AValue> = Vec::new();
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while !self.peekend()? {
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pieces.push(self.next()?);
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}
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Self::decodecompound(minor, pieces)
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}
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pub fn next(&mut self) -> Result<AValue> {
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match self.nextop()? {
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(0, 0, 0) => Ok(Value::from(false).wrap()),
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(0, 0, 1) => Ok(Value::from(true).wrap()),
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(0, 0, 2) => {
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let bs: &[u8] = &self.readbytes(4)?;
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Ok(Value::from(f32::from_bits(u32::from_be_bytes(bs.try_into().unwrap()))).wrap())
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}
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(0, 0, 3) => {
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let bs: &[u8] = &self.readbytes(8)?;
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Ok(Value::from(f64::from_bits(u64::from_be_bytes(bs.try_into().unwrap()))).wrap())
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}
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(0, 0, 5) => {
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let a = self.next()?;
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let mut v = self.next()?;
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v.annotations_mut().push(a);
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Ok(v)
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}
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(0, 0, _) => Err(Error::Syntax("Invalid format A encoding")),
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(0, 1, arg) => {
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let n = self.wirelength(arg)?;
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match self.placeholders.get(&n) {
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Some(v) => Ok(v.clone().wrap()),
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None => Err(Error::Syntax("Invalid Preserves placeholder")),
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}
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}
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(0, 2, arg) => {
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let t = arg >> 2;
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let n = arg & 3;
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match t {
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1 => self.binarystream(n),
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2 => self.valuestream(n),
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_ => Err(Error::Syntax("Invalid format C start byte")),
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}
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}
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(0, 3, arg) => {
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let n = if arg > 12 { i32::from(arg) - 16 } else { i32::from(arg) };
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Ok(Value::from(n).wrap())
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}
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(0, _, _) => panic!(),
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(1, minor, arg) => {
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let n = self.wirelength(arg)?;
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Self::decodebinary(minor, self.readbytes(n)?)
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}
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(2, minor, arg) => {
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let n = self.wirelength(arg)?;
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Self::decodecompound(minor, self.readvalues(n)?)
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}
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(3, _, _) => Err(Error::Syntax("Invalid lead byte (major 3)")),
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(_, _, _) => panic!(),
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}
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}
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}
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@ -1 +1,2 @@
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pub mod value;
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pub mod codec;
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@ -21,26 +21,30 @@ pub enum Value {
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Symbol(String),
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Record(Record),
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Sequence(Vec<AValue>),
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Set(BTreeSet<AValue>),
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Dictionary(BTreeMap<AValue, AValue>),
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Set(Set),
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Dictionary(Dictionary),
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}
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/// An possibly-annotated Value, with annotations (themselves
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/// possibly-annotated) in order of appearance.
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#[derive(Clone, Debug)]
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pub struct AValue(Vec<AValue>, Value);
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pub struct AValue(pub Vec<AValue>, pub Value);
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/// Single-precision IEEE 754 Value
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#[derive(Clone, Debug)]
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pub struct Float(f32);
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pub struct Float(pub f32);
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/// Double-precision IEEE 754 Value
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#[derive(Clone, Debug)]
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pub struct Double(f64);
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pub struct Double(pub f64);
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/// A Record `Value`
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pub type Record = (Rc<AValue>, Vec<AValue>);
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pub type Set = BTreeSet<AValue>;
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pub type Dictionary = BTreeMap<AValue, AValue>;
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impl From<f32> for Float {
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fn from(v: f32) -> Self {
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Float(v)
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@ -174,6 +178,8 @@ impl From<String> for Value { fn from(v: String) -> Self { Value::String(v) } }
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impl From<&[u8]> for Value { fn from(v: &[u8]) -> Self { Value::ByteString(Vec::from(v)) } }
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impl From<Vec<u8>> for Value { fn from(v: Vec<u8>) -> Self { Value::ByteString(v) } }
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impl From<Vec<AValue>> for Value { fn from(v: Vec<AValue>) -> Self { Value::Sequence(v) } }
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//---------------------------------------------------------------------------
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impl AValue {
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@ -395,7 +401,7 @@ impl Value {
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self.as_set().is_some()
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}
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pub fn as_set(&self) -> Option<&BTreeSet<AValue>> {
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pub fn as_set(&self) -> Option<&Set> {
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if let Value::Set(ref s) = *self {
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Some(s)
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} else {
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@ -403,7 +409,7 @@ impl Value {
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}
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}
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pub fn as_set_mut(&mut self) -> Option<&mut BTreeSet<AValue>> {
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pub fn as_set_mut(&mut self) -> Option<&mut Set> {
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if let Value::Set(ref mut s) = *self {
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Some(s)
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} else {
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@ -415,7 +421,7 @@ impl Value {
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self.as_dictionary().is_some()
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}
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pub fn as_dictionary(&self) -> Option<&BTreeMap<AValue, AValue>> {
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pub fn as_dictionary(&self) -> Option<&Dictionary> {
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if let Value::Dictionary(ref s) = *self {
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Some(s)
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} else {
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@ -423,7 +429,7 @@ impl Value {
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}
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}
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pub fn as_dictionary_mut(&mut self) -> Option<&mut BTreeMap<AValue, AValue>> {
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pub fn as_dictionary_mut(&mut self) -> Option<&mut Dictionary> {
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if let Value::Dictionary(ref mut s) = *self {
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Some(s)
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} else {
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