Rust Encoder

implementations/rust/Cargo.toml

@@ -6,5 +6,6 @@ edition = "2018"
 
 [dependencies]
 num = "0.2"
+num_enum = "0.4.1"
 serde = "1.0"
 serde_bytes = "0.11"

implementations/rust/src/lib.rs

@@ -175,7 +175,8 @@ mod value_tests {
 
 #[cfg(test)]
 mod decoder_tests {
-    use crate::value::codec::Decoder;
+    use crate::value::decoder::Decoder;
+    use crate::value::encoder::Encoder;
     use crate::value::value::Value;
 
     #[test] fn read_123() {
@@ -204,6 +205,11 @@ mod decoder_tests {
 
     #[test] fn read_samples() {
         let mut d = Decoder::new(std::fs::File::open("../../tests/samples.bin").unwrap(), None);
-        println!("{:#?}", d.next().ok().unwrap());
+        let v = d.next().ok().unwrap();
+        println!("{:#?}", v);
+        // let mut buf = Vec::new();
+        // let mut e = Encoder::new(&mut buf, None);
+        // e.write(&v).ok().unwrap();
+        // println!("{:?}", Value::from(buf))
     }
 }

implementations/rust/src/value/constants.rs

@@ -0,0 +1,52 @@
+use std::convert::{TryFrom, From};
+use num_enum::TryFromPrimitive;
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum Op {
+    Misc(u8),
+    Atom(AtomMinor),
+    Compound(CompoundMinor),
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct InvalidOp;
+
+impl TryFrom<u8> for Op {
+    type Error = InvalidOp;
+    fn try_from(v: u8) -> Result<Self, Self::Error> {
+        match v >> 2 {
+            0 => Ok(Self::Misc(v & 3)),
+            1 => Ok(Self::Atom(AtomMinor::try_from(v & 3).unwrap())),
+            2 => Ok(Self::Compound(CompoundMinor::try_from(v & 3).unwrap())),
+            _ => Err(InvalidOp),
+        }
+    }
+}
+
+impl From<Op> for u8 {
+    fn from(v: Op) -> Self {
+        match v {
+            Op::Misc(minor) => minor & 3,
+            Op::Atom(minor) => (1 << 2) | ((minor as u8) & 3),
+            Op::Compound(minor) => (2 << 2) | ((minor as u8) & 3),
+        }
+    }
+}
+
+#[derive(Debug, TryFromPrimitive, PartialEq, Eq)]
+#[repr(u8)]
+pub enum AtomMinor {
+    SignedInteger = 0,
+    String = 1,
+    ByteString = 2,
+    Symbol = 3,
+}
+
+#[derive(Debug, TryFromPrimitive, PartialEq, Eq)]
+#[repr(u8)]
+pub enum CompoundMinor {
+    Record = 0,
+    Sequence = 1,
+    Set = 2,
+    Dictionary = 3,
+}

implementations/rust/src/value/decoder.rs

@@ -1,7 +1,9 @@
 use std::io::Read;
 use std::convert::TryInto;
+use std::convert::TryFrom;
 use crate::value::value::{Value, AValue, Set, Dictionary};
 use num::bigint::BigInt;
+use crate::value::constants::{Op, InvalidOp, AtomMinor, CompoundMinor};
 
 pub type Result<V> = std::result::Result<V, Error>;
 
@@ -24,29 +26,35 @@ impl From<std::str::Utf8Error> for Error {
     }
 }
 
+impl From<InvalidOp> for Error {
+    fn from(_v: InvalidOp) -> Self {
+        Error::Syntax("Invalid lead byte major value")
+    }
+}
+
 impl Error {
     pub fn is_io(&self) -> bool { if let Error::Io(_) = *self { true } else { false } }
     pub fn is_syntax(&self) -> bool { if let Error::Syntax(_) = *self { true } else { false } }
     pub fn is_eof(&self) -> bool { if let Error::Eof = *self { true } else { false } }
 }
 
-pub type PlaceholderMap = std::collections::BTreeMap<usize, Value>;
+pub type DecodePlaceholderMap = std::collections::BTreeMap<usize, Value>;
 
 pub struct Decoder<R: Read> {
     read: R,
     index: usize,
     buf: Box<Option<Option<u8>>>,
-    placeholders: PlaceholderMap,
+    placeholders: DecodePlaceholderMap,
     read_annotations: bool,
 }
 
 impl<R: Read> Decoder<R> {
-    pub fn new(read: R, placeholders: Option<PlaceholderMap>) -> Self {
+    pub fn new(read: R, placeholders: Option<DecodePlaceholderMap>) -> Self {
         Decoder{
             read,
             index: 0,
             buf: Box::new(None),
-            placeholders: placeholders.unwrap_or(PlaceholderMap::new()),
+            placeholders: placeholders.unwrap_or(DecodePlaceholderMap::new()),
             read_annotations: true,
         }
     }
@@ -119,15 +127,12 @@ impl<R: Read> Decoder<R> {
         Ok(pieces)
     }
 
-    pub fn decodeop(b: u8) -> (u8, u8, u8) {
-        let major = b >> 6;
-        let minor = (b >> 4) & 3;
-        let arg = b & 15;
-        (major, minor, arg)
+    pub fn decodeop(b: u8) -> Result<(Op, u8)> {
+        Ok((Op::try_from(b >> 4)?, b & 15))
     }
 
-    pub fn nextop(&mut self) -> Result<(u8, u8, u8)> {
-        Ok(Self::decodeop(self.read()?))
+    pub fn nextop(&mut self) -> Result<(Op, u8)> {
+        Self::decodeop(self.read()?)
     }
 
     pub fn varint(&mut self) -> Result<usize> {
@@ -160,34 +165,33 @@ impl<R: Read> Decoder<R> {
         BigInt::from_signed_bytes_be(bs)
     }
 
-    pub fn decodebinary(minor: u8, bs: Vec<u8>) -> Result<AValue> {
+    pub fn decodebinary(minor: AtomMinor, bs: Vec<u8>) -> Result<AValue> {
         Ok(match minor {
-            0 => Value::from(Self::decodeint(&bs)).wrap(),
-            1 => Value::from(std::str::from_utf8(&bs)?).wrap(),
-            2 => Value::from(bs).wrap(),
-            3 => Value::symbol(std::str::from_utf8(&bs)?).wrap(),
-            _ => panic!()
+            AtomMinor::SignedInteger => Value::from(Self::decodeint(&bs)).wrap(),
+            AtomMinor::String => Value::from(std::str::from_utf8(&bs)?).wrap(),
+            AtomMinor::ByteString => Value::from(bs).wrap(),
+            AtomMinor::Symbol => Value::symbol(std::str::from_utf8(&bs)?).wrap(),
         })
     }
 
-    pub fn decodecompound(minor: u8, mut pieces: Vec<AValue>) -> Result<AValue> {
+    pub fn decodecompound(minor: CompoundMinor, mut pieces: Vec<AValue>) -> Result<AValue> {
         match minor {
-            0 =>
+            CompoundMinor::Record =>
                 if pieces.len() == 0 {
                     Err(Error::Syntax("Too few elements in encoded record"))
                 } else {
                     let label = pieces.remove(0).rc();
                     Ok(Value::record(&label, pieces).wrap())
                 },
-            1 => Ok(Value::from(pieces).wrap()),
-            2 => {
+            CompoundMinor::Sequence => Ok(Value::from(pieces).wrap()),
+            CompoundMinor::Set => {
                 let mut s = Set::new();
                 while let Some(v) = pieces.pop() {
                     s.insert(v);
                 }
                 Ok(Value::Set(s).wrap())
             }
-            3 =>
+            CompoundMinor::Dictionary =>
                 if pieces.len() % 2 != 0 {
                     Err(Error::Syntax("Missing dictionary value"))
                 } else {
@@ -198,11 +202,10 @@ impl<R: Read> Decoder<R> {
                     }
                     Ok(Value::Dictionary(d).wrap())
                 },
-            _ => panic!()
         }
     }
 
-    pub fn binarystream(&mut self, minor: u8) -> Result<AValue> {
+    pub fn binarystream(&mut self, minor: AtomMinor) -> Result<AValue> {
         let mut bs: Vec<u8> = Vec::new();
         while !self.peekend()? {
             match self.next()?.1.as_bytestring() {
@@ -213,7 +216,7 @@ impl<R: Read> Decoder<R> {
         Self::decodebinary(minor, bs)
     }
 
-    pub fn valuestream(&mut self, minor: u8) -> Result<AValue> {
+    pub fn valuestream(&mut self, minor: CompoundMinor) -> Result<AValue> {
         let mut pieces: Vec<AValue> = Vec::new();
         while !self.peekend()? {
             pieces.push(self.next()?);
@@ -223,20 +226,20 @@ impl<R: Read> Decoder<R> {
 
     pub fn next(&mut self) -> Result<AValue> {
         match self.nextop()? {
-            (0, 0, 0) => Ok(Value::from(false).wrap()),
-            (0, 0, 1) => Ok(Value::from(true).wrap()),
-            (0, 0, 2) => {
+            (Op::Misc(0), 0) => Ok(Value::from(false).wrap()),
+            (Op::Misc(0), 1) => Ok(Value::from(true).wrap()),
+            (Op::Misc(0), 2) => {
                 let bs: &[u8] = &self.readbytes(4)?;
                 Ok(Value::from(f32::from_bits(u32::from_be_bytes(bs.try_into().unwrap()))).wrap())
             }
-            (0, 0, 3) => {
+            (Op::Misc(0), 3) => {
                 let bs: &[u8] = &self.readbytes(8)?;
                 Ok(Value::from(f64::from_bits(u64::from_be_bytes(bs.try_into().unwrap()))).wrap())
             }
-            (0, 0, 5) => {
+            (Op::Misc(0), 5) => {
                 if self.read_annotations {
                     let mut annotations = vec![self.next()?];
-                    while Self::decodeop(self.peek()?) == (0, 0, 5) {
+                    while Self::decodeop(self.peek()?).ok() == Some((Op::Misc(0), 5)) {
                         self.skip()?;
                         annotations.push(self.next()?);
                     }
@@ -248,38 +251,34 @@ impl<R: Read> Decoder<R> {
                     self.next()
                 }
             }
-            (0, 0, _) => Err(Error::Syntax("Invalid format A encoding")),
-            (0, 1, arg) => {
+            (Op::Misc(0), _) => Err(Error::Syntax("Invalid format A encoding")),
+            (Op::Misc(1), arg) => {
                 let n = self.wirelength(arg)?;
                 match self.placeholders.get(&n) {
                     Some(v) => Ok(v.clone().wrap()),
                     None => Err(Error::Syntax("Invalid Preserves placeholder")),
                 }
             }
-            (0, 2, arg) => {
-                let t = arg >> 2;
-                let n = arg & 3;
-                match t {
-                    1 => self.binarystream(n),
-                    2 => self.valuestream(n),
+            (Op::Misc(2), arg) => {
+                match Op::try_from(arg)? {
+                    Op::Atom(minor) => self.binarystream(minor),
+                    Op::Compound(minor) => self.valuestream(minor),
                     _ => Err(Error::Syntax("Invalid format C start byte")),
                 }
             }
-            (0, 3, arg) => {
+            (Op::Misc(3), arg) => {
                 let n = if arg > 12 { i32::from(arg) - 16 } else { i32::from(arg) };
                 Ok(Value::from(n).wrap())
             }
-            (0, _, _) => panic!(),
-            (1, minor, arg) => {
-                let n = self.wirelength(arg)?;
-                Self::decodebinary(minor, self.readbytes(n)?)
+            (Op::Misc(_), _) => panic!(),
+            (Op::Atom(minor), arg) => {
+                let count = self.wirelength(arg)?;
+                Self::decodebinary(minor, self.readbytes(count)?)
             }
-            (2, minor, arg) => {
-                let n = self.wirelength(arg)?;
-                Self::decodecompound(minor, self.readvalues(n)?)
+            (Op::Compound(minor), arg) => {
+                let count = self.wirelength(arg)?;
+                Self::decodecompound(minor, self.readvalues(count)?)
             }
-            (3, _, _) => Err(Error::Syntax("Invalid lead byte (major 3)")),
-            (_, _, _) => panic!(),
         }
     }
 }

implementations/rust/src/value/encoder.rs

@@ -0,0 +1,118 @@
+use std::io::Write;
+use crate::value::value::{Value, AValue, Float, Double};
+use num::bigint::BigInt;
+use num::cast::ToPrimitive;
+use std::io::Error;
+use crate::value::constants::{Op, AtomMinor, CompoundMinor};
+
+pub type Result = std::result::Result<(), Error>;
+
+pub type EncodePlaceholderMap = std::collections::BTreeMap<Value, usize>;
+
+pub struct Encoder<'a, W: Write> {
+    write: &'a mut W,
+    placeholders: EncodePlaceholderMap,
+}
+
+impl<'a, W: Write> Encoder<'a, W> {
+    pub fn new(write: &'a mut W, placeholders: Option<EncodePlaceholderMap>) -> Self {
+        Encoder{
+            write,
+            placeholders: placeholders.unwrap_or(EncodePlaceholderMap::new()),
+        }
+    }
+
+    pub fn _write(&mut self, v: u8) -> Result {
+        self.write_all(&[v])
+    }
+
+    pub fn write_all(&mut self, vs: &[u8]) -> Result {
+        self.write.write_all(vs)
+    }
+
+    pub fn varint(&mut self, v: usize) -> Result {
+        if v < 128 {
+            self._write(v as u8)
+        } else {
+            self._write(((v & 0x7f) + 128) as u8)?;
+            self.varint(v >> 7)
+        }
+    }
+
+    pub fn write_op(&mut self, op: Op, arg: u8) -> Result {
+        self._write((u8::from(op) << 4) | (arg & 15))
+    }
+
+    pub fn write_header(&mut self, op: Op, wirelength: usize) -> Result {
+        if wirelength < 15 {
+            self.write_op(op, wirelength as u8)
+        } else {
+            self.write_op(op, 15)?;
+            self.varint(wirelength)
+        }
+    }
+
+    pub fn write_int(&mut self, v: &BigInt) -> Result {
+        match v.to_i8() {
+            Some(n) if n >= 0 && n <= 12 => self.write_op(Op::Misc(3), n as u8),
+            Some(n) if n >= -3 && n < 0 => self.write_op(Op::Misc(3), (n + 16) as u8),
+            _ => self.write_atom(AtomMinor::SignedInteger, &v.to_signed_bytes_be()),
+        }
+    }
+
+    pub fn write_stream_header(&mut self, op: Op) -> Result {
+        self.write_op(Op::Misc(2), u8::from(op))
+    }
+
+    pub fn write_stream_footer(&mut self) -> Result {
+        self.write_op(Op::Misc(0), 4)
+    }
+
+    pub fn write_atom(&mut self, minor: AtomMinor, bs: &[u8]) -> Result {
+        self.write_header(Op::Atom(minor), bs.len())?;
+        self.write_all(bs)
+    }
+
+    pub fn write(&mut self, v: &AValue) -> Result {
+        for ann in v.annotations() {
+            self.write_header(Op::Misc(0), 5)?;
+            self.write(ann)?;
+        }
+        match self.placeholders.get(&v.value()) {
+            Some(&n) => self.write_header(Op::Misc(1), n),
+            None => match v.value() {
+                Value::Boolean(false) => self.write_op(Op::Misc(0), 0),
+                Value::Boolean(true) => self.write_op(Op::Misc(0), 1),
+                Value::Float(Float(f)) => {
+                    self.write_op(Op::Misc(0), 2)?;
+                    self.write_all(&u32::to_be_bytes(f32::to_bits(*f)))
+                }
+                Value::Double(Double(d)) => {
+                    self.write_op(Op::Misc(0), 3)?;
+                    self.write_all(&u64::to_be_bytes(f64::to_bits(*d)))
+                }
+                Value::SignedInteger(ref b) => self.write_int(b),
+                Value::String(ref s) => self.write_atom(AtomMinor::String, s.as_bytes()),
+                Value::ByteString(ref bs) => self.write_atom(AtomMinor::ByteString, bs),
+                Value::Symbol(ref s) => self.write_atom(AtomMinor::Symbol, s.as_bytes()),
+                Value::Record((ref l, ref fs)) => {
+                    self.write_header(Op::Compound(CompoundMinor::Record), fs.len() + 1)?;
+                    self.write(l)?;
+                    Ok(for f in fs { self.write(f)?; })
+                }
+                Value::Sequence(ref vs) => {
+                    self.write_header(Op::Compound(CompoundMinor::Sequence), vs.len())?;
+                    Ok(for v in vs { self.write(v)?; })
+                }
+                Value::Set(ref vs) => {
+                    self.write_header(Op::Compound(CompoundMinor::Set), vs.len())?;
+                    Ok(for v in vs { self.write(v)?; })
+                }
+                Value::Dictionary(ref vs) => {
+                    self.write_header(Op::Compound(CompoundMinor::Dictionary), vs.len() << 1)?;
+                    Ok(for (k, v) in vs { self.write(k)?; self.write(v)?; })
+                }
+            }
+        }
+    }
+}

implementations/rust/src/value/mod.rs

@@ -1,2 +1,4 @@
 pub mod value;
-pub mod codec;
+pub mod decoder;
+pub mod encoder;
+pub mod constants;

implementations/rust/src/value/value.rs

@@ -185,8 +185,8 @@ impl std::fmt::Debug for Value {
     // doesn't escape strings/symbols properly.
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
-            Value::Boolean(true) => f.write_str("#true"),
             Value::Boolean(false) => f.write_str("#false"),
+            Value::Boolean(true) => f.write_str("#true"),
             Value::Float(Float(v)) => write!(f, "{:?}f", v),
             Value::Double(Double(v)) => write!(f, "{:?}", v),
             Value::SignedInteger(v) => write!(f, "{}", v),