The first incarnation of the pack serialiser/deserialiser.

.rustfmt.toml

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+indent_style="Block"
+imports_indent="Block"
+use_try_shorthand=true
+use_field_init_shorthand=true
+merge_imports=true

.travis.yml

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+language: rust
+
+rust:
+    - stable
+    - nightly
+
+before_script:
+    - "[ \"$TRAVIS_RUST_VERSION\" == 'nightly' ] || rustup component add rustfmt"
+
+script:
+    - cargo build --tests
+    - cargo test
+    - "[ \"$TRAVIS_RUST_VERSION\" == 'nightly' ] || cargo fmt --all -- --check"
+
+cache: cargo

Cargo.toml

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+[package]
+name = "ykmir"
+version = "0.1.0"
+authors = ["Edd Barrett <vext01@gmail.com>"]
+edition = "2018"
+
+[dependencies]
+serde = "1.0"
+serde_derive = "1.0"
+fallible-iterator = "0.1"
+
+# We are using a git version to work around a bug:
+# https://github.com/3Hren/msgpack-rust/issues/183
+[dependencies.rmp-serde]
+git = "https://github.com/3Hren/msgpack-rust"
+rev = "40b3d480b20961e6eeceb416b32bcd0a3383846a"

README.md

@@ -1,2 +1,6 @@
-# ykmir
-MIR encoder / decoder for Yorick.
+# ykpack
+
+Pack encoder / decoder for Yorick.
+
+This library allows ykrustc to serialise various compile-time information for
+later reading at run-time.

src/decode.rs

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+// Copyright 2019 King's College London.
+// Created by the Software Development Team <http://soft-dev.org/>.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use crate::Pack;
+use fallible_iterator::FallibleIterator;
+use rmp_serde::{
+    decode::{self, ReadReader},
+    Deserializer,
+};
+use serde::Deserialize;
+use std::io::Read;
+
+/// The pack decoder.
+/// Offers a simple iterator interface to serialised packs.
+pub struct Decoder<'a> {
+    deser: Deserializer<ReadReader<&'a mut dyn Read>>,
+}
+
+impl<'a> Decoder<'a> {
+    /// Returns a new decoder which will deserialise from `read_from`.
+    pub fn from(read_from: &'a mut dyn Read) -> Self {
+        let deser = Deserializer::new(read_from);
+        Self { deser }
+    }
+}
+
+impl<'a> FallibleIterator for Decoder<'a> {
+    type Item = Pack;
+    type Error = decode::Error;
+
+    fn next(&mut self) -> Result<Option<Self::Item>, Self::Error> {
+        Option::<Pack>::deserialize(&mut self.deser)
+    }
+}

src/encode.rs

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+// Copyright 2019 King's College London.
+// Created by the Software Development Team <http://soft-dev.org/>.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use crate::Pack;
+use rmp_serde::{encode, Serializer};
+use serde::Serialize;
+use std::{io::prelude::*, ops::Drop};
+
+/// The pack encoder.
+///
+/// Packs are written using the `serialise()` method. Once all of the desired packs is serialised,
+/// the consumer must call `done()`.
+pub struct Encoder<'a> {
+    ser: Serializer<&'a mut dyn Write>,
+    done: bool,
+}
+
+impl<'a> Encoder<'a> {
+    /// Creates a new encoder which serialises `Pack` into the writable `write_into`.
+    pub fn from(write_into: &'a mut dyn Write) -> Self {
+        let ser = Serializer::new(write_into);
+        Self { ser, done: false }
+    }
+
+    /// Serialises a pack.
+    pub fn serialise(&mut self, md: Pack) -> Result<(), encode::Error> {
+        Some(md).serialize(&mut self.ser)
+    }
+
+    /// Finalises the serialisation and writes a sentinel.
+    pub fn done(mut self) -> Result<(), encode::Error> {
+        None::<Option<Pack>>.serialize(&mut self.ser)?;
+        self.done = true;
+        Ok(())
+    }
+}
+
+impl<'a> Drop for Encoder<'a> {
+    fn drop(&mut self) {
+        if !self.done {
+            panic!("Encoder not marked done()");
+        }
+    }
+}

src/lib.rs

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+// Copyright 2019 King's College London.
+// Created by the Software Development Team <http://soft-dev.org/>.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+/// ykpack -- Serialiser and deserialiser for carrying data from compile-time to run-time.
+///
+/// This crate allows ykrustc to serialise various compile-time information for later
+/// deserialisation by the Yorick runtime.
+///
+/// The encoder and decoder API is structured in such a way that each item -- or "Pack" -- can be
+/// streamed to/from the serialised format one item at a time. This helps to reduce memory
+/// consumption.
+///
+/// The MIR data is serialised in the msgpack format in the following form:
+///
+///  -----------
+///  pack_0:             \
+///  ...                  - Packs.
+///  pack_n              /
+///  sentinel           -- End of packs marker.
+///  -----------
+///
+///  Where each pack_i is an instance of `Some(Pack)` and the sentinel is a `None`.
+///
+///  The version field is automatically written and checked by the `Encoder` and `Decoder`
+///  respectively.
+
+#[macro_use]
+extern crate serde_derive;
+
+mod decode;
+mod encode;
+
+pub use decode::Decoder;
+pub use encode::Encoder;
+
+pub type CrateHash = u64;
+pub type DefIndex = u32;
+pub type BasicBlockIndex = u32;
+
+/// A mirror of the compiler's notion of a "definition ID".
+#[derive(Serialize, Deserialize, PartialEq, Eq, Debug, Clone)]
+pub struct DefId {
+    crate_hash: CrateHash,
+    def_idx: DefIndex,
+}
+
+impl DefId {
+    pub fn new(crate_hash: CrateHash, def_idx: DefIndex) -> Self {
+        Self {
+            crate_hash,
+            def_idx,
+        }
+    }
+}
+
+/// A MIR.
+#[derive(Serialize, Deserialize, PartialEq, Eq, Debug, Clone)]
+pub struct Mir {
+    def_id: DefId,
+    blocks: Vec<BasicBlock>,
+}
+
+impl Mir {
+    /// Create a new MIR.
+    pub fn new(def_id: DefId, blocks: Vec<BasicBlock>) -> Self {
+        Self { def_id, blocks }
+    }
+}
+
+/// A MIR block.
+#[derive(Serialize, Deserialize, PartialEq, Eq, Debug, Clone)]
+pub struct BasicBlock {
+    stmts: Vec<Statement>,
+    term: Terminator,
+}
+
+impl BasicBlock {
+    /// Create a new MIR block.
+    pub fn new(stmts: Vec<Statement>, term: Terminator) -> Self {
+        Self { stmts, term }
+    }
+}
+
+/// A MIR statement.
+/// FIXME to be populated.
+#[derive(Serialize, Deserialize, PartialEq, Eq, Debug, Clone)]
+pub enum Statement {
+    Nop,
+}
+
+/// A call target.
+#[derive(Serialize, Deserialize, PartialEq, Eq, Debug, Clone)]
+pub enum CallOperand {
+    /// A statically known function identified by its DefId.
+    Fn(DefId),
+    /// An unknown or unhandled callable.
+    Unknown, // FIXME -- Find out what else. Closures jump to mind.
+}
+
+/// A MIR block terminator.
+#[derive(Serialize, Deserialize, PartialEq, Eq, Debug, Clone)]
+pub enum Terminator {
+    Goto {
+        target_bb: BasicBlockIndex,
+    },
+    SwitchInt {
+        target_bbs: Vec<BasicBlockIndex>,
+    },
+    Resume,
+    Abort,
+    Return,
+    Unreachable,
+    Drop {
+        target_bb: BasicBlockIndex,
+        unwind_bb: Option<BasicBlockIndex>,
+    },
+    DropAndReplace {
+        target_bb: BasicBlockIndex,
+        unwind_bb: Option<BasicBlockIndex>,
+    },
+    Call {
+        operand: CallOperand,
+        cleanup_bb: Option<BasicBlockIndex>,
+    },
+    Assert {
+        target_bb: BasicBlockIndex,
+        cleanup_bb: Option<BasicBlockIndex>,
+    },
+    Yield {
+        resume_bb: BasicBlockIndex,
+        drop_bb: Option<BasicBlockIndex>,
+    },
+    GeneratorDrop,
+    FalseEdges {
+        real_target_bb: BasicBlockIndex,
+    },
+    FalseUnwind {
+        real_target_bb: BasicBlockIndex,
+    },
+}
+
+/// The top-level pack type.
+#[derive(Serialize, Deserialize, PartialEq, Eq, Debug, Clone)]
+pub enum Pack {
+    Mir(Mir),
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{BasicBlock, Decoder, DefId, Encoder, Mir, Pack, Statement, Terminator};
+    use fallible_iterator::{self, FallibleIterator};
+    use std::io::{Cursor, Seek, SeekFrom};
+
+    // Get a cursor to serialise to and deserialise from. For real, we'd be reading from a file,
+    // but for tests we use a vector of bytes.
+    fn get_curs() -> Cursor<Vec<u8>> {
+        let buf: Vec<u8> = Vec::new();
+        Cursor::new(buf)
+    }
+
+    // Rewind a cursor to the beginning.
+    fn rewind_curs(curs: &mut Cursor<Vec<u8>>) {
+        curs.seek(SeekFrom::Start(0)).unwrap();
+    }
+
+    // Makes some sample stuff to round trip test.
+    fn get_sample_packs() -> Vec<Pack> {
+        let dummy_term = Terminator::Abort;
+
+        let stmts1_b1 = vec![Statement::Nop; 16];
+        let stmts1_b2 = vec![Statement::Nop; 3];
+        let blocks1 = vec![
+            BasicBlock::new(stmts1_b1, dummy_term.clone()),
+            BasicBlock::new(stmts1_b2, dummy_term.clone()),
+        ];
+        let mir1 = Pack::Mir(Mir::new(DefId::new(1, 2), blocks1));
+
+        let stmts2_b1 = vec![Statement::Nop; 7];
+        let stmts2_b2 = vec![Statement::Nop; 200];
+        let stmts2_b3 = vec![Statement::Nop; 1];
+        let blocks2 = vec![
+            BasicBlock::new(stmts2_b1, dummy_term.clone()),
+            BasicBlock::new(stmts2_b2, dummy_term.clone()),
+            BasicBlock::new(stmts2_b3, dummy_term.clone()),
+        ];
+        let mir2 = Pack::Mir(Mir::new(DefId::new(4, 5), blocks2));
+
+        vec![mir1, mir2]
+    }
+
+    // Check serialising and deserialising works for zero packs.
+    #[test]
+    fn test_empty() {
+        let mut curs = get_curs();
+
+        let enc = Encoder::from(&mut curs);
+        enc.done().unwrap();
+
+        rewind_curs(&mut curs);
+        let mut dec = Decoder::from(&mut curs);
+        assert!(dec.next().unwrap().is_none());
+    }
+
+    // Check a typical serialising and deserialising session.
+    #[test]
+    fn test_basic() {
+        let inputs = get_sample_packs();
+        let mut curs = get_curs();
+
+        let mut enc = Encoder::from(&mut curs);
+        for md in &inputs {
+            enc.serialise(md.clone()).unwrap();
+        }
+        enc.done().unwrap();
+
+        rewind_curs(&mut curs);
+        let dec = Decoder::from(&mut curs);
+
+        // Obtain two fallible iterators, so we can zip them.
+        let expect_iter = fallible_iterator::convert(inputs.into_iter().map(|e| Ok(e)));
+
+        let mut itr = dec.zip(expect_iter);
+        while let Some((got, expect)) = itr.next().unwrap() {
+            assert_eq!(expect, got);
+        }
+    }
+
+    #[test]
+    #[should_panic(expected = "not marked done")]
+    fn test_encode_not_done() {
+        let inputs = get_sample_packs();
+        let mut curs = get_curs();
+
+        let mut enc = Encoder::from(&mut curs);
+        for md in &inputs {
+            enc.serialise(md.clone()).unwrap();
+        }
+        // We expect this to panic, as the encoder wasn't finalised with a call to `enc.done()`.
+    }
+}