Auto protobuf build

.gitignore

@@ -1,2 +1,3 @@
 Cargo.lock
 target/
+src/proto/proof.rs

.travis.yml

@@ -1,5 +1,9 @@
 language: rust
-cache: cargo # https://docs.travis-ci.com/user/caching/#Rust-Cargo-cache
+cache:
+  directories:
+    - $HOME/protobuf
+    - $HOME/.cargo
+    - $TRAVIS_BUILD_DIR/target
 
 rust:
   - stable
@@ -15,12 +19,22 @@ matrix:
   include:
     - env: NAME='nightly'
       rust: nightly
-    - env: NAME='rustfmt'
+    - env:
+        - NAME='rustfmt'
+        - PROTOBUF_CODEGEN_VERSION=2.0.0
+        - PATH=$PATH:$HOME/.cargo/bin
       rust: nightly
       before_script:
         - rustup component add rustfmt-preview
+        # Protoc plugin needed to generate proof.rs from proof.proto
+        - cargo install protobuf-codegen --version $PROTOBUF_CODEGEN_VERSION || echo "protobuf-codegen already installed"
+        # TODO: see if we can avoid installing protobuf-codegen and generating
+        # proof.rs in this build by using rustfmt options (see
+        # https://github.com/SpinResearch/merkle.rs/pull/38#issuecomment-391336829,
+        # paragraph 2).
+        - protoc --rust_out src/proto/ protobuf/proof.proto
       script:
-        - cargo fmt --all -- --write-mode=diff
+        - cargo fmt --all -- --check
     - env: NAME='kcov'
       sudo: required # travis-ci/travis-ci#9061
       before_script:
@@ -57,3 +71,7 @@ script:
   - cargo build --verbose --all-features
   - cargo test --verbose --all-features
   - cargo doc --verbose --all-features --no-deps
+
+before_install:
+  - export PATH=$PATH:$HOME/protobuf/bin
+  - bash install_protobuf.sh

Cargo.toml

@@ -19,15 +19,18 @@ categories    = ["data-structures", "cryptography"]
 
 [dependencies]
 ring = "^0.12.0"
-protobuf = { version = "^1.6.0", optional = true }
+protobuf = { version = "1.7.1", optional = true }
 serde = { version = "^1.0.55", optional = true }
 serde_derive = { version = "^1.0.55", optional = true }
 
+[build-dependencies]
+protoc-rust = { version = "1.7.1", optional = true }
+
 [dev-dependencies]
 serde_json = "1.0.17"
 
 [features]
-serialization-protobuf = [ "protobuf" ]
+serialization-protobuf = [ "protobuf", "protoc-rust" ]
 serialization-serde = [ "serde", "serde_derive" ]
 
 [package.metadata.release]

build.rs

@@ -0,0 +1,41 @@
+#[cfg(feature = "serialization-protobuf")]
+extern crate protoc_rust;
+
+#[cfg(feature = "serialization-protobuf")]
+fn assert_protobuf_version(version: &str) {
+    use std::process::{Command, Stdio};
+    let protoc = Command::new("protoc")
+        .stdin(Stdio::null())
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped())
+        .args(&["--version"])
+        .spawn()
+        .unwrap();
+    let version_output = protoc.wait_with_output().unwrap();
+    assert!(version_output.status.success());
+    assert_eq!(
+        String::from_utf8(version_output.stdout).unwrap().trim(),
+        version
+    );
+}
+
+#[cfg(feature = "serialization-protobuf")]
+fn build_protobuf(out_dir: &str, input: &[&str], includes: &[&str]) {
+    use self::protoc_rust::{run, Args};
+    run(Args {
+        out_dir,
+        input,
+        includes,
+    }).expect("protoc");
+}
+
+#[cfg(feature = "serialization-protobuf")]
+fn build_protobuf_schemata() {
+    assert_protobuf_version("libprotoc 3.5.1");
+    build_protobuf("src/proto", &["protobuf/proof.proto"], &[]);
+}
+
+fn main() {
+    #[cfg(feature = "serialization-protobuf")]
+    build_protobuf_schemata();
+}

install_protobuf.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/bash
+set -e
+
+check_protoc_version () {
+    version="libprotoc $1"
+    PROTOC="$HOME/protobuf/bin/protoc"
+    if [ -f $PROTOC ]; then
+        this_version=`$PROTOC --version`
+        return `[ "$version" = "$this_version" ]`
+    else
+        return 1
+    fi
+}
+
+if check_protoc_version '3.5.1'; then
+    echo protoc version 3.5.1 detected.
+    exit
+fi
+
+wget https://github.com/google/protobuf/archive/v3.5.1.tar.gz
+tar -xzvf v3.5.1.tar.gz
+cd protobuf-3.5.1 && ./autogen.sh && ./configure --prefix=$HOME/protobuf && make && make install

rustfmt.toml

@@ -0,0 +1,3 @@
+ignore = [
+    "src/proto/proof.rs",
+]

src/merkletree.rs

@@ -28,7 +28,9 @@ pub struct MerkleTree<T> {
 impl<T: PartialEq> PartialEq for MerkleTree<T> {
     #[allow(trivial_casts)]
     fn eq(&self, other: &MerkleTree<T>) -> bool {
-        self.root == other.root && self.height == other.height && self.count == other.count
+        self.root == other.root
+            && self.height == other.height
+            && self.count == other.count
             && (self.algorithm as *const Algorithm) == (other.algorithm as *const Algorithm)
     }
 }