Reduce dependency on standard library in favor of core-only alternatives

Author: ZackPierce

rust/car_example/src/main.rs

@@ -1,11 +1,11 @@
-
 /// Note that the included codec file and the data file further below
 /// are generated through SBE's gradle tooling. `./gradlew generateRustCodecs`
-include!("car_example_generated_codec.rs");
+mod car_example_generated_codec;
+use car_example_generated_codec::*;
 
 use std::fs::File;
 use std::io::prelude::*;
-use std::io::Write;
+use std::io::{Error as IoError, ErrorKind as IoErrorKind, Write};
 
 pub fn main() {
  ::std::process::exit(match run_car_example() {
@@ -17,15 +17,15 @@ pub fn main() {
  });
 }
 
-fn read_sbe_file_generated_from_java_example() -> IoResult<Vec<u8>> {
+fn read_sbe_file_generated_from_java_example() -> ::std::io::Result<Vec<u8>> {
  // Generated by the generateCarExampleDataFile gradle task.
  let mut f = File::open("car_example_data.sbe")?;
  let mut buffer = Vec::new();
  f.read_to_end(&mut buffer)?;
  Ok(buffer)
 }
 
-fn run_car_example() -> IoResult<()> {
+fn run_car_example() -> ::std::io::Result<()> {
  let reference_example_bytes = read_sbe_file_generated_from_java_example()?;
  decode_car_and_assert_expected_content(&reference_example_bytes)?;
  let bytes_encoded_from_rust = encode_car_from_scratch()?;
@@ -34,7 +34,16 @@ fn run_car_example() -> IoResult<()> {
  Ok(())
 }
 
-fn decode_car_and_assert_expected_content(buffer: &[u8]) -> IoResult<()> {
+impl std::convert::From<CodecErr> for IoError {
+ fn from(codec_err: CodecErr) -> Self {
+ IoError::new(IoErrorKind::Other, match codec_err {
+ CodecErr::NotEnoughBytes => "not enough bytes",
+ CodecErr::SliceIsLongerThanAllowedBySchema => "slice is longer than allowed by schema",
+ })
+ }
+}
+
+fn decode_car_and_assert_expected_content(buffer: &[u8]) -> CodecResult<()> {
  let (h, dec_fields) = start_decoding_car(&buffer).header()?;
  assert_eq!(49u16, h.block_length);
  assert_eq!(1u16, h.template_id);
@@ -55,7 +64,6 @@ fn decode_car_and_assert_expected_content(buffer: &[u8]) -> IoResult<()> {
  let dec_perf_figures_header = match dec_fuel_figures_header.fuel_figures_individually()? {
  Either::Left(mut dec_ff_members) => {
  println!("Got some fuel figure members");
- let mut decoder_after_group = None;
  loop {
  let (ff_fields, dec_usage_description) = dec_ff_members.next_fuel_figures_member()?;
  let (usage_description, next_step) = dec_usage_description.usage_description()?;
@@ -72,12 +80,10 @@ fn decode_car_and_assert_expected_content(buffer: &[u8]) -> IoResult<()> {
  match next_step {
  Either::Left(more_members) => dec_ff_members = more_members,
  Either::Right(done_with_group) => {
- decoder_after_group = Some(done_with_group);
- break;
+ break done_with_group;
  }
  }
  }
- decoder_after_group.unwrap()
  }
  Either::Right(next_decoder) => next_decoder,
  };
@@ -89,7 +95,6 @@ fn decode_car_and_assert_expected_content(buffer: &[u8]) -> IoResult<()> {
 
  let dec_manufacturer = match dec_perf_figures_header.performance_figures_individually()? {
  Either::Left(mut dec_pf_members) => {
- let mut decoder_after_pf_group = None;
  println!("Got some performance figure members");
  loop {
  let (pf_fields, dec_acceleration_header) = dec_pf_members
@@ -105,12 +110,10 @@ fn decode_car_and_assert_expected_content(buffer: &[u8]) -> IoResult<()> {
  match next_step {
  Either::Left(more_members) => dec_pf_members = more_members,
  Either::Right(done_with_group) => {
- decoder_after_pf_group = Some(done_with_group);
- break;
+ break done_with_group;
  }
  }
  }
- decoder_after_pf_group.unwrap()
  }
  Either::Right(next_decoder) => next_decoder,
  };
@@ -136,7 +139,7 @@ fn decode_car_and_assert_expected_content(buffer: &[u8]) -> IoResult<()> {
  Ok(())
 }
 
-fn encode_car_from_scratch() -> IoResult<Vec<u8>> {
+fn encode_car_from_scratch() -> CodecResult<Vec<u8>> {
  let mut buffer = vec![0u8; 256];
  let used_pos = {
  let enc_header = start_encoding_car(&mut buffer);

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/rust/RustCodecType.java

@@ -31,7 +31,7 @@ void appendDirectCodeMethods(final Appendable appendable, final String methodNam
  final String representationType, final String nextCoderType,
  final int numBytes) throws IOException
  {
- indent(appendable, 1, "pub fn %s(mut self) -> IoResult<(&%s %s, %s)> {\n",
+ indent(appendable, 1, "pub fn %s(mut self) -> CodecResult<(&%s %s, %s)> {\n",
  methodName, DATA_LIFETIME, representationType,
  RustGenerator.withLifetime(nextCoderType));
  indent(appendable, 2, "let v = self.%s.read_type::<%s>(%s)?;\n",
@@ -67,15 +67,15 @@ void appendDirectCodeMethods(final Appendable appendable, final String methodNam
  final int numBytes) throws IOException
  {
 
- indent(appendable, 1, "pub fn %s(mut self) -> IoResult<(&%s mut %s, %s)> {\n",
+ indent(appendable, 1, "pub fn %s(mut self) -> CodecResult<(&%s mut %s, %s)> {\n",
  methodName, DATA_LIFETIME, representationType, RustGenerator.withLifetime(nextCoderType));
  indent(appendable, 2, "let v = self.%s.writable_overlay::<%s>(%s)?;\n",
  RustCodecType.Encoder.scratchProperty(), representationType, numBytes);
  indent(appendable, 2, "Ok((v, %s::wrap(self.%s)))\n",
  nextCoderType, RustCodecType.Encoder.scratchProperty());
  indent(appendable).append("}\n");
 
- indent(appendable).append(String.format("pub fn %s_copy(mut self, t: &%s) -> IoResult<%s> {\n",
+ indent(appendable).append(String.format("pub fn %s_copy(mut self, t: &%s) -> CodecResult<%s> {\n",
  methodName, representationType, RustGenerator.withLifetime(nextCoderType)));
  indent(appendable, 2)
  .append(format("self.%s.write_type::<%s>(t, %s)?;\n",