mirror of
https://github.com/rust-lang-nursery/rust-cookbook
synced 2024-11-27 22:00:17 +00:00
JSON rust implementation recipe
This commit is contained in:
trentspi
parent
28245801d5
commit
71fb77af9b
3 changed files with 43 additions and 98 deletions
7
Cargo.lock
generated
7
Cargo.lock
generated
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@ -4,6 +4,7 @@ version = "0.1.0"
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dependencies = [
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"byteorder 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
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"error-chain 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)",
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"json 0.11.5 (registry+https://github.com/rust-lang/crates.io-index)",
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"skeptic 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)",
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]
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@ -67,6 +68,11 @@ name = "getopts"
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version = "0.2.14"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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[[package]]
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name = "json"
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version = "0.11.5"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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[[package]]
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name = "kernel32-sys"
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version = "0.2.2"
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@ -138,6 +144,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
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"checksum error-chain 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)" = "6930e04918388a9a2e41d518c25cf679ccafe26733fb4127dbf21993f2575d46"
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"checksum gcc 0.3.43 (registry+https://github.com/rust-lang/crates.io-index)" = "c07c758b972368e703a562686adb39125707cc1ef3399da8c019fc6c2498a75d"
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"checksum getopts 0.2.14 (registry+https://github.com/rust-lang/crates.io-index)" = "d9047cfbd08a437050b363d35ef160452c5fe8ea5187ae0a624708c91581d685"
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"checksum json 0.11.5 (registry+https://github.com/rust-lang/crates.io-index)" = "5e7eb285e773498f9473a6e2255feffe95db9c55579c7931a6db83c9e02a4673"
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"checksum kernel32-sys 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "7507624b29483431c0ba2d82aece8ca6cdba9382bff4ddd0f7490560c056098d"
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"checksum libc 0.2.20 (registry+https://github.com/rust-lang/crates.io-index)" = "684f330624d8c3784fb9558ca46c4ce488073a8d22450415c5eb4f4cfb0d11b5"
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"checksum pulldown-cmark 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "8361e81576d2e02643b04950e487ec172b687180da65c731c03cf336784e6c07"
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@ -8,6 +8,7 @@ build = "build.rs"
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[dependencies]
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byteorder = "1.0.0"
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error-chain = "0.8.0"
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json = "0.11.5"
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[build-dependencies]
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skeptic = "0.6"
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133
README.md
133
README.md
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@ -1,117 +1,54 @@
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# Cookin' with Rust
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#JSON
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A practical guide to the Rust crate ecosystem.
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- [Read and write integers in little-endian byte order](#byteorder)
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[![byteorder][byteorder-badge]][byteorder]
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##JSON implementation in Rust:
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# A note about error handling
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[![json][json-badge]][json]
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Error handling in Rust is robust when done correctly, but in today's
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Rust it requires a fair bit of boilerplate. Because of this one often
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seees Rust examples filled with `unwrap` calls instead of proper error
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handling.
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Since these recipes are intended to be reused as-is and encourage best
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practices, they set up error handling correctly, and when necessary to
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reduce boilerplate, they use the [error-chain] crate.
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The code for this setup generally looks like:
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```rust
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#[macro_use]
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extern crate error_chain;
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mod errors {
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error_chain! {
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foreign_links {
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Io(::std::io::Error);
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}
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#[macro_use]
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extern crate json;
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fn main() {
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let parsed = json::parse(r#"
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{
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"code": 200,
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"success": true,
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"payload": {
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"features": [
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"awesome",
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"easyAPI",
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"lowLearningCurve"
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]
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}
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}
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use errors::*;
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"#).unwrap();
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fn main() { run().unwrap() }
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fn run() -> Result<()> {
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use std::io::Write;
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let ref mut stdout = ::std::io::stdout();
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writeln!(stdout, "hello, world")?;
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Ok(())
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}
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```
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This is using the `error_chain!` macro to define a custom `Error`
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and `Result` type, along with an automatic conversion from
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the common `::std::io::Error` type. The automatic conversion
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makes the `?` operator work
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For more background on error handling in Rust, read TODO and TODO.
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<a id="byteorder"></a>
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## Read and write integers in little-endian byte order
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[![byteorder][byteorder-badge]][byteorder]
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```rust
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extern crate byteorder;
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use std::io::Cursor;
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use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
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#[derive(Default, Eq, PartialEq, Debug)]
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struct Payload {
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kind: u8,
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value: u16,
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}
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fn run() -> Result<()> {
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let original_payload = Payload::default();
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let encoded_buf = encode(&original_payload)?;
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let decoded_payload = decode(&encoded_buf)?;
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assert_eq!(original_payload, decoded_payload);
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Ok(())
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}
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fn encode(payload: &Payload) -> Result<Vec<u8>> {
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let mut wtr = vec![];
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wtr.write_u8(payload.kind)?;
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wtr.write_u16::<LittleEndian>(payload.value)?;
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Ok(wtr)
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}
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fn decode(buf: &[u8]) -> Result<Payload> {
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let mut rdr = Cursor::new(buf);
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Ok(Payload {
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kind: rdr.read_u8()?,
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value: rdr.read_u16::<LittleEndian>()?,
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})
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}
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#[macro_use]
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extern crate error_chain;
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mod errors {
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error_chain! {
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foreign_links {
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Io(::std::io::Error);
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}
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let instantiated = object!{
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"code" => 200,
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"success" => true,
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"payload" => object!{
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"features" => array![
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"awesome",
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"easyAPI",
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"lowLearningCurve"
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]
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}
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};
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assert_eq!(parsed, instantiated);
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}
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use errors::*;
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fn main() { run().unwrap() }
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```
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# License
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MIT/Apache-2.0
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<!-- Links -->
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[byteorder-badge]: https://img.shields.io/crates/v/rustc-serialize.svg
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[byteorder]: https://docs.rs/byteorder
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[json-badge]: https://img.shields.io/crates/v/rustc-serialize.svg
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[json]: http://json.rs/doc/json/
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