tonic/tonic-build/src/lib.rs

//! `tonic-build` compiles `proto` files via `prost` and generates service stubs
//! and proto definitiones for use with `tonic`.
//!
//! # Features
//!
//! - `rustfmt`: This feature enables the use of `rustfmt` to format the output code
//! this makes the code readable and the error messages nice. This requires that `rustfmt`
//! is installed. This is enabled by default.
//!
//! # Required dependencies
//!
//! ```toml
//! [dependencies]
//! tonic = <tonic-version>
//! prost = <prost-version>
//!
//! [build-dependencies]
//! tonic-build = <tonic-version>
//! ```
//!
//! # Examples
//! Simple
//!
//! ```rust,no_run
//! fn main() -> Result<(), Box<dyn std::error::Error>> {
//!     tonic_build::compile_protos("proto/service.proto")?;
//!     Ok(())
//! }
//! ```
//!
//! Configuration
//!
//! ```rust,no_run
//! fn main() -> Result<(), Box<dyn std::error::Error>> {
//!    tonic_build::configure()
//!         .build_server(false)
//!         .compile(
//!             &["proto/helloworld/helloworld.proto"],
//!             &["proto/helloworld"],
//!         )?;
//!    Ok(())
//! }
//!```
//!
//! ## NixOS related hints
//!
//! On NixOS, it is better to specify the location of `PROTOC` and `PROTOC_INCLUDE` explicitly.
//!
//! ```bash
//! $ export PROTOBUF_LOCATION=$(nix-env -q protobuf --out-path --no-name)
//! $ export PROTOC=$PROTOBUF_LOCATION/bin/protoc
//! $ export PROTOC_INCLUDE=$PROTOBUF_LOCATION/include
//! $ cargo build
//! ```
//!
//! The reason being that if `prost_build::compile_protos` fails to generate the resultant package,
//! the failure is not obvious until the `include!(concat!(env!("OUT_DIR"), "/resultant.rs"));`
//! fails with `No such file or directory` error.

#![recursion_limit = "256"]
#![warn(
    missing_debug_implementations,
    missing_docs,
    rust_2018_idioms,
    unreachable_pub
)]
#![doc(
    html_logo_url = "https://raw.githubusercontent.com/tokio-rs/website/master/public/img/icons/tonic.svg"
)]
#![doc(html_root_url = "https://docs.rs/tonic-build/0.4.0")]
#![doc(issue_tracker_base_url = "https://github.com/hyperium/tonic/issues/")]
#![doc(test(no_crate_inject, attr(deny(rust_2018_idioms))))]
#![cfg_attr(docsrs, feature(doc_cfg))]

use proc_macro2::{Delimiter, Group, Ident, Literal, Punct, Spacing, Span, TokenStream};
use quote::TokenStreamExt;

/// Prost generator
#[cfg(feature = "prost")]
#[cfg_attr(docsrs, doc(cfg(feature = "prost")))]
mod prost;

#[cfg(feature = "prost")]
#[cfg_attr(docsrs, doc(cfg(feature = "prost")))]
pub use prost::{compile_protos, configure, Builder};

#[cfg(feature = "rustfmt")]
#[cfg_attr(docsrs, doc(cfg(feature = "rustfmt")))]
use std::io::{self, Write};
#[cfg(feature = "rustfmt")]
#[cfg_attr(docsrs, doc(cfg(feature = "rustfmt")))]
use std::process::{exit, Command};

/// Service code generation for client
pub mod client;
/// Service code generation for Server
pub mod server;

/// Service generation trait.
///
/// This trait can be implemented and consumed
/// by `client::generate` and `server::generate`
/// to allow any codegen module to generate service
/// abstractions.
pub trait Service {
    /// Path to the codec.
    const CODEC_PATH: &'static str;

    /// Comment type.
    type Comment: AsRef<str>;

    /// Method type.
    type Method: Method;

    /// Name of service.
    fn name(&self) -> &str;
    /// Package name of service.
    fn package(&self) -> &str;
    /// Identifier used to generate type name.
    fn identifier(&self) -> &str;
    /// Methods provided by service.
    fn methods(&self) -> &[Self::Method];
    /// Get comments about this item.
    fn comment(&self) -> &[Self::Comment];
}

/// Method generation trait.
///
/// Each service contains a set of generic
/// `Methods`'s that will be used by codegen
/// to generate abstraction implementations for
/// the provided methods.
pub trait Method {
    /// Path to the codec.
    const CODEC_PATH: &'static str;
    /// Comment type.
    type Comment: AsRef<str>;

    /// Name of method.
    fn name(&self) -> &str;
    /// Identifier used to generate type name.
    fn identifier(&self) -> &str;
    /// Method is streamed by client.
    fn client_streaming(&self) -> bool;
    /// Method is streamed by server.
    fn server_streaming(&self) -> bool;
    /// Get comments about this item.
    fn comment(&self) -> &[Self::Comment];
    /// Type name of request and response.
    fn request_response_name(
        &self,
        proto_path: &str,
        compile_well_known_types: bool,
    ) -> (TokenStream, TokenStream);
}

/// Format files under the out_dir with rustfmt
#[cfg(feature = "rustfmt")]
#[cfg_attr(docsrs, doc(cfg(feature = "rustfmt")))]
pub fn fmt(out_dir: &str) {
    let dir = std::fs::read_dir(out_dir).unwrap();

    for entry in dir {
        let file = entry.unwrap().file_name().into_string().unwrap();
        if !file.ends_with(".rs") {
            continue;
        }
        let result =
            Command::new(std::env::var("RUSTFMT").unwrap_or_else(|_| "rustfmt".to_owned()))
                .arg("--emit")
                .arg("files")
                .arg("--edition")
                .arg("2018")
                .arg(format!("{}/{}", out_dir, file))
                .output();

        match result {
            Err(e) => {
                eprintln!("error running rustfmt: {:?}", e);
                exit(1)
            }
            Ok(output) => {
                if !output.status.success() {
                    io::stderr().write_all(&output.stderr).unwrap();
                    exit(output.status.code().unwrap_or(1))
                }
            }
        }
    }
}

// Generate a singular line of a doc comment
fn generate_doc_comment<S: AsRef<str>>(comment: S) -> TokenStream {
    let mut doc_stream = TokenStream::new();

    doc_stream.append(Ident::new("doc", Span::call_site()));
    doc_stream.append(Punct::new('=', Spacing::Alone));
    doc_stream.append(Literal::string(comment.as_ref()));

    let group = Group::new(Delimiter::Bracket, doc_stream);

    let mut stream = TokenStream::new();
    stream.append(Punct::new('#', Spacing::Alone));
    stream.append(group);
    stream
}

// Generate a larger doc comment composed of many lines of doc comments
fn generate_doc_comments<T: AsRef<str>>(comments: &[T]) -> TokenStream {
    let mut stream = TokenStream::new();

    for comment in comments {
        stream.extend(generate_doc_comment(comment));
    }

    stream
}

fn naive_snake_case(name: &str) -> String {
    let mut s = String::new();
    let mut it = name.chars().peekable();

    while let Some(x) = it.next() {
        s.push(x.to_ascii_lowercase());
        if let Some(y) = it.peek() {
            if y.is_uppercase() {
                s.push('_');
            }
        }
    }

    s
}

#[test]
fn test_snake_case() {
    for case in &[
        ("Service", "service"),
        ("ThatHasALongName", "that_has_a_long_name"),
        ("greeter", "greeter"),
        ("ABCServiceX", "a_b_c_service_x"),
    ] {
        assert_eq!(naive_snake_case(case.0), case.1)
    }
}