build.rs

//! # build.rs for s3d
//!
//! This is the cargo build script which is called during build.
//! We use it to generate code that for the S3 protocol.
//!
//! It reads the S3 smithy model as input, and writes generated code out to `$OUT_DIR/`,
//! which is then included! in the src/build_gen.rs file.
//!
//! The S3 protocol is defined in a Smithy JSON AST model:
//! - https://github.com/awslabs/smithy-rs/blob/main/aws/sdk/aws-models/s3.json
//!

// the build script flow uses a module not under src
mod codegen;

use crate::{
    codegen::gen_commands::GenCommands,
    codegen::gen_converters::GenConverters,
    codegen::smithy_model::{FromJson, SmithyModel},
};
use std::{env, path::Path};

/// main function of the project's cargo build script
/// See https://doc.rust-lang.org/cargo/reference/build-scripts.html
fn main() {
    println!("cargo:warning=build codegen starting...");

    let out_dir = env::var("OUT_DIR").unwrap();
    let out_path = Path::new(out_dir.as_str());
    let model_path = Path::new("smithy-rs/aws/sdk/aws-models/s3.json");

    // printing out cargo directives
    println!("cargo:rerun-if-changed=build.rs");
    println!("cargo:rerun-if-changed=codegen/");
    println!("cargo:rerun-if-changed={}", model_path.display());

    // load the smithy model and invoke code generators
    let model = SmithyModel::from_json_file(&model_path);
    GenCommands::new(&model, &out_path.join("s3_cli.rs")).generate();
    GenConverters::new(&model, &out_path.join("s3_conv.rs")).generate();

    println!("cargo:warning=build codegen done.");
}