74 lines
2.2 KiB
Rust
74 lines
2.2 KiB
Rust
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//! Derive the runtime surface descriptor from the trait declarations
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//! in `src/runtime/mod.rs`.
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//!
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//! Parsing the source with `syn` at build time means the descriptor
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//! cannot drift: a signature edit that does not also touch
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//! `surface.lock` fails `tests/surface_locked.rs`.
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//!
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//! Output goes to `$OUT_DIR/surface_descriptor.txt` and is consumed by
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//! `src/runtime/mod.rs` via `include_str!`.
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use std::env;
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use std::fs;
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use std::path::PathBuf;
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use quote::ToTokens;
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const RUNTIME_SRC: &str = "src/runtime/mod.rs";
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fn main() {
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println!("cargo:rerun-if-changed={RUNTIME_SRC}");
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println!("cargo:rerun-if-changed=build.rs");
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let src = fs::read_to_string(RUNTIME_SRC).expect("read runtime source");
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let file = syn::parse_file(&src).expect("parse runtime source");
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let descriptor = build_descriptor(&file);
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let out_dir = PathBuf::from(env::var_os("OUT_DIR").expect("OUT_DIR not set"));
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fs::write(out_dir.join("surface_descriptor.txt"), descriptor)
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.expect("write surface_descriptor.txt");
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}
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fn build_descriptor(file: &syn::File) -> String {
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let mut out = String::new();
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out.push_str("runtime surface descriptor v1\n");
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let traits_mod = file
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.items
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.iter()
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.find_map(|item| match item {
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syn::Item::Mod(m) if m.ident == "traits" => Some(m),
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_ => None,
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})
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.expect("`pub mod traits` not found in runtime source");
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let (_, items) = traits_mod
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.content
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.as_ref()
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.expect("`pub mod traits` is declaration-only; expected inline body");
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for item in items {
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if let syn::Item::Trait(t) = item {
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out.push_str("trait ");
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out.push_str(&t.ident.to_string());
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out.push('\n');
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for trait_item in &t.items {
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if let syn::TraitItem::Fn(f) = trait_item {
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let sig = normalize_whitespace(&f.sig.to_token_stream().to_string());
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out.push_str(" ");
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out.push_str(&sig);
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out.push('\n');
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}
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}
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}
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}
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out
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}
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fn normalize_whitespace(s: &str) -> String {
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s.split_whitespace().collect::<Vec<_>>().join(" ")
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}
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