Generate license cache at build time

.gitignore

@@ -13,3 +13,6 @@
 
 # nix result from nix-build
 result
+
+# generated license cache
+resources/licenses/cache.bin.gz

Cargo.toml

@@ -19,6 +19,9 @@ strum = "0.16.0"
 strum_macros = "0.16.0"
 image = "0.22.3"
 
+[build-dependencies]
+askalono = "0.3.0"
+
 [target.'cfg(windows)'.dependencies]
 ansi_term = "0.12"
 

build.rs

@@ -0,0 +1,23 @@
+extern crate askalono;
+
+use std::fs::File;
+use std::path::Path;
+
+use askalono::Store;
+
+const EMBEDDED_CACHE: &str = "resources/licenses/cache.bin.gz";
+
+fn main() {
+    if Path::new(EMBEDDED_CACHE).exists() {
+        println!("cargo:warning=onefetch license cache file already exists; not re-building");
+        return;
+    }
+
+    let mut store = Store::new();
+    store
+        .load_spdx(Path::new("resources/licenses/spdx/json/details"), false)
+        .expect("Couldn't create a store from SPDX data");
+
+    let mut cache = File::create(EMBEDDED_CACHE).unwrap();
+    store.to_cache(&mut cache).unwrap();
+}

src/license.rs

@@ -4,7 +4,7 @@ use crate::Error;
 
 type Result<T> = std::result::Result<T, Error>;
 
-static CACHE_DATA: &[u8] = include_bytes!("../resources/license-cache.bin.gz");
+static CACHE_DATA: &[u8] = include_bytes!("../resources/licenses/cache.bin.gz");
 
 pub struct Detector {
     store: Store,