1 files changed, 95 insertions, 0 deletions
diff --git a/core/snapshot_util.rs b/core/snapshot_util.rs
new file mode 100644
index 000000000..b408bad56
--- /dev/null
+++ b/core/snapshot_util.rs
@@ -0,0 +1,95 @@
+use crate::Extension;
+use crate::JsRuntime;
+use crate::RuntimeOptions;
+use crate::Snapshot;
+use std::path::Path;
+use std::path::PathBuf;
+
+pub type CompressionCb = dyn Fn(&mut Vec<u8>, &[u8]);
+
+pub struct CreateSnapshotOptions {
+  pub cargo_manifest_dir: &'static str,
+  pub snapshot_path: PathBuf,
+  pub startup_snapshot: Option<Snapshot>,
+  pub extensions: Vec<Extension>,
+  pub additional_files: Vec<PathBuf>,
+  pub compression_cb: Option<Box<CompressionCb>>,
+}
+
+pub fn create_snapshot(create_snapshot_options: CreateSnapshotOptions) {
+  let mut js_runtime = JsRuntime::new(RuntimeOptions {
+    will_snapshot: true,
+    startup_snapshot: create_snapshot_options.startup_snapshot,
+    extensions: create_snapshot_options.extensions,
+    ..Default::default()
+  });
+
+  // TODO(nayeemrmn): https://github.com/rust-lang/cargo/issues/3946 to get the
+  // workspace root.
+  let display_root = Path::new(create_snapshot_options.cargo_manifest_dir)
+    .parent()
+    .unwrap();
+  for file in create_snapshot_options.additional_files {
+    let display_path = file.strip_prefix(display_root).unwrap_or(&file);
+    let display_path_str = display_path.display().to_string();
+    js_runtime
+      .execute_script(
+        &("deno:".to_string() + &display_path_str.replace('\\', "/")),
+        &std::fs::read_to_string(&file).unwrap(),
+      )
+      .unwrap();
+  }
+
+  let snapshot = js_runtime.snapshot();
+  let snapshot_slice: &[u8] = &snapshot;
+  println!("Snapshot size: {}", snapshot_slice.len());
+
+  let maybe_compressed_snapshot: Box<dyn AsRef<[u8]>> =
+    if let Some(compression_cb) = create_snapshot_options.compression_cb {
+      let mut vec = vec![];
+
+      vec.extend_from_slice(
+        &u32::try_from(snapshot.len())
+          .expect("snapshot larger than 4gb")
+          .to_le_bytes(),
+      );
+
+      (compression_cb)(&mut vec, snapshot_slice);
+
+      println!("Snapshot compressed size: {}", vec.len());
+
+      Box::new(vec)
+    } else {
+      Box::new(snapshot_slice)
+    };
+
+  std::fs::write(
+    &create_snapshot_options.snapshot_path,
+    &*maybe_compressed_snapshot,
+  )
+  .unwrap();
+  println!(
+    "Snapshot written to: {} ",
+    create_snapshot_options.snapshot_path.display()
+  );
+}
+
+pub fn get_js_files(
+  cargo_manifest_dir: &'static str,
+  directory: &str,
+) -> Vec<PathBuf> {
+  let manifest_dir = Path::new(cargo_manifest_dir);
+  let mut js_files = std::fs::read_dir(directory)
+    .unwrap()
+    .map(|dir_entry| {
+      let file = dir_entry.unwrap();
+      manifest_dir.join(file.path())
+    })
+    .filter(|path| {
+      path.extension().unwrap_or_default() == "js"
+        && !path.ends_with("99_main.js")
+    })
+    .collect::<Vec<PathBuf>>();
+  js_files.sort();
+  js_files
+}