1 files changed, 70 insertions, 0 deletions
diff --git a/cli/lockfile.rs b/cli/lockfile.rs
new file mode 100644
index 000000000..f8700dac1
--- /dev/null
+++ b/cli/lockfile.rs
@@ -0,0 +1,70 @@
+use crate::compilers::CompiledModule;
+use serde_json::json;
+pub use serde_json::Value;
+use std::collections::HashMap;
+use std::io::Result;
+
+pub struct Lockfile {
+  need_read: bool,
+  map: HashMap<String, String>,
+  pub filename: String,
+}
+
+impl Lockfile {
+  pub fn new(filename: String) -> Lockfile {
+    Lockfile {
+      map: HashMap::new(),
+      filename,
+      need_read: true,
+    }
+  }
+
+  pub fn write(&self) -> Result<()> {
+    let j = json!(self.map);
+    let s = serde_json::to_string_pretty(&j).unwrap();
+    let mut f = std::fs::OpenOptions::new()
+      .write(true)
+      .create(true)
+      .truncate(true)
+      .open(&self.filename)?;
+    use std::io::Write;
+    f.write_all(s.as_bytes())?;
+    debug!("lockfile write {}", self.filename);
+    Ok(())
+  }
+
+  pub fn read(&mut self) -> Result<()> {
+    debug!("lockfile read {}", self.filename);
+    let s = std::fs::read_to_string(&self.filename)?;
+    self.map = serde_json::from_str(&s)?;
+    self.need_read = false;
+    Ok(())
+  }
+
+  /// Lazily reads the filename, checks the given module is included.
+  /// Returns Ok(true) if check passed
+  pub fn check(&mut self, m: &CompiledModule) -> Result<bool> {
+    if m.name.starts_with("file:") {
+      return Ok(true);
+    }
+    if self.need_read {
+      self.read()?;
+    }
+    assert!(!self.need_read);
+    Ok(if let Some(lockfile_checksum) = self.map.get(&m.name) {
+      let compiled_checksum = crate::checksum::gen2(&m.code);
+      lockfile_checksum == &compiled_checksum
+    } else {
+      false
+    })
+  }
+
+  // Returns true if module was not already inserted.
+  pub fn insert(&mut self, m: &CompiledModule) -> bool {
+    if m.name.starts_with("file:") {
+      return false;
+    }
+    let checksum = crate::checksum::gen2(&m.code);
+    self.map.insert(m.name.clone(), checksum).is_none()
+  }
+}