initial commit

src/output.rs

@@ -0,0 +1,28 @@
+use std::collections::BTreeMap;
+
+use eyre::{bail, Context};
+use serde::Serialize;
+use serde_json::Value;
+
+#[derive(Default)]
+pub struct Output {
+    elements: BTreeMap<&'static str, Value>,
+}
+
+impl Output {
+    pub fn write(&mut self, key: &'static str, v: &impl Serialize) -> eyre::Result<()> {
+        let v = serde_json::to_value(v).wrap_err("failed to serialize output")?;
+        if self.elements.insert(key, v).is_some() {
+            bail!("duplicated output key {key:?}");
+        }
+        Ok(())
+    }
+}
+
+impl Drop for Output {
+    fn drop(&mut self) {
+        let out =
+            serde_json::to_string_pretty(&self.elements).expect("can serialize output as json");
+        println!("{out}",);
+    }
+}