Add rust code to invoke the shim

src/duster/mod.rs

@@ -0,0 +1,7 @@
+//! This module contains a rust implementation of LinkedIn Dust
+
+mod node_invoker;
+
+pub use node_invoker::run_node_dust;
+pub use node_invoker::NodeError;
+pub use node_invoker::Result;

src/duster/node_invoker.rs

@@ -0,0 +1,61 @@
+use std::error;
+use std::fmt;
+use std::io::Write;
+use std::process::Output;
+use std::process::{Command, Stdio};
+
+pub type Result<T> = std::result::Result<T, NodeError>;
+
+#[derive(Clone)]
+pub struct NodeError {
+    output: Output,
+}
+
+impl fmt::Display for NodeError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(
+            f,
+            "Error from node: {}",
+            String::from_utf8_lossy(&self.output.stderr)
+        )
+    }
+}
+
+impl fmt::Debug for NodeError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(
+            f,
+            "Error from node: {}",
+            String::from_utf8_lossy(&self.output.stderr)
+        )
+    }
+}
+
+impl error::Error for NodeError {
+    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
+        None
+    }
+}
+
+/// Invokes Node to run the authentic LinkedIn Dust
+pub fn run_node_dust(template_path: &str, context: &str) -> Result<String> {
+    let mut proc = Command::new("node")
+        .arg("./src/js/dustjs_shim.js")
+        .arg(template_path)
+        .stdin(Stdio::piped())
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped())
+        .spawn()
+        .expect("failed to execute process");
+    proc.stdin
+        .take()
+        .unwrap()
+        .write_all(context.as_bytes())
+        .expect("Failed to write to stdin of node process");
+    let output = proc.wait_with_output().expect("Failed to wait on node");
+    if output.status.success() {
+        Ok(String::from_utf8(output.stdout).expect("Invalid UTF-8 from node process"))
+    } else {
+        Err(NodeError { output: output })
+    }
+}