Dump the elisp when running compare.

src/compare/mod.rs

@@ -1 +1,2 @@
-
+mod parse;
+pub use parse::emacs_parse_org_document;

src/compare/parse.rs

@@ -0,0 +1,26 @@
+use std::path::Path;
+use std::process::Command;
+
+pub fn emacs_parse_org_document<'a, C>(file_path: C) -> Result<String, Box<dyn std::error::Error>>
+where
+    C: AsRef<Path>,
+{
+    let elisp_script = r#"(progn
+     (org-mode)
+     (message "%s" (pp-to-string (org-element-parse-buffer)))
+)"#;
+    let mut cmd = Command::new("emacs");
+    let proc = cmd
+        .arg("-q")
+        .arg("--no-site-file")
+        .arg("--no-splash")
+        .arg("--batch")
+        .arg("--insert")
+        .arg(file_path.as_ref().as_os_str())
+        .arg("--eval")
+        .arg(elisp_script);
+    let out = proc.output()?;
+    out.status.exit_ok()?;
+    let org_sexp = out.stderr;
+    Ok(String::from_utf8(org_sexp)?)
+}