Get the emacs and org-mode versions when launching the compare script.

src/compare/mod.rs

@@ -3,3 +3,5 @@ mod parse;
 mod util;
 pub use diff::compare_document;
 pub use parse::emacs_parse_org_document;
+pub use parse::get_emacs_version;
+pub use parse::get_org_mode_version;

src/compare/parse.rs

@@ -49,3 +49,40 @@ where
     }
     output
 }
+
+pub fn get_emacs_version() -> Result<String, Box<dyn std::error::Error>> {
+    let elisp_script = r#"(progn
+     (message "%s" (version))
+)"#;
+    let mut cmd = Command::new("emacs");
+    let proc = cmd
+        .arg("-q")
+        .arg("--no-site-file")
+        .arg("--no-splash")
+        .arg("--batch")
+        .arg("--eval")
+        .arg(elisp_script);
+
+    let out = proc.output()?;
+    out.status.exit_ok()?;
+    Ok(String::from_utf8(out.stderr)?)
+}
+
+pub fn get_org_mode_version() -> Result<String, Box<dyn std::error::Error>> {
+    let elisp_script = r#"(progn
+     (org-mode)
+     (message "%s" (org-version nil t nil))
+)"#;
+    let mut cmd = Command::new("emacs");
+    let proc = cmd
+        .arg("-q")
+        .arg("--no-site-file")
+        .arg("--no-splash")
+        .arg("--batch")
+        .arg("--eval")
+        .arg(elisp_script);
+
+    let out = proc.output()?;
+    out.status.exit_ok()?;
+    Ok(String::from_utf8(out.stderr)?)
+}