change to a library

src/lib.rs

@@ -2016,7 +2016,7 @@ struct Parser<'ctx> {
 }
 
 #[derive(Debug)]
-struct Error(String, Backtrace);
+pub struct Error(String, Backtrace);
 
 impl fmt::Display for Error {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
@@ -2026,6 +2026,8 @@ impl fmt::Display for Error {
     }
 }
 
+impl std::error::Error for Error {}
+
 trait IntoError: fmt::Display {}
 
 impl<T: IntoError> From<T> for Error {
@@ -3831,10 +3833,22 @@ fn main_inner() -> Result<(), Error> {
     } else {
         None
     };
+
+    std::fs::write(
+        "powerisa-instructions.xml",
+        parse_powerisa_pdf_and_generate_xml(&args[1], page_numbers, dump_mupdf_page_xml)?,
+    )?;
+    Ok(())
+}
+
+pub fn parse_powerisa_pdf_and_generate_xml(
+    file_name: &str,
+    page_numbers: Option<Box<dyn Iterator<Item = NonZero<u32>>>>,
+    dump_mupdf_page_xml: bool,
+) -> Result<String, Error> {
     mupdf_ffi::Context::with(|ctx| {
         let mut parser = Parser::new();
         let is_subset = page_numbers.is_some();
-        let file_name = &args[1];
         parser.parse_pdf(ctx, file_name, page_numbers, dump_mupdf_page_xml)?;
         let mut insns = xml_tree::Element::new(
             "instructions".into(),
@@ -3858,16 +3872,15 @@ fn main_inner() -> Result<(), Error> {
         }
         let mut output = Vec::new();
         insns.write(&mut output, true)?;
-        std::fs::write("powerisa-instructions.xml", output)?;
-        Ok(())
+        Ok(String::from_utf8(output).expect("known to generate valid utf-8"))
     })
 }
 
-fn main() -> std::process::ExitCode {
+pub fn main() -> std::process::ExitCode {
     match main_inner() {
         Ok(()) => std::process::ExitCode::SUCCESS,
         Err(e) => {
-            println!("Error: {e}");
+            eprintln!("Error: {e}");
             std::process::ExitCode::FAILURE
         }
     }

src/main.rs

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: LGPL-3.0-or-later
+// See Notices.txt for copyright information
+
+fn main() -> std::process::ExitCode {
+    parse_powerisa_pdf::main()
+}