Refactor and refine PDF exporter ♻

1 files changed, 11 insertions, 19 deletions

diff --git a/src/bin/main.rs b/src/bin/main.rs
index 58b2c00e..c8028c7f 100644
--- a/src/bin/main.rs
+++ b/src/bin/main.rs
@@ -16,7 +16,6 @@ fn main() {
     }
 }
 
-/// The actual main function.
 fn run() -> Result<(), Box<dyn Error>> {
     let args: Vec<String> = env::args().collect();
     if args.len() < 2 || args.len() > 3 {
@@ -24,42 +23,30 @@ fn run() -> Result<(), Box<dyn Error>> {
     }
 
     let source_path = Path::new(&args[1]);
-
-    // Compute the output filename from the input filename by replacing the
-    // extension.
     let dest_path = if args.len() <= 2 {
-        let stem = source_path
-            .file_stem()
-            .ok_or_else(|| "missing destation file name")?;
-
-        let base = source_path
-            .parent()
-            .ok_or_else(|| "missing destation folder")?;
-
-        base.join(format!("{}.pdf", stem.to_string_lossy()))
+        source_path.with_extension("pdf")
     } else {
         PathBuf::from(&args[2])
     };
 
     if dest_path == source_path {
-        return Err("source and destination path are the same".into());
+        return err("source and destination path are the same");
     }
 
+    let mut source_file = File::open(source_path)
+        .map_err(|_| "failed to open source file")?;
+
     let mut src = String::new();
-    let mut source_file = File::open(source_path).map_err(|_| "failed to open source file")?;
     source_file
         .read_to_string(&mut src)
         .map_err(|_| "failed to read from source file")?;
 
-    // Create a typesetter with a font provider that provides the default fonts.
     let mut typesetter = Typesetter::new();
     let provider = FileSystemFontProvider::from_listing("fonts/fonts.toml").unwrap();
     typesetter.add_font_provider(provider);
 
-    // Typeset the source code.
     let document = typesetter.typeset(&src)?;
 
-    // Export the document into a PDF file.
     let exporter = PdfExporter::new();
     let dest_file = File::create(&dest_path)?;
     exporter.export(&document, typesetter.loader(), BufWriter::new(dest_file))?;
@@ -67,7 +54,12 @@ fn run() -> Result<(), Box<dyn Error>> {
     Ok(())
 }
 
-/// Print a usage message and quit.
+/// Construct an error `Result` from a message.
+fn err<S: Into<String>, T>(message: S) -> Result<T, Box<dyn Error>> {
+    Err(message.into().into())
+}
+
+/// Print a usage message and exit the process.
 fn help_and_quit() {
     let name = env::args().next().unwrap_or("typst".to_string());
     println!("usage: {} source [destination]", name);