Replace spv-lower-dump example with a more useful spv-lower-print…

… one. (#30)

examples/spv-lower-print.rs

@@ -0,0 +1,47 @@
+use std::fs;
+use std::path::Path;
+use std::rc::Rc;
+
+fn main() -> std::io::Result<()> {
+    match &std::env::args().collect::<Vec<_>>()[..] {
+        [_, in_files @ ..] => {
+            for in_file in in_files {
+                let in_file_path = Path::new(in_file);
+
+                let save_print_plan = |suffix: &str, plan: spirt::print::Plan| {
+                    let pretty = plan.pretty_print();
+                    let ext = if suffix.is_empty() {
+                        "spirt".into()
+                    } else {
+                        format!("{suffix}.spirt")
+                    };
+
+                    // FIXME(eddyb) don't allocate whole `String`s here.
+                    fs::write(in_file_path.with_extension(&ext), pretty.to_string())?;
+                    fs::write(
+                        in_file_path.with_extension(ext + ".html"),
+                        pretty
+                            .render_to_html()
+                            .with_dark_mode_support()
+                            .to_html_doc(),
+                    )
+                };
+
+                let mut module = spirt::Module::lower_from_spv_file(
+                    Rc::new(spirt::Context::new()),
+                    in_file_path,
+                )?;
+                save_print_plan("", spirt::print::Plan::for_module(&module))?;
+
+                spirt::passes::legalize::structurize_func_cfgs(&mut module);
+                save_print_plan("structured", spirt::print::Plan::for_module(&module))?;
+            }
+
+            Ok(())
+        }
+        args => {
+            eprintln!("Usage: {} FILES", args[0]);
+            std::process::exit(1);
+        }
+    }
+}