Add ability to make compile_commands.json (#13)

issue: #8
Reviewed-on: http://192.168.1.227:3000/sfrembling/pallet/pulls/13
Co-authored-by: godsfryingpan <sfrembling@gmail.com>
Co-committed-by: godsfryingpan <sfrembling@gmail.com>

src/app.rs

@@ -9,7 +9,7 @@ use colored::Colorize;
 use glob::glob;
 
 const MAIN_C: &str = include_str!("templates/main.c");
-const GITIGNORE: &str = "target/";
+const GITIGNORE: &str = "target/\ncompile_commands.json\n";
 
 #[derive(clap::Parser)]
 #[clap(version, about)]
@@ -65,6 +65,11 @@ enum UtilSubcommand {
         #[arg(value_enum, long, short)]
         shell: ShellCompletions,
     },
+    /// Generate compile_commands.json for IDE support
+    GenCompileCommands {
+        /// The build mode to generate for
+        mode: Option<String>,
+    },
 }
 
 #[derive(Clone, clap::ValueEnum)]
@@ -150,6 +155,12 @@ impl App {
                         ),
                     }
                 }
+                UtilSubcommand::GenCompileCommands { mode } => {
+                    if let Err(e) = gen_compile_commands(&mode) {
+                        eprintln!("Error generating compile commands: {e}");
+                        std::process::exit(1);
+                    }
+                }
             },
             Subcommand::List => {
                 if let Err(e) = list() {
@@ -161,6 +172,55 @@ impl App {
     }
 }
 
+fn gen_compile_commands(mode: &Option<String>) -> std::io::Result<()> {
+    let conf = get_config().ok_or(std::io::Error::new(
+        std::io::ErrorKind::NotFound,
+        "no Pallet.toml found in current directory",
+    ))?;
+
+    let build_config = conf.get_or_default(mode).ok_or(std::io::Error::new(
+        std::io::ErrorKind::NotFound,
+        "build layout not found",
+    ))?;
+
+    let compiler = conf.compiler.as_deref().unwrap_or("gcc");
+    let cwd = std::env::current_dir()?;
+    let obj_dir = format!("target/{}/obj", build_config.name);
+
+    let source_files: Vec<PathBuf> = glob("src/*.c")
+        .map_err(|e| std::io::Error::new(std::io::ErrorKind::NotFound, format!("{e}")))?
+        .filter_map(|e| e.ok())
+        .collect();
+
+    let entries: Vec<serde_json::Value> = source_files
+        .iter()
+        .map(|src| {
+            let stem = src.file_stem().unwrap().to_string_lossy();
+            let obj = format!("{}/{}.o", obj_dir, stem);
+            let command = std::iter::once(compiler.to_string())
+                .chain(build_config.args.iter().cloned())
+                .chain(["-c".to_string(), src.to_string_lossy().to_string()])
+                .chain(["-o".to_string(), obj])
+                .collect::<Vec<_>>()
+                .join(" ");
+            serde_json::json!({
+                "directory": cwd.to_string_lossy(),
+                "file": cwd.join(src).to_string_lossy(),
+                "command": command
+            })
+        })
+        .collect();
+
+    let json = serde_json::to_string_pretty(&entries)
+        .map_err(|e| std::io::Error::new(std::io::ErrorKind::Other, format!("{e}")))?;
+
+    std::fs::write("compile_commands.json", json)?;
+
+    println!("  {} compile_commands.json", "Generated".green().bold());
+
+    Ok(())
+}
+
 fn list() -> std::io::Result<()> {
     let conf = get_config().ok_or(std::io::Error::new(
         std::io::ErrorKind::NotFound,
@@ -331,6 +391,8 @@ fn build(mode: &Option<String>, force_recompile: bool) -> std::io::Result<()> {
 
     let stop = start.elapsed();
 
+    gen_compile_commands(&mode)?;
+
     println!(
         "   {} '{}' profile for project '{}' in {:.2}s",
         "Finished".green().bold(),