cli: add subcommand support

crates/app/src/config.rs

@@ -1,18 +1,11 @@
-use std::path::PathBuf;
+use self::config_file::{find_config_file, Configs};
-
+pub(crate) use cli::CliConfigs;
-use clap::Parser;
-
-use self::{
-    cli::Args,
-    config_file::{find_config_file, Configs},
-};
 
 mod cli;
 mod config_file;
 
 /// this struct may hold all configuration
 pub struct Config {
-    pub source: PathBuf,
     pub evaluator: eval::Available,
 
     pub startup_msg: bool,
@@ -20,10 +13,9 @@ pub struct Config {
 
 impl Config {
     /// Get the configs from all possible places (args, file, env...)
-    pub fn read() -> Self {
+    pub fn read(args: &CliConfigs) -> Self {
-        let args = Args::parse();
+        let config = if let Some(config) = &args.config_path {
-        let config = if let Some(config) = args.config_path {
+            Ok(config.clone())
-            Ok(config)
         } else {
             find_config_file()
         };
@@ -42,7 +34,6 @@ impl Config {
 
         if let Some(file) = config {
             Self {
-                source: args.source,
                 evaluator: args.evaluator.and(file.evaluator).unwrap_or_default(),
                 // this is negated because to an outward api, the negative is more intuitive,
                 // while in the source the other way around is more intuitive
@@ -50,7 +41,6 @@ impl Config {
             }
         } else {
             Self {
-                source: args.source,
                 startup_msg: !args.no_startup_message,
                 evaluator: args.evaluator.unwrap_or_default(),
             }

crates/app/src/config/cli.rs

@@ -1,12 +1,9 @@
 use std::path::PathBuf;
 
-use clap::{builder::BoolishValueParser, ArgAction, Parser};
+use clap::{builder::BoolishValueParser, ArgAction, Args};
-
-#[derive(Parser)]
-pub(crate) struct Args {
-    /// What file contains the pipeline to evaluate.
-    pub source: PathBuf,
 
+#[derive(Args)]
+pub(crate) struct CliConfigs {
     /// How to actually run the pipeline.
     /// Overrides the config file. Defaults to the debug evaluator.
     #[arg(short, long)]

crates/app/src/main.rs

@@ -1,6 +1,7 @@
-use std::fs;
+use std::{fs, path::PathBuf};
 
-use config::Config;
+use clap::{Parser, Subcommand};
+use config::{CliConfigs, Config};
 use welcome_msg::print_startup_msg;
 
 mod config;
@@ -9,19 +10,44 @@ mod config;
 mod error_reporting;
 mod welcome_msg;
 
+#[derive(Parser)]
+struct Args {
+    #[command(flatten)]
+    configs: CliConfigs,
+    #[command(subcommand)]
+    command: Commands,
+}
+
+#[derive(Subcommand)]
+enum Commands {
+    Run {
+        /// What file contains the pipeline to evaluate.
+        source: PathBuf,
+    },
+    Dev,
+}
+
 fn main() {
     // TODO: proper error handling across the whole function
     //       don't forget to also look inside `Config`
-    let cfg = Config::read();
+    let args = Args::parse();
+    let cfg = Config::read(&args.configs);
 
     if cfg.startup_msg {
         print_startup_msg();
     }
 
-    let source = fs::read_to_string(cfg.source).expect("can't find source file");
+    match args.command {
+        Commands::Run { source } => {
+            let source = fs::read_to_string(source).expect("can't find source file");
             let ir = ir::from_ron(&source).expect("failed to parse source to graph ir");
 
             let mut machine = cfg.evaluator.pick();
             machine.feed(ir);
             machine.eval_full();
         }
+        Commands::Dev => {
+            println!("Hello world!");
+        }
+    }
+}