Add lsp command to fix rust-analyzer

src/main.rs

@@ -1,4 +1,5 @@
 use crate::exercise::{Exercise, ExerciseList};
+use crate::project::RustAnalyzerProject;
 use crate::run::run;
 use crate::verify::verify;
 use argh::FromArgs;
@@ -20,6 +21,7 @@ use std::time::Duration;
 mod ui;
 
 mod exercise;
+mod project;
 mod run;
 mod verify;
 
@@ -47,6 +49,7 @@ enum Subcommands {
     Run(RunArgs),
     Hint(HintArgs),
     List(ListArgs),
+    Lsp(LspArgs),
 }
 
 #[derive(FromArgs, PartialEq, Debug)]
@@ -77,6 +80,12 @@ struct HintArgs {
     name: String,
 }
 
+#[derive(FromArgs, PartialEq, Debug)]
+#[argh(subcommand, name = "lsp")]
+/// Enable rust-analyzer for exercises
+struct LspArgs {}
+
+
 #[derive(FromArgs, PartialEq, Debug)]
 #[argh(subcommand, name = "list")]
 /// Lists the exercises available in Rustlings
@@ -206,6 +215,25 @@ fn main() {
             verify(&exercises, (0, exercises.len()), verbose).unwrap_or_else(|_| std::process::exit(1));
         }
 
+        Subcommands::Lsp(_subargs) => {
+            let mut project = RustAnalyzerProject::new();
+            project
+                .get_sysroot_src()
+                .expect("Couldn't find toolchain path, do you have `rustc` installed?");
+            project
+                .exercies_to_json()
+                .expect("Couldn't parse rustlings exercises files");
+
+            if project.crates.is_empty() {
+                println!("Failed find any exercises, make sure you're in the `rustlings` folder");
+            } else if project.write_to_disk().is_err() {
+                println!("Failed to write rust-project.json to disk for rust-analyzer");
+            } else {
+                println!("Successfully generated rust-project.json");
+                println!("rust-analyzer will now parse exercises, restart your language server or editor")
+            }
+        }
+
         Subcommands::Watch(_subargs) => match watch(&exercises, verbose) {
             Err(e) => {
                 println!("Error: Could not watch your progress. Error message was {:?}.", e);
@@ -224,6 +252,7 @@ fn main() {
     }
 }
 
+
 fn spawn_watch_shell(failed_exercise_hint: &Arc<Mutex<Option<String>>>, should_quit: Arc<AtomicBool>) {
     let failed_exercise_hint = Arc::clone(failed_exercise_hint);
     println!("Welcome to watch mode! You can type 'help' to get an overview of the commands you can use here.");
@@ -367,6 +396,8 @@ started, here's a couple of notes about how Rustlings operates:
 4. If an exercise doesn't make sense to you, feel free to open an issue on GitHub!
    (https://github.com/rust-lang/rustlings/issues/new). We look at every issue,
    and sometimes, other learners do too so you can help each other out!
+5. If you want to use `rust-analyzer` with exercises, which provides features like 
+   autocompletion, run the command `rustlings lsp`. 
 
 Got all that? Great! To get started, run `rustlings watch` in order to get the first
 exercise. Make sure to have your editor open!"#;

src/project.rs

@@ -0,0 +1,90 @@
+use glob::glob;
+use serde::{Deserialize, Serialize};
+use std::error::Error;
+use std::process::Command;
+
+/// Contains the structure of resulting rust-project.json file
+/// and functions to build the data required to create the file
+#[derive(Serialize, Deserialize)]
+pub struct RustAnalyzerProject {
+    sysroot_src: String,
+    pub crates: Vec<Crate>,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct Crate {
+    root_module: String,
+    edition: String,
+    deps: Vec<String>,
+    cfg: Vec<String>,
+}
+
+impl RustAnalyzerProject {
+    pub fn new() -> RustAnalyzerProject {
+        RustAnalyzerProject {
+            sysroot_src: String::new(),
+            crates: Vec::new(),
+        }
+    }
+
+    /// Write rust-project.json to disk
+    pub fn write_to_disk(&self) -> Result<(), std::io::Error> {
+        std::fs::write(
+            "./rust-project.json",
+            serde_json::to_vec(&self).expect("Failed to serialize to JSON"),
+        )?;
+        Ok(())
+    }
+
+    /// If path contains .rs extension, add a crate to `rust-project.json`
+    fn path_to_json(&mut self, path: String) {
+        if let Some((_, ext)) = path.split_once('.') {
+            if ext == "rs" {
+                self.crates.push(Crate {
+                    root_module: path,
+                    edition: "2021".to_string(),
+                    deps: Vec::new(),
+                    // This allows rust_analyzer to work inside #[test] blocks
+                    cfg: vec!["test".to_string()],
+                })
+            }
+        }
+    }
+
+    /// Parse the exercises folder for .rs files, any matches will create
+    /// a new `crate` in rust-project.json which allows rust-analyzer to
+    /// treat it like a normal binary
+    pub fn exercies_to_json(&mut self) -> Result<(), Box<dyn Error>> {
+        for e in glob("./exercises/**/*")? {
+            let path = e?.to_string_lossy().to_string();
+            self.path_to_json(path);
+        }
+        Ok(())
+    }
+
+    /// Use `rustc` to determine the default toolchain
+    pub fn get_sysroot_src(&mut self) -> Result<(), Box<dyn Error>> {
+        let toolchain = Command::new("rustc")
+            .arg("--print")
+            .arg("sysroot")
+            .output()?
+            .stdout;
+
+        let toolchain = String::from_utf8_lossy(&toolchain);
+        let mut whitespace_iter = toolchain.split_whitespace();
+
+        let toolchain = whitespace_iter.next().unwrap_or(&toolchain);
+
+        println!("Determined toolchain: {}\n", &toolchain);
+
+        self.sysroot_src = (std::path::Path::new(&*toolchain)
+            .join("lib")
+            .join("rustlib")
+            .join("src")
+            .join("rust")
+            .join("library")
+            .to_string_lossy())
+        .to_string();
+        Ok(())
+    }
+}