Merge pull request #1917 from mo8it/project

Rewrite `project.rs`

4 files changed, 75 insertions, 94 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 2cb0b9f..11880b7 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -60,6 +60,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "anyhow"
+version = "1.0.81"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0952808a6c2afd1aa8947271f3a60f1a6763c7b912d210184c5149b5cf147247"
+
+[[package]]
 name = "assert_cmd"
 version = "2.0.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -560,6 +566,7 @@ dependencies = [
 name = "rustlings"
 version = "5.6.1"
 dependencies = [
+ "anyhow",
  "assert_cmd",
  "clap",
  "console",
diff --git a/Cargo.toml b/Cargo.toml
index 89366a0..36e1123 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,9 +9,9 @@ authors = [
 edition = "2021"
 
 [dependencies]
+anyhow = "1.0.81"
 clap = { version = "4.5.2", features = ["derive"] }
 console = "0.15.8"
-glob = "0.3.0"
 indicatif = "0.17.8"
 notify-debouncer-mini = "0.4.1"
 serde_json = "1.0.114"
diff --git a/src/main.rs b/src/main.rs
index a513e71..8f73dbb 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,7 +1,8 @@
 use crate::exercise::{Exercise, ExerciseList};
-use crate::project::RustAnalyzerProject;
+use crate::project::write_project_json;
 use crate::run::{reset, run};
 use crate::verify::verify;
+use anyhow::Result;
 use clap::{Parser, Subcommand};
 use console::Emoji;
 use notify_debouncer_mini::notify::{self, RecursiveMode};
@@ -85,7 +86,7 @@ enum Subcommands {
     Lsp,
 }
 
-fn main() {
+fn main() -> Result<()> {
     let args = Args::parse();
 
     if args.command.is_none() {
@@ -218,18 +219,8 @@ fn main() {
         }
 
         Subcommands::Lsp => {
-            let mut project = RustAnalyzerProject::new();
-            project
-                .get_sysroot_src()
-                .expect("Couldn't find toolchain path, do you have `rustc` installed?");
-            project
-                .exercises_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");
+            if let Err(e) = write_project_json(exercises) {
+                println!("Failed to write rust-project.json to disk for rust-analyzer: {e}");
             } else {
                 println!("Successfully generated rust-project.json");
                 println!("rust-analyzer will now parse exercises, restart your language server or editor");
@@ -255,6 +246,8 @@ fn main() {
             }
         },
     }
+
+    Ok(())
 }
 
 fn spawn_watch_shell(
diff --git a/src/project.rs b/src/project.rs
index 00fc304..0f56de9 100644
--- a/src/project.rs
+++ b/src/project.rs
@@ -1,102 +1,83 @@
-use glob::glob;
-use serde::{Deserialize, Serialize};
+use anyhow::{Context, Result};
+use serde::Serialize;
 use std::env;
-use std::error::Error;
-use std::path::{Path, PathBuf};
-use std::process::Command;
+use std::path::PathBuf;
+use std::process::{Command, Stdio};
+
+use crate::exercise::Exercise;
 
 /// 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)]
+struct RustAnalyzerProject {
+    sysroot_src: PathBuf,
+    crates: Vec<Crate>,
 }
 
-#[derive(Serialize, Deserialize)]
-pub struct Crate {
-    root_module: String,
-    edition: String,
-    deps: Vec<String>,
-    cfg: Vec<String>,
+#[derive(Serialize)]
+struct Crate {
+    root_module: PathBuf,
+    edition: &'static str,
+    // Not used, but required in the JSON file.
+    deps: Vec<()>,
+    // Only `test` is used for all crates.
+    // Therefore, an array is used instead of a `Vec`.
+    cfg: [&'static str; 1],
 }
 
 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(())
-    }
+    fn build(exercises: Vec<Exercise>) -> Result<Self> {
+        let crates = exercises
+            .into_iter()
+            .map(|exercise| Crate {
+                root_module: exercise.path,
+                edition: "2021",
+                deps: Vec::new(),
+                // This allows rust_analyzer to work inside `#[test]` blocks
+                cfg: ["test"],
+            })
+            .collect();
 
-    /// If path contains .rs extension, add a crate to `rust-project.json`
-    fn path_to_json(&mut self, path: PathBuf) -> Result<(), Box<dyn Error>> {
-        if let Some(ext) = path.extension() {
-            if ext == "rs" {
-                self.crates.push(Crate {
-                    root_module: path.display().to_string(),
-                    edition: "2021".to_string(),
-                    deps: Vec::new(),
-                    // This allows rust_analyzer to work inside #[test] blocks
-                    cfg: vec!["test".to_string()],
-                })
-            }
-        }
-
-        Ok(())
-    }
-
-    /// 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 exercises_to_json(&mut self) -> Result<(), Box<dyn Error>> {
-        for path in glob("./exercises/**/*")? {
-            self.path_to_json(path?)?;
-        }
-        Ok(())
-    }
-
-    /// Use `rustc` to determine the default toolchain
-    pub fn get_sysroot_src(&mut self) -> Result<(), Box<dyn Error>> {
-        // check if RUST_SRC_PATH is set
-        if let Ok(path) = env::var("RUST_SRC_PATH") {
-            self.sysroot_src = path;
-            return Ok(());
+        if let Some(path) = env::var_os("RUST_SRC_PATH") {
+            return Ok(Self {
+                sysroot_src: PathBuf::from(path),
+                crates,
+            });
         }
 
         let toolchain = Command::new("rustc")
             .arg("--print")
             .arg("sysroot")
-            .output()?
+            .stderr(Stdio::inherit())
+            .output()
+            .context("Failed to get the sysroot from `rustc`. Do you have `rustc` installed?")?
             .stdout;
 
-        let toolchain = String::from_utf8(toolchain)?;
+        let toolchain =
+            String::from_utf8(toolchain).context("The toolchain path is invalid UTF8")?;
         let toolchain = toolchain.trim_end();
-
         println!("Determined toolchain: {toolchain}\n");
 
-        let Ok(path) = Path::new(toolchain)
-            .join("lib")
-            .join("rustlib")
-            .join("src")
-            .join("rust")
-            .join("library")
-            .into_os_string()
-            .into_string()
-        else {
-            return Err("The sysroot path is invalid UTF8".into());
-        };
-        self.sysroot_src = path;
+        let mut sysroot_src = PathBuf::with_capacity(256);
+        sysroot_src.extend([toolchain, "lib", "rustlib", "src", "rust", "library"]);
 
-        Ok(())
+        Ok(Self {
+            sysroot_src,
+            crates,
+        })
     }
 }
+
+/// Write `rust-project.json` to disk.
+pub fn write_project_json(exercises: Vec<Exercise>) -> Result<()> {
+    let content = RustAnalyzerProject::build(exercises)?;
+
+    // Using the capacity 2^14 since the file length in bytes is higher than 2^13.
+    // The final length is not known exactly because it depends on the user's sysroot path,
+    // the current number of exercises etc.
+    let mut buf = Vec::with_capacity(1 << 14);
+    serde_json::to_writer(&mut buf, &content)?;
+    std::fs::write("rust-project.json", buf)?;
+
+    Ok(())
+}