Add solutions to bins

solutions/00_intro/intro1.rs

@@ -1,2 +1,5 @@
-// The exercise `intro1` only requires entering `n` in the terminal to go to the next exercise.
-// It is just an introduction to how Rustlings works.
+fn main() {
+    // Congratulations, you finished the first exercise 🎉
+    // As an introduction to Rustlings, the first exercise only required
+    // entering `n` in the terminal to go to the next exercise.
+}

src/cargo_toml.rs

@@ -1,4 +1,5 @@
 use anyhow::{Context, Result};
+use std::path::Path;
 
 use crate::info_file::ExerciseInfo;
 
@@ -40,6 +41,24 @@ pub fn append_bins(
         }
         buf.extend_from_slice(exercise_info.name.as_bytes());
         buf.extend_from_slice(b".rs\" },\n");
+
+        let sol_path = exercise_info.sol_path();
+        if !Path::new(&sol_path).exists() {
+            continue;
+        }
+
+        buf.extend_from_slice(b"  { name = \"");
+        buf.extend_from_slice(exercise_info.name.as_bytes());
+        buf.extend_from_slice(b"_sol");
+        buf.extend_from_slice(b"\", path = \"");
+        buf.extend_from_slice(exercise_path_prefix);
+        buf.extend_from_slice(b"solutions/");
+        if let Some(dir) = &exercise_info.dir {
+            buf.extend_from_slice(dir.as_bytes());
+            buf.push(b'/');
+        }
+        buf.extend_from_slice(exercise_info.name.as_bytes());
+        buf.extend_from_slice(b".rs\" },\n");
     }
 }
 

src/embedded.rs

@@ -1,6 +1,6 @@
 use anyhow::{Context, Error, Result};
 use std::{
-    fs::{create_dir, create_dir_all, OpenOptions},
+    fs::{create_dir, OpenOptions},
     io::{self, Write},
 };
 
@@ -43,8 +43,8 @@ struct ExerciseFiles {
 }
 
 // A directory in the `exercises/` directory.
-struct ExerciseDir {
-    name: &'static str,
+pub struct ExerciseDir {
+    pub name: &'static str,
     readme: &'static [u8],
 }
 
@@ -78,7 +78,7 @@ pub struct EmbeddedFiles {
     /// The content of the `info.toml` file.
     pub info_file: &'static str,
     exercise_files: &'static [ExerciseFiles],
-    exercise_dirs: &'static [ExerciseDir],
+    pub exercise_dirs: &'static [ExerciseDir],
 }
 
 impl EmbeddedFiles {
@@ -121,13 +121,9 @@ impl EmbeddedFiles {
 
         // 14 = 10 + 1 + 3
         // solutions/ + / + .rs
-        let mut dir_path = String::with_capacity(14 + dir.name.len() + exercise_name.len());
-        dir_path.push_str("solutions/");
-        dir_path.push_str(dir.name);
-        create_dir_all(&dir_path)
-            .with_context(|| format!("Failed to create the directory {dir_path}"))?;
-
-        let mut solution_path = dir_path;
+        let mut solution_path = String::with_capacity(14 + dir.name.len() + exercise_name.len());
+        solution_path.push_str("solutions/");
+        solution_path.push_str(dir.name);
         solution_path.push('/');
         solution_path.push_str(exercise_name);
         solution_path.push_str(".rs");

src/info_file.rs

@@ -49,6 +49,30 @@ impl ExerciseInfo {
 
         path
     }
+
+    /// Path to the solution file starting with the `solutions/` directory.
+    pub fn sol_path(&self) -> String {
+        let mut path = if let Some(dir) = &self.dir {
+            // 14 = 10 + 1 + 3
+            // solutions/ + / + .rs
+            let mut path = String::with_capacity(14 + dir.len() + self.name.len());
+            path.push_str("solutions/");
+            path.push_str(dir);
+            path.push('/');
+            path
+        } else {
+            // 13 = 10 + 3
+            // solutions/ + .rs
+            let mut path = String::with_capacity(13 + self.name.len());
+            path.push_str("solutions/");
+            path
+        };
+
+        path.push_str(&self.name);
+        path.push_str(".rs");
+
+        path
+    }
 }
 
 /// The deserialized `info.toml` file.

src/init.rs

@@ -34,6 +34,20 @@ pub fn init() -> Result<()> {
         .init_exercises_dir(&info_file.exercises)
         .context("Failed to initialize the `rustlings/exercises` directory")?;
 
+    create_dir("solutions").context("Failed to create the `solutions/` directory")?;
+    for dir in EMBEDDED_FILES.exercise_dirs {
+        let mut dir_path = String::with_capacity(10 + dir.name.len());
+        dir_path.push_str("solutions/");
+        dir_path.push_str(dir.name);
+        create_dir(&dir_path)
+            .with_context(|| format!("Failed to create the directory {dir_path}"))?;
+    }
+    for exercise_info in &info_file.exercises {
+        let solution_path = exercise_info.sol_path();
+        fs::write(&solution_path, INIT_SOLUTION_FILE)
+            .with_context(|| format!("Failed to create the file {solution_path}"))?;
+    }
+
     let current_cargo_toml = include_str!("../dev-Cargo.toml");
     // Skip the first line (comment).
     let newline_ind = current_cargo_toml
@@ -72,6 +86,12 @@ pub fn init() -> Result<()> {
     Ok(())
 }
 
+const INIT_SOLUTION_FILE: &[u8] = b"fn main() {
+    // DON'T EDIT THIS SOLUTION FILE!
+    // It will be automatically filled after you finish the exercise.
+}
+";
+
 const GITIGNORE: &[u8] = b".rustlings-state.txt
 solutions
 Cargo.lock