Add "dev update"

src/dev/update.rs

@@ -0,0 +1,53 @@
+use std::fs;
+
+use anyhow::{Context, Result};
+
+use crate::{
+    info_file::{ExerciseInfo, InfoFile},
+    DEVELOPING_OFFIFICAL_RUSTLINGS,
+};
+
+use super::check::{append_bins, bins_start_end_ind};
+
+fn update_cargo_toml(
+    exercise_infos: &[ExerciseInfo],
+    current_cargo_toml: &str,
+    cargo_toml_path: &str,
+    exercise_path_prefix: &[u8],
+) -> Result<()> {
+    let (bins_start_ind, bins_end_ind) = bins_start_end_ind(current_cargo_toml)?;
+
+    let mut new_cargo_toml = Vec::with_capacity(1 << 13);
+    new_cargo_toml.extend_from_slice(current_cargo_toml[..bins_start_ind].as_bytes());
+    append_bins(&mut new_cargo_toml, exercise_infos, exercise_path_prefix);
+    new_cargo_toml.extend_from_slice(current_cargo_toml[bins_end_ind..].as_bytes());
+
+    fs::write(cargo_toml_path, new_cargo_toml).context("Failed to write the `Cargo.toml` file")?;
+
+    Ok(())
+}
+
+pub fn update() -> Result<()> {
+    let info_file = InfoFile::parse()?;
+
+    if DEVELOPING_OFFIFICAL_RUSTLINGS {
+        update_cargo_toml(
+            &info_file.exercises,
+            include_str!("../../dev/Cargo.toml"),
+            "dev/Cargo.toml",
+            b"../",
+        )
+        .context("Failed to update the file `dev/Cargo.toml`")?;
+
+        println!("Updated `dev/Cargo.toml`");
+    } else {
+        let current_cargo_toml =
+            fs::read_to_string("Cargo.toml").context("Failed to read the file `Cargo.toml`")?;
+        update_cargo_toml(&info_file.exercises, &current_cargo_toml, "Cargo.toml", b"")
+            .context("Failed to update the file `Cargo.toml`")?;
+
+        println!("Updated `Cargo.toml`");
+    }
+
+    Ok(())
+}