feat: Add Rust version segment (#15)

src/modules/mod.rs

@@ -2,6 +2,7 @@ mod character;
 mod directory;
 mod line_break;
 mod nodejs;
+mod rust;
 
 use crate::context::Context;
 use crate::segment::Segment;
@@ -11,6 +12,7 @@ pub fn handle(module: &str, context: &Context) -> Option<Segment> {
         "dir" | "directory" => directory::segment(context),
         "char" | "character" => character::segment(context),
         "node" | "nodejs" => nodejs::segment(context),
+        "rust" | "rustlang" => rust::segment(context),
         "line_break" => line_break::segment(context),
 
         _ => panic!("Unknown module: {}", module),

src/modules/rust.rs

@@ -0,0 +1,75 @@
+use super::Segment;
+use crate::context::Context;
+use ansi_term::Color;
+use std::fs::{self, DirEntry};
+use std::process::Command;
+
+/// Creates a segment with the current Rust version
+///
+/// Will display the Rust version if any of the following criteria are met:
+///     - Current directory contains a `.rs` or 'Cargo.toml' file
+pub fn segment(context: &Context) -> Option<Segment> {
+    let files = fs::read_dir(&context.current_dir).unwrap();
+    let is_rs_project = files.filter_map(Result::ok).any(has_rs_files);
+    if !is_rs_project {
+        return None;
+    }
+
+    match get_rust_version() {
+        Some(rust_version) => {
+            const RUST_LOGO: &str = "🦀";
+            const SECTION_COLOR: Color = Color::Red;
+
+            let mut segment = Segment::new("rust");
+            segment.set_style(SECTION_COLOR);
+
+            let formatted_version = format_rustc_version(rust_version);
+            segment.set_value(format!("{} {}", RUST_LOGO, formatted_version));
+
+            Some(segment)
+        }
+        None => None,
+    }
+}
+
+fn has_rs_files(dir_entry: DirEntry) -> bool {
+    let is_rs_file = |d: &DirEntry| -> bool {
+        d.path().is_file() && d.path().extension().unwrap_or_default() == "rs"
+    };
+    let is_cargo_toml = |d: &DirEntry| -> bool {
+        d.path().is_file() && d.path().file_name().unwrap_or_default() == "Cargo.toml"
+    };
+
+    is_rs_file(&dir_entry) || is_cargo_toml(&dir_entry)
+}
+
+fn get_rust_version() -> Option<String> {
+    match Command::new("rustc").arg("-V").output() {
+        Ok(output) => Some(String::from_utf8(output.stdout).unwrap()),
+        Err(_) => None,
+    }
+}
+
+fn format_rustc_version(mut rustc_stdout: String) -> String {
+    let offset = &rustc_stdout.find('(').unwrap();
+    let formatted_version: String = rustc_stdout.drain(..offset).collect();
+
+    format!("v{}", formatted_version.replace("rustc", "").trim())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_format_rustc_version() {
+        let nightly_input = String::from("rustc 1.34.0-nightly (b139669f3 2019-04-10)");
+        assert_eq!(format_rustc_version(nightly_input), "v1.34.0-nightly");
+
+        let beta_input = String::from("rustc 1.34.0-beta.1 (2bc1d406d 2019-04-10)");
+        assert_eq!(format_rustc_version(beta_input), "v1.34.0-beta.1");
+
+        let stable_input = String::from("rustc 1.34.0 (91856ed52 2019-04-10)");
+        assert_eq!(format_rustc_version(stable_input), "v1.34.0");
+    }
+}

src/print.rs

@@ -5,7 +5,7 @@ use crate::context::Context;
 use crate::modules;
 
 pub fn prompt(args: ArgMatches) {
-    let prompt_order = vec!["directory", "nodejs", "line_break", "character"];
+    let prompt_order = vec!["directory", "nodejs", "rust", "line_break", "character"];
     let context = Context::new(args);
 
     // TODO: