//! Provides support for language toolchains.//!//! A language can have associated toolchains,//! which is a set of tools used to interact with the projects written in said language.//! For example, a Python project can have an associated virtual environment; a Rust project can have a toolchain override. use std::{path::PathBuf, sync::Arc}; use async_trait::async_trait;use collections::HashMap;use gpui::{AsyncAppContext, SharedString};use settings::WorktreeId; use crate::LanguageName; /// Represents a single toolchain.#[derive(Clone, Debug, PartialEq)]pub struct Toolchain {    /// User-facing label    pub name: SharedString,    pub path: SharedString,    pub language_name: LanguageName,    /// Full toolchain data (including language-specific details)    pub as_json: serde_json::Value,} #[async_trait]pub trait ToolchainLister: Send + Sync {    async fn list(        &self,        worktree_root: PathBuf,        project_env: Option<HashMap<String, String>>,    ) -> ToolchainList;    // Returns a term which we should use in UI to refer to a toolchain.    fn term(&self) -> SharedString;} #[async_trait(?Send)]pub trait LanguageToolchainStore {    async fn active_toolchain(        self: Arc<Self>,        worktree_id: WorktreeId,        language_name: LanguageName,        cx: &mut AsyncAppContext,    ) -> Option<Toolchain>;} type DefaultIndex = usize;#[derive(Default, Clone)]pub struct ToolchainList {    pub toolchains: Vec<Toolchain>,    pub default: Option<DefaultIndex>,    pub groups: Box<[(usize, SharedString)]>,} impl ToolchainList {    pub fn toolchains(&self) -> &[Toolchain] {        &self.toolchains    }    pub fn default_toolchain(&self) -> Option<Toolchain> {        self.default.and_then(|ix| self.toolchains.get(ix)).cloned()    }    pub fn group_for_index(&self, index: usize) -> Option<(usize, SharedString)> {        if index >= self.toolchains.len() {            return None;        }        let first_equal_or_greater = self            .groups            .partition_point(|(group_lower_bound, _)| group_lower_bound <= &index);        self.groups            .get(first_equal_or_greater.checked_sub(1)?)            .cloned()    }}