Rename runnables into tasks (#8119)

Release Notes:

- N/A

crates/task/src/lib.rs

@@ -0,0 +1,70 @@
+//! Baseline interface of Tasks in Zed: all tasks in Zed are intended to use those for implementing their own logic.
+#![deny(missing_docs)]
+
+pub mod static_source;
+mod static_task;
+
+pub use static_task::StaticTask;
+
+use collections::HashMap;
+use gpui::ModelContext;
+use std::any::Any;
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+
+/// Task identifier, unique within the application.
+/// Based on it, task reruns and terminal tabs are managed.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct TaskId(pub String);
+
+/// Contains all information needed by Zed to spawn a new terminal tab for the given task.
+#[derive(Debug, Clone)]
+pub struct SpawnInTerminal {
+    /// Id of the task to use when determining task tab affinity.
+    pub id: TaskId,
+    /// Human readable name of the terminal tab.
+    pub label: String,
+    /// Executable command to spawn.
+    pub command: String,
+    /// Arguments to the command.
+    pub args: Vec<String>,
+    /// Current working directory to spawn the command into.
+    pub cwd: Option<PathBuf>,
+    /// Env overrides for the command, will be appended to the terminal's environment from the settings.
+    pub env: HashMap<String, String>,
+    /// Whether to use a new terminal tab or reuse the existing one to spawn the process.
+    pub use_new_terminal: bool,
+    /// Whether to allow multiple instances of the same task to be run, or rather wait for the existing ones to finish.
+    pub allow_concurrent_runs: bool,
+    /// Whether the command should be spawned in a separate shell instance.
+    pub separate_shell: bool,
+}
+
+/// Represents a short lived recipe of a task, whose main purpose
+/// is to get spawned.
+pub trait Task {
+    /// Unique identifier of the task to spawn.
+    fn id(&self) -> &TaskId;
+    /// Human readable name of the task to display in the UI.
+    fn name(&self) -> &str;
+    /// Task's current working directory. If `None`, current project's root will be used.
+    fn cwd(&self) -> Option<&Path>;
+    /// Sets up everything needed to spawn the task in the given directory (`cwd`).
+    /// If a task is intended to be spawned in the terminal, it should return the corresponding struct filled with the data necessary.
+    fn exec(&self, cwd: Option<PathBuf>) -> Option<SpawnInTerminal>;
+}
+
+/// [`Source`] produces tasks that can be scheduled.
+///
+/// Implementations of this trait could be e.g. [`StaticSource`] that parses tasks from a .json files and provides process templates to be spawned;
+/// another one could be a language server providing lenses with tests or build server listing all targets for a given project.
+pub trait Source: Any {
+    /// A way to erase the type of the source, processing and storing them generically.
+    fn as_any(&mut self) -> &mut dyn Any;
+    /// Collects all tasks available for scheduling, for the path given.
+    fn tasks_for_path(
+        &mut self,
+        path: Option<&Path>,
+        cx: &mut ModelContext<Box<dyn Source>>,
+    ) -> Vec<Arc<dyn Task>>;
+}