task: Add task contexts (#8675)

This PR supplements tasks with additional environment variables; ideally
we'll be able to write a task like:
`cargo test -p $ZED_CURRENT_PACKAGE -- $ZED_CURRENT_FUNCTION`
- [x] Flesh out multibuffer interactions
- [x] Add ZED_SYMBOL detection based on tree-sitter queries
- [ ] Add release note and demo
- [x] Figure out a solution for rerun dilemma - should `task: rerun`
reevaluate contexts for tasks?

This PR introduced the following variables:
- ZED_COLUMN - current line column
- ZED_ROW - current line row
and the following, which are available for buffers with associated
files:
- ZED_WORKTREE_ROOT - absolute path to the root of the current worktree.
- ZED_FILE - absolute path to the file
- ZED_SYMBOL - currently selected symbol; should match the last symbol
shown in a symbol breadcrumb (e.g. `mod tests > fn test_task_contexts`
should be equal to ZED_SYMBOL of `test_task_contexts`). Note that this
isn't necessarily a test function or a function at all.

Also, you can use them in `cwd` field of definitions (note though that
we're using https://docs.rs/subst/latest/subst/#features for that, so
don't expect a full shell functionality to work); the syntax should
match up with your typical Unix shell.


Release Notes:

- Added task contexts, which are additional environment variables set by
Zed for task execution; task content is dependent on the state of the
editor at the time the task is spawned.

---------

Co-authored-by: Anthony <anthonyeid7@protonmail.com>

crates/task/Cargo.toml

@@ -13,6 +13,7 @@ gpui.workspace = true
 schemars.workspace = true
 serde.workspace = true
 serde_json_lenient.workspace = true
+subst = "0.3.0"
 util.workspace = true
 
 [dev-dependencies]

crates/task/src/lib.rs

@@ -36,6 +36,15 @@ pub struct SpawnInTerminal {
     pub allow_concurrent_runs: bool,
 }
 
+/// Keeps track of the file associated with a task and context of tasks execution (i.e. current file or current function)
+#[derive(Clone, Debug, Default, PartialEq, Eq)]
+pub struct TaskContext {
+    /// A path to a directory in which the task should be executed.
+    pub cwd: Option<PathBuf>,
+    /// Additional environment variables associated with a given task.
+    pub env: HashMap<String, String>,
+}
+
 /// Represents a short lived recipe of a task, whose main purpose
 /// is to get spawned.
 pub trait Task {
@@ -44,10 +53,10 @@ pub trait Task {
     /// 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>;
+    fn cwd(&self) -> Option<&str>;
     /// 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>;
+    fn exec(&self, cx: TaskContext) -> Option<SpawnInTerminal>;
 }
 
 /// [`Source`] produces tasks that can be scheduled.

crates/task/src/oneshot_source.rs

@@ -2,7 +2,7 @@
 
 use std::sync::Arc;
 
-use crate::{SpawnInTerminal, Task, TaskId, TaskSource};
+use crate::{SpawnInTerminal, Task, TaskContext, TaskId, TaskSource};
 use gpui::{AppContext, Context, Model};
 
 /// A storage and source of tasks generated out of user command prompt inputs.
@@ -30,21 +30,22 @@ impl Task for OneshotTask {
         &self.id.0
     }
 
-    fn cwd(&self) -> Option<&std::path::Path> {
+    fn cwd(&self) -> Option<&str> {
         None
     }
 
-    fn exec(&self, cwd: Option<std::path::PathBuf>) -> Option<SpawnInTerminal> {
+    fn exec(&self, cx: TaskContext) -> Option<SpawnInTerminal> {
         if self.id().0.is_empty() {
             return None;
         }
+        let TaskContext { cwd, env } = cx;
         Some(SpawnInTerminal {
             id: self.id().clone(),
             label: self.name().to_owned(),
             command: self.id().0.clone(),
             args: vec![],
             cwd,
-            env: Default::default(),
+            env,
             use_new_terminal: Default::default(),
             allow_concurrent_runs: Default::default(),
         })

crates/task/src/static_source.rs

@@ -1,10 +1,6 @@
 //! A source of tasks, based on a static configuration, deserialized from the tasks config file, and related infrastructure for tracking changes to the file.
 
-use std::{
-    borrow::Cow,
-    path::{Path, PathBuf},
-    sync::Arc,
-};
+use std::{borrow::Cow, path::Path, sync::Arc};
 
 use collections::HashMap;
 use futures::StreamExt;
@@ -13,7 +9,7 @@ use schemars::{gen::SchemaSettings, JsonSchema};
 use serde::{Deserialize, Serialize};
 use util::ResultExt;
 
-use crate::{SpawnInTerminal, Task, TaskId, TaskSource};
+use crate::{SpawnInTerminal, Task, TaskContext, TaskId, TaskSource};
 use futures::channel::mpsc::UnboundedReceiver;
 
 /// A single config file entry with the deserialized task definition.
@@ -24,7 +20,16 @@ struct StaticTask {
 }
 
 impl Task for StaticTask {
-    fn exec(&self, cwd: Option<PathBuf>) -> Option<SpawnInTerminal> {
+    fn exec(&self, cx: TaskContext) -> Option<SpawnInTerminal> {
+        let TaskContext { cwd, env } = cx;
+        let cwd = self
+            .definition
+            .cwd
+            .clone()
+            .and_then(|path| subst::substitute(&path, &env).map(Into::into).ok())
+            .or(cwd);
+        let mut definition_env = self.definition.env.clone();
+        definition_env.extend(env);
         Some(SpawnInTerminal {
             id: self.id.clone(),
             cwd,
@@ -33,7 +38,7 @@ impl Task for StaticTask {
             label: self.definition.label.clone(),
             command: self.definition.command.clone(),
             args: self.definition.args.clone(),
-            env: self.definition.env.clone(),
+            env: definition_env,
         })
     }
 
@@ -45,7 +50,7 @@ impl Task for StaticTask {
         &self.id
     }
 
-    fn cwd(&self) -> Option<&Path> {
+    fn cwd(&self) -> Option<&str> {
         self.definition.cwd.as_deref()
     }
 }
@@ -72,7 +77,7 @@ pub(crate) struct Definition {
     pub env: HashMap<String, String>,
     /// Current working directory to spawn the command into, defaults to current project root.
     #[serde(default)]
-    pub cwd: Option<PathBuf>,
+    pub cwd: Option<String>,
     /// Whether to use a new terminal tab or reuse the existing one to spawn the process.
     #[serde(default)]
     pub use_new_terminal: bool,