commands: move cmd_run into run.rs.

This also does two cosmetic changes, changing `jobs` from a plain usize to a Option<usize>
and making execute a no-op boolean, like `-r` in describe. It also contains a minor documentation
update to match newer `jj` features and a fix to the `pre-submit` invocation.

While we're at it, teach it to resolve the passed Revsets.

cli/src/commands/mod.rs

@@ -42,6 +42,7 @@ mod operation;
 mod prev;
 mod rebase;
 mod resolve;
+mod run;
 
 use std::collections::HashSet;
 use std::fmt::Debug;
@@ -129,7 +130,7 @@ enum Commands {
     Restore(RestoreArgs),
     #[command(hide = true)]
     // TODO: Flesh out.
-    Run(RunArgs),
+    Run(run::RunArgs),
     Show(ShowArgs),
     #[command(subcommand)]
     Sparse(SparseArgs),
@@ -280,27 +281,34 @@ struct RestoreArgs {
     revision: Option<RevisionArg>,
 }
 
-/// Run a command across a set of revisions.
+/// Touch up the content changes in a revision with a diff editor
 ///
+/// With the `-r` option, which is the default, starts a diff editor (`meld` by
+/// default) on the changes in the revision.
 ///
-/// All recorded state will be persisted in the `.jj` directory, so occasionally
-/// a `jj run --clean` is needed to clean up disk space.
+/// With the `--from` and/or `--to` options, starts a diff editor comparing the
+/// "from" revision to the "to" revision.
 ///
-/// # Example
+/// Edit the right side of the diff until it looks the way you want. Once you
+/// close the editor, the revision specified with `-r` or `--to` will be
+/// updated. Descendants will be rebased on top as usual, which may result in
+/// conflicts.
 ///
-/// # Run pre-commit on your local work
-/// $ jj run 'pre-commit.py .github/pre-commit.yaml' -r (main..@) -j 4
-///
-/// This allows pre-commit integration and other funny stuff.
+/// See `jj restore` if you want to move entire files from one revision to
+/// another. See `jj squash -i` or `jj unsquash -i` if you instead want to move
+/// changes into or out of the parent revision.
 #[derive(clap::Args, Clone, Debug)]
-#[command(verbatim_doc_comment)]
-struct RunArgs {
-    /// The command to run across all selected revisions.
-    #[arg(long, short, alias = "x")]
-    command: String,
-    /// The revisions to change.
-    #[arg(long, short, default_value = "@")]
-    revisions: Vec<RevisionArg>,
+struct DiffeditArgs {
+    /// The revision to touch up. Defaults to @ if neither --to nor --from are
+    /// specified.
+    #[arg(long, short)]
+    revision: Option<RevisionArg>,
+    /// Show changes from this revision. Defaults to @ if --to is specified.
+    #[arg(long, conflicts_with = "revision")]
+    from: Option<RevisionArg>,
+    /// Edit changes in this revision. Defaults to @ if --from is specified.
+    #[arg(long, conflicts_with = "revision")]
+    to: Option<RevisionArg>,
 }
 
 /// Split a revision in two
@@ -1259,11 +1267,6 @@ don't make any changes, then the operation will be aborted.
     Ok(())
 }
 
-// TODO: Move to run.rs
-fn cmd_run(_ui: &mut Ui, _command: &CommandHelper, _args: &RunArgs) -> Result<(), CommandError> {
-    Err(user_error("This is a stub, do not use"))
-}
-
 fn make_branch_term(branch_names: &[impl fmt::Display]) -> String {
     match branch_names {
         [branch_name] => format!("branch {}", branch_name),
@@ -1668,7 +1671,7 @@ pub fn run_command(ui: &mut Ui, command_helper: &CommandHelper) -> Result<(), Co
         Commands::Squash(sub_args) => cmd_squash(ui, command_helper, sub_args),
         Commands::Unsquash(sub_args) => cmd_unsquash(ui, command_helper, sub_args),
         Commands::Restore(sub_args) => cmd_restore(ui, command_helper, sub_args),
-        Commands::Run(sub_args) => cmd_run(ui, command_helper, sub_args),
+        Commands::Run(sub_args) => run::cmd_run(ui, command_helper, sub_args),
         Commands::Diffedit(sub_args) => diffedit::cmd_diffedit(ui, command_helper, sub_args),
         Commands::Split(sub_args) => cmd_split(ui, command_helper, sub_args),
         Commands::Merge(sub_args) => merge::cmd_merge(ui, command_helper, sub_args),

cli/src/commands/run.rs

@@ -0,0 +1,42 @@
+//! This file contains the internals of the `run` command.
+use crate::cli_util::{
+    resolve_multiple_nonempty_revsets, user_error, CommandError, CommandHelper, RevisionArg,
+};
+use crate::ui::Ui;
+
+/// Run a command across a set of revisions.
+///
+///
+/// All recorded state will be persisted in the `.jj` directory, so occasionally
+/// a `jj run --clean` is needed to clean up disk space.
+///
+/// # Example
+///
+/// # Run pre-commit on your local work
+/// $ jj run 'pre-commit run .github/pre-commit.yaml' -r (trunk()..@) -j 4
+///
+/// This allows pre-commit integration and other funny stuff.
+#[derive(clap::Args, Clone, Debug)]
+#[command(verbatim_doc_comment)]
+pub struct RunArgs {
+    /// The command to run across all selected revisions.
+    shell_command: String,
+    /// A no-op option to match the interface of `git bisect -x`.
+    #[arg(long, short, alias = "x")]
+    command: bool,
+    /// The revisions to change.
+    /// Multiple revsets are accepted and the work will be done on a
+    /// intersection of them.
+    #[arg(long, short, default_value = "@")]
+    revisions: Vec<RevisionArg>,
+    /// How many processes should run in parallel, uses by default all cores.
+    #[arg(long, short)]
+    jobs: Option<usize>,
+}
+
+pub fn cmd_run(ui: &mut Ui, command: &CommandHelper, args: &RunArgs) -> Result<(), CommandError> {
+    let workspace_command = command.workspace_helper(ui)?;
+    let _resolved_commits =
+        resolve_multiple_nonempty_revsets(&args.revisions, &workspace_command, ui)?;
+    Err(user_error("This is a stub, do not use"))
+}