cli: add convenient method to intersect user revset with other expression

This pattern is common, and most callers of evaluate_revset() can now be
migrated to the wrapper API.

cli/src/cli_util.rs

@@ -1016,10 +1016,10 @@ impl WorkspaceCommandHelper {
                 .map(|commit| commit.id().clone())
                 .collect(),
         );
-        let immutable_revset =
-            revset_util::parse_immutable_expression(&self.revset_parse_context())?;
-        let revset = self.evaluate_revset(to_rewrite_revset.intersection(&immutable_revset))?;
-        if let Some(commit) = revset.iter().commits(self.repo().store()).next() {
+        let immutable = revset_util::parse_immutable_expression(&self.revset_parse_context())?;
+        let mut expression = self.attach_revset_evaluator(immutable)?;
+        expression.intersect_with(&to_rewrite_revset);
+        if let Some(commit) = expression.evaluate_to_commits()?.next() {
             let commit = commit?;
             let error = if commit.id() == self.repo().store().root_commit_id() {
                 user_error(format!(

cli/src/commands/branch.rs

@@ -18,7 +18,6 @@ use std::io::Write as _;
 
 use clap::builder::NonEmptyStringValueParser;
 use itertools::Itertools;
-use jj_lib::backend::CommitId;
 use jj_lib::git;
 use jj_lib::object_id::ObjectId;
 use jj_lib::op_store::{RefTarget, RemoteRef};
@@ -624,15 +623,10 @@ fn cmd_branch_list(
         }
         if !args.revisions.is_empty() {
             // Match against local targets only, which is consistent with "jj git push".
-            let filter_expression = workspace_command
-                .parse_union_revsets(&args.revisions)?
-                .expression()
-                .clone();
+            let mut expression = workspace_command.parse_union_revsets(&args.revisions)?;
             // Intersects with the set of local branch targets to minimize the lookup space.
-            let revset_expression = RevsetExpression::branches(StringPattern::everything())
-                .intersection(&filter_expression);
-            let revset = workspace_command.evaluate_revset(revset_expression)?;
-            let filtered_targets: HashSet<CommitId> = revset.iter().collect();
+            expression.intersect_with(&RevsetExpression::branches(StringPattern::everything()));
+            let filtered_targets: HashSet<_> = expression.evaluate_to_commit_ids()?.collect();
             branch_names.extend(
                 view.local_branches()
                     .filter(|(_, target)| {

cli/src/commands/git.rs

@@ -1203,12 +1203,9 @@ fn find_branches_targeted_by_revisions<'a>(
         }
     }
     for rev_str in revisions {
-        let expression = workspace_command
-            .parse_revset(rev_str)?
-            .expression()
-            .intersection(&RevsetExpression::branches(StringPattern::everything()));
-        let revset = workspace_command.evaluate_revset(expression)?;
-        let mut commit_ids = revset.iter().peekable();
+        let mut expression = workspace_command.parse_revset(rev_str)?;
+        expression.intersect_with(&RevsetExpression::branches(StringPattern::everything()));
+        let mut commit_ids = expression.evaluate_to_commit_ids()?.peekable();
         if commit_ids.peek().is_none() {
             let rev_str: &str = rev_str;
             writeln!(

cli/src/commands/log.rs

@@ -81,24 +81,22 @@ pub(crate) fn cmd_log(
             workspace_command.parse_revset(&command.settings().default_revset())?
         } else {
             workspace_command.parse_union_revsets(&args.revisions)?
-        }
-        .expression()
-        .clone();
+        };
         if !args.paths.is_empty() {
             let repo_paths: Vec<_> = args
                 .paths
                 .iter()
                 .map(|path_arg| workspace_command.parse_file_path(path_arg))
                 .try_collect()?;
-            expression = expression.intersection(&RevsetExpression::filter(
-                RevsetFilterPredicate::File(Some(repo_paths)),
-            ));
+            expression.intersect_with(&RevsetExpression::filter(RevsetFilterPredicate::File(
+                Some(repo_paths),
+            )));
         }
         expression
     };
     let repo = workspace_command.repo();
     let matcher = workspace_command.matcher_from_values(&args.paths)?;
-    let revset = workspace_command.evaluate_revset(revset_expression)?;
+    let revset = revset_expression.evaluate()?;
 
     let store = repo.store();
     let diff_formats =

cli/src/revset_util.rs

@@ -67,6 +67,11 @@ impl<'repo> RevsetExpressionEvaluator<'repo> {
         &self.expression
     }
 
+    /// Intersects the underlying expression with the `other` expression.
+    pub fn intersect_with(&mut self, other: &Rc<RevsetExpression>) {
+        self.expression = self.expression.intersection(other);
+    }
+
     /// Evaluates the expression.
     pub fn evaluate(&self) -> Result<Box<dyn Revset + 'repo>, UserRevsetEvaluationError> {
         let symbol_resolver = default_symbol_resolver(self.repo, self.id_prefix_context);