feat: add revision::walk::Platform::hide().

This finally makes safe traversals possible and is what most people would want to use
instead of `boundary()`.

Author: Byron

gix/src/config/tree/sections/core.rs

@@ -442,17 +442,6 @@ mod abbrev {
 mod validate {
     use crate::{bstr::BStr, config::tree::keys};
 
-    pub struct LockTimeout;
-    impl keys::Validate for LockTimeout {
-        fn validate(&self, value: &BStr) -> Result<(), Box<dyn std::error::Error + Send + Sync + 'static>> {
-            let value = gix_config::Integer::try_from(value)?
-                .to_decimal()
-                .ok_or_else(|| format!("integer {value} cannot be represented as integer"));
-            super::Core::FILES_REF_LOCK_TIMEOUT.try_into_lock_timeout(Ok(value?))?;
-            Ok(())
-        }
-    }
-
     pub struct Disambiguate;
     impl keys::Validate for Disambiguate {
         #[cfg_attr(not(feature = "revision"), allow(unused_variables))]

gix/src/revision/walk.rs

@@ -155,6 +155,7 @@ pub struct Platform<'repo> {
     /// The owning repository.
     pub repo: &'repo Repository,
     pub(crate) tips: Vec<ObjectId>,
+    pub(crate) hidden: Vec<ObjectId>,
     pub(crate) boundary: Vec<ObjectId>,
     pub(crate) sorting: Sorting,
     pub(crate) parents: gix_traverse::commit::Parents,
@@ -167,6 +168,7 @@ impl<'repo> Platform<'repo> {
         revision::walk::Platform {
             repo,
             tips: tips.into_iter().map(Into::into).collect(),
+            hidden: Vec::new(),
             sorting: Default::default(),
             parents: Default::default(),
             use_commit_graph: None,
@@ -210,13 +212,13 @@ impl Platform<'_> {
         self
     }
 
-    /// Don't cross the given `ids` during traversal.
+    /// Don't cross the given `ids` (commits) during traversal.
     ///
     /// Note that this forces the [sorting](Self::sorting()) to [`ByCommitTimeCutoff`](Sorting::ByCommitTimeCutoff)
     /// configured with the oldest available commit time, ensuring that no commits older than the oldest of `ids` will be returned either.
     /// Also note that commits that can't be accessed or are missing are simply ignored for the purpose of obtaining the cutoff date.
     ///
-    /// A boundary is distinctly different from exclusive refsepcs `^branch-to-not-list` in Git log.
+    /// A boundary is distinctly different from exclusive revspecs `^branch-to-not-list` in Git log.
     ///
     /// If this is not desired, [set the sorting](Self::sorting()) to something else right after this call.
     pub fn with_boundary(mut self, ids: impl IntoIterator<Item = impl Into<ObjectId>>) -> Self {
@@ -242,6 +244,20 @@ impl Platform<'_> {
         }
         self
     }
+
+    /// Don't cross the given `tips` (commits) during traversal or return them, and also don't return any of their ancestors.
+    ///
+    /// This allows achieving revspecs like `^branch-to-not-list`, where the commit behind that name would be passed as `ids`.
+    ///
+    /// In other words, each of the `tips` acts like a starting point for an iteration that will paint commits as unwanted, and
+    /// wanted commits cannot cross it.
+    ///
+    /// The side effect of this is that commits can't be returned immediately as one still has to wait and see if they may be unwanted later.
+    /// This makes traversals with hidden commits more costly, with a chance to traverse all commits if the hidden and non-hidden commits are disjoint.
+    pub fn with_hidden(mut self, tips: impl IntoIterator<Item = impl Into<ObjectId>>) -> Self {
+        self.hidden = tips.into_iter().map(Into::into).collect();
+        self
+    }
 }
 
 /// Produce the iterator
@@ -262,6 +278,7 @@ impl<'repo> Platform<'repo> {
             use_commit_graph,
             commit_graph,
             mut boundary,
+            hidden,
         } = self;
         boundary.sort();
         Ok(revision::Walk {
@@ -301,6 +318,7 @@ impl<'repo> Platform<'repo> {
                 })
                 .sorting(sorting.into_simple().expect("for now there is nothing else"))?
                 .parents(parents)
+                .hide(hidden)?
                 .commit_graph(
                     commit_graph.or(use_commit_graph
                         .map_or_else(|| self.repo.config.may_use_commit_graph(), Ok)?