rust-revlog: add methods for getting parent revs and entries

Differential Revision: https://phab.mercurial-scm.org/D12442

rust/hg-core/src/revlog/changelog.rs

@@ -1,6 +1,6 b''
 use crate::errors::HgError;
 use crate::repo::Repo;
-use crate::revlog::revlog::{Revlog, RevlogError};
+use crate::revlog::revlog::{Revlog, RevlogEntry, RevlogError};
 use crate::revlog::Revision;
 use crate::revlog::{Node, NodePrefix};
 use crate::utils::hg_path::HgPath;
@@ -30,6 +30,14 b' impl Changelog {'
         self.data_for_rev(rev)
     }
 
+    /// Return the `RevlogEntry` of the given revision number.
+    pub fn entry_for_rev(
+        &self,
+        rev: Revision,
+    ) -> Result<RevlogEntry, RevlogError> {
+        self.revlog.get_entry(rev)
+    }
+
     /// Return the `ChangelogEntry` of the given revision number.
     pub fn data_for_rev(
         &self,
@@ -51,6 +59,13 b' impl Changelog {'
     pub fn node_from_rev(&self, rev: Revision) -> Option<&Node> {
         self.revlog.node_from_rev(rev)
     }
+
+    pub fn rev_from_node(
+        &self,
+        node: NodePrefix,
+    ) -> Result<Revision, RevlogError> {
+        self.revlog.rev_from_node(node)
+    }
 }
 
 /// `Changelog` entry which knows how to interpret the `changelog` data bytes.

rust/hg-core/src/revlog/revlog.rs

@@ -331,6 +331,10 b" impl<'a> RevlogEntry<'a> {"
         self.rev
     }
 
+    pub fn node(&self) -> &Node {
+        &self.hash
+    }
+
     pub fn uncompressed_len(&self) -> Option<u32> {
         u32::try_from(self.uncompressed_len).ok()
     }
@@ -339,6 +343,38 b" impl<'a> RevlogEntry<'a> {"
         self.p1 != NULL_REVISION
     }
 
+    pub fn p1_entry(&self) -> Result<Option<RevlogEntry>, RevlogError> {
+        if self.p1 == NULL_REVISION {
+            Ok(None)
+        } else {
+            Ok(Some(self.revlog.get_entry(self.p1)?))
+        }
+    }
+
+    pub fn p2_entry(&self) -> Result<Option<RevlogEntry>, RevlogError> {
+        if self.p2 == NULL_REVISION {
+            Ok(None)
+        } else {
+            Ok(Some(self.revlog.get_entry(self.p2)?))
+        }
+    }
+
+    pub fn p1(&self) -> Option<Revision> {
+        if self.p1 == NULL_REVISION {
+            None
+        } else {
+            Some(self.p1)
+        }
+    }
+
+    pub fn p2(&self) -> Option<Revision> {
+        if self.p2 == NULL_REVISION {
+            None
+        } else {
+            Some(self.p2)
+        }
+    }
+
     pub fn is_cencored(&self) -> bool {
         (self.flags & REVISION_FLAG_CENSORED) != 0
     }