object_id: extract ObjectId trait and macros to separate module

I'm going to add a prefix resolution method to OpStore, but OpStore is
unrelated to the index. I think ObjectId, HexPrefix, and PrefixResolution can
be extracted to this module.

cli/src/cli_util.rs

@@ -30,7 +30,7 @@ use clap::builder::{NonEmptyStringValueParser, TypedValueParser, ValueParserFact
 use clap::{Arg, ArgAction, ArgMatches, Command, FromArgMatches};
 use indexmap::{IndexMap, IndexSet};
 use itertools::Itertools;
-use jj_lib::backend::{BackendError, ChangeId, CommitId, MergedTreeId, ObjectId};
+use jj_lib::backend::{BackendError, ChangeId, CommitId, MergedTreeId};
 use jj_lib::commit::Commit;
 use jj_lib::git::{
     FailedRefExport, FailedRefExportReason, GitConfigParseError, GitExportError, GitImportError,
@@ -42,6 +42,7 @@ use jj_lib::hex_util::to_reverse_hex;
 use jj_lib::id_prefix::IdPrefixContext;
 use jj_lib::matchers::{EverythingMatcher, Matcher, PrefixMatcher};
 use jj_lib::merged_tree::MergedTree;
+use jj_lib::object_id::ObjectId;
 use jj_lib::op_heads_store::{self, OpHeadResolutionError};
 use jj_lib::op_store::{OpStoreError, OperationId, WorkspaceId};
 use jj_lib::op_walk::OpsetEvaluationError;

cli/src/commands/abandon.rs

@@ -14,7 +14,7 @@
 
 use std::io::Write;
 
-use jj_lib::backend::ObjectId;
+use jj_lib::object_id::ObjectId;
 use tracing::instrument;
 
 use crate::cli_util::{

cli/src/commands/backout.rs

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use jj_lib::backend::ObjectId;
+use jj_lib::object_id::ObjectId;
 use jj_lib::rewrite::back_out_commit;
 use tracing::instrument;
 

cli/src/commands/branch.rs

@@ -19,8 +19,9 @@ use std::str::FromStr;
 
 use clap::builder::NonEmptyStringValueParser;
 use itertools::Itertools;
-use jj_lib::backend::{CommitId, ObjectId};
+use jj_lib::backend::CommitId;
 use jj_lib::git;
+use jj_lib::object_id::ObjectId;
 use jj_lib::op_store::{RefTarget, RemoteRef};
 use jj_lib::repo::Repo;
 use jj_lib::revset::{self, RevsetExpression};

cli/src/commands/checkout.rs

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use jj_lib::backend::ObjectId;
+use jj_lib::object_id::ObjectId;
 use tracing::instrument;
 
 use crate::cli_util::{join_message_paragraphs, CommandError, CommandHelper, RevisionArg};

cli/src/commands/chmod.rs

@@ -13,8 +13,9 @@
 // limitations under the License.
 
 use itertools::Itertools;
-use jj_lib::backend::{ObjectId, TreeValue};
+use jj_lib::backend::TreeValue;
 use jj_lib::merged_tree::MergedTreeBuilder;
+use jj_lib::object_id::ObjectId;
 use tracing::instrument;
 
 use crate::cli_util::{user_error, CommandError, CommandHelper, RevisionArg};

cli/src/commands/commit.rs

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use jj_lib::backend::ObjectId;
+use jj_lib::object_id::ObjectId;
 use jj_lib::repo::Repo;
 use jj_lib::rewrite::merge_commit_trees;
 use tracing::instrument;

cli/src/commands/debug.rs

@@ -17,9 +17,9 @@ use std::fmt::Debug;
 use std::io::Write as _;
 
 use clap::Subcommand;
-use jj_lib::backend::ObjectId;
 use jj_lib::default_index::{AsCompositeIndex as _, DefaultIndexStore, DefaultReadonlyIndex};
 use jj_lib::local_working_copy::LocalWorkingCopy;
+use jj_lib::object_id::ObjectId;
 use jj_lib::repo::Repo;
 use jj_lib::working_copy::WorkingCopy;
 use jj_lib::{op_walk, revset};

cli/src/commands/describe.rs

@@ -14,7 +14,7 @@
 
 use std::io::{self, Read, Write};
 
-use jj_lib::backend::ObjectId;
+use jj_lib::object_id::ObjectId;
 use tracing::instrument;
 
 use crate::cli_util::{join_message_paragraphs, CommandError, CommandHelper, RevisionArg};

cli/src/commands/diffedit.rs

@@ -14,8 +14,8 @@
 
 use std::io::Write;
 
-use jj_lib::backend::ObjectId;
 use jj_lib::matchers::EverythingMatcher;
+use jj_lib::object_id::ObjectId;
 use jj_lib::rewrite::merge_commit_trees;
 use tracing::instrument;
 

cli/src/commands/edit.rs

@@ -14,7 +14,7 @@
 
 use std::io::Write;
 
-use jj_lib::backend::ObjectId;
+use jj_lib::object_id::ObjectId;
 use tracing::instrument;
 
 use crate::cli_util::{CommandError, CommandHelper, RevisionArg};

cli/src/commands/git.rs

@@ -23,11 +23,12 @@ use std::{fmt, fs, io};
 
 use clap::{ArgGroup, Subcommand};
 use itertools::Itertools;
-use jj_lib::backend::{ObjectId, TreeValue};
+use jj_lib::backend::TreeValue;
 use jj_lib::git::{
     self, parse_gitmodules, GitBranchPushTargets, GitFetchError, GitFetchStats, GitPushError,
 };
 use jj_lib::git_backend::GitBackend;
+use jj_lib::object_id::ObjectId;
 use jj_lib::op_store::RefTarget;
 use jj_lib::refs::{
     classify_branch_push_action, BranchPushAction, BranchPushUpdate, TrackingRefPair,

cli/src/commands/move.rs

@@ -13,7 +13,7 @@
 // limitations under the License.
 
 use clap::ArgGroup;
-use jj_lib::backend::ObjectId;
+use jj_lib::object_id::ObjectId;
 use jj_lib::repo::Repo;
 use jj_lib::rewrite::merge_commit_trees;
 use tracing::instrument;

cli/src/commands/operation.rs

@@ -17,7 +17,7 @@ use std::slice;
 
 use clap::Subcommand;
 use itertools::Itertools as _;
-use jj_lib::backend::ObjectId;
+use jj_lib::object_id::ObjectId;
 use jj_lib::op_store::OperationId;
 use jj_lib::op_walk;
 use jj_lib::repo::Repo;

cli/src/commands/rebase.rs

@@ -19,8 +19,9 @@ use std::sync::Arc;
 use clap::ArgGroup;
 use indexmap::IndexSet;
 use itertools::Itertools;
-use jj_lib::backend::{CommitId, ObjectId};
+use jj_lib::backend::CommitId;
 use jj_lib::commit::Commit;
+use jj_lib::object_id::ObjectId;
 use jj_lib::repo::{ReadonlyRepo, Repo};
 use jj_lib::revset::{RevsetExpression, RevsetIteratorExt};
 use jj_lib::rewrite::{rebase_commit, rebase_commit_with_options, EmptyBehaviour, RebaseOptions};

cli/src/commands/resolve.rs

@@ -16,8 +16,9 @@ use std::collections::BTreeMap;
 use std::io::Write;
 
 use itertools::Itertools;
-use jj_lib::backend::{ObjectId, TreeValue};
+use jj_lib::backend::TreeValue;
 use jj_lib::merge::MergedTreeValue;
+use jj_lib::object_id::ObjectId;
 use jj_lib::repo_path::RepoPathBuf;
 use tracing::instrument;
 

cli/src/commands/restore.rs

@@ -14,7 +14,7 @@
 
 use std::io::Write;
 
-use jj_lib::backend::ObjectId;
+use jj_lib::object_id::ObjectId;
 use jj_lib::rewrite::{merge_commit_trees, restore_tree};
 use tracing::instrument;
 

cli/src/commands/split.rs

@@ -13,7 +13,7 @@
 // limitations under the License.
 use std::io::Write;
 
-use jj_lib::backend::ObjectId;
+use jj_lib::object_id::ObjectId;
 use jj_lib::repo::Repo;
 use jj_lib::rewrite::merge_commit_trees;
 use tracing::instrument;

cli/src/commands/squash.rs

@@ -13,7 +13,7 @@
 // limitations under the License.
 
 use clap::parser::ValueSource;
-use jj_lib::backend::ObjectId;
+use jj_lib::object_id::ObjectId;
 use jj_lib::revset;
 use tracing::instrument;
 

cli/src/commands/unsquash.rs

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use jj_lib::backend::ObjectId;
 use jj_lib::matchers::EverythingMatcher;
+use jj_lib::object_id::ObjectId;
 use jj_lib::rewrite::merge_commit_trees;
 use tracing::instrument;
 

cli/src/commands/workspace.rs

@@ -18,8 +18,8 @@ use std::io::Write;
 
 use clap::Subcommand;
 use itertools::Itertools;
-use jj_lib::backend::ObjectId;
 use jj_lib::file_util;
+use jj_lib::object_id::ObjectId;
 use jj_lib::op_store::WorkspaceId;
 use jj_lib::repo::Repo;
 use jj_lib::rewrite::merge_commit_trees;

cli/src/commit_templater.rs

@@ -18,10 +18,11 @@ use std::io;
 use std::rc::Rc;
 
 use itertools::Itertools as _;
-use jj_lib::backend::{ChangeId, CommitId, ObjectId as _};
+use jj_lib::backend::{ChangeId, CommitId};
 use jj_lib::commit::Commit;
 use jj_lib::hex_util::to_reverse_hex;
 use jj_lib::id_prefix::IdPrefixContext;
+use jj_lib::object_id::ObjectId as _;
 use jj_lib::op_store::{RefTarget, WorkspaceId};
 use jj_lib::repo::Repo;
 use jj_lib::{git, rewrite};

cli/src/diff_util.rs

@@ -19,14 +19,15 @@ use std::ops::Range;
 
 use futures::{try_join, Stream, StreamExt};
 use itertools::Itertools;
-use jj_lib::backend::{BackendResult, ObjectId, TreeValue};
+use jj_lib::backend::{BackendResult, TreeValue};
 use jj_lib::commit::Commit;
 use jj_lib::conflicts::{materialize_tree_value, MaterializedTreeValue};
 use jj_lib::diff::{Diff, DiffHunk};
 use jj_lib::files::DiffLine;
 use jj_lib::matchers::Matcher;
 use jj_lib::merge::MergedTreeValue;
 use jj_lib::merged_tree::{MergedTree, TreeDiffStream};
+use jj_lib::object_id::ObjectId;
 use jj_lib::repo::Repo;
 use jj_lib::repo_path::{RepoPath, RepoPathBuf};
 use jj_lib::settings::{ConfigResultExt as _, UserSettings};

cli/src/merge_tools/builtin.rs

@@ -4,12 +4,13 @@ use std::sync::Arc;
 
 use futures::{StreamExt, TryStreamExt};
 use itertools::Itertools;
-use jj_lib::backend::{BackendError, FileId, MergedTreeId, ObjectId, TreeValue};
+use jj_lib::backend::{BackendError, FileId, MergedTreeId, TreeValue};
 use jj_lib::diff::{find_line_ranges, Diff, DiffHunk};
 use jj_lib::files::{self, ContentHunk, MergeResult};
 use jj_lib::matchers::Matcher;
 use jj_lib::merge::Merge;
 use jj_lib::merged_tree::{MergedTree, MergedTreeBuilder};
+use jj_lib::object_id::ObjectId;
 use jj_lib::repo_path::{RepoPath, RepoPathBuf};
 use jj_lib::store::Store;
 use pollster::FutureExt;

cli/src/operation_templater.rs

@@ -15,7 +15,7 @@
 use std::io;
 
 use itertools::Itertools as _;
-use jj_lib::backend::ObjectId;
+use jj_lib::object_id::ObjectId;
 use jj_lib::op_store::{OperationId, OperationMetadata};
 use jj_lib::operation::Operation;
 use jj_lib::repo::ReadonlyRepo;

cli/tests/test_git_import_export.rs

@@ -14,7 +14,8 @@
 use std::path::Path;
 
 use itertools::Itertools as _;
-use jj_lib::backend::{CommitId, ObjectId as _};
+use jj_lib::backend::CommitId;
+use jj_lib::object_id::ObjectId as _;
 
 use crate::common::TestEnvironment;
 

lib/src/backend.rs

@@ -26,75 +26,10 @@ use thiserror::Error;
 
 use crate::content_hash::ContentHash;
 use crate::merge::Merge;
+use crate::object_id::{id_type, ObjectId};
 use crate::repo_path::{RepoPath, RepoPathComponent, RepoPathComponentBuf};
 use crate::signing::SignResult;
 
-pub trait ObjectId {
-    fn new(value: Vec<u8>) -> Self;
-    fn object_type(&self) -> String;
-    fn from_bytes(bytes: &[u8]) -> Self;
-    fn as_bytes(&self) -> &[u8];
-    fn to_bytes(&self) -> Vec<u8>;
-    fn from_hex(hex: &str) -> Self;
-    fn hex(&self) -> String;
-}
-
-macro_rules! id_type {
-    ($vis:vis $name:ident) => {
-        content_hash! {
-            #[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Hash)]
-            $vis struct $name(Vec<u8>);
-        }
-        $crate::backend::impl_id_type!($name);
-    };
-}
-
-macro_rules! impl_id_type {
-    ($name:ident) => {
-        impl std::fmt::Debug for $name {
-            fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
-                f.debug_tuple(stringify!($name)).field(&self.hex()).finish()
-            }
-        }
-
-        impl crate::backend::ObjectId for $name {
-            fn new(value: Vec<u8>) -> Self {
-                Self(value)
-            }
-
-            fn object_type(&self) -> String {
-                stringify!($name)
-                    .strip_suffix("Id")
-                    .unwrap()
-                    .to_ascii_lowercase()
-                    .to_string()
-            }
-
-            fn from_bytes(bytes: &[u8]) -> Self {
-                Self(bytes.to_vec())
-            }
-
-            fn as_bytes(&self) -> &[u8] {
-                &self.0
-            }
-
-            fn to_bytes(&self) -> Vec<u8> {
-                self.0.clone()
-            }
-
-            fn from_hex(hex: &str) -> Self {
-                Self(hex::decode(hex).unwrap())
-            }
-
-            fn hex(&self) -> String {
-                hex::encode(&self.0)
-            }
-        }
-    };
-}
-
-pub(crate) use {id_type, impl_id_type};
-
 id_type!(pub CommitId);
 id_type!(pub ChangeId);
 id_type!(pub TreeId);

lib/src/default_index/composite.rs

@@ -26,8 +26,9 @@ use super::entry::{
 };
 use super::readonly::ReadonlyIndexSegment;
 use super::rev_walk::RevWalk;
-use crate::backend::{ChangeId, CommitId, ObjectId};
+use crate::backend::{ChangeId, CommitId};
 use crate::index::{HexPrefix, Index, PrefixResolution};
+use crate::object_id::ObjectId;
 use crate::revset::{ResolvedExpression, Revset, RevsetEvaluationError};
 use crate::store::Store;
 use crate::{default_revset_engine, hex_util};

lib/src/default_index/entry.rs

@@ -20,7 +20,8 @@ use std::hash::{Hash, Hasher};
 use smallvec::SmallVec;
 
 use super::composite::{CompositeIndex, IndexSegment};
-use crate::backend::{ChangeId, CommitId, ObjectId};
+use crate::backend::{ChangeId, CommitId};
+use crate::object_id::ObjectId;
 
 /// Global index position.
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone, Copy, Hash)]

lib/src/default_index/mod.rs

@@ -43,8 +43,9 @@ mod tests {
     use super::entry::SmallIndexPositionsVec;
     use super::mutable::MutableIndexSegment;
     use super::*;
-    use crate::backend::{ChangeId, CommitId, ObjectId};
+    use crate::backend::{ChangeId, CommitId};
     use crate::index::{HexPrefix, Index, PrefixResolution};
+    use crate::object_id::ObjectId;
 
     /// Generator of unique 16-byte ChangeId excluding root id
     fn change_id_generator() -> impl FnMut() -> ChangeId {