Refactor reference parsing code

Several changes have been committed to allow the user to create
in-memory references and write back to disk. Peeling of symbolic
references has been made explicit. Added getter and setter methods for
all attributes on a reference. Added corresponding documentation.

Signed-off-by: Vicent Marti <tanoku@gmail.com>

src/git2.h

@@ -38,6 +38,7 @@
 
 #include "git2/repository.h"
 #include "git2/revwalk.h"
+#include "git2/refs.h"
 
 #include "git2/object.h"
 #include "git2/blob.h"

src/git2/refs.h

+/*
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2,
+ * as published by the Free Software Foundation.
+ *
+ * In addition to the permissions in the GNU General Public License,
+ * the authors give you unlimited permission to link the compiled
+ * version of this file into combinations with other programs,
+ * and to distribute those combinations without any restriction
+ * coming from the use of this file.  (The General Public License
+ * restrictions do apply in other respects; for example, they cover
+ * modification of the file, and distribution when not linked into
+ * a combined executable.)
+ *
+ * This file is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+#ifndef INCLUDE_git_refs_h__
+#define INCLUDE_git_refs_h__
+
+#include "common.h"
+#include "types.h"
+
+/**
+ * @file git2/refs.h
+ * @brief Git reference management routines
+ * @defgroup git_reference Git reference management routines
+ * @ingroup Git
+ * @{
+ */
+GIT_BEGIN_DECL
+
+/**
+ * Create a new reference.
+ *
+ * The reference will be empty and exclusively
+ * in-memory until it is filled with the setter
+ * methods and written back to disk using
+ * `git_reference_write`.
+ *
+ * @param ref_out Pointer to the newly created reference
+ * @param repo Repository where that reference exists
+ * @return 0 on success; error code otherwise
+ */
+GIT_EXTERN(int) git_reference_new(git_reference **ref_out, git_repository *repo);
+
+/**
+ * Get the OID pointed to by a reference.
+ * 
+ * Only available if the reference is direct (i.e. not symbolic)
+ *
+ * @param ref The reference
+ * @return a pointer to the oid if available, NULL otherwise
+ */
+GIT_EXTERN(const git_oid *) git_reference_oid(git_reference *ref);
+
+/**
+ * Get full name to the reference pointed by this reference
+ * 
+ * Only available if the reference is symbolic
+ *
+ * @param ref The reference
+ * @return a pointer to the name if available, NULL otherwise
+ */
+GIT_EXTERN(const char *) git_reference_target(git_reference *ref);
+
+/**
+ * Get the type of a reference
+ *
+ * Either direct (GIT_REF_OID) or symbolic (GIT_REF_SYMBOLIC)
+ *
+ * @param ref The reference
+ * @return the type
+ */
+GIT_EXTERN(git_rtype) git_reference_type(git_reference *ref);
+
+/**
+ * Get the full name of a reference
+ *
+ * @param ref The reference
+ * @return the full name for the ref
+ */
+GIT_EXTERN(const char *) git_reference_name(git_reference *ref);
+
+/**
+ * Resolve a symbolic reference 
+ *
+ * Thie method iteratively peels a symbolic reference
+ * until it resolves to a direct reference to an OID.
+ *
+ * If a direct reference is passed as an argument,
+ * that reference is returned immediately
+ *
+ * @param resolved_ref Pointer to the peeled reference
+ * @param ref The reference
+ * @return 0 on success; error code otherwise
+ */
+GIT_EXTERN(int) git_reference_resolve(git_reference **resolved_ref, git_reference *ref);
+
+/**
+ * Write a reference back to disk.
+ *
+ * The reference must have a valid name and a valid target
+ * (either direct or symbolic).
+ *
+ * If the reference has been loaded from disk and no changes
+ * have been made, no action will take place.
+ *
+ * The writing to disk is atomic.
+ *
+ * @param ref The reference
+ * @return 0 on success; error code otherwise
+ */
+GIT_EXTERN(int) git_reference_write(git_reference *ref);
+
+/**
+ * Get the repository where a reference resides
+ *
+ * @param ref The reference
+ * @return a pointer to the repo
+ */
+GIT_EXTERN(git_repository *) git_reference_owner(git_reference *ref);
+
+/**
+ * Set the name of a reference.
+ *
+ * This marks the reference as modified; changes
+ * won't take effect until it is manually written back
+ * to disk.
+ *
+ * @param ref The reference
+ * @param name The new name for the reference
+ */
+GIT_EXTERN(void) git_reference_set_name(git_reference *ref, const char *name);
+
+/**
+ * Set the target reference of a reference.
+ *
+ * This converts the reference into a symbolic
+ * reference.
+ *
+ * This marks the reference as modified; changes
+ * won't take effect until it is manually written back
+ * to disk.
+ *
+ * @param ref The reference
+ * @param target The new target for the reference
+ */
+GIT_EXTERN(void) git_reference_set_target(git_reference *ref, const char *target);
+
+/**
+ * Set the OID target of a reference.
+ *
+ * This converts the reference into a direct
+ * reference.
+ *
+ * This marks the reference as modified; changes
+ * won't take effect until it is manually written back
+ * to disk.
+ *
+ * @param ref The reference
+ * @param target The new target OID for the reference
+ */
+GIT_EXTERN(void) git_reference_set_oid(git_reference *ref, const git_oid *id);
+
+/** @} */
+GIT_END_DECL
+#endif

src/git2/repository.h

@@ -229,7 +229,7 @@ GIT_EXTERN(int) git_repository_init(git_repository **repo_out, const char *path,
  * @param name the long name for the reference (e.g. HEAD, ref/heads/master, refs/tags/v0.1.0, ...)
  * @return a reference to the reference
  */
-GIT_EXTERN(int) git_repository_reference_lookup(git_reference **reference_out, git_repository *repo, const char *name);
+GIT_EXTERN(int) git_repository_lookup_ref(git_reference **reference_out, git_repository *repo, const char *name);
 	
 /** @} */
 GIT_END_DECL

src/git2/types.h

@@ -138,17 +138,11 @@ typedef struct git_signature {
 /** In-memory representation of a reference. */
 typedef struct git_reference git_reference;
 
-/** In-memory representation of a reference to an object id. */
-typedef struct git_reference_object_id git_reference_object_id;
-
-/** In-memory representation of a reference which points at another reference. The target reference is embedded. */
-typedef struct git_reference_symbolic git_reference_symbolic;
-
 /** Basic type of any Git reference. */
 typedef enum {
-	GIT_REF_ANY = -2,		/** Reference can be any of the following */
-	GIT_REF_OBJECT_ID = 0,	/** A reference which points at an object id */
-	GIT_REF_SYMBOLIC = 1,	/** A reference which points at another reference */
+	GIT_REF_INVALID = -1, /** Invalid reference */
+	GIT_REF_OID = 1, /** A reference which points at an object id */
+	GIT_REF_SYMBOLIC = 2, /** A reference which points at another reference */
 } git_rtype;
 
 /** @} */

src/refs.h

@@ -9,40 +9,32 @@
 #define GIT_REFS_HEADS_DIR GIT_REFS_DIR "heads/"
 #define GIT_REFS_TAGS_DIR GIT_REFS_DIR "tags/"
 
-#define GIT_SYMREF "ref:"
+#define GIT_SYMREF "ref: "
 #define GIT_PACKEDREFS_FILE "packed-refs"
 #define GIT_PACKEDREFS_HEADER "# pack-refs with: peeled \n"
 #define MAX_GITDIR_TREE_STRUCTURE_PATH_LENGTH 100
 
 struct git_reference {
+	git_repository *owner;
 	git_rtype type;
 	char *name;
 
-	unsigned is_packed:1;
-};
-
-struct git_reference_object_id {
-	git_reference base;
+	unsigned packed:1,
+			 modified:1;
 
-	git_oid id;
+	union {
+		char *ref;
+		git_oid oid;
+	} target;
 };
 
-struct git_reference_symbolic {
-	git_reference base;
+typedef struct {
+	git_hashtable *cache;
+	unsigned pack_loaded:1;
+} git_refcache;
+
 
-	git_reference *target;
-};
+void git_repository__refcache_free(git_refcache *refs);
+int git_repository__refcache_init(git_refcache *refs);
 
-typedef struct {
-	git_hashtable *references;
-	
-	unsigned is_fully_loaded:1;
-	unsigned have_packed_refs_been_parsed:1;
-	unsigned is_busy:1;
-} git_reference_database;
-
-git_reference_database *git_reference_database__alloc();
-void git_reference_database__free(git_reference_database *ref_database);
-int git_reference_lookup(git_reference **reference_out, git_reference_database *ref_database, const char *name, const char *path_repository, int *nesting_level);
-
-#endif
+#endif
\ No newline at end of file

src/repository.c

@@ -227,8 +227,7 @@ static git_repository *repository_alloc()
 		return NULL;
 	}
 
-	repo->ref_database = git_reference_database__alloc();
-	if (repo->ref_database == NULL) {
+	if (git_repository__refcache_init(&repo->references) < GIT_SUCCESS) {
 		git_hashtable_free(repo->objects);
 		free(repo);
 		return NULL;
@@ -364,7 +363,7 @@ void git_repository_free(git_repository *repo)
 
 	git_hashtable_free(repo->objects);
 
-	git_reference_database__free(repo->ref_database);
+	git_repository__refcache_free(&repo->references);
 
 	if (repo->db != NULL)
 		git_odb_close(repo->db);
@@ -633,15 +632,3 @@ cleanup:
 	free(results.path_repository);
 	return error;
 }
-
-int git_repository_reference_lookup(git_reference **reference_out, git_repository *repo, const char *name)
-{
-	int error = GIT_SUCCESS;
-	int nesting_level = 0;
-
-	assert(repo && reference_out && name);
-
-	error = git_reference_lookup(reference_out, repo->ref_database, name, repo->path_repository, &nesting_level);
-
-	return error;
-}

src/repository.h

@@ -28,7 +28,8 @@ struct git_repository {
 	git_odb *db;
 	git_index *index;
 	git_hashtable *objects;
-	git_reference_database *ref_database;
+
+	git_refcache references;
 
 	char *path_repository;
 	char *path_index;

tests/t1001-readtag.c

@@ -12,18 +12,15 @@ BEGIN_TEST(loose_tag_reference_looking_up)
 
 	must_pass(git_repository_open(&repo, REPOSITORY_FOLDER));
 
-
-	must_pass(git_repository_reference_lookup(&reference, repo, loose_tag_ref_name));
-	must_be_true(reference->type == GIT_REF_OBJECT_ID);
-	must_be_true(reference->is_packed == 0);
+	must_pass(git_repository_lookup_ref(&reference, repo, loose_tag_ref_name));
+	must_be_true(reference->type == GIT_REF_OID);
+	must_be_true(reference->packed == 0);
 	must_be_true(strcmp(reference->name, loose_tag_ref_name) == 0);
 
-
-	must_pass(git_repository_lookup(&object, repo, &((git_reference_object_id *)reference)->id, GIT_OBJ_ANY));
+	must_pass(git_repository_lookup(&object, repo, git_reference_oid(reference), GIT_OBJ_ANY));
 	must_be_true(object != NULL);
 	must_be_true(git_object_type(object) == GIT_OBJ_TAG);
 
-
 	git_repository_free(repo);
 END_TEST
 
@@ -32,8 +29,7 @@ BEGIN_TEST(non_existing_tag_reference_looking_up)
 	git_reference *reference;
 
 	must_pass(git_repository_open(&repo, REPOSITORY_FOLDER));
-
-	must_fail(git_repository_reference_lookup(&reference, repo, non_existing_tag_ref_name));
+	must_fail(git_repository_lookup_ref(&reference, repo, non_existing_tag_ref_name));
 
 	git_repository_free(repo);
-END_TEST
+END_TEST
\ No newline at end of file

tests/t1002-readsymref.c

@@ -8,54 +8,37 @@ static const char *current_master_tip = "be3563ae3f795b2b4353bcce3a527ad0a4f7f64
 
 BEGIN_TEST(symbolic_reference_looking_up)
 	git_repository *repo;
-	git_reference *reference;
-	git_reference_symbolic *head_ref;
-	git_reference_object_id *target_ref;
+	git_reference *reference, *resolved_ref;
 	git_object *object;
 	git_oid id;
 
 	must_pass(git_repository_open(&repo, REPOSITORY_FOLDER));
 
-
-	must_pass(git_repository_reference_lookup(&reference, repo, head_ref_name));
+	must_pass(git_repository_lookup_ref(&reference, repo, head_ref_name));
 	must_be_true(reference->type == GIT_REF_SYMBOLIC);
-	must_be_true(reference->is_packed == 0);
+	must_be_true(reference->packed == 0);
 	must_be_true(strcmp(reference->name, head_ref_name) == 0);
 
-	head_ref = (git_reference_symbolic *)reference;
-	must_be_true(head_ref->target != NULL);
-	must_be_true(head_ref->target->type == GIT_REF_OBJECT_ID);					/* Current HEAD directly points to the object id reference */
-	must_be_true(strcmp(head_ref->target->name, current_head_target) == 0);
+	must_pass(git_reference_resolve(&resolved_ref, reference));
+	must_be_true(resolved_ref->type == GIT_REF_OID);
 
-	target_ref = (git_reference_object_id *)head_ref->target;
-
-	must_pass(git_repository_lookup(&object, repo, &target_ref->id, GIT_OBJ_ANY));
+	must_pass(git_repository_lookup(&object, repo, git_reference_oid(resolved_ref), GIT_OBJ_ANY));
 	must_be_true(object != NULL);
 	must_be_true(git_object_type(object) == GIT_OBJ_COMMIT);
 
 	git_oid_mkstr(&id, current_master_tip);
 	must_be_true(git_oid_cmp(&id, git_object_id(object)) == 0);
 
-
 	git_repository_free(repo);
 END_TEST
 
 BEGIN_TEST(looking_up_head_then_master)
 	git_repository *repo;
 	git_reference *reference;
-	git_reference_symbolic *head_ref;
 
 	must_pass(git_repository_open(&repo, REPOSITORY_FOLDER));
-
-
-	must_pass(git_repository_reference_lookup(&reference, repo, head_ref_name));
-
-	head_ref = (git_reference_symbolic *)reference;
-	must_be_true(head_ref->target != NULL);
-
-	must_pass(git_repository_reference_lookup(&reference, repo, current_head_target));
-	must_be_true(head_ref->target == reference);
-
+	must_pass(git_repository_lookup_ref(&reference, repo, head_ref_name));
+	must_pass(git_repository_lookup_ref(&reference, repo, current_head_target));
 
 	git_repository_free(repo);
 END_TEST
@@ -63,19 +46,10 @@ END_TEST
 BEGIN_TEST(looking_up_master_then_head)
 	git_repository *repo;
 	git_reference *reference, *master_ref;
-	git_reference_symbolic *head_ref;
 
 	must_pass(git_repository_open(&repo, REPOSITORY_FOLDER));
-
-
-	must_pass(git_repository_reference_lookup(&master_ref, repo, current_head_target));
-
-	must_pass(git_repository_reference_lookup(&reference, repo, head_ref_name));
-	head_ref = (git_reference_symbolic *)reference;
-	must_be_true(head_ref->target != NULL);
-	
-	must_be_true(head_ref->target == master_ref);
-
+	must_pass(git_repository_lookup_ref(&master_ref, repo, current_head_target));
+	must_pass(git_repository_lookup_ref(&reference, repo, head_ref_name));
 
 	git_repository_free(repo);
-END_TEST
+END_TEST
\ No newline at end of file

tests/t1003-readpackedref.c

@@ -8,45 +8,32 @@ static const char *packed_test_head_name = "refs/heads/packed-test";
 BEGIN_TEST(packed_reference_looking_up)
 	git_repository *repo;
 	git_reference *reference;
-	git_reference_object_id *packed_ref;
 	git_object *object;
-	git_oid id;
 
 	must_pass(git_repository_open(&repo, REPOSITORY_FOLDER));
 
-
-	must_pass(git_repository_reference_lookup(&reference, repo, packed_head_name));
-	must_be_true(reference->type == GIT_REF_OBJECT_ID);
-	must_be_true(reference->is_packed == 1);
+	must_pass(git_repository_lookup_ref(&reference, repo, packed_head_name));
+	must_be_true(reference->type == GIT_REF_OID);
+	must_be_true(reference->packed == 1);
 	must_be_true(strcmp(reference->name, packed_head_name) == 0);
 
-	packed_ref = (git_reference_object_id *)reference;
-
-	must_pass(git_repository_lookup(&object, repo, &packed_ref->id, GIT_OBJ_ANY));
+	must_pass(git_repository_lookup(&object, repo, git_reference_oid(reference), GIT_OBJ_ANY));
 	must_be_true(object != NULL);
 	must_be_true(git_object_type(object) == GIT_OBJ_COMMIT);
 
-
 	git_repository_free(repo);
 END_TEST
 
 BEGIN_TEST(packed_exists_but_more_recent_loose_reference_is_retrieved)
 	git_repository *repo;
 	git_reference *reference;
-	git_reference_object_id *packed_ref;
-	git_object *object;
-	git_oid id;
 
 	must_pass(git_repository_open(&repo, REPOSITORY_FOLDER));
-
-
-	must_pass(git_repository_reference_lookup(&reference, repo, packed_head_name));			/* Triggers load and eager parsing of all packed references */
-
-	must_pass(git_repository_reference_lookup(&reference, repo, packed_test_head_name));
-	must_be_true(reference->type == GIT_REF_OBJECT_ID);
-	must_be_true(reference->is_packed == 0);
+	must_pass(git_repository_lookup_ref(&reference, repo, packed_head_name));
+	must_pass(git_repository_lookup_ref(&reference, repo, packed_test_head_name));
+	must_be_true(reference->type == GIT_REF_OID);
+	must_be_true(reference->packed == 0);
 	must_be_true(strcmp(reference->name, packed_test_head_name) == 0);
 
-
 	git_repository_free(repo);
-END_TEST
+END_TEST
\ No newline at end of file