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>

3 files changed, 179 insertions, 10 deletions

diff --git a/src/git2/refs.h b/src/git2/refs.h
new file mode 100644
index 000000000..c9efac34f
--- /dev/null
+++ b/src/git2/refs.h
@@ -0,0 +1,175 @@
+/*
+ * 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
diff --git a/src/git2/repository.h b/src/git2/repository.h
index 129d3bb5f..ecf3db99f 100644
--- a/src/git2/repository.h
+++ b/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
diff --git a/src/git2/types.h b/src/git2/types.h
index 389f32868..4f66742f0 100644
--- a/src/git2/types.h
+++ b/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;
 
 /** @} */