libgit2/include/git2/object.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_object_h__
#define INCLUDE_git_object_h__

#include "common.h"
#include "types.h"
#include "oid.h"

/**
 * @file git2/object.h
 * @brief Git revision object management routines
 * @defgroup git_object Git revision object management routines
 * @ingroup Git
 * @{
 */
GIT_BEGIN_DECL

/**
 * Lookup a reference to one of the objects in a repostory.
 *
 * The generated reference is owned by the repository and
 * should not be freed by the user.
 *
 * The 'type' parameter must match the type of the object
 * in the odb; the method will fail otherwise.
 * The special value 'GIT_OBJ_ANY' may be passed to let
 * the method guess the object's type.
 *
 * @param object pointer to the looked-up object
 * @param repo the repository to look up the object
 * @param id the unique identifier for the object
 * @param type the type of the object
 * @return a reference to the object
 */
GIT_EXTERN(int) git_object_lookup(git_object **object, git_repository *repo, const git_oid *id, git_otype type);

/**
 * Create a new in-memory repository object with
 * the given type.
 *
 * The object's attributes can be filled in using the
 * corresponding setter methods.
 *
 * The object will be written back to given git_repository
 * when the git_object_write() function is called; objects
 * cannot be written to disk until all their main
 * attributes have been properly filled.
 *
 * Objects are instantiated with no SHA1 id; their id
 * will be automatically generated when writing to the
 * repository.
 *
 * @param object pointer to the new object
 * @parem repo Repository where the object belongs
 * @param type Type of the object to be created
 * @return the new object
 */
GIT_EXTERN(int) git_object_new(git_object **object, git_repository *repo, git_otype type);


/**
 * Write back an object to disk.
 *
 * The object will be written to its corresponding
 * repository.
 *
 * If the object has no changes since it was first
 * read from the repository, no actions will take place.
 *
 * If the object has been modified since it was read from
 * the repository, or it has been created from scratch
 * in memory, it will be written to the repository and
 * its SHA1 ID will be updated accordingly.
 *
 * @param object Git object to write back
 * @return 0 on success; otherwise an error code
 */
GIT_EXTERN(int) git_object_write(git_object *object);

/**
 * Get the id (SHA1) of a repository object
 *
 * In-memory objects created by git_object_new() do not
 * have a SHA1 ID until they are written on a repository.
 *
 * @param obj the repository object
 * @return the SHA1 id
 */
GIT_EXTERN(const git_oid *) git_object_id(const git_object *obj);

/**
 * Get the object type of an object
 *
 * @param obj the repository object
 * @return the object's type
 */
GIT_EXTERN(git_otype) git_object_type(const git_object *obj);

/**
 * Get the repository that owns this object
 *
 * @param obj the object
 * @return the repository who owns this object
 */
GIT_EXTERN(git_repository *) git_object_owner(const git_object *obj);

/**
 * Close an open object
 *
 * This method instructs the library to close an existing
 * object; note that git_objects are owned by the repository
 * and are reference counted, so the object may or may not be
 * freed after this library call, depending on whether any other 
 * objects still depend on it.
 *
 * IMPORTANT:
 * It is *not* necessary to call this method when you stop using
 * an object, since all object memory is automatically reclaimed
 * by the repository when it is freed.
 *
 * Forgetting to call `git_object_close` does not cause memory
 * leaks, but it's is recommended to close as soon as possible
 * the biggest objects (e.g. blobs) to prevent wasting memory
 * space.
 *
 * @param object the object to close
 */
GIT_EXTERN(void) git_object_close(git_object *object);

/**
 * Convert an object type to it's string representation.
 *
 * The result is a pointer to a string in static memory and
 * should not be free()'ed.
 *
 * @param type object type to convert.
 * @return the corresponding string representation.
 */
GIT_EXTERN(const char *) git_object_type2string(git_otype type);

/**
 * Convert a string object type representation to it's git_otype.
 *
 * @param str the string to convert.
 * @return the corresponding git_otype.
 */
GIT_EXTERN(git_otype) git_object_string2type(const char *str);

/**
 * Determine if the given git_otype is a valid loose object type.
 *
 * @param type object type to test.
 * @return true if the type represents a valid loose object type,
 * false otherwise.
 */
GIT_EXTERN(int) git_object_typeisloose(git_otype type);

/**
 * Get the size in bytes for the structure which
 * acts as an in-memory representation of any given
 * object type.
 *
 * For all the core types, this would the equivalent
 * of calling `sizeof(git_commit)` if the core types
 * were not opaque on the external API.
 *
 * @param type object type to get its size
 * @return size in bytes of the object
 */
GIT_EXTERN(size_t) git_object__size(git_otype type);

/** @} */
GIT_END_DECL

#endif