include/git2/object.h

/*
 * Copyright (C) 2009-2012 the libgit2 contributors
 *
 * This file is part of libgit2, distributed under the GNU GPL v2 with
 * a Linking Exception. For full terms see the included COPYING file.
 */
#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 repository.
 *
 * The generated reference is owned by the repository and
 * should be closed with the `git_object_free` method
 * instead of free'd manually.
 *
 * 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);

/**
 * Lookup a reference to one of the objects in a repository,
 * given a prefix of its identifier (short id).
 *
 * The object obtained will be so that its identifier
 * matches the first 'len' hexadecimal characters
 * (packets of 4 bits) of the given 'id'.
 * 'len' must be at least GIT_OID_MINPREFIXLEN, and
 * long enough to identify a unique object matching
 * the prefix; otherwise the method will fail.
 *
 * The generated reference is owned by the repository and
 * should be closed with the `git_object_free` method
 * instead of free'd manually.
 *
 * 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_out pointer where to store the looked-up object
 * @param repo the repository to look up the object
 * @param id a short identifier for the object
 * @param len the length of the short identifier
 * @param type the type of the object
 * @return 0 or an error code
 */
GIT_EXTERN(int) git_object_lookup_prefix(
		git_object **object_out,
		git_repository *repo,
		const git_oid *id,
		size_t len,
		git_otype type);

/**
 * Get the id (SHA1) of a repository object
 *
 * @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
 *
 * Freeing or calling `git_repository_close` on the
 * returned pointer will invalidate the actual object.
 *
 * Any other operation may be run on the repository without
 * affecting the 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 and cached by the repository
 * so the object may or may not be freed after this library call,
 * depending on how aggressive is the caching mechanism used
 * by the repository.
 *
 * IMPORTANT:
 * It *is* necessary to call this method when you stop using
 * an object. Failure to do so will cause a memory leak.
 *
 * @param object the object to close
 */
GIT_EXTERN(void) git_object_free(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);

/**
 * Recursively peel an object until an object of the specified type is met.
 *
 * The retrieved `peeled` object is owned by the repository and should be
 * closed with the `git_object_free` method.
 *
 * If you pass `GIT_OBJ_ANY` as the target type, then the object will be
 * peeled until the type changes (e.g. a tag will be chased until the
 * referenced object is no longer a tag).
 *
 * @param peeled Pointer to the peeled git_object
 * @param object The object to be processed
 * @param target_type The type of the requested object
 * @return 0 or an error code
 */
GIT_EXTERN(int) git_object_peel(
		git_object **peeled,
		const git_object *object,
		git_otype target_type);

/** @} */
GIT_END_DECL

#endif