Support reading attributes from index

[libgit2.git] / include / git2 / attr.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_attr_h__
#define INCLUDE_git_attr_h__

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

/**
 * @file git2/attr.h
 * @brief Git attribute management routines
 * @defgroup git_attr Git attribute management routines
 * @ingroup Git
 * @{
 */
GIT_BEGIN_DECL

/**
 * GIT_ATTR_TRUE checks if an attribute is set on.  In core git
 * parlance, this the value for "Set" attributes.
 *
 * For example, if the attribute file contains:
 *
 *    *.c foo
 *
 * Then for file `xyz.c` looking up attribute "foo" gives a value for
 * which `GIT_ATTR_TRUE(value)` is true.
 */
#define GIT_ATTR_TRUE(attr)		((attr) == git_attr__true)

/**
 * GIT_ATTR_FALSE checks if an attribute is set off.  In core git
 * parlance, this is the value for attributes that are "Unset" (not to
 * be confused with values that a "Unspecified").
 *
 * For example, if the attribute file contains:
 *
 *    *.h -foo
 *
 * Then for file `zyx.h` looking up attribute "foo" gives a value for
 * which `GIT_ATTR_FALSE(value)` is true.
 */
#define GIT_ATTR_FALSE(attr)	((attr) == git_attr__false)

/**
 * GIT_ATTR_UNSPECIFIED checks if an attribute is unspecified.  This
 * may be due to the attribute not being mentioned at all or because
 * the attribute was explicitly set unspecified via the `!` operator.
 *
 * For example, if the attribute file contains:
 *
 *    *.c foo
 *    *.h -foo
 *    onefile.c !foo
 *
 * Then for `onefile.c` looking up attribute "foo" yields a value with
 * `GIT_ATTR_UNSPECIFIED(value)` of true.  Also, looking up "foo" on
 * file `onefile.rb` or looking up "bar" on any file will all give
 * `GIT_ATTR_UNSPECIFIED(value)` of true.
 */
#define GIT_ATTR_UNSPECIFIED(attr)	(!(attr) || (attr) == git_attr__unset)

/**
 * GIT_ATTR_SET_TO_VALUE checks if an attribute is set to a value (as
 * opposied to TRUE, FALSE or UNSPECIFIED).  This would be the case if
 * for a file with something like:
 *
 *    *.txt eol=lf
 *
 * Given this, looking up "eol" for `onefile.txt` will give back the
 * string "lf" and `GIT_ATTR_SET_TO_VALUE(attr)` will return true.
 */
#define GIT_ATTR_SET_TO_VALUE(attr) \
	((attr) && (attr) != git_attr__unset && \
	 (attr) != git_attr__true && (attr) != git_attr__false)

GIT_EXTERN(const char *) git_attr__true;
GIT_EXTERN(const char *) git_attr__false;
GIT_EXTERN(const char *) git_attr__unset;

/**
 * Check attribute flags: Reading values from index and working directory.
 *
 * When checking attributes, it is possible to check attribute files
 * in both the working directory (if there is one) and the index (if
 * there is one).  You can explicitly choose where to check and in
 * which order using the following flags.
 *
 * Core git usually checks the working directory then the index,
 * except during a checkout when it checks the index first.  It will
 * use index only for creating archives or for a bare repo (if an
 * index has been specified for the bare repo).
 */
#define GIT_ATTR_CHECK_FILE_THEN_INDEX	0
#define GIT_ATTR_CHECK_INDEX_THEN_FILE	1
#define GIT_ATTR_CHECK_INDEX_ONLY		2

/**
 * Check attribute flags: Using the system attributes file.
 *
 * Normally, attribute checks include looking in the /etc (or system
 * equivalent) directory for a `gitattributes` file.  Passing this
 * flag will cause attribute checks to ignore that file.
 */
#define GIT_ATTR_CHECK_NO_SYSTEM		(1 << 2)

/**
 * Look up the value of one git attribute for path.
 *
 * @param repo The repository containing the path.
 * @param flags A combination of GIT_ATTR_CHECK... flags.
 * @param path The path to check for attributes.  Relative paths are
 *             interpreted relative to the repo root.  The file does
 *             not have to exist, but if it does not, then it will be
 *             treated as a plain file (not a directory).
 * @param name The name of the attribute to look up.
 * @param value Output of the value of the attribute.  Use the GIT_ATTR_...
 *             macros to test for TRUE, FALSE, UNSPECIFIED, etc. or just
 *             use the string value for attributes set to a value.  You
 *             should NOT modify or free this value.
 */
GIT_EXTERN(int) git_attr_get(
    git_repository *repo,
	uint32_t flags,
	const char *path,
	const char *name,
	const char **value);

/**
 * Look up a list of git attributes for path.
 *
 * Use this if you have a known list of attributes that you want to
 * look up in a single call.  This is somewhat more efficient than
 * calling `git_attr_get()` multiple times.
 *
 * For example, you might write:
 *
 *     const char *attrs[] = { "crlf", "diff", "foo" };
 *     const char **values[3];
 *     git_attr_get_many(repo, 0, "my/fun/file.c", 3, attrs, values);
 *
 * Then you could loop through the 3 values to get the settings for
 * the three attributes you asked about.
 *
 * @param repo The repository containing the path.
 * @param flags A combination of GIT_ATTR_CHECK... flags.
 * @param path The path inside the repo to check attributes.  This
 *             does not have to exist, but if it does not, then
 *             it will be treated as a plain file (i.e. not a directory).
 * @param num_attr The number of attributes being looked up
 * @param names An array of num_attr strings containing attribute names.
 * @param values An array of num_attr entries that will have string
 *             pointers written into it for the values of the attributes.
 *             You should not modify or free the values that are written
 *             into this array (although of course, you should free the
 *             array itself if you allocated it).
 */
GIT_EXTERN(int) git_attr_get_many(
    git_repository *repo,
	uint32_t flags,
	const char *path,
    size_t num_attr,
	const char **names,
	const char **values);

/**
 * Loop over all the git attributes for a path.
 *
 * @param repo The repository containing the path.
 * @param flags A combination of GIT_ATTR_CHECK... flags.
 * @param path The path inside the repo to check attributes.  This
 *             does not have to exist, but if it does not, then
 *             it will be treated as a plain file (i.e. not a directory).
 * @param callback The function that will be invoked on each attribute
 *             and attribute value.  The name parameter will be the name
 *             of the attribute and the value will be the value it is
 *             set to, including possibly NULL if the attribute is
 *             explicitly set to UNSPECIFIED using the ! sign.  This
 *             will be invoked only once per attribute name, even if
 *             there are multiple rules for a given file.  The highest
 *             priority rule will be used.
 * @param payload Passed on as extra parameter to callback function.
 */
GIT_EXTERN(int) git_attr_foreach(
    git_repository *repo,
	uint32_t flags,
	const char *path,
	int (*callback)(const char *name, const char *value, void *payload),
	void *payload);

/**
 * Flush the gitattributes cache.
 *
 * Call this if you have reason to believe that the attributes files on
 * disk no longer match the cached contents of memory.  This will cause
 * the attributes files to be reloaded the next time that an attribute
 * access function is called.
 */
GIT_EXTERN(void) git_attr_cache_flush(
	git_repository *repo);

/**
 * Add a macro definition.
 *
 * Macros will automatically be loaded from the top level `.gitattributes`
 * file of the repository (plus the build-in "binary" macro).  This
 * function allows you to add others.  For example, to add the default
 * macro, you would call:
 *
 *    git_attr_add_macro(repo, "binary", "-diff -crlf");
 */
GIT_EXTERN(int) git_attr_add_macro(
	git_repository *repo,
	const char *name,
	const char *values);

/** @} */
GIT_END_DECL
#endif