attr: move doc to attr.h

Move the documentation from Documentation/technical/api-gitattributes.txt
to attr.h as it's easier for the developers to find the usage
information beside the code instead of looking for it in another doc file.

Also documentation/technical/api-gitattributes.txt is removed because the
information it has is now redundant and it'll be hard to keep it up to
date and synchronized with the documentation in the header file.

Signed-off-by: Heba Waly <heba.waly@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Heba Waly 2019-11-17 21:04:47 +00:00 committed by Junio C Hamano
parent 126c1ccefb
commit 3a1b3415d9
3 changed files with 135 additions and 163 deletions

View File

@ -1,154 +0,0 @@
gitattributes API
=================
gitattributes mechanism gives a uniform way to associate various
attributes to set of paths.
Data Structure
--------------
`struct git_attr`::
An attribute is an opaque object that is identified by its name.
Pass the name to `git_attr()` function to obtain the object of
this type. The internal representation of this structure is
of no interest to the calling programs. The name of the
attribute can be retrieved by calling `git_attr_name()`.
`struct attr_check_item`::
This structure represents one attribute and its value.
`struct attr_check`::
This structure represents a collection of `attr_check_item`.
It is passed to `git_check_attr()` function, specifying the
attributes to check, and receives their values.
Attribute Values
----------------
An attribute for a path can be in one of four states: Set, Unset,
Unspecified or set to a string, and `.value` member of `struct
attr_check_item` records it. There are three macros to check these:
`ATTR_TRUE()`::
Returns true if the attribute is Set for the path.
`ATTR_FALSE()`::
Returns true if the attribute is Unset for the path.
`ATTR_UNSET()`::
Returns true if the attribute is Unspecified for the path.
If none of the above returns true, `.value` member points at a string
value of the attribute for the path.
Querying Specific Attributes
----------------------------
* Prepare `struct attr_check` using attr_check_initl()
function, enumerating the names of attributes whose values you are
interested in, terminated with a NULL pointer. Alternatively, an
empty `struct attr_check` can be prepared by calling
`attr_check_alloc()` function and then attributes you want to
ask about can be added to it with `attr_check_append()`
function.
* Call `git_check_attr()` to check the attributes for the path.
* Inspect `attr_check` structure to see how each of the
attribute in the array is defined for the path.
Example
-------
To see how attributes "crlf" and "ident" are set for different paths.
. Prepare a `struct attr_check` with two elements (because
we are checking two attributes):
------------
static struct attr_check *check;
static void setup_check(void)
{
if (check)
return; /* already done */
check = attr_check_initl("crlf", "ident", NULL);
}
------------
. Call `git_check_attr()` with the prepared `struct attr_check`:
------------
const char *path;
setup_check();
git_check_attr(path, check);
------------
. Act on `.value` member of the result, left in `check->items[]`:
------------
const char *value = check->items[0].value;
if (ATTR_TRUE(value)) {
The attribute is Set, by listing only the name of the
attribute in the gitattributes file for the path.
} else if (ATTR_FALSE(value)) {
The attribute is Unset, by listing the name of the
attribute prefixed with a dash - for the path.
} else if (ATTR_UNSET(value)) {
The attribute is neither set nor unset for the path.
} else if (!strcmp(value, "input")) {
If none of ATTR_TRUE(), ATTR_FALSE(), or ATTR_UNSET() is
true, the value is a string set in the gitattributes
file for the path by saying "attr=value".
} else if (... other check using value as string ...) {
...
}
------------
To see how attributes in argv[] are set for different paths, only
the first step in the above would be different.
------------
static struct attr_check *check;
static void setup_check(const char **argv)
{
check = attr_check_alloc();
while (*argv) {
struct git_attr *attr = git_attr(*argv);
attr_check_append(check, attr);
argv++;
}
}
------------
Querying All Attributes
-----------------------
To get the values of all attributes associated with a file:
* Prepare an empty `attr_check` structure by calling
`attr_check_alloc()`.
* Call `git_all_attrs()`, which populates the `attr_check`
with the attributes attached to the path.
* Iterate over the `attr_check.items[]` array to examine
the attribute names and values. The name of the attribute
described by an `attr_check.items[]` object can be retrieved via
`git_attr_name(check->items[i].attr)`. (Please note that no items
will be returned for unset attributes, so `ATTR_UNSET()` will return
false for all returned `attr_check.items[]` objects.)
* Free the `attr_check` struct by calling `attr_check_free()`.

3
attr.c
View File

@ -1,7 +1,6 @@
/*
* Handle git attributes. See gitattributes(5) for a description of
* the file syntax, and Documentation/technical/api-gitattributes.txt
* for a description of the API.
* the file syntax, and attr.h for a description of the API.
*
* One basic design decision here is that we are not going to support
* an insanely large number of attributes.

141
attr.h
View File

@ -1,9 +1,121 @@
#ifndef ATTR_H
#define ATTR_H
/**
* gitattributes mechanism gives a uniform way to associate various attributes
* to set of paths.
*
*
* Querying Specific Attributes
* ----------------------------
*
* - Prepare `struct attr_check` using attr_check_initl() function, enumerating
* the names of attributes whose values you are interested in, terminated with
* a NULL pointer. Alternatively, an empty `struct attr_check` can be
* prepared by calling `attr_check_alloc()` function and then attributes you
* want to ask about can be added to it with `attr_check_append()` function.
*
* - Call `git_check_attr()` to check the attributes for the path.
*
* - Inspect `attr_check` structure to see how each of the attribute in the
* array is defined for the path.
*
*
* Example
* -------
*
* To see how attributes "crlf" and "ident" are set for different paths.
*
* - Prepare a `struct attr_check` with two elements (because we are checking
* two attributes):
*
* ------------
* static struct attr_check *check;
* static void setup_check(void)
* {
* if (check)
* return; // already done
* check = attr_check_initl("crlf", "ident", NULL);
* }
* ------------
*
* - Call `git_check_attr()` with the prepared `struct attr_check`:
*
* ------------
* const char *path;
*
* setup_check();
* git_check_attr(path, check);
* ------------
*
* - Act on `.value` member of the result, left in `check->items[]`:
*
* ------------
* const char *value = check->items[0].value;
*
* if (ATTR_TRUE(value)) {
* The attribute is Set, by listing only the name of the
* attribute in the gitattributes file for the path.
* } else if (ATTR_FALSE(value)) {
* The attribute is Unset, by listing the name of the
* attribute prefixed with a dash - for the path.
* } else if (ATTR_UNSET(value)) {
* The attribute is neither set nor unset for the path.
* } else if (!strcmp(value, "input")) {
* If none of ATTR_TRUE(), ATTR_FALSE(), or ATTR_UNSET() is
* true, the value is a string set in the gitattributes
* file for the path by saying "attr=value".
* } else if (... other check using value as string ...) {
* ...
* }
* ------------
*
* To see how attributes in argv[] are set for different paths, only
* the first step in the above would be different.
*
* ------------
* static struct attr_check *check;
* static void setup_check(const char **argv)
* {
* check = attr_check_alloc();
* while (*argv) {
* struct git_attr *attr = git_attr(*argv);
* attr_check_append(check, attr);
* argv++;
* }
* }
* ------------
*
*
* Querying All Attributes
* -----------------------
*
* To get the values of all attributes associated with a file:
*
* - Prepare an empty `attr_check` structure by calling `attr_check_alloc()`.
*
* - Call `git_all_attrs()`, which populates the `attr_check` with the
* attributes attached to the path.
*
* - Iterate over the `attr_check.items[]` array to examine the attribute
* names and values. The name of the attribute described by an
* `attr_check.items[]` object can be retrieved via
* `git_attr_name(check->items[i].attr)`. (Please note that no items will be
* returned for unset attributes, so `ATTR_UNSET()` will return false for all
* returned `attr_check.items[]` objects.)
*
* - Free the `attr_check` struct by calling `attr_check_free()`.
*/
struct index_state;
/* An attribute is a pointer to this opaque structure */
/**
* An attribute is an opaque object that is identified by its name. Pass the
* name to `git_attr()` function to obtain the object of this type.
* The internal representation of this structure is of no interest to the
* calling programs. The name of the attribute can be retrieved by calling
* `git_attr_name()`.
*/
struct git_attr;
/* opaque structures used internally for attribute collection */
@ -21,21 +133,36 @@ const struct git_attr *git_attr(const char *);
extern const char git_attr__true[];
extern const char git_attr__false[];
/* For public to check git_attr_check results */
/**
* Attribute Values
* ----------------
*
* An attribute for a path can be in one of four states: Set, Unset, Unspecified
* or set to a string, and `.value` member of `struct attr_check_item` records
* it. The three macros check these, if none of them returns true, `.value`
* member points at a string value of the attribute for the path.
*/
/* Returns true if the attribute is Set for the path. */
#define ATTR_TRUE(v) ((v) == git_attr__true)
/* Returns true if the attribute is Unset for the path. */
#define ATTR_FALSE(v) ((v) == git_attr__false)
/* Returns true if the attribute is Unspecified for the path. */
#define ATTR_UNSET(v) ((v) == NULL)
/*
* Send one or more git_attr_check to git_check_attrs(), and
* each 'value' member tells what its value is.
* Unset one is returned as NULL.
*/
/* This structure represents one attribute and its value. */
struct attr_check_item {
const struct git_attr *attr;
const char *value;
};
/**
* This structure represents a collection of `attr_check_item`. It is passed to
* `git_check_attr()` function, specifying the attributes to check, and
* receives their values.
*/
struct attr_check {
int nr;
int alloc;