928f0ab4ba
Signed-off-by: Ville Skyttä <ville.skytta@iki.fi> Reviewed-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
155 lines
4.2 KiB
Plaintext
155 lines
4.2 KiB
Plaintext
gitattributes API
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=================
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gitattributes mechanism gives a uniform way to associate various
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attributes to set of paths.
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Data Structure
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--------------
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`struct git_attr`::
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An attribute is an opaque object that is identified by its name.
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Pass the name to `git_attr()` function to obtain the object of
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this type. The internal representation of this structure is
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of no interest to the calling programs. The name of the
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attribute can be retrieved by calling `git_attr_name()`.
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`struct attr_check_item`::
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This structure represents one attribute and its value.
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`struct attr_check`::
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This structure represents a collection of `attr_check_item`.
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It is passed to `git_check_attr()` function, specifying the
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attributes to check, and receives their values.
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Attribute Values
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----------------
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An attribute for a path can be in one of four states: Set, Unset,
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Unspecified or set to a string, and `.value` member of `struct
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attr_check_item` records it. There are three macros to check these:
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`ATTR_TRUE()`::
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Returns true if the attribute is Set for the path.
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`ATTR_FALSE()`::
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Returns true if the attribute is Unset for the path.
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`ATTR_UNSET()`::
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Returns true if the attribute is Unspecified for the path.
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If none of the above returns true, `.value` member points at a string
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value of the attribute for the path.
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Querying Specific Attributes
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----------------------------
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* Prepare `struct attr_check` using attr_check_initl()
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function, enumerating the names of attributes whose values you are
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interested in, terminated with a NULL pointer. Alternatively, an
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empty `struct attr_check` can be prepared by calling
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`attr_check_alloc()` function and then attributes you want to
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ask about can be added to it with `attr_check_append()`
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function.
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* Call `git_check_attr()` to check the attributes for the path.
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* Inspect `attr_check` structure to see how each of the
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attribute in the array is defined for the path.
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Example
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-------
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To see how attributes "crlf" and "ident" are set for different paths.
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. Prepare a `struct attr_check` with two elements (because
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we are checking two attributes):
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------------
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static struct attr_check *check;
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static void setup_check(void)
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{
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if (check)
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return; /* already done */
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check = attr_check_initl("crlf", "ident", NULL);
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}
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------------
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. Call `git_check_attr()` with the prepared `struct attr_check`:
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------------
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const char *path;
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setup_check();
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git_check_attr(path, check);
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------------
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. Act on `.value` member of the result, left in `check->items[]`:
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------------
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const char *value = check->items[0].value;
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if (ATTR_TRUE(value)) {
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The attribute is Set, by listing only the name of the
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attribute in the gitattributes file for the path.
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} else if (ATTR_FALSE(value)) {
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The attribute is Unset, by listing the name of the
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attribute prefixed with a dash - for the path.
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} else if (ATTR_UNSET(value)) {
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The attribute is neither set nor unset for the path.
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} else if (!strcmp(value, "input")) {
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If none of ATTR_TRUE(), ATTR_FALSE(), or ATTR_UNSET() is
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true, the value is a string set in the gitattributes
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file for the path by saying "attr=value".
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} else if (... other check using value as string ...) {
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...
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}
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------------
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To see how attributes in argv[] are set for different paths, only
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the first step in the above would be different.
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------------
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static struct attr_check *check;
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static void setup_check(const char **argv)
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{
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check = attr_check_alloc();
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while (*argv) {
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struct git_attr *attr = git_attr(*argv);
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attr_check_append(check, attr);
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argv++;
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}
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}
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------------
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Querying All Attributes
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-----------------------
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To get the values of all attributes associated with a file:
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* Prepare an empty `attr_check` structure by calling
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`attr_check_alloc()`.
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* Call `git_all_attrs()`, which populates the `attr_check`
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with the attributes attached to the path.
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* Iterate over the `attr_check.items[]` array to examine
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the attribute names and values. The name of the attribute
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described by an `attr_check.items[]` object can be retrieved via
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`git_attr_name(check->items[i].attr)`. (Please note that no items
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will be returned for unset attributes, so `ATTR_UNSET()` will return
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false for all returned `attr_check.items[]` objects.)
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* Free the `attr_check` struct by calling `attr_check_free()`.
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