Andrew's git / gitweb.git /
ab3a84d2f716e7f43209b8fda10f8713facce008
   1gitattributes API
   2=================
   3
   4gitattributes mechanism gives a uniform way to associate various
   5attributes to set of paths.
   6
   7
   8Data Structure
   9--------------
  10
  11`struct git_attr`::
  12
  13        An attribute is an opaque object that is identified by its name.
  14        Pass the name to `git_attr()` function to obtain the object of
  15        this type.  The internal representation of this structure is
  16        of no interest to the calling programs.  The name of the
  17        attribute can be retrieved by calling `git_attr_name()`.
  18
  19`struct git_attr_check`::
  20
  21        This structure represents a set of attributes to check in a call
  22        to `git_checkattr()` function, and receives the results.
  23
  24
  25Calling Sequence
  26----------------
  27
  28* Prepare an array of `struct git_attr_check` to define the list of
  29  attributes you would want to check.  To populate this array, you would
  30  need to define necessary attributes by calling `git_attr()` function.
  31
  32* Call git_checkattr() to check the attributes for the path.
  33
  34* Inspect `git_attr_check` structure to see how each of the attribute in
  35  the array is defined for the path.
  36
  37
  38Attribute Values
  39----------------
  40
  41An attribute for a path can be in one of four states: Set, Unset,
  42Unspecified or set to a string, and `.value` member of `struct
  43git_attr_check` records it.  There are three macros to check these:
  44
  45`ATTR_TRUE()`::
  46
  47        Returns true if the attribute is Set for the path.
  48
  49`ATTR_FALSE()`::
  50
  51        Returns true if the attribute is Unset for the path.
  52
  53`ATTR_UNSET()`::
  54
  55        Returns true if the attribute is Unspecified for the path.
  56
  57If none of the above returns true, `.value` member points at a string
  58value of the attribute for the path.
  59
  60
  61Example
  62-------
  63
  64To see how attributes "crlf" and "indent" are set for different paths.
  65
  66. Prepare an array of `struct git_attr_check` with two elements (because
  67  we are checking two attributes).  Initialize their `attr` member with
  68  pointers to `struct git_attr` obtained by calling `git_attr()`:
  69
  70------------
  71static struct git_attr_check check[2];
  72static void setup_check(void)
  73{
  74        if (check[0].attr)
  75                return; /* already done */
  76        check[0].attr = git_attr("crlf");
  77        check[1].attr = git_attr("ident");
  78}
  79------------
  80
  81. Call `git_checkattr()` with the prepared array of `struct git_attr_check`:
  82
  83------------
  84        const char *path;
  85
  86        setup_check();
  87        git_checkattr(path, ARRAY_SIZE(check), check);
  88------------
  89
  90. Act on `.value` member of the result, left in `check[]`:
  91
  92------------
  93        const char *value = check[0].value;
  94
  95        if (ATTR_TRUE(value)) {
  96                The attribute is Set, by listing only the name of the
  97                attribute in the gitattributes file for the path.
  98        } else if (ATTR_FALSE(value)) {
  99                The attribute is Unset, by listing the name of the
 100                attribute prefixed with a dash - for the path.
 101        } else if (ATTR_UNSET(value)) {
 102                The attribute is not set nor unset for the path.
 103        } else if (!strcmp(value, "input")) {
 104                If none of ATTR_TRUE(), ATTR_FALSE(), or ATTR_UNSET() is
 105                true, the value is a string set in the gitattributes
 106                file for the path by saying "attr=value".
 107        } else if (... other check using value as string ...) {
 108                ...
 109        }
 110------------
 111
 112(JC)