| Junio C Hamano | 3dac504 | 2007-12-15 08:40:54 | [diff] [blame^] | 1 | gitattributes API |
| 2 | ================= |
| 3 | |
| 4 | gitattributes mechanism gives a uniform way to associate various |
| 5 | attributes to set of paths. |
| 6 | |
| 7 | |
| 8 | Data 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 and its length to `git_attr()` function to obtain |
| 15 | the object of this type. The internal representation of this |
| 16 | structure is of no interest to the calling programs. |
| 17 | |
| 18 | `struct git_attr_check`:: |
| 19 | |
| 20 | This structure represents a set of attributes to check in a call |
| 21 | to `git_checkattr()` function, and receives the results. |
| 22 | |
| 23 | |
| 24 | Calling Sequence |
| 25 | ---------------- |
| 26 | |
| 27 | * Prepare an array of `struct git_attr_check` to define the list of |
| 28 | attributes you would want to check. To populate this array, you would |
| 29 | need to define necessary attributes by calling `git_attr()` function. |
| 30 | |
| 31 | * Call git_checkattr() to check the attributes for the path. |
| 32 | |
| 33 | * Inspect `git_attr_check` structure to see how each of the attribute in |
| 34 | the array is defined for the path. |
| 35 | |
| 36 | |
| 37 | Attribute Values |
| 38 | ---------------- |
| 39 | |
| 40 | An attribute for a path can be in one of four states: Set, Unset, |
| 41 | Unspecified or set to a string, and `.value` member of `struct |
| 42 | git_attr_check` records it. There are three macros to check these: |
| 43 | |
| 44 | `ATTR_TRUE()`:: |
| 45 | |
| 46 | Returns true if the attribute is Set for the path. |
| 47 | |
| 48 | `ATTR_FALSE()`:: |
| 49 | |
| 50 | Returns true if the attribute is Unset for the path. |
| 51 | |
| 52 | `ATTR_UNSET()`:: |
| 53 | |
| 54 | Returns true if the attribute is Unspecified for the path. |
| 55 | |
| 56 | If none of the above returns true, `.value` member points at a string |
| 57 | value of the attribute for the path. |
| 58 | |
| 59 | |
| 60 | Example |
| 61 | ------- |
| 62 | |
| 63 | To see how attributes "crlf" and "indent" are set for different paths. |
| 64 | |
| 65 | . Prepare an array of `struct git_attr_check` with two elements (because |
| 66 | we are checking two attributes). Initialize their `attr` member with |
| 67 | pointers to `struct git_attr` obtained by calling `git_attr()`: |
| 68 | |
| 69 | ------------ |
| 70 | static struct git_attr_check check[2]; |
| 71 | static void setup_check(void) |
| 72 | { |
| 73 | if (check[0].attr) |
| 74 | return; /* already done */ |
| 75 | check[0].attr = git_attr("crlf", 4); |
| 76 | check[1].attr = git_attr("ident", 5); |
| 77 | } |
| 78 | ------------ |
| 79 | |
| 80 | . Call `git_checkattr()` with the prepared array of `struct git_attr_check`: |
| 81 | |
| 82 | ------------ |
| 83 | const char *path; |
| 84 | |
| 85 | setup_check(); |
| 86 | git_checkattr(path, ARRAY_SIZE(check), check); |
| 87 | ------------ |
| 88 | |
| 89 | . Act on `.value` member of the result, left in `check[]`: |
| 90 | |
| 91 | ------------ |
| 92 | const char *value = check[0].value; |
| 93 | |
| 94 | if (ATTR_TRUE(value)) { |
| 95 | The attribute is Set, by listing only the name of the |
| 96 | attribute in the gitattributes file for the path. |
| 97 | } else if (ATTR_FALSE(value)) { |
| 98 | The attribute is Unset, by listing the name of the |
| 99 | attribute prefixed with a dash - for the path. |
| 100 | } else if (ATTR_UNSET(value)) { |
| 101 | The attribute is not set nor unset for the path. |
| 102 | } else if (!strcmp(value, "input")) { |
| 103 | If none of ATTR_TRUE(), ATTR_FALSE(), or ATTR_UNSET() is |
| 104 | true, the value is a string set in the gitattributes |
| 105 | file for the path by saying "attr=value". |
| 106 | } else if (... other check using value as string ...) { |
| 107 | ... |
| 108 | } |
| 109 | ------------ |
| 110 | |
| 111 | (JC) |
