Junio C Hamano | 530e741 | 2007-11-24 23:48:04 -0800 | [diff] [blame] | 1 | tree walking API |
| 2 | ================ |
| 3 | |
Stephen Boyd | 6639ffc | 2009-08-03 21:13:21 -0700 | [diff] [blame] | 4 | The tree walking API is used to traverse and inspect trees. |
Junio C Hamano | 530e741 | 2007-11-24 23:48:04 -0800 | [diff] [blame] | 5 | |
Stephen Boyd | 6639ffc | 2009-08-03 21:13:21 -0700 | [diff] [blame] | 6 | Data Structures |
| 7 | --------------- |
Junio C Hamano | 530e741 | 2007-11-24 23:48:04 -0800 | [diff] [blame] | 8 | |
Stephen Boyd | 6639ffc | 2009-08-03 21:13:21 -0700 | [diff] [blame] | 9 | `struct name_entry`:: |
| 10 | |
| 11 | An entry in a tree. Each entry has a sha1 identifier, pathname, and |
| 12 | mode. |
| 13 | |
| 14 | `struct tree_desc`:: |
| 15 | |
| 16 | A semi-opaque data structure used to maintain the current state of the |
| 17 | walk. |
| 18 | + |
| 19 | * `buffer` is a pointer into the memory representation of the tree. It always |
| 20 | points at the current entry being visited. |
| 21 | |
| 22 | * `size` counts the number of bytes left in the `buffer`. |
| 23 | |
| 24 | * `entry` points to the current entry being visited. |
| 25 | |
| 26 | `struct traverse_info`:: |
| 27 | |
| 28 | A structure used to maintain the state of a traversal. |
| 29 | + |
| 30 | * `prev` points to the traverse_info which was used to descend into the |
| 31 | current tree. If this is the top-level tree `prev` will point to |
| 32 | a dummy traverse_info. |
| 33 | |
| 34 | * `name` is the entry for the current tree (if the tree is a subtree). |
| 35 | |
| 36 | * `pathlen` is the length of the full path for the current tree. |
| 37 | |
| 38 | * `conflicts` can be used by callbacks to maintain directory-file conflicts. |
| 39 | |
| 40 | * `fn` is a callback called for each entry in the tree. See Traversing for more |
| 41 | information. |
| 42 | |
| 43 | * `data` can be anything the `fn` callback would want to use. |
| 44 | |
Matthieu Moy | e6c111b | 2010-08-11 10:38:07 +0200 | [diff] [blame] | 45 | * `show_all_errors` tells whether to stop at the first error or not. |
| 46 | |
Stephen Boyd | 6639ffc | 2009-08-03 21:13:21 -0700 | [diff] [blame] | 47 | Initializing |
| 48 | ------------ |
| 49 | |
| 50 | `init_tree_desc`:: |
| 51 | |
| 52 | Initialize a `tree_desc` and decode its first entry. The buffer and |
| 53 | size parameters are assumed to be the same as the buffer and size |
| 54 | members of `struct tree`. |
| 55 | |
| 56 | `fill_tree_descriptor`:: |
| 57 | |
| 58 | Initialize a `tree_desc` and decode its first entry given the sha1 of |
| 59 | a tree. Returns the `buffer` member if the sha1 is a valid tree |
| 60 | identifier and NULL otherwise. |
| 61 | |
| 62 | `setup_traverse_info`:: |
| 63 | |
| 64 | Initialize a `traverse_info` given the pathname of the tree to start |
| 65 | traversing from. The `base` argument is assumed to be the `path` |
| 66 | member of the `name_entry` being recursed into unless the tree is a |
| 67 | top-level tree in which case the empty string ("") is used. |
| 68 | |
| 69 | Walking |
| 70 | ------- |
| 71 | |
| 72 | `tree_entry`:: |
| 73 | |
| 74 | Visit the next entry in a tree. Returns 1 when there are more entries |
| 75 | left to visit and 0 when all entries have been visited. This is |
| 76 | commonly used in the test of a while loop. |
| 77 | |
| 78 | `tree_entry_len`:: |
| 79 | |
| 80 | Calculate the length of a tree entry's pathname. This utilizes the |
| 81 | memory structure of a tree entry to avoid the overhead of using a |
| 82 | generic strlen(). |
| 83 | |
| 84 | `update_tree_entry`:: |
| 85 | |
| 86 | Walk to the next entry in a tree. This is commonly used in conjunction |
| 87 | with `tree_entry_extract` to inspect the current entry. |
| 88 | |
| 89 | `tree_entry_extract`:: |
| 90 | |
| 91 | Decode the entry currently being visited (the one pointed to by |
| 92 | `tree_desc's` `entry` member) and return the sha1 of the entry. The |
| 93 | `pathp` and `modep` arguments are set to the entry's pathname and mode |
| 94 | respectively. |
| 95 | |
| 96 | `get_tree_entry`:: |
| 97 | |
| 98 | Find an entry in a tree given a pathname and the sha1 of a tree to |
| 99 | search. Returns 0 if the entry is found and -1 otherwise. The third |
| 100 | and fourth parameters are set to the entry's sha1 and mode |
| 101 | respectively. |
| 102 | |
| 103 | Traversing |
| 104 | ---------- |
| 105 | |
| 106 | `traverse_trees`:: |
| 107 | |
| 108 | Traverse `n` number of trees in parallel. The `fn` callback member of |
| 109 | `traverse_info` is called once for each tree entry. |
| 110 | |
| 111 | `traverse_callback_t`:: |
| 112 | The arguments passed to the traverse callback are as follows: |
| 113 | + |
| 114 | * `n` counts the number of trees being traversed. |
| 115 | |
| 116 | * `mask` has its nth bit set if something exists in the nth entry. |
| 117 | |
| 118 | * `dirmask` has its nth bit set if the nth tree's entry is a directory. |
| 119 | |
| 120 | * `entry` is an array of size `n` where the nth entry is from the nth tree. |
| 121 | |
| 122 | * `info` maintains the state of the traversal. |
| 123 | |
| 124 | + |
| 125 | Returning a negative value will terminate the traversal. Otherwise the |
| 126 | return value is treated as an update mask. If the nth bit is set the nth tree |
| 127 | will be updated and if the bit is not set the nth tree entry will be the |
| 128 | same in the next callback invocation. |
| 129 | |
| 130 | `make_traverse_path`:: |
| 131 | |
| 132 | Generate the full pathname of a tree entry based from the root of the |
| 133 | traversal. For example, if the traversal has recursed into another |
| 134 | tree named "bar" the pathname of an entry "baz" in the "bar" |
| 135 | tree would be "bar/baz". |
| 136 | |
| 137 | `traverse_path_len`:: |
| 138 | |
| 139 | Calculate the length of a pathname returned by `make_traverse_path`. |
| 140 | This utilizes the memory structure of a tree entry to avoid the |
| 141 | overhead of using a generic strlen(). |
| 142 | |
| 143 | Authors |
| 144 | ------- |
| 145 | |
| 146 | Written by Junio C Hamano <gitster@pobox.com> and Linus Torvalds |
| 147 | <torvalds@linux-foundation.org> |