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| -rw-r--r-- | Documentation/technical/api-tree-walking.txt | 149 | ||||
| -rw-r--r-- | tree-walk.h | 122 |
2 files changed, 120 insertions, 151 deletions
diff --git a/Documentation/technical/api-tree-walking.txt b/Documentation/technical/api-tree-walking.txt deleted file mode 100644 index 7962e32854..0000000000 --- a/Documentation/technical/api-tree-walking.txt +++ /dev/null @@ -1,149 +0,0 @@ -tree walking API -================ - -The tree walking API is used to traverse and inspect trees. - -Data Structures ---------------- - -`struct name_entry`:: - - An entry in a tree. Each entry has a sha1 identifier, pathname, and - mode. - -`struct tree_desc`:: - - A semi-opaque data structure used to maintain the current state of the - walk. -+ -* `buffer` is a pointer into the memory representation of the tree. It always -points at the current entry being visited. - -* `size` counts the number of bytes left in the `buffer`. - -* `entry` points to the current entry being visited. - -`struct traverse_info`:: - - A structure used to maintain the state of a traversal. -+ -* `prev` points to the traverse_info which was used to descend into the -current tree. If this is the top-level tree `prev` will point to -a dummy traverse_info. - -* `name` is the entry for the current tree (if the tree is a subtree). - -* `pathlen` is the length of the full path for the current tree. - -* `conflicts` can be used by callbacks to maintain directory-file conflicts. - -* `fn` is a callback called for each entry in the tree. See Traversing for more -information. - -* `data` can be anything the `fn` callback would want to use. - -* `show_all_errors` tells whether to stop at the first error or not. - -Initializing ------------- - -`init_tree_desc`:: - - Initialize a `tree_desc` and decode its first entry. The buffer and - size parameters are assumed to be the same as the buffer and size - members of `struct tree`. - -`fill_tree_descriptor`:: - - Initialize a `tree_desc` and decode its first entry given the - object ID of a tree. Returns the `buffer` member if the latter - is a valid tree identifier and NULL otherwise. - -`setup_traverse_info`:: - - Initialize a `traverse_info` given the pathname of the tree to start - traversing from. - -Walking -------- - -`tree_entry`:: - - Visit the next entry in a tree. Returns 1 when there are more entries - left to visit and 0 when all entries have been visited. This is - commonly used in the test of a while loop. - -`tree_entry_len`:: - - Calculate the length of a tree entry's pathname. This utilizes the - memory structure of a tree entry to avoid the overhead of using a - generic strlen(). - -`update_tree_entry`:: - - Walk to the next entry in a tree. This is commonly used in conjunction - with `tree_entry_extract` to inspect the current entry. - -`tree_entry_extract`:: - - Decode the entry currently being visited (the one pointed to by - `tree_desc's` `entry` member) and return the sha1 of the entry. The - `pathp` and `modep` arguments are set to the entry's pathname and mode - respectively. - -`get_tree_entry`:: - - Find an entry in a tree given a pathname and the sha1 of a tree to - search. Returns 0 if the entry is found and -1 otherwise. The third - and fourth parameters are set to the entry's sha1 and mode - respectively. - -Traversing ----------- - -`traverse_trees`:: - - Traverse `n` number of trees in parallel. The `fn` callback member of - `traverse_info` is called once for each tree entry. - -`traverse_callback_t`:: - The arguments passed to the traverse callback are as follows: -+ -* `n` counts the number of trees being traversed. - -* `mask` has its nth bit set if something exists in the nth entry. - -* `dirmask` has its nth bit set if the nth tree's entry is a directory. - -* `entry` is an array of size `n` where the nth entry is from the nth tree. - -* `info` maintains the state of the traversal. - -+ -Returning a negative value will terminate the traversal. Otherwise the -return value is treated as an update mask. If the nth bit is set the nth tree -will be updated and if the bit is not set the nth tree entry will be the -same in the next callback invocation. - -`make_traverse_path`:: - - Generate the full pathname of a tree entry based from the root of the - traversal. For example, if the traversal has recursed into another - tree named "bar" the pathname of an entry "baz" in the "bar" - tree would be "bar/baz". - -`traverse_path_len`:: - - Calculate the length of a pathname returned by `make_traverse_path`. - This utilizes the memory structure of a tree entry to avoid the - overhead of using a generic strlen(). - -`strbuf_make_traverse_path`:: - - Convenience wrapper to `make_traverse_path` into a strbuf. - -Authors -------- - -Written by Junio C Hamano <gitster@pobox.com> and Linus Torvalds -<torvalds@linux-foundation.org> diff --git a/tree-walk.h b/tree-walk.h index abe2caf4e0..826396c8ed 100644 --- a/tree-walk.h +++ b/tree-walk.h @@ -3,6 +3,13 @@ #include "cache.h" +/** + * The tree walking API is used to traverse and inspect trees. + */ + +/** + * An entry in a tree. Each entry has a sha1 identifier, pathname, and mode. + */ struct name_entry { struct object_id oid; const char *path; @@ -10,12 +17,29 @@ struct name_entry { unsigned int mode; }; +/** + * A semi-opaque data structure used to maintain the current state of the walk. + */ struct tree_desc { + /* + * pointer into the memory representation of the tree. It always + * points at the current entry being visited. + */ const void *buffer; + + /* points to the current entry being visited. */ struct name_entry entry; + + /* counts the number of bytes left in the `buffer`. */ unsigned int size; }; +/** + * Decode the entry currently being visited (the one pointed to by + * `tree_desc's` `entry` member) and return the sha1 of the entry. The + * `pathp` and `modep` arguments are set to the entry's pathname and mode + * respectively. + */ static inline const struct object_id *tree_entry_extract(struct tree_desc *desc, const char **pathp, unsigned short *modep) { *pathp = desc->entry.path; @@ -23,6 +47,11 @@ static inline const struct object_id *tree_entry_extract(struct tree_desc *desc, return &desc->entry.oid; } +/** + * Calculate the length of a tree entry's pathname. This utilizes the + * memory structure of a tree entry to avoid the overhead of using a + * generic strlen(). + */ static inline int tree_entry_len(const struct name_entry *ne) { return ne->pathlen; @@ -33,52 +62,141 @@ static inline int tree_entry_len(const struct name_entry *ne) * corrupt tree entry rather than dying, */ +/** + * Walk to the next entry in a tree. This is commonly used in conjunction + * with `tree_entry_extract` to inspect the current entry. + */ void update_tree_entry(struct tree_desc *); + int update_tree_entry_gently(struct tree_desc *); + +/** + * Initialize a `tree_desc` and decode its first entry. The buffer and + * size parameters are assumed to be the same as the buffer and size + * members of `struct tree`. + */ void init_tree_desc(struct tree_desc *desc, const void *buf, unsigned long size); + int init_tree_desc_gently(struct tree_desc *desc, const void *buf, unsigned long size); /* - * Helper function that does both tree_entry_extract() and update_tree_entry() - * and returns true for success + * Visit the next entry in a tree. Returns 1 when there are more entries + * left to visit and 0 when all entries have been visited. This is + * commonly used in the test of a while loop. */ int tree_entry(struct tree_desc *, struct name_entry *); + int tree_entry_gently(struct tree_desc *, struct name_entry *); +/** + * Initialize a `tree_desc` and decode its first entry given the + * object ID of a tree. Returns the `buffer` member if the latter + * is a valid tree identifier and NULL otherwise. + */ void *fill_tree_descriptor(struct repository *r, struct tree_desc *desc, const struct object_id *oid); struct traverse_info; typedef int (*traverse_callback_t)(int n, unsigned long mask, unsigned long dirmask, struct name_entry *entry, struct traverse_info *); + +/** + * Traverse `n` number of trees in parallel. The `fn` callback member of + * `traverse_info` is called once for each tree entry. + */ int traverse_trees(struct index_state *istate, int n, struct tree_desc *t, struct traverse_info *info); enum get_oid_result get_tree_entry_follow_symlinks(struct repository *r, struct object_id *tree_oid, const char *name, struct object_id *result, struct strbuf *result_path, unsigned short *mode); +/** + * A structure used to maintain the state of a traversal. + */ struct traverse_info { const char *traverse_path; + + /* + * points to the traverse_info which was used to descend into the + * current tree. If this is the top-level tree `prev` will point to + * a dummy traverse_info. + */ struct traverse_info *prev; + + /* is the entry for the current tree (if the tree is a subtree). */ const char *name; + size_t namelen; unsigned mode; + /* is the length of the full path for the current tree. */ size_t pathlen; + struct pathspec *pathspec; + /* can be used by callbacks to maintain directory-file conflicts. */ unsigned long df_conflicts; + + /* a callback called for each entry in the tree. + * + * The arguments passed to the traverse callback are as follows: + * + * - `n` counts the number of trees being traversed. + * + * - `mask` has its nth bit set if something exists in the nth entry. + * + * - `dirmask` has its nth bit set if the nth tree's entry is a directory. + * + * - `entry` is an array of size `n` where the nth entry is from the nth tree. + * + * - `info` maintains the state of the traversal. + * + * Returning a negative value will terminate the traversal. Otherwise the + * return value is treated as an update mask. If the nth bit is set the nth tree + * will be updated and if the bit is not set the nth tree entry will be the + * same in the next callback invocation. + */ traverse_callback_t fn; + + /* can be anything the `fn` callback would want to use. */ void *data; + + /* tells whether to stop at the first error or not. */ int show_all_errors; }; +/** + * Find an entry in a tree given a pathname and the sha1 of a tree to + * search. Returns 0 if the entry is found and -1 otherwise. The third + * and fourth parameters are set to the entry's sha1 and mode respectively. + */ int get_tree_entry(struct repository *, const struct object_id *, const char *, struct object_id *, unsigned short *); + +/** + * Generate the full pathname of a tree entry based from the root of the + * traversal. For example, if the traversal has recursed into another + * tree named "bar" the pathname of an entry "baz" in the "bar" + * tree would be "bar/baz". + */ char *make_traverse_path(char *path, size_t pathlen, const struct traverse_info *info, const char *name, size_t namelen); + +/** + * Convenience wrapper to `make_traverse_path` into a strbuf. + */ void strbuf_make_traverse_path(struct strbuf *out, const struct traverse_info *info, const char *name, size_t namelen); + +/** + * Initialize a `traverse_info` given the pathname of the tree to start + * traversing from. + */ void setup_traverse_info(struct traverse_info *info, const char *base); +/** + * Calculate the length of a pathname returned by `make_traverse_path`. + * This utilizes the memory structure of a tree entry to avoid the + * overhead of using a generic strlen(). + */ static inline size_t traverse_path_len(const struct traverse_info *info, size_t namelen) { |