From: Elijah Newren <newren@xxxxxxxxx> Add strmap as a new struct and associated utility functions, specifically for hashmaps that map strings to some value. The API is taken directly from Peff's proposal at https://lore.kernel.org/git/20180906191203.GA26184@xxxxxxxxxxxxxxxxxxxxx/ A couple of items of note: * Similar to string-list, I have a strdup_strings setting. However, unlike string-list, strmap_init() does not take a parameter for this setting and instead automatically sets it to 1; callers who want to control this detail need to instead call strmap_ocd_init(). * I do not have a STRMAP_INIT macro. I could possibly add one, but #define STRMAP_INIT { { NULL, cmp_str_entry, NULL, 0, 0, 0, 0, 0 }, 1 } feels a bit unwieldy and possibly error-prone in terms of future expansion of the hashmap struct. The fact that cmp_str_entry needs to be in there prevents us from passing all zeros for the hashmap, and makes me worry that STRMAP_INIT would just be more trouble than it is worth. Signed-off-by: Elijah Newren <newren@xxxxxxxxx> --- Makefile | 1 + strmap.c | 102 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ strmap.h | 57 +++++++++++++++++++++++++++++++ 3 files changed, 160 insertions(+) create mode 100644 strmap.c create mode 100644 strmap.h diff --git a/Makefile b/Makefile index 95571ee3fc..777a34c01c 100644 --- a/Makefile +++ b/Makefile @@ -1000,6 +1000,7 @@ LIB_OBJS += stable-qsort.o LIB_OBJS += strbuf.o LIB_OBJS += streaming.o LIB_OBJS += string-list.o +LIB_OBJS += strmap.o LIB_OBJS += strvec.o LIB_OBJS += sub-process.o LIB_OBJS += submodule-config.o diff --git a/strmap.c b/strmap.c new file mode 100644 index 0000000000..4b48d64274 --- /dev/null +++ b/strmap.c @@ -0,0 +1,102 @@ +#include "git-compat-util.h" +#include "strmap.h" + +static int cmp_strmap_entry(const void *hashmap_cmp_fn_data, + const struct hashmap_entry *entry1, + const struct hashmap_entry *entry2, + const void *keydata) +{ + const struct strmap_entry *e1, *e2; + + e1 = container_of(entry1, const struct strmap_entry, ent); + e2 = container_of(entry2, const struct strmap_entry, ent); + return strcmp(e1->key, e2->key); +} + +static struct strmap_entry *find_strmap_entry(struct strmap *map, + const char *str) +{ + struct strmap_entry entry; + hashmap_entry_init(&entry.ent, strhash(str)); + entry.key = str; + return hashmap_get_entry(&map->map, &entry, ent, NULL); +} + +void strmap_init(struct strmap *map) +{ + strmap_ocd_init(map, 1); +} + +void strmap_ocd_init(struct strmap *map, + int strdup_strings) +{ + hashmap_init(&map->map, cmp_strmap_entry, NULL, 0); + map->strdup_strings = strdup_strings; +} + +static void strmap_free_entries_(struct strmap *map, int free_util) +{ + struct hashmap_iter iter; + struct strmap_entry *e; + + if (!map) + return; + + /* + * We need to iterate over the hashmap entries and free + * e->key and e->value ourselves; hashmap has no API to + * take care of that for us. Since we're already iterating over + * the hashmap, though, might as well free e too and avoid the need + * to make some call into the hashmap API to do that. + */ + hashmap_for_each_entry(&map->map, &iter, e, ent) { + if (free_util) + free(e->value); + if (map->strdup_strings) + free((char*)e->key); + free(e); + } +} + +void strmap_clear(struct strmap *map, int free_util) +{ + strmap_free_entries_(map, free_util); + hashmap_free(&map->map); +} + +void *strmap_put(struct strmap *map, const char *str, void *data) +{ + struct strmap_entry *entry = find_strmap_entry(map, str); + void *old = NULL; + + if (entry) { + old = entry->value; + entry->value = data; + } else { + /* + * We won't modify entry->key so it really should be const. + */ + const char *key = str; + + entry = xmalloc(sizeof(*entry)); + hashmap_entry_init(&entry->ent, strhash(str)); + + if (map->strdup_strings) + key = xstrdup(str); + entry->key = key; + entry->value = data; + hashmap_add(&map->map, &entry->ent); + } + return old; +} + +void *strmap_get(struct strmap *map, const char *str) +{ + struct strmap_entry *entry = find_strmap_entry(map, str); + return entry ? entry->value : NULL; +} + +int strmap_contains(struct strmap *map, const char *str) +{ + return find_strmap_entry(map, str) != NULL; +} diff --git a/strmap.h b/strmap.h new file mode 100644 index 0000000000..493d19cbc0 --- /dev/null +++ b/strmap.h @@ -0,0 +1,57 @@ +#ifndef STRMAP_H +#define STRMAP_H + +#include "hashmap.h" + +struct strmap { + struct hashmap map; + unsigned int strdup_strings:1; +}; + +struct strmap_entry { + struct hashmap_entry ent; + const char *key; + void *value; +}; + +/* + * Initialize the members of the strmap. Any keys added to the strmap will + * be strdup'ed with their memory managed by the strmap. + */ +void strmap_init(struct strmap *map); + +/* + * Same as strmap_init, but for those who want to control the memory management + * carefully instead of using the default of strdup_strings=1. + * (OCD = Obsessive Compulsive Disorder, a joke that those who use this function + * are obsessing over minor details.) + */ +void strmap_ocd_init(struct strmap *map, + int strdup_strings); + +/* + * Remove all entries from the map, releasing any allocated resources. + */ +void strmap_clear(struct strmap *map, int free_values); + +/* + * Insert "str" into the map, pointing to "data". + * + * If an entry for "str" already exists, its data pointer is overwritten, and + * the original data pointer returned. Otherwise, returns NULL. + */ +void *strmap_put(struct strmap *map, const char *str, void *data); + +/* + * Return the data pointer mapped by "str", or NULL if the entry does not + * exist. + */ +void *strmap_get(struct strmap *map, const char *str); + +/* + * Return non-zero iff "str" is present in the map. This differs from + * strmap_get() in that it can distinguish entries with a NULL data pointer. + */ +int strmap_contains(struct strmap *map, const char *str); + +#endif /* STRMAP_H */ -- gitgitgadget
