--- /dev/null
+#include <stdio.h>
+#include <string.h>
+#include <Eina.h>
+
+/*
+ * Eina Hash - phonebook
+ *
+ * This example demonstrate the use of Eina Hash by implementing a phonebook
+ * that stores its contact data into the hash.
+ *
+ * It indexes the phone numbers by Contact Full Name, so it's a hash with
+ * string keys.
+ */
+
+struct _Phone_Entry {
+ const char *name; // Full name.
+ const char *number; // Phone number.
+};
+
+typedef struct _Phone_Entry Phone_Entry;
+
+static Phone_Entry _start_entries[] = {
+ { "Wolfgang Amadeus Mozart", "+01 23 456-78910" },
+ { "Ludwig van Beethoven", "+12 34 567-89101" },
+ { "Richard Georg Strauss", "+23 45 678-91012" },
+ { "Heitor Villa-Lobos", "+34 56 789-10123" },
+ { NULL, NULL }
+}; // _start_entries
+
+static void
+_phone_entry_free_cb(void *data)
+{
+ free(data);
+}
+
+static Eina_Bool
+_phone_book_foreach_cb(const Eina_Hash *phone_book, const void *key,
+ void *data, void *fdata)
+{
+ const char *name = key;
+ const char *number = data;
+ printf("%s: %s\n", name, number);
+
+ // Return EINA_FALSE to stop this callback from being called
+ return EINA_TRUE;
+}
+
+int
+main(int argc, const char *argv[])
+{
+ Eina_Hash *phone_book = NULL;
+ int i;
+ const char *entry_name = "Heitor Villa-Lobos";
+ char *phone = NULL;
+ Eina_Bool r;
+ Eina_Iterator *it;
+ void *data;
+
+ eina_init();
+
+ phone_book = eina_hash_string_superfast_new(_phone_entry_free_cb);
+
+ // Add initial entries to our hash
+ for (i = 0; _start_entries[i].name != NULL; i++)
+ {
+ eina_hash_add(phone_book, _start_entries[i].name,
+ strdup(_start_entries[i].number));
+ }
+
+ // Look for a specific entry and get its phone number
+ phone = eina_hash_find(phone_book, entry_name);
+ if (phone)
+ {
+ printf("Printing entry.\n");
+ printf("Name: %s\n", entry_name);
+ printf("Number: %s\n\n", phone);
+ }
+
+ // Delete this entry
+ r = eina_hash_del(phone_book, entry_name, NULL);
+ printf("Hash entry successfully deleted? %d\n\n", r);
+
+ // Modify the pointer data of an entry and free the old one
+ phone = eina_hash_modify(phone_book, "Richard Georg Strauss",
+ strdup("+23 45 111-11111"));
+ free(phone);
+
+ // Modify or add an entry to the hash with eina_hash_set
+ // Let's first add a new entry
+ eina_error_set(0);
+ phone = eina_hash_set(phone_book, "Raul Seixas",
+ strdup("+55 01 234-56789"));
+ if (!phone)
+ {
+ Eina_Error err = eina_error_get();
+ if (!err)
+ {
+ printf("No previous phone found for Raul Seixas. ");
+ printf("Creating new entry.\n");
+ }
+ else
+ printf("Error when setting phone for Raul Seixas\n");
+ }
+ else
+ {
+ printf("Old phone for Raul Seixas was %s\n", phone);
+ free(phone);
+ }
+
+ printf("\n");
+
+ // Now change the phone number
+ eina_error_set(0);
+ phone = eina_hash_set(phone_book, "Raul Seixas",
+ strdup("+55 02 234-56789"));
+ if (phone)
+ {
+ printf("Changing phone for Raul Seixas to +55 02 234-56789. ");
+ printf("Old phone was %s\n", phone);
+ free(phone);
+ }
+ else
+ {
+ Eina_Error err = eina_error_get();
+ if (err)
+ printf("Error when changing phone for Raul Seixas\n");
+ else
+ {
+ printf("No previous phone found for Raul Seixas. ");
+ printf("Creating new entry.\n");
+ }
+ }
+
+ // There are many ways to iterate over our Phone book.
+ // First, iterate showing the names and associated numbers.
+ printf("List of phones:\n");
+ eina_hash_foreach(phone_book, _phone_book_foreach_cb, NULL);
+ printf("\n");
+
+ // Now iterate using an iterator
+ printf("List of phones:\n");
+ it = eina_hash_iterator_tuple_new(phone_book);
+ while (eina_iterator_next(it, &data))
+ {
+ Eina_Hash_Tuple *t = data;
+ const char *name = t->key;
+ const char *number = t->data;
+ printf("%s: %s\n", name, number);
+ }
+ eina_iterator_free(it); // Always free the iterator after its use
+ printf("\n");
+
+ // Just iterate over the keys (names)
+ printf("List of names in the phone book:\n");
+ it = eina_hash_iterator_key_new(phone_book);
+ while (eina_iterator_next(it, &data))
+ {
+ const char *name = data;
+ printf("%s\n", name);
+ }
+ eina_iterator_free(it);
+ printf("\n");
+
+ // Just iterate over the data (numbers)
+ printf("List of numbers in the phone book:\n");
+ it = eina_hash_iterator_data_new(phone_book);
+ while (eina_iterator_next(it, &data))
+ {
+ const char *number = data;
+ printf("%s\n", number);
+ }
+ eina_iterator_free(it);
+ printf("\n");
+
+ // Check how many items are in the phone book
+ printf("There are %d items in the hash.\n\n",
+ eina_hash_population(phone_book));
+
+ // Change the name (key) on an entry
+ eina_hash_move(phone_book, "Raul Seixas", "Alceu Valenca");
+ printf("List of phones after change:\n");
+ eina_hash_foreach(phone_book, _phone_book_foreach_cb, NULL);
+ printf("\n");
+
+ // Empty the phone book, but don't destroy it
+ eina_hash_free_buckets(phone_book);
+ printf("There are %d items in the hash.\n\n",
+ eina_hash_population(phone_book));
+
+ // Phone book could still be used, but we are freeing it since we are
+ // done for now
+ eina_hash_free(phone_book);
+
+ eina_shutdown();
+}
--- /dev/null
+#include <stdio.h>
+#include <string.h>
+#include <Eina.h>
+
+/*
+ * Eina Hash - Two more types of hash
+ *
+ * This example demonstrate two other types of hash in action - using
+ * eina_hash_stringshared_new and eina_hash_new.
+ *
+ * It indexes the phone numbers by Contact Full Name, so it's a hash with string
+ * keys, exactly the same as the other example.
+ */
+
+struct _Phone_Entry {
+ const char *name; // Full name.
+ const char *number; // Phone number.
+};
+
+typedef struct _Phone_Entry Phone_Entry;
+
+static Phone_Entry _start_entries[] = {
+ { "Wolfgang Amadeus Mozart", "+01 23 456-78910" },
+ { "Ludwig van Beethoven", "+12 34 567-89101" },
+ { "Richard Georg Strauss", "+23 45 678-91012" },
+ { "Heitor Villa-Lobos", "+34 56 789-10123" },
+ { NULL, NULL }
+};
+
+static void
+_phone_entry_free_cb(void *data)
+{
+ free(data);
+}
+
+static void
+_phone_book_stringshared_free_cb(void *data)
+{
+ Phone_Entry *e = data;
+ eina_stringshare_del(e->name);
+ eina_stringshare_del(e->number);
+ free(e);
+}
+
+static Eina_Bool
+_phone_book_stringshared_foreach_cb(const Eina_Hash *phone_book,
+ const void *key, void *data, void *fdata)
+{
+ Phone_Entry *e = data;
+ const char *name = e->name; // e->name == key
+ const char *number = e->number;
+ printf("%s: %s\n", name, number);
+
+ return EINA_TRUE;
+}
+
+static void
+example_hash_stringshared(void)
+{
+ Eina_Hash *phone_book = NULL;
+ int i;
+
+ // Create the hash as before
+ phone_book = eina_hash_stringshared_new(_phone_book_stringshared_free_cb);
+
+ // Add initial entries to our hash, using direct_add
+ for (i = 0; _start_entries[i].name != NULL; i++)
+ {
+ Phone_Entry *e = malloc(sizeof(Phone_Entry));
+ e->name = eina_stringshare_add(_start_entries[i].name);
+ e->number = eina_stringshare_add(_start_entries[i].number);
+ // Since we are storing the key (name) in our struct, we can use
+ // eina_hash_direct_add. It could be used in the previous example
+ // too, since each key is already stored in the _start_entries
+ // static array, but we started it with the default add function.
+ eina_hash_direct_add(phone_book, e->name, e);
+ }
+
+ // Iterate over the elements
+ printf("List of phones:\n");
+ eina_hash_foreach(phone_book, _phone_book_stringshared_foreach_cb, NULL);
+ printf("\n");
+
+ eina_hash_free(phone_book);
+}
+
+static unsigned int
+_phone_book_string_key_length(const char *key)
+{
+ if (!key)
+ return 0;
+
+ return (int)strlen(key) + 1;
+}
+
+static int
+_phone_book_string_key_cmp(const char *key1, int key1_length,
+ const char *key2, int key2_length)
+{
+ return strcmp(key1, key2);
+}
+
+static void
+example_hash_big(void)
+{
+ Eina_Hash *phone_book = NULL;
+ int i;
+ const char *phone;
+
+ // Create the same hash as used in eina_hash_01.c, but
+ // use 1024 (2 ^ 10) buckets.
+ phone_book = eina_hash_new(EINA_KEY_LENGTH(_phone_book_string_key_length),
+ EINA_KEY_CMP(_phone_book_string_key_cmp),
+ EINA_KEY_HASH(eina_hash_superfast),
+ _phone_entry_free_cb,
+ 10);
+ for (i = 0; _start_entries[i].name != NULL; i++)
+ {
+ eina_hash_add(phone_book, _start_entries[i].name,
+ strdup(_start_entries[i].number));
+ }
+
+ // Look for a specific entry and get its phone number
+ phone = eina_hash_find(phone_book, "Heitor Villa-Lobos");
+ if (phone)
+ {
+ printf("Printing entry.\n");
+ printf("Name: Heitor Villa-Lobos\n");
+ printf("Number: %s\n\n", phone);
+ }
+
+ eina_hash_free(phone_book);
+}
+
+int
+main(int argc, const char *argv[])
+{
+ eina_init();
+
+ example_hash_stringshared();
+ example_hash_big();
+
+ eina_shutdown();
+}
#include "eina_iterator.h"
/**
+ * @page hash_01_example_page Eina_Hash in action
+ * @dontinclude eina_hash_01.c
+ *
+ * We are going to store some tuples into our table, that will map each @a name
+ * to a @a number. The cost to access a given number from the name should be
+ * very small, even with many entries in our table. This is the initial data:
+ * @skip _Phone_Entry
+ * @until // _start_entries
+ *
+ * Before starting to play with the hash, let's write a callback that will be
+ * used to free the elements from it. Since we are just storing strduped
+ * strings, we just need to free them:
+ *
+ * @skip static
+ * @until }
+ *
+ * We also need a callback to iterate over the elements of the list later, so
+ * we are defining it now:
+ *
+ * @skip Eina_Bool
+ * @until }
+ *
+ * Now let's create our @ref Eina_Hash using @ref
+ * eina_hash_string_superfast_new :
+ *
+ * @skip eina_init
+ * @until phone_book
+ *
+ * Now we add the keys and data to the hash using @ref eina_hash_add . This
+ * means that the key is copied inside the table, together with the pointer to
+ * the data (phone numbers).
+ *
+ * @skip for
+ * @until }
+ *
+ * Some basic manipulations with the hash, like finding a value given a key,
+ * deleting an entry, modifying an entry are exemplified in the following lines.
+ * Notice that the @ref eina_hash_modify function returns the old value stored
+ * in that entry, and it needs to be freed, while the @ref eina_hash_del
+ * function already calls our free callback:
+ *
+ * @skip Look for
+ * @until free(
+ *
+ * The @ref eina_hash_set function can be used to set a key-value entry to the
+ * table if it doesn't exist, or to modify an existent entry. It returns the old
+ * entry if it was already set, and NULL otherwise. But since it will
+ * return NULL on error too, we need to check if an error has occurred:
+ *
+ * @skip Modify
+ * @until printf("\n");
+ *
+ * There are different ways of iterate over the entries of a hash. Here we show
+ * two of them: using @ref eina_hash_foreach and @ref Eina_Iterator .
+ *
+ * @skip List of phones
+ * @until eina_iterator_free(it);
+ *
+ * It's also possible to change the key for a specific entry, without having to
+ * remove the entry from the table and adding it again:
+ *
+ * @skipline eina_hash_move
+ *
+ * We can remove all the elements from the table without free the table itself:
+ *
+ * @skip Empty the phone book
+ * @until eina_hash_population
+ *
+ * Or free the the entire table with its content:
+ *
+ * @skipline eina_hash_free
+ *
+ *
+ * The full code for this example can be seen here: @ref eina_hash_01_c
+ */
+
+/**
+ * @page eina_hash_01_c Hash table in action
+ *
+ * @include eina_hash_01.c
+ * @example eina_hash_01.c
+ */
+
+/**
+ * @page hash_02_example_page Different types of tables
+ *
+ * This example shows two more types of hash tables that can be created using
+ * @ref Eina_Hash . For more types, consult the reference documentation of @ref
+ * eina_hash_new.
+ * @include eina_hash_02.c
+ * @example eina_hash_02.c
+ */
+
+/**
* @addtogroup Eina_Hash_Group Hash Table
*
- * @brief give a small description here : what it is for, what it does
- * , etc...
- * Different implementations exists depending on what to store: strings,
- * integers, pointers, stringshared or your own...
+ * @brief Hash table management. Useful for mapping keys to values.
+ *
+ * The hash table is useful for when one wants to implement a table that maps
+ * keys (usually strings) to data, and have relatively fast access time. The
+ * performance is proportional to the load factor of the table (number of
+ * elements / number of buckets). See @ref hashtable_algo for implementation
+ * details.
+ *
+ * Different implementations exists depending on what kind of key will be used
+ * to access the data: strings, integers, pointers, stringshared or your own.
+ *
* Eina hash tables can copy the keys when using eina_hash_add() or not when
* using eina_hash_direct_add().
*
- * Hash API. Give some hints about the use (functions that must be
- * used like init / shutdown), general use, etc... Give also a link to
- * tutorial below.
- *
* @section hashtable_algo Algorithm
*
- * Give here the algorithm used in the implementation
+ * The Eina_Hash is implemented using an array of N "buckets", where each
+ * bucket is a pointer to a structure that is the head of a <a
+ * href="http://en.wikipedia.org/wiki/Red-black_tree">red-black tree</a>. The
+ * array can then be indexed by the [hash_of_element mod N]. The
+ * hash_of_element is calculated using the hashing function, passed as
+ * parameter to the @ref eina_hash_new function. N is the number of buckets
+ * (array positions), and is calculated based on the buckets_power_size
+ * (argument of @ref eina_hash_new too). The following picture ilustrates the
+ * basic idea:
+ *
+ * @image html 01_hash-table.jpg
+ *
+ * Adding an element to the hash table is made of:
+ * @li calculating the hash for that key (using the specified hash function);
+ * @li calculate the array position [hash mod N];
+ * @li add the element to the rbtree on that position.
+ *
+ * The two first steps have constant time, proportional to the hash function
+ * being used. Adding the key to the rbtree will be proportional on the number
+ * of keys on that bucket.
+ *
+ * The average cost of lookup depends on the number of keys per
+ * bucket (load factor) of the table, if the distribution of keys is
+ * sufficiently uniform.
*
* @section hashtable_perf Performance
*
- * Give some hints about performance if it is possible, and an image !
+ * As said before, the performance depends on the load factor. So trying to keep
+ * it as small as possible will improve the hash table performance. But
+ * increasing the buckets_power_size will also increase the memory consumption.
+ * The default hash table creation functions already have a good number of
+ * buckets, enough for most cases. Particularly for strings, if just a few keys
+ * (less than 30) will be added to the hash table, @ref
+ * eina_hash_string_small_new should be used. If just stringshared keys are
+ * being added, use @ref eina_hash_stringshared_new. If a lot of keys will be
+ * added to the hash table (e.g. more than 1000), then it's better to increase
+ * the buckets_power_size. See @ref eina_hash_new for more details.
+ *
+ * When adding a new key to a hash table, use @ref eina_hash_add or @ref
+ * eina_hash_direct_add (the latter if this key is already stored elsewhere). If
+ * the key may be already inside the hash table, instead of checking with
+ * @ref eina_hash_find and then doing @ref eina_hash_add, one can use just @ref
+ * eina_hash_set (this will change the data pointed by this key if it was
+ * already present in the table).
*
* @section hashtable_tutorial Tutorial
*
- * Here is a fantastic tutorial about our hash table
+ * These examples show many Eina_Hash functions in action:
+ * @li @ref hash_01_example_page
+ * @li @ref hash_02_example_page
*
* @{
*/
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