145 lines
3.4 KiB
C
145 lines
3.4 KiB
C
#ifndef AD3_TERNARYTRIE
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#define AD3_TERNARYTRIE
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#define ALPHABET_SIZE 256
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#define DELIMITER '\0'
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#define MAX(x, y) (((x) > (y)) ? (x) : (y))
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// Should not be higher than 254 or stuff will break
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#define TRIE_MAX_SKIP_SIZE 8
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/**
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* The implementation of a Ternary Trie.
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*
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* Each node should be represented by a binary tree in order to reduce the
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* memory usage.
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*/
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#include <stdbool.h>
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#include <stddef.h>
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#include <string.h>
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static const char charset[] =
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"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
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static const size_t charset_len = sizeof(charset) - 1;
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// Length of randomly generated keys
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#define RANDOM_KEY_LENGTH_SHORT 4
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#define RANDOM_KEY_LENGTH_LONG 16
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/**
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* Type definition for the struct representing the current Trie.
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*
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* You can (and should) redefine this in your c-file with the concrete fields.
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*/
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typedef struct ttrie Trie;
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typedef enum entry_type { Redirect, Paste, Unknown } EntryType;
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typedef struct entry {
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EntryType type;
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char *string;
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} Entry;
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Entry *entry_new(EntryType type, const char *string);
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/**
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* Allocate and initialize an empty Trie.
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*
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* @return a pointer to an empty Trie struct
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*/
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Trie *trie_init();
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/**
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* Populate trie with entries stored in the given file.
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*
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* @param trie
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* @param file_path path to file containing entries
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* @return amount of entries added; -1 if an error occured
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*/
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int trie_populate(Trie *trie, const char *file_path);
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/**
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* De-allocate a trie by freeing the memory occupied by this trie.
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*
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* @param trie which should be freed
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*/
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void trie_free(Trie *trie);
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/**
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* Search for an entry in the trie.
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*
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* @param trie
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* @param key key representing the entry
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* @return pointer to entry; NULL if not found
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*/
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Entry *trie_search(Trie *trie, const char *key);
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/**
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* Add a string to this trie.
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*
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* @param trie
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* @param key key to represent entry with
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* @param entry entry to add
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* @return true if the trie was changed by this operation, false if it was
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* already present
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*/
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bool trie_add(Trie *trie, const char *key, Entry *entry);
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bool trie_add_no_lock(Trie *trie, const char *key, Entry *entry);
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/**
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* Add an entry by generating a random string as the key.
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*
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* @param trie
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* @param entry entry to add
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* @param secure whether to generate a longer, more secure random key
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* @return pointer to the generated key. This pointer is safe to use after
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* unlocking the trie, and should be freed manually.
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*/
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char *trie_add_random(Trie *trie, Entry *entry, bool secure);
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/**
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* Remove an entry from this trie given its key.
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*
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* @param trie
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* @param key key representing entry
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* @return true if the entry was present and has been removed, false if it was
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* not present
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*/
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bool trie_remove(Trie *trie, const char *key);
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/**
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* Returns the number of entries in this trie.
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*
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* @param trie
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* @return the number of entries in this trie
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*/
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size_t trie_size(Trie *trie);
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/*
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* Acquire a read lock on the trie.
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*
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* @return 0 if successful, non-zero otherwise (return value of
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* pthread_rwlock_rdlock)
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*/
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int trie_rlock(Trie *trie);
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/*
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* Acquire a write lock on the trie.
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*
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* @return 0 if successful, non-zero otherwise (return value of
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* pthread_rwlock_wrlock)
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*/
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int trie_wlock(Trie *trie);
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/*
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* Release the lock on a trie after having acquired it beforehand.
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*
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* @return 0 if successful, non-zero otherwise (return value of
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* pthread_rwlock_unlock)
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*/
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int trie_unlock(Trie *trie);
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#endif // AD3_TERNARYTRIE
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