refactor: decouple trie into static library

trie/include/trie.h

@@ -0,0 +1,148 @@
+#ifndef AD3_TERNARYTRIE
+#define AD3_TERNARYTRIE
+
+#define ALPHABET_SIZE 256
+#define DELIMITER '\0'
+#define MAX(x, y) (((x) > (y)) ? (x) : (y))
+
+// Should not be higher than 254 or stuff will break
+#define TRIE_MAX_SKIP_SIZE 8
+
+/**
+ * The implementation of a Ternary Trie.
+ *
+ * Each node should be represented by a binary tree in order to reduce the
+ * memory usage.
+ */
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <string.h>
+
+static const char charset[] =
+    "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
+static const size_t charset_len = sizeof(charset) - 1;
+
+// Length of randomly generated keys
+#define RANDOM_KEY_LENGTH_SHORT 4
+#define RANDOM_KEY_LENGTH_LONG 16
+
+/**
+ * Type definition for the struct representing the current Trie.
+ *
+ * You can (and should) redefine this in your c-file with the concrete fields.
+ */
+typedef struct ttrie Trie;
+
+typedef enum entry_type { Redirect, Paste, Unknown } EntryType;
+
+typedef struct entry {
+  EntryType type;
+  char *string;
+} Entry;
+
+typedef enum trie_exit_code {
+  Ok = 0,
+  NotFound,
+  AlreadyPresent,
+  FileError
+} TrieExitCode;
+
+Entry *entry_new(EntryType type, const char *string);
+
+/**
+ * Allocate & initialize a new trie, and populate it with the data from the
+ * given data file.
+ *
+ * @return 0 if everything was successful, non-zero otherwise
+ */
+TrieExitCode trie_init(Trie **trie_ptr, const char *file_path);
+
+/**
+ * De-allocate a trie by freeing the memory occupied by this trie.
+ *
+ * @param trie which should be freed
+ */
+void trie_free(Trie *trie);
+
+/**
+ * Search for an entry in the trie.
+ *
+ * @param trie
+ * @param entry_ptr pointer to Entry will be stored here, if found
+ * @param key key representing the entry
+ * @return 0 if the search was successful, 1 if not found
+ */
+TrieExitCode trie_search(Trie *trie, Entry **entry_ptr, const char *key);
+
+TrieExitCode trie_search_len(Trie *trie, Entry **entry_ptr, const char *key,
+                             size_t key_len);
+
+/**
+ * Add a string to this trie.
+ *
+ * @param trie
+ * @param key key to represent entry with
+ * @param entry entry to add
+ * @return 0 if added, 1 if already in trie, something else if other errors
+ */
+TrieExitCode trie_add(Trie *trie, const char *key, Entry *entry);
+
+TrieExitCode trie_add_len(Trie *trie, const char *key, size_t key_len,
+                          Entry *entry);
+
+/**
+ * Add an entry by generating a random string as the key.
+ *
+ * @param trie
+ * @param entry entry to add
+ * @param secure whether to generate a longer, more secure random key
+ * @return pointer to the generated key. This pointer is safe to use after
+ * unlocking the trie, and should be freed manually.
+ */
+TrieExitCode trie_add_random(Trie *trie, char **key_ptr, Entry *entry,
+                             bool secure);
+
+/**
+ * Remove an entry from this trie given its key.
+ *
+ * @param trie
+ * @param key key representing entry
+ * @return true if the entry was present and has been removed, false if it was
+ * not present
+ */
+bool trie_remove(Trie *trie, const char *key);
+
+/**
+ * Returns the number of entries in this trie.
+ *
+ * @param trie
+ * @return the number of entries in this trie
+ */
+size_t trie_size(Trie *trie);
+
+/*
+ * Acquire a read lock on the trie.
+ *
+ * @return 0 if successful, non-zero otherwise (return value of
+ * pthread_rwlock_rdlock)
+ */
+int trie_rlock(Trie *trie);
+
+/*
+ * Acquire a write lock on the trie.
+ *
+ * @return 0 if successful, non-zero otherwise (return value of
+ * pthread_rwlock_wrlock)
+ */
+int trie_wlock(Trie *trie);
+
+/*
+ * Release the lock on a trie after having acquired it beforehand.
+ *
+ * @return 0 if successful, non-zero otherwise (return value of
+ * pthread_rwlock_unlock)
+ */
+int trie_unlock(Trie *trie);
+
+#endif // AD3_TERNARYTRIE