diff options
Diffstat (limited to 'lib/generic/trie.h')
| -rw-r--r-- | lib/generic/trie.h | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/lib/generic/trie.h b/lib/generic/trie.h new file mode 100644 index 0000000..0550e95 --- /dev/null +++ b/lib/generic/trie.h @@ -0,0 +1,150 @@ +/* Copyright (C) 2017-2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz> + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#pragma once + +#include <stdbool.h> +#include <stdint.h> + +#include <libknot/mm_ctx.h> +#include "lib/defines.h" + +/*! + * \brief Native API of QP-tries: + * + * - keys are char strings, not necessarily zero-terminated, + * the structure copies the contents of the passed keys + * - values are void* pointers, typically you get an ephemeral pointer to it + * - key lengths are limited by 2^32-1 ATM + * + * XXX EDITORS: trie.{h,c} are synced from + * https://gitlab.labs.nic.cz/knot/knot-dns/tree/68352fc969/src/contrib/qp-trie + * only with tiny adjustments, mostly #includes and KR_EXPORT. + */ + +/*! \brief Element value. */ +typedef void* trie_val_t; + +/*! \brief Opaque structure holding a QP-trie. */ +typedef struct trie trie_t; + +/*! \brief Opaque type for holding a QP-trie iterator. */ +typedef struct trie_it trie_it_t; + +/*! \brief Create a trie instance. Pass NULL to use malloc+free. */ +KR_EXPORT +trie_t* trie_create(knot_mm_t *mm); + +/*! \brief Free a trie instance. */ +KR_EXPORT +void trie_free(trie_t *tbl); + +/*! \brief Clear a trie instance (make it empty). */ +KR_EXPORT +void trie_clear(trie_t *tbl); + +/*! \brief Return the number of keys in the trie. */ +KR_EXPORT +size_t trie_weight(const trie_t *tbl); + +/*! \brief Search the trie, returning NULL on failure. */ +KR_EXPORT +trie_val_t* trie_get_try(trie_t *tbl, const char *key, uint32_t len); + +/*! + * \brief Return pointer to the minimum. Optionally with key and its length. */ +KR_EXPORT +trie_val_t* trie_get_first(trie_t *tbl, char **key, uint32_t *len); + +/*! \brief Search the trie, inserting NULL trie_val_t on failure. */ +KR_EXPORT +trie_val_t* trie_get_ins(trie_t *tbl, const char *key, uint32_t len); + +/*! + * \brief Search for less-or-equal element. + * + * \param tbl Trie. + * \param key Searched key. + * \param len Key length. + * \param val Must be valid; it will be set to NULL if not found or errored. + * \return KNOT_EOK for exact match, 1 for previous, KNOT_ENOENT for not-found, + * or KNOT_E*. + */ +KR_EXPORT +int trie_get_leq(trie_t *tbl, const char *key, uint32_t len, trie_val_t **val); + +/*! + * \brief Apply a function to every trie_val_t, in order. + * + * \param d Parameter passed as the second argument to f(). + * \return First nonzero from f() or zero (i.e. KNOT_EOK). + */ +int trie_apply(trie_t *tbl, int (*f)(trie_val_t *, void *), void *d); + +/*! + * \brief Remove an item, returning KNOT_EOK if succeeded or KNOT_ENOENT if not found. + * + * If val!=NULL and deletion succeeded, the deleted value is set. + */ +KR_EXPORT +int trie_del(trie_t *tbl, const char *key, uint32_t len, trie_val_t *val); + +/*! + * \brief Remove the first item, returning KNOT_EOK on success. + * + * You may optionally get the key and/or value. + * The key is copied, so you need to pass sufficient len, + * otherwise kr_error(ENOSPC) is returned. + */ +KR_EXPORT +int trie_del_first(trie_t *tbl, char *key, uint32_t *len, trie_val_t *val); + +/*! \brief Create a new iterator pointing to the first element (if any). */ +KR_EXPORT +trie_it_t* trie_it_begin(trie_t *tbl); + +/*! + * \brief Advance the iterator to the next element. + * + * Iteration is in ascending lexicographical order. + * In particular, the empty string would be considered as the very first. + * + * \note You may not use this function if the trie's key-set has been modified + * during the lifetime of the iterator (modifying values only is OK). + */ +KR_EXPORT +void trie_it_next(trie_it_t *it); + +/*! \brief Test if the iterator has gone past the last element. */ +KR_EXPORT +bool trie_it_finished(trie_it_t *it); + +/*! \brief Free any resources of the iterator. It's OK to call it on NULL. */ +KR_EXPORT +void trie_it_free(trie_it_t *it); + +/*! + * \brief Return pointer to the key of the current element. + * + * \note The optional len is uint32_t internally but size_t is better for our usage, + * as it is without an additional type conversion. + */ +KR_EXPORT +const char* trie_it_key(trie_it_t *it, size_t *len); + +/*! \brief Return pointer to the value of the current element (writable). */ +KR_EXPORT +trie_val_t* trie_it_val(trie_it_t *it); |