diff options
| -rw-r--r-- | src/trie.c | 59 |
1 files changed, 28 insertions, 31 deletions
@@ -132,34 +132,34 @@ struct trie_node { uintptr_t children[]; }; -/** Check if an encoded pointer is to a leaf. */ -static bool trie_is_leaf(uintptr_t ptr) { +/** Check if an encoded pointer is to an internal node. */ +static bool trie_is_node(uintptr_t ptr) { return ptr & 1; } -/** Decode a pointer to a leaf. */ -static struct trie_leaf *trie_decode_leaf(uintptr_t ptr) { - bfs_assert(trie_is_leaf(ptr)); - return (struct trie_leaf *)(ptr ^ 1); +/** Decode a pointer to an internal node. */ +static struct trie_node *trie_decode_node(uintptr_t ptr) { + bfs_assert(trie_is_node(ptr)); + return (struct trie_node *)(ptr - 1); } -/** Encode a pointer to a leaf. */ -static uintptr_t trie_encode_leaf(const struct trie_leaf *leaf) { - uintptr_t ptr = (uintptr_t)leaf ^ 1; - bfs_assert(trie_is_leaf(ptr)); +/** Encode a pointer to an internal node. */ +static uintptr_t trie_encode_node(const struct trie_node *node) { + uintptr_t ptr = (uintptr_t)node + 1; + bfs_assert(trie_is_node(ptr)); return ptr; } -/** Decode a pointer to an internal node. */ -static struct trie_node *trie_decode_node(uintptr_t ptr) { - bfs_assert(!trie_is_leaf(ptr)); - return (struct trie_node *)ptr; +/** Decode a pointer to a leaf. */ +static struct trie_leaf *trie_decode_leaf(uintptr_t ptr) { + bfs_assert(!trie_is_node(ptr)); + return (struct trie_leaf *)ptr; } -/** Encode a pointer to an internal node. */ -static uintptr_t trie_encode_node(const struct trie_node *node) { - uintptr_t ptr = (uintptr_t)node; - bfs_assert(!trie_is_leaf(ptr)); +/** Encode a pointer to a leaf. */ +static uintptr_t trie_encode_leaf(const struct trie_leaf *leaf) { + uintptr_t ptr = (uintptr_t)leaf; + bfs_assert(!trie_is_node(ptr)); return ptr; } @@ -201,12 +201,9 @@ static unsigned char trie_leaf_nibble(const struct trie_leaf *leaf, size_t offse _trie_clones static struct trie_leaf *trie_representative(const struct trie *trie, const void *key, size_t length) { uintptr_t ptr = trie->root; - if (!ptr) { - return NULL; - } size_t offset = 0; - while (!trie_is_leaf(ptr)) { + while (trie_is_node(ptr)) { struct trie_node *node = trie_decode_node(ptr); offset += node->offset; @@ -269,10 +266,10 @@ static struct trie_leaf *trie_terminal_leaf(const struct trie_node *node) { } uintptr_t ptr = node->children[0]; - if (trie_is_leaf(ptr)) { - return trie_decode_leaf(ptr); - } else { + if (trie_is_node(ptr)) { node = trie_decode_node(ptr); + } else { + return trie_decode_leaf(ptr); } } @@ -300,7 +297,7 @@ static struct trie_leaf *trie_find_prefix_impl(const struct trie *trie, const ch size_t length = strlen(key) + 1; size_t offset = 0; - while (!trie_is_leaf(ptr)) { + while (trie_is_node(ptr)) { struct trie_node *node = trie_decode_node(ptr); offset += node->offset; if ((offset >> 1) >= length) { @@ -552,7 +549,7 @@ static struct trie_leaf *trie_split(struct trie *trie, uintptr_t *ptr, struct tr node->bitmap = (1 << key_nibble) | (1 << rep_nibble); size_t delta = mismatch - offset; - if (!trie_is_leaf(*ptr)) { + if (trie_is_node(*ptr)) { struct trie_node *child = trie_decode_node(*ptr); child->offset -= delta; } @@ -595,7 +592,7 @@ static struct trie_leaf *trie_insert_mem_impl(struct trie *trie, const void *key size_t offset = 0; uintptr_t *ptr = &trie->root; - while (!trie_is_leaf(*ptr)) { + while (trie_is_node(*ptr)) { struct trie_node *node = trie_decode_node(*ptr); if (offset + node->offset > mismatch) { break; @@ -631,7 +628,7 @@ struct trie_leaf *trie_insert_mem(struct trie *trie, const void *key, size_t len /** Free a chain of singleton nodes. */ static void trie_free_singletons(struct trie *trie, uintptr_t ptr) { - while (!trie_is_leaf(ptr)) { + while (trie_is_node(ptr)) { struct trie_node *node = trie_decode_node(ptr); // Make sure the bitmap is a power of two, i.e. it has just one child @@ -663,7 +660,7 @@ static void trie_free_singletons(struct trie *trie, uintptr_t ptr) { */ static int trie_collapse_node(struct trie *trie, uintptr_t *parent, struct trie_node *parent_node, unsigned int child_index) { uintptr_t other = parent_node->children[child_index ^ 1]; - if (!trie_is_leaf(other)) { + if (trie_is_node(other)) { struct trie_node *other_node = trie_decode_node(other); if (other_node->offset + parent_node->offset <= OFFSET_MAX) { other_node->offset += parent_node->offset; @@ -683,7 +680,7 @@ static void trie_remove_impl(struct trie *trie, struct trie_leaf *leaf) { uintptr_t *parent = NULL; unsigned int child_bit = 0, child_index = 0; size_t offset = 0; - while (!trie_is_leaf(*child)) { + while (trie_is_node(*child)) { struct trie_node *node = trie_decode_node(*child); offset += node->offset; |