Edit
kc3-lang/libxkbcommon/src/atom.c
Ran Benita
- src/atom.c
-
/*********************************************************** * Copyright 1987, 1998 The Open Group * * Permission to use, copy, modify, distribute, and sell this software and its * documentation for any purpose is hereby granted without fee, provided that * the above copyright notice appear in all copies and that both that * copyright notice and this permission notice appear in supporting * documentation. * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. * * Except as contained in this notice, the name of The Open Group shall not be * used in advertising or otherwise to promote the sale, use or other dealings * in this Software without prior written authorization from The Open Group. * * * Copyright 1987 by Digital Equipment Corporation, Maynard, Massachusetts. * * All Rights Reserved * * Permission to use, copy, modify, and distribute this software and its * documentation for any purpose and without fee is hereby granted, * provided that the above copyright notice appear in all copies and that * both that copyright notice and this permission notice appear in * supporting documentation, and that the name of Digital not be * used in advertising or publicity pertaining to distribution of the * software without specific, written prior permission. * * DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING * ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL * DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR * ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, * WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, * ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS * SOFTWARE. * ******************************************************************/ /************************************************************ * Copyright 1994 by Silicon Graphics Computer Systems, Inc. * * Permission to use, copy, modify, and distribute this * software and its documentation for any purpose and without * fee is hereby granted, provided that the above copyright * notice appear in all copies and that both that copyright * notice and this permission notice appear in supporting * documentation, and that the name of Silicon Graphics not be * used in advertising or publicity pertaining to distribution * of the software without specific prior written permission. * Silicon Graphics makes no representation about the suitability * of this software for any purpose. It is provided "as is" * without any express or implied warranty. * * SILICON GRAPHICS DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY * AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON * GRAPHICS BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH * THE USE OR PERFORMANCE OF THIS SOFTWARE. * ********************************************************/ #include "utils.h" #include "atom.h" /* FNV-1a (http://www.isthe.com/chongo/tech/comp/fnv/). */ static inline uint32_t hash_buf(const char *string, size_t len) { uint32_t hash = 2166136261u; for (size_t i = 0; i < (len + 1) / 2; i++) { hash ^= (uint8_t) string[i]; hash *= 0x01000193; hash ^= (uint8_t) string[len - 1 - i]; hash *= 0x01000193; } return hash; } /* * The atom table is a insert-only unbalanced binary search tree * mapping strings to atoms. * * The tree nodes are kept contiguously in the `table` array. * * The atom value is the index of the tree node in the array. * * As an optimization, strings are not compared by value directly, * s1 < s2 * instead, they are compared by fingerprint (hash) and the value * is only used to resolve collisions: * (fingerprint(s1), s1) < (fingerprint(s2), s2) * Fingerprint are pre-calculated and saved in the tree nodes. * * Why is this not just a hash table? Who knows! */ struct atom_node { xkb_atom_t left, right; uint32_t fingerprint; char *string; }; struct atom_table { xkb_atom_t root; darray(struct atom_node) table; }; struct atom_table * atom_table_new(void) { struct atom_table *table = calloc(1, sizeof(*table)); if (!table) return NULL; darray_init(table->table); /* The original throw-away root is here, at the illegal atom 0. */ darray_resize0(table->table, 1); return table; } void atom_table_free(struct atom_table *table) { if (!table) return; struct atom_node *node; darray_foreach(node, table->table) free(node->string); darray_free(table->table); free(table); } const char * atom_text(struct atom_table *table, xkb_atom_t atom) { assert(atom < darray_size(table->table)); return darray_item(table->table, atom).string; } xkb_atom_t atom_intern(struct atom_table *table, const char *string, size_t len, bool add) { uint32_t fingerprint = hash_buf(string, len); xkb_atom_t *atomp = &table->root; while (*atomp != XKB_ATOM_NONE) { struct atom_node *node = &darray_item(table->table, *atomp); if (fingerprint > node->fingerprint) { atomp = &node->right; } else if (fingerprint < node->fingerprint) { atomp = &node->left; } else { /* Now start testing the strings. */ const int cmp = strncmp(string, node->string, len); if (likely(cmp == 0 && node->string[len] == '\0')) { return *atomp; } else if (cmp > 0) { atomp = &node->right; } else { atomp = &node->left; } } } if (!add) return XKB_ATOM_NONE; struct atom_node node; node.string = strndup(string, len); assert(node.string != NULL); node.left = node.right = XKB_ATOM_NONE; node.fingerprint = fingerprint; xkb_atom_t atom = darray_size(table->table); /* Do this before the append, as it may realloc and change the offsets. */ *atomp = atom; darray_append(table->table, node); return atom; }