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Diffstat (limited to '')
| -rw-r--r-- | runtime/hashtable_itr.c | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/runtime/hashtable_itr.c b/runtime/hashtable_itr.c new file mode 100644 index 0000000..a065f12 --- /dev/null +++ b/runtime/hashtable_itr.c @@ -0,0 +1,189 @@ +/* Copyright (C) 2002, 2004 Christopher Clark <firstname.lastname@cl.cam.ac.uk> */ + +#include "hashtable_private.h" +#include "hashtable_itr.h" +#include <stdlib.h> /* defines NULL */ + +/*****************************************************************************/ +/* hashtable_iterator - iterator constructor */ + +struct hashtable_itr * +hashtable_iterator(struct hashtable *h) +{ + unsigned int i, tablelength; + struct hashtable_itr *itr = (struct hashtable_itr *) + malloc(sizeof(struct hashtable_itr)); + if (NULL == itr) return NULL; + itr->h = h; + itr->e = NULL; + itr->parent = NULL; + tablelength = h->tablelength; + itr->index = tablelength; + if (0 == h->entrycount) return itr; + + for (i = 0; i < tablelength; i++) + { + if (NULL != h->table[i]) + { + itr->e = h->table[i]; + itr->index = i; + break; + } + } + return itr; +} + +/*****************************************************************************/ +/* key - return the key of the (key,value) pair at the current position */ +/* value - return the value of the (key,value) pair at the current position */ + +#if 0 /* these are now inline functions! */ +void * +hashtable_iterator_key(struct hashtable_itr *i) +{ return i->e->k; } + +void * +hashtable_iterator_value(struct hashtable_itr *i) +{ return i->e->v; } +#endif + +/*****************************************************************************/ +/* advance - advance the iterator to the next element + * returns zero if advanced to end of table */ + +int +hashtable_iterator_advance(struct hashtable_itr *itr) +{ + unsigned int j,tablelength; + struct entry **table; + struct entry *next; + if (NULL == itr->e) return 0; /* stupidity check */ + + next = itr->e->next; + if (NULL != next) + { + itr->parent = itr->e; + itr->e = next; + return -1; + } + tablelength = itr->h->tablelength; + itr->parent = NULL; + if (tablelength <= (j = ++(itr->index))) + { + itr->e = NULL; + return 0; + } + table = itr->h->table; + while (NULL == (next = table[j])) + { + if (++j >= tablelength) + { + itr->index = tablelength; + itr->e = NULL; + return 0; + } + } + itr->index = j; + itr->e = next; + return -1; +} + +/*****************************************************************************/ +/* remove - remove the entry at the current iterator position + * and advance the iterator, if there is a successive + * element. + * If you want the value, read it before you remove: + * beware memory leaks if you don't. + * Returns zero if end of iteration. */ + +int +hashtable_iterator_remove(struct hashtable_itr *itr) +{ + struct entry *remember_e, *remember_parent; + int ret; + + /* Do the removal */ + if (NULL == (itr->parent)) + { + /* element is head of a chain */ + itr->h->table[itr->index] = itr->e->next; + } else { + /* element is mid-chain */ + itr->parent->next = itr->e->next; + } + /* itr->e is now outside the hashtable */ + remember_e = itr->e; + itr->h->entrycount--; + freekey(remember_e->k); + + /* Advance the iterator, correcting the parent */ + remember_parent = itr->parent; + ret = hashtable_iterator_advance(itr); + if (itr->parent == remember_e) { itr->parent = remember_parent; } + free(remember_e); + return ret; +} + +/*****************************************************************************/ +int /* returns zero if not found */ +hashtable_iterator_search(struct hashtable_itr *itr, + struct hashtable *h, void *k) +{ + struct entry *e, *parent; + unsigned int hashvalue, index; + + hashvalue = hash(h,k); + index = indexFor(h->tablelength,hashvalue); + + e = h->table[index]; + parent = NULL; + while (NULL != e) + { + /* Check hash value to short circuit heavier comparison */ + if ((hashvalue == e->h) && (h->eqfn(k, e->k))) + { + itr->index = index; + itr->e = e; + itr->parent = parent; + itr->h = h; + return -1; + } + parent = e; + e = e->next; + } + return 0; +} + + +/* + * Copyright (c) 2002, 2004, Christopher Clark + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * * Neither the name of the original author; nor the names of any contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER + * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, + * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR + * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +*/ |