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pippijn |
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/* |
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* shstr.C: Shared string class |
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* |
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* Copyright © 2007 Pippijn van Steenhoven / The Ermyth Team |
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* Rights to this code are as documented in COPYING. |
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*/ |
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pippijn |
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static char const rcsid[] = "$Id: shstr.C,v 1.2 2007-09-16 18:54:45 pippijn Exp $"; |
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pippijn |
1.2 |
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pippijn |
1.1 |
#include <ermyth/shstr.h> |
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shstr::shstr (char const * const str) |
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{ |
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insert (str); |
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} |
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shstr::shstr (const shstr &rhs) |
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{ |
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insert (rhs.m_str); |
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} |
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shstr::~shstr () |
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{ |
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erase (); |
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} |
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char const * const |
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shstr::c_str () const |
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{ |
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return m_str; |
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} |
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shstr::size_type |
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shstr::length () const |
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{ |
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return m_len; |
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} |
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shstr & |
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shstr::operator = (char const * const rhs) |
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{ |
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erase (); |
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insert (rhs); |
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return *this; |
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} |
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shstr & |
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shstr::operator = (const shstr &rhs) |
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{ |
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if (m_str == rhs.m_str) |
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return *this; |
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erase (); |
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insert (rhs.m_str); |
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return *this; |
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} |
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bool |
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shstr::operator == (const shstr &rhs) const |
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{ |
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return m_str == rhs.m_str; |
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} |
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bool |
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shstr::operator != (const shstr &rhs) const |
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{ |
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return m_str != rhs.m_str; |
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} |
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// string manager functions |
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shentry * |
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shstr::prepare (char const * const str) |
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{ |
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size_t n = hash (str); |
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pairs::iterator it = find (str, n); |
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shentry *entry; |
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if (it == m_buckets[n].end ()) |
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{ |
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entry = new shentry (str, n); |
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m_buckets[n].push_back (entry); |
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} |
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else |
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entry = *it; |
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return entry; |
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} |
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bool |
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shstr::unref (char const * const str) |
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{ |
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size_t n = hash (str); |
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pairs::iterator it = find (str, n); |
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if (it == m_buckets[n].end ()) |
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return false; |
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else |
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{ |
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shentry *entry = *it; |
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--entry->m_refcnt; |
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if (entry->m_refcnt == 0) |
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{ |
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m_buckets[n].erase (it); |
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delete entry; |
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return true; |
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} |
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else |
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return false; |
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} |
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} |
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const shentry * |
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shstr::get (char const * const str) |
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{ |
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size_t n = hash (str); |
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pairs::iterator it = find (str, n); |
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if (it == m_buckets[n].end ()) |
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return NULL; |
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else |
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return *it; |
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} |
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shstr::pairs::iterator |
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shstr::find (char const * const str, size_t n) |
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{ |
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pairs &bucket = m_buckets[n]; |
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pairs::iterator it = bucket.begin (); |
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pairs::iterator et = bucket.end (); |
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while (it != et) |
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{ |
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/* we first check hash equality, because if the hash is not |
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* equal, then the string most definately is not |
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*/ |
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if (n == (*it)->m_hash && __builtin_expect (!strcmp ((*it)->m_str, str), 0)) |
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return it; |
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++it; |
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} |
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return et; |
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} |
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size_t |
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shstr::hash (char const * const str) |
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{ |
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char const *s = str; |
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unsigned long hash = 0; |
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// use the one-at-a-time hash function |
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// see http://burtleburtle.net/bob/hash/doobs.html |
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while (*s) |
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{ |
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hash += *s++; |
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hash += hash << 10; |
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hash ^= hash >> 6; |
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} |
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hash += hash << 3; |
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hash ^= hash >> 11; |
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hash += hash << 15; |
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return hash % m_bucketcnt; |
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} |
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char const * const |
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shstr::insert (char const * const str, size_t *size) |
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{ |
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shentry *entry = prepare (str); |
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++entry->m_refcnt; |
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if (entry->m_refcnt == 1) |
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++m_cnt; |
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*size = entry->m_len; |
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return entry->m_str; |
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} |
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void |
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shstr::erase (char const * const str) |
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{ |
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bool removed = unref (str); |
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if (removed) |
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--m_cnt; |
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} |
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size_t |
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shstr::refs (char const * const str) |
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{ |
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const shentry *entry = get (str); |
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if (entry == NULL) |
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return 0; |
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else |
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return entry->m_refcnt; |
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} |
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size_t |
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shstr::strcnt () |
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{ |
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return m_cnt; |
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} |
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size_t shstr::m_cnt = 0; |
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size_t shstr::m_bucketcnt = 1024; |
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shstr::pairs *shstr::m_buckets; |