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chromium / external / gitster / git-htmldocs / 9587de99358a1debfc8b67662206da15e5472cd5 / . / technical / api-hash.html
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Junio C Hamano3dac5042007-12-15 08:40:54[diff] [blame]305</style>
306<title>hash API</title>
307</head>
308<body>
309<div id="header">
310<h1>hash API</h1>
311</div>
312<div id="preamble">
313<div class="sectionbody">
Junio C Hamanoda098c32009-12-20 23:01:31[diff] [blame]314<div class="para"><p>The hash API is a collection of simple hash table functions. Users are expected
315to implement their own hashing.</p></div>
Junio C Hamano3dac5042007-12-15 08:40:54[diff] [blame]316</div>
317</div>
Junio C Hamanoda098c32009-12-20 23:01:31[diff] [blame]318<h2 id="_data_structures">Data Structures</h2>
319<div class="sectionbody">
320<div class="vlist"><dl>
321<dt>
322<tt>struct hash_table</tt>
323</dt>
324<dd>
325<p>
326 The hash table structure. The <tt>array</tt> member points to the hash table
327 entries. The <tt>size</tt> member counts the total number of valid and invalid
328 entries in the table. The <tt>nr</tt> member keeps track of the number of
329 valid entries.
330</p>
331</dd>
332<dt>
333<tt>struct hash_table_entry</tt>
334</dt>
335<dd>
336<p>
337 An opaque structure representing an entry in the hash table. The <tt>hash</tt>
338 member is the entry's hash key and the <tt>ptr</tt> member is the entry's
339 value.
340</p>
341</dd>
342</dl></div>
343</div>
344<h2 id="_functions">Functions</h2>
345<div class="sectionbody">
346<div class="vlist"><dl>
347<dt>
348<tt>init_hash</tt>
349</dt>
350<dd>
351<p>
352 Initialize the hash table.
353</p>
354</dd>
355<dt>
356<tt>free_hash</tt>
357</dt>
358<dd>
359<p>
360 Release memory associated with the hash table.
361</p>
362</dd>
363<dt>
364<tt>insert_hash</tt>
365</dt>
366<dd>
367<p>
368 Insert a pointer into the hash table. If an entry with that hash
369 already exists, a pointer to the existing entry's value is returned.
370 Otherwise NULL is returned. This allows callers to implement
371 chaining, etc.
372</p>
373</dd>
374<dt>
375<tt>lookup_hash</tt>
376</dt>
377<dd>
378<p>
379 Lookup an entry in the hash table. If an entry with that hash exists
380 the entry's value is returned. Otherwise NULL is returned.
381</p>
382</dd>
383<dt>
384<tt>for_each_hash</tt>
385</dt>
386<dd>
387<p>
388 Call a function for each entry in the hash table. The function is
389 expected to take the entry's value as its only argument and return an
390 int. If the function returns a negative int the loop is aborted
391 immediately. Otherwise, the return value is accumulated and the sum
392 returned upon completion of the loop.
393</p>
394</dd>
395</dl></div>
396</div>
Junio C Hamano3dac5042007-12-15 08:40:54[diff] [blame]397<div id="footer">
398<div id="footer-text">
Junio C Hamanodca34822010-02-13 01:02:52[diff] [blame]399Last updated 2010-02-13 01:00:08 UTC
Junio C Hamano3dac5042007-12-15 08:40:54[diff] [blame]400</div>
401</div>
402</body>
403</html>