From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by dcvr.yhbt.net (Postfix) with ESMTP id 9BA601F66F for ; Wed, 4 Nov 2020 20:22:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731133AbgKDUVx (ORCPT ); Wed, 4 Nov 2020 15:21:53 -0500 Received: from cloud.peff.net ([104.130.231.41]:47852 "EHLO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729633AbgKDUVx (ORCPT ); Wed, 4 Nov 2020 15:21:53 -0500 Received: (qmail 11268 invoked by uid 109); 4 Nov 2020 20:21:53 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with ESMTP; Wed, 04 Nov 2020 20:21:53 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 14752 invoked by uid 111); 4 Nov 2020 20:21:52 -0000 Received: from coredump.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.2) by peff.net (qpsmtpd/0.94) with (TLS_AES_256_GCM_SHA384 encrypted) ESMTPS; Wed, 04 Nov 2020 15:21:52 -0500 Authentication-Results: peff.net; auth=none Date: Wed, 4 Nov 2020 15:21:52 -0500 From: Jeff King To: Elijah Newren via GitGitGadget Cc: git@vger.kernel.org, Elijah Newren Subject: Re: [PATCH v3 09/13] strmap: add functions facilitating use as a string->int map Message-ID: <20201104202152.GB3629238@coredump.intra.peff.net> References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Mon, Nov 02, 2020 at 06:55:09PM +0000, Elijah Newren via GitGitGadget wrote: > From: Elijah Newren > > Although strmap could be used as a string->int map, one either had to > allocate an int for every entry and then deallocate later, or one had to > do a bunch of casting between (void*) and (intptr_t). > > Add some special functions that do the casting. Also, rename put->set > for such wrapper functions since 'put' implied there may be some > deallocation needed if the string was already found in the map, which > isn't the case when we're storing an int value directly in the void* > slot instead of using the void* slot as a pointer to data. > > A note on the name: if anyone has a better name suggestion than > strintmap, I'm happy to take it. It seems slightly unwieldy, but I have > not been able to come up with a better name. You can probably drop this last paragraph. It's good for review, but probably not in the commit message. :) > +void strintmap_incr(struct strintmap *map, const char *str, intptr_t amt) > +{ > + struct strmap_entry *entry = find_strmap_entry(&map->map, str); > + if (entry) { > + intptr_t *whence = (intptr_t*)&entry->value; > + *whence += amt; > + } > + else > + strintmap_set(map, str, map->default_value + amt); > +} Here we use the new default_value. Neat. > diff --git a/strmap.h b/strmap.h > index 10b4642860..31474f781e 100644 > --- a/strmap.h > +++ b/strmap.h > @@ -23,6 +23,11 @@ int cmp_strmap_entry(const void *hashmap_cmp_fn_data, > .map = HASHMAP_INIT(cmp_strmap_entry, NULL), \ > .strdup_strings = 1, \ > } > +#define STRINTMAP_INIT { \ > + .map.map = HASHMAP_INIT(cmp_strmap_entry, NULL), \ > + .map.strdup_strings = 1, \ > + .default_value = 0, \ > + } Re-using STRMAP_INIT would shorten this (and avoid repeating internal details of how strmap works). Like: #define STRINTMAP_INIT { \ .map = STRMAP_INIT, \ .default_value = 0, \ } You can also omit default_value, as the value of any un-mentioned elements will get the usual C zero-initialization. So: #define STRINTMAP_INIT { .map = STRMAP_INIT } would be sufficient (though I don't mind making the .default_value part explicit). It could also be a parameter to the macro, but I suspect it would be rarely used. I don't mind leaving it as something that advanced callers can get from using strintmap_init(). > +/* > + * strintmap: > + * A map of string -> int, typecasting the void* of strmap to an int. > + * > + * Primary differences: > + * 1) Since the void* value is just an int in disguise, there is no value > + * to free. (Thus one fewer argument to strintmap_clear) > + * 2) strintmap_get() returns an int; it also requires an extra parameter to > + * be specified so it knows what value to return if the underlying strmap > + * has not key matching the given string. > + * 3) No strmap_put() equivalent; strintmap_set() and strintmap_incr() > + * instead. > + */ I think (2) here is out-of-date, as we now use map->default_value. > +/* > + * Returns the value for str in the map. If str isn't found in the map, > + * the map's default_value is returned. > + */ > +static inline int strintmap_get(struct strintmap *map, const char *str) > +{ > + struct strmap_entry *result = strmap_get_entry(&map->map, str); > + if (!result) > + return map->default_value; > + return (intptr_t)result->value; > +} And we get to reuse default_value here again. Nice. -Peff