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Mon, 19 Oct 2020 11:03:03 +0200 (CEST) From: Markus Armbruster To: Eric Blake Subject: Re: [PATCH v4 1/7] keyval: Fix and clarify grammar References: <20201011073505.1185335-1-armbru@redhat.com> <20201011073505.1185335-2-armbru@redhat.com> Date: Mon, 19 Oct 2020 11:03:03 +0200 In-Reply-To: (Eric Blake's message of "Mon, 12 Oct 2020 06:43:39 -0500") Message-ID: <875z761tbs.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain Received-SPF: pass client-ip=216.205.24.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/19 01:44:30 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, qemu-devel@nongnu.org, qemu-block@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Eric Blake writes: > On 10/11/20 2:34 AM, Markus Armbruster wrote: >> The grammar has a few issues: >> * key-fragment = / [^=,.]* / >> Prose restricts key fragments: they "must be valid QAPI names or >> consist only of decimal digits". Technically, '' consists only of >> decimal digits. The code rejects that. Fix the grammar. >> * val = { / [^,]* / | ',,' } >> Use + instead of *. Accepts the same language. >> * val-no-key = / [^=,]* / >> The code rejects an empty value. Fix the grammar. >> * Section "Additional syntax for use with an implied key" is >> confusing. Rewrite it. >> Signed-off-by: Markus Armbruster >> --- >> util/keyval.c | 16 ++++++++++------ >> 1 file changed, 10 insertions(+), 6 deletions(-) >> diff --git a/util/keyval.c b/util/keyval.c >> index 13def4af54..82d8497c71 100644 >> --- a/util/keyval.c >> +++ b/util/keyval.c >> @@ -16,8 +16,8 @@ >> * key-vals = [ key-val { ',' key-val } [ ',' ] ] >> * key-val = key '=' val >> * key = key-fragment { '.' key-fragment } >> - * key-fragment = / [^=,.]* / >> - * val = { / [^,]* / | ',,' } >> + * key-fragment = / [^=,.]+ / > > This requires a non-empty string. Good (we don't allow an empty key). > >> + * val = { / [^,]+ / | ',,' } > > I agree that this has no real change. Previously, you allowed zero or > more repetitions of a regex that could produce zero characters; now, > each outer repetition must make progress. > >> * >> * Semantics defined by reduction to JSON: >> * >> @@ -71,12 +71,16 @@ >> * Awkward. Note that we carefully restrict alternate types to avoid >> * similar ambiguity. >> * >> - * Additional syntax for use with an implied key: >> + * Alternative syntax for use with an implied key: >> * >> - * key-vals-ik = val-no-key [ ',' key-vals ] >> - * val-no-key = / [^=,]* / >> + * key-vals = [ key-val-1st { ',' key-val } [ ',' ] ] >> + * key-val-1st = val-no-key | key-val >> + * val-no-key = / [^=,]+ / >> * >> - * where no-key is syntactic sugar for implied-key=val-no-key. >> + * where val-no-key is syntactic sugar for implied-key=val-no-key. >> + * >> + * Note that you can't use the sugared form when the value contains >> + * '=' or ','. > > Nor can you use the sugared form when the value is intended to be > empty True. Spelling it out wouldn't hurt. Takes a follow-up patch; this one is already in master. > (although this may be academic, as your other patches enumerate > the list of clients, and none of them seem to allow an empty value > even when desugared). > > Reviewed-by: Eric Blake Thanks!