Order of nodes in reversed axes

On Wed, Apr 16, 2014 at 8:45 PM, David Rudel <fwqhgads at gmail.com> wrote: > Mr. Atria, > You left out a key element from the answer you got from stack overflow. > > Note that Dimitre's response used a filter expression > (path expression) [predicate] > > not a simple path expression > > The ()s are critical. > > $test//child/ancestor-or-self::test[ last() ] > > is very different from > > ($test//child/ancestor-or-self::test)[ last() ] > > The ancestor axis is a reverse axis, but when the xpath expression is > complete, the sequence of nodes are then put in document order > regardless of what order the last axis had. > > In any event, I don't understand what is wrong with simply > $test/ancestor::element()[1] > > Perhaps I don't understand your question (which is simpler than the > Stack Overflow question you linked to). But if you are just looking > for the nearest ancestor element, then it seems that > $test/ancestor::element()[1] should give it to you.

On Wed, Apr 16, 2014 at 8:48 PM, José Tomás Atria <jtatria at gmail.com> wrote: > Thank you all for your answers. > > I was just tryig to determine if $test/ancestor::element()[1] would be the > correct way of getting the nearest ancestor, as I couldn't find whether axes > were ordered or not in the xpath specification. > > Thanks! > > ps: Parent doesn't apply, because the relevant node is not always the > parent, but the first node with a given name. > > > On Wed, Apr 16, 2014 at 2:45 PM, David Rudel <fwqhgads at gmail.com> wrote: >> >> Mr. Atria, >> You left out a key element from the answer you got from stack overflow. >> >> Note that Dimitre's response used a filter expression >> (path expression) [predicate] >> >> not a simple path expression >> >> The ()s are critical. >> >> $test//child/ancestor-or-self::test[ last() ] >> >> is very different from >> >> ($test//child/ancestor-or-self::test)[ last() ] >> >> The ancestor axis is a reverse axis, but when the xpath expression is >> complete, the sequence of nodes are then put in document order >> regardless of what order the last axis had. >> >> In any event, I don't understand what is wrong with simply >> $test/ancestor::element()[1] >> >> Perhaps I don't understand your question (which is simpler than the >> Stack Overflow question you linked to). But if you are just looking >> for the nearest ancestor element, then it seems that >> $test/ancestor::element()[1] should give it to you. > > > > > -- > entia non sunt multiplicanda praeter necessitatem

On Wed, Apr 16, 2014 at 9:22 PM, José Tomás Atria <jtatria at gmail.com> wrote: > That should have been ancestor::div1[1]. pardon the typo. > > > On Wed, Apr 16, 2014 at 3:21 PM, José Tomás Atria <jtatria at gmail.com> wrote: >> >> let $test := >> element div0{ >> attribute id { 4 }, >> element div1 { >> attribute id { 3 }, >> element div1 { >> attribute id { 2 }, >> element para { >> attribute id { 1 }, >> element child { } >> } >> } >> } >> } >> >> I want to get the "smallest" div1 for a given child. this is, the <div1 >> id=2> element. >> >> As far as I've understood the answers given here, reverse axes are ordered >> from the context node, so the expression >> >> $test//child/ancestor-or-self::div1[1] will get me what i want, while >> $test//child/parent() will give me <para id=1> >> >> Needless to say, my data is not particularly well behaved :) >> >> Thanks! >> >> >> On Wed, Apr 16, 2014 at 3:16 PM, David Rudel <fwqhgads at gmail.com> wrote: >>> >>> I apologize if I'm being dense, but I don't understand how the nearest >>> ancestor can be anything other than the parent. Could you please give >>> an example? >>> >>> I just want to make sure I haven't sent you off with the wrong >>> expression for your intended usage. >>> >>> On Wed, Apr 16, 2014 at 8:48 PM, José Tomás Atria <jtatria at gmail.com> >>> wrote: >>> > Thank you all for your answers. >>> > >>> > I was just tryig to determine if $test/ancestor::element()[1] would be >>> > the >>> > correct way of getting the nearest ancestor, as I couldn't find whether >>> > axes >>> > were ordered or not in the xpath specification. >>> > >>> > Thanks! >>> > >>> > ps: Parent doesn't apply, because the relevant node is not always the >>> > parent, but the first node with a given name. >>> > >>> > >>> > On Wed, Apr 16, 2014 at 2:45 PM, David Rudel <fwqhgads at gmail.com> >>> > wrote: >>> >> >>> >> Mr. Atria, >>> >> You left out a key element from the answer you got from stack >>> >> overflow. >>> >> >>> >> Note that Dimitre's response used a filter expression >>> >> (path expression) [predicate] >>> >> >>> >> not a simple path expression >>> >> >>> >> The ()s are critical. >>> >> >>> >> $test//child/ancestor-or-self::test[ last() ] >>> >> >>> >> is very different from >>> >> >>> >> ($test//child/ancestor-or-self::test)[ last() ] >>> >> >>> >> The ancestor axis is a reverse axis, but when the xpath expression is >>> >> complete, the sequence of nodes are then put in document order >>> >> regardless of what order the last axis had. >>> >> >>> >> In any event, I don't understand what is wrong with simply >>> >> $test/ancestor::element()[1] >>> >> >>> >> Perhaps I don't understand your question (which is simpler than the >>> >> Stack Overflow question you linked to). But if you are just looking >>> >> for the nearest ancestor element, then it seems that >>> >> $test/ancestor::element()[1] should give it to you. >>> > >>> > >>> > >>> > >>> > -- >>> > entia non sunt multiplicanda praeter necessitatem >>> >>> >>> >>> -- >>> >>> "A false conclusion, once arrived at and widely accepted is not >>> dislodged easily, and the less it is understood, the more tenaciously >>> it is held." - Cantor's Law of Preservation of Ignorance. >> >> >> >> >> -- >> entia non sunt multiplicanda praeter necessitatem > > > > > -- > entia non sunt multiplicanda praeter necessitatem

On Wed, Apr 16, 2014 at 2:45 PM, David Rudel <fwqhgads at gmail.com> wrote: > Mr. Atria, > You left out a key element from the answer you got from stack overflow. > > Note that Dimitre's response used a filter expression > (path expression) [predicate] > > not a simple path expression > > The ()s are critical. > > $test//child/ancestor-or-self::test[ last() ] > > is very different from > > ($test//child/ancestor-or-self::test)[ last() ] > > The ancestor axis is a reverse axis, but when the xpath expression is > complete, the sequence of nodes are then put in document order > regardless of what order the last axis had. > > In any event, I don't understand what is wrong with simply > $test/ancestor::element()[1] > > Perhaps I don't understand your question (which is simpler than the > Stack Overflow question you linked to). But if you are just looking > for the nearest ancestor element, then it seems that > $test/ancestor::element()[1] should give it to you. >

On Wed, Apr 16, 2014 at 3:16 PM, David Rudel <fwqhgads at gmail.com> wrote: > I apologize if I'm being dense, but I don't understand how the nearest > ancestor can be anything other than the parent. Could you please give > an example? > > I just want to make sure I haven't sent you off with the wrong > expression for your intended usage. > > On Wed, Apr 16, 2014 at 8:48 PM, José Tomás Atria <jtatria at gmail.com> > wrote: > > Thank you all for your answers. > > > > I was just tryig to determine if $test/ancestor::element()[1] would be > the > > correct way of getting the nearest ancestor, as I couldn't find whether > axes > > were ordered or not in the xpath specification. > > > > Thanks! > > > > ps: Parent doesn't apply, because the relevant node is not always the > > parent, but the first node with a given name. > > > > > > On Wed, Apr 16, 2014 at 2:45 PM, David Rudel <fwqhgads at gmail.com> wrote: > >> > >> Mr. Atria, > >> You left out a key element from the answer you got from stack overflow. > >> > >> Note that Dimitre's response used a filter expression > >> (path expression) [predicate] > >> > >> not a simple path expression > >> > >> The ()s are critical. > >> > >> $test//child/ancestor-or-self::test[ last() ] > >> > >> is very different from > >> > >> ($test//child/ancestor-or-self::test)[ last() ] > >> > >> The ancestor axis is a reverse axis, but when the xpath expression is > >> complete, the sequence of nodes are then put in document order > >> regardless of what order the last axis had. > >> > >> In any event, I don't understand what is wrong with simply > >> $test/ancestor::element()[1] > >> > >> Perhaps I don't understand your question (which is simpler than the > >> Stack Overflow question you linked to). But if you are just looking > >> for the nearest ancestor element, then it seems that > >> $test/ancestor::element()[1] should give it to you. > > > > > > > > > > -- > > entia non sunt multiplicanda praeter necessitatem > > > > -- > > "A false conclusion, once arrived at and widely accepted is not > dislodged easily, and the less it is understood, the more tenaciously > it is held." - Cantor's Law of Preservation of Ignorance. >

On Wed, Apr 16, 2014 at 3:21 PM, José Tomás Atria <jtatria at gmail.com> wrote: > let $test := > element div0{ > attribute id { 4 }, > element div1 { > attribute id { 3 }, > element div1 { > attribute id { 2 }, > element para { > attribute id { 1 }, > element child { } > } > } > } > } > > I want to get the "smallest" div1 for a given child. this is, the <div1 > id=2> element. > > As far as I've understood the answers given here, reverse axes are ordered > from the context node, so the expression > > $test//child/ancestor-or-self::div1[1] will get me what i want, while > $test//child/parent() will give me <para id=1> > > Needless to say, my data is not particularly well behaved :) > > Thanks! > > > On Wed, Apr 16, 2014 at 3:16 PM, David Rudel <fwqhgads at gmail.com> wrote: > >> I apologize if I'm being dense, but I don't understand how the nearest >> ancestor can be anything other than the parent. Could you please give >> an example? >> >> I just want to make sure I haven't sent you off with the wrong >> expression for your intended usage. >> >> On Wed, Apr 16, 2014 at 8:48 PM, José Tomás Atria <jtatria at gmail.com> >> wrote: >> > Thank you all for your answers. >> > >> > I was just tryig to determine if $test/ancestor::element()[1] would be >> the >> > correct way of getting the nearest ancestor, as I couldn't find whether >> axes >> > were ordered or not in the xpath specification. >> > >> > Thanks! >> > >> > ps: Parent doesn't apply, because the relevant node is not always the >> > parent, but the first node with a given name. >> > >> > >> > On Wed, Apr 16, 2014 at 2:45 PM, David Rudel <fwqhgads at gmail.com> >> wrote: >> >> >> >> Mr. Atria, >> >> You left out a key element from the answer you got from stack overflow. >> >> >> >> Note that Dimitre's response used a filter expression >> >> (path expression) [predicate] >> >> >> >> not a simple path expression >> >> >> >> The ()s are critical. >> >> >> >> $test//child/ancestor-or-self::test[ last() ] >> >> >> >> is very different from >> >> >> >> ($test//child/ancestor-or-self::test)[ last() ] >> >> >> >> The ancestor axis is a reverse axis, but when the xpath expression is >> >> complete, the sequence of nodes are then put in document order >> >> regardless of what order the last axis had. >> >> >> >> In any event, I don't understand what is wrong with simply >> >> $test/ancestor::element()[1] >> >> >> >> Perhaps I don't understand your question (which is simpler than the >> >> Stack Overflow question you linked to). But if you are just looking >> >> for the nearest ancestor element, then it seems that >> >> $test/ancestor::element()[1] should give it to you. >> > >> > >> > >> > >> > -- >> > entia non sunt multiplicanda praeter necessitatem >> >> >> >> -- >> >> "A false conclusion, once arrived at and widely accepted is not >> dislodged easily, and the less it is understood, the more tenaciously >> it is held." - Cantor's Law of Preservation of Ignorance. >> > > > > -- > entia non sunt multiplicanda praeter necessitatem >

Ah, okay. I didn't catch that you wanted "the nearest ancestor with a > particular name." In that case then I think you are golden. If there > is a chance that the element itself is a div1 element, then you will > want to use ancestor-or-self instead, but otherwise I think you have > it right. >

On Wed, 2014-04-16 at 15:59 -0400, José Tomás Atria wrote: > Just for the sake of completion, the authoritative answer is > here<http://www.w3.org/TR/xpath/#predicates>