[mkgmap-dev] Enhance PartFilter.java to return last parts of a value list

Thu Aug 8 22:04:05 BST 2013

Folks, I added some more tweaks to the PartFilter class, beside being able
to use negative numbers to take a part from the tail of the value list, it
is now possible to use the "<" or ">" operator (in addition to ":") in
order to return a concatenation of all the parts before or after a certain
part. The default behavior is not changed and this come at the expense of
just 2 logical "IF" more when no operators are specified.  Attached the
class.

Example, if the value is "Aa#Bb#Cc#Dd#Ee"
part:#:1  returns Aa
part:#:-1 returns Ee
part:#:-2 returns Dd
part:#>1  returns Bb#Cc#Dd#Ee#
part:#<5  returns Aa#Bb#Cc#Dd#
part:#<-1 returns Aa#Bb#Cc#Dd#

This can be expecially useful in some circumstances  to overcome the
limitation that does not allow to use expressions within expressions, i.e.:

{set foo:bar='${name|part: :1}}' }  // take the first word in name
{set name='${name|subst:${foo:bar}}' } // remove it - this would not work

wont' work but now:

{set name='${name|part: >1}}' } // returns all the words after the first one

will do the job. Some more elaborated things like:

// Via Wolfgang Amadeus Mozart -> Mozart, Via Wolfgang Amadeus
{set  new:name='${name|part: :-1}}, ${name|part: <-1}}' }

// a_word [Dd]e [Ee]l anything-> a_word, anything [Dd]e [Ee]l
// Calle De el Gato Loco-> Gato Loco, Calle De el
highway=* & name ~ '.*\s[Dd]e [Ee]l .*' {set  new:name='${name|part: >3}},
${name|part: <4}}' }

On Wed, Aug 7, 2013 at 1:06 AM, Enrico Liboni <eliboni at gmail.com> wrote:

> It might be useful to be able to get the last part of a value list but the
> current implementation of PartFilter does not allow this, i.e. you can get
> the 1st, 2nd, 3rd and so on but you can't get the last, the one before the
> last and so on.
>
> The change is trivial,  in doFilter replace:
>
>         if (temp.length >= partnumber)
>             return temp[partnumber-1].trim();
> with:
>         if (temp.length >= Math.abs(partnumber) ) {
>             if (partnumber > 0) {
>                 return temp[partnumber-1].trim();
>             } else {
>                 return temp[temp.length+partnumber].trim();
>             }
>         }
>
> attached the new class which I compiled, plugged in r2661 and works as
> expected.
>
> This could be useful for example, emh...,  when adding a rule like:
>
> highway=* { set street:name='${name|part: :-1}, ${name}'}
> street:name=* {set name='${street:name}'}
>
> so that the most meaningful part of a street name in some countries
> appears at the beginning of the name thus facilitating the address search ;)
>
> Let me know if you believe this is useful and if you prefer a patch.
>
> Enrico
>
>
>
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