[stringtemplate-interest] handling of arrays
Nate
misc at n4te.com
Thu Feb 1 12:18:32 PST 2007
It does work, I was wrong. In fact, you don't even need a cast...
String[] strings = new String[] {"abc", "def", "ghi"};
Object[] stringsHiddenByObjectArray = strings;
What I was thinking of was going the other way...
Object[] objects = new Object[] {"jkl", "mno", "pqr"};
String[] thisDoesntWork = (String[])objects;
-Nate
Harry Karadimas wrote:
> Sorry about the lengthy post, but I checked and found that the cast to
> (Object[])
> actually works !
>
> Below is a "small" demo class that demonstrates various uses.
> To make it short, what works is :
> public static Object convertArrayToList(Object value)
> {
> if (value==null || !value.getClass().isArray()) return value;
> return Arrays.asList((Object[])value);
> }
>
> --------
>
> package stringtemplate_test;
>
> import java.util.ArrayList;
> import java.util.Arrays;
> import java.util.Collection;
> import java.util.Iterator;
> import java.util.List;
>
> /**
> * "Lots of Lists", to test various Array to List conversion strategies
> * @author KARADIMAS
> */
> public class Lol
> {
> static Object[] myArray = {"A", "B", "C"};
> static List myList = new ArrayList();
> static Object[][][] threeLevels = {
> {
> {"1.1.1", "1.1.2", "1.1.3"},
> {"1.2.1", "1.2.2"}
> },
> {
> {"2.1.1"},
> {"2.2.1", "2.2.2"}
> },
> {
> {"3.1.1", "3.1.2"},
> {"3.2.1"}
> },
> {
> {myList}
> },
> };
> static int[] myInts = {1,2,3};
>
> public static void main(String[] args)
> {
> //further init of myList
> myList.add("X");
> myList.add(myArray);
> myList.add("Z");
> System.out.println("Original list :");
> printList(threeLevels);
> System.out.println("convertArrayToList1() :");
> Object r = convertArrayToList1(threeLevels);
> printList((List) r);
> System.out.println("convertArrayToList2() :");
> r = convertArrayToList2(threeLevels);
> printList((List) r);
> System.out.println("convertAllForStUsage() :");
> r = convertAllAtOnce(threeLevels);
> printList((List) r);
> r = convertArrayToList1(myInts);
> printList(r);
> }
>
> /**
> * simplest, works ok if called before each use, maybe the best
> approach if
> * used in lazy (= just in time) execution.
> * Note here that Object[][]...[] is an instance of Object[] (and of
> * Object, incidentally)
> */
> public static Object convertArrayToList1(Object value)
> {
> if (value==null || !value.getClass().isArray()) return value;
> return Arrays.asList((Object[])value);
> }
>
> /**
> * handles sub-arrays recursively at once, but what about arrays
> inside lists?
> */
> public static Object convertArrayToList2(Object value)
> {
> if (value==null || !value.getClass().isArray()) return value;
> Object[] oa1 = (Object[]) value;
> Object[] oa2 = new Object[oa1.length];
> System.arraycopy(oa1, 0, oa2, 0, oa1.length);
> for (int i = 0; i < oa2.length; i++) oa2[i] =
> convertArrayToList2(oa2[i]);
> return Arrays.asList(oa2);
> }
>
> /**
> * More complex method.
> * Manages both lists and arrays, but what about arrays inside maps, for
> * example ? And also, why convert now arrays that might never be used ?
> */
> public static Object convertAllAtOnce(Object value)
> {
> if ( !isListable(value) ) return value;
> ArrayList res = new ArrayList(); //we always return a new list
> if (value instanceof List) {
> //process the list
> List vList = (List) value;
> for (Iterator iter = vList.iterator(); iter.hasNext();) {
> res.add(convertAllAtOnce(iter.next()));
> }
> return res;
> }
> //it's an array, process its elements
> Object[] oa = (Object[]) value;
> for (int i = 0; i < oa.length; i++)
> res.add(convertAllAtOnce(oa[i]));
> return res;
> }
>
> /** helper function to clarify code */
> private static final boolean isListable(Object o)
> {
> return (o instanceof List) || (o != null && o.getClass().isArray());
> }
>
> public static void printList(Object v) { printList("", v); }
>
> public static void printList(String indent, Object v) {
> if (!isListable(v)) {
> System.out.println(indent+"v="+v);
> return;
> }
> if (v instanceof List) {
> System.out.println(indent+"(");
> List lst = (List) v;
> for (Iterator iter = lst.iterator(); iter.hasNext();) {
> Object o = (Object) iter.next();
> printList(indent+" ", o);
> }
> System.out.println(indent+")");
> return;
> }
> Object[] oa = (Object[]) v;
> System.out.println(indent+"[//array");
> for (int i = 0; i < oa.length; i++) printList(indent+" ", oa[i]);
> System.out.println(indent+"]//array");
> }
>
> }
>
> Harry Karadimas
> /______________________________________________________________________
> Dr Harry Karadimas Medecin Ingenieur resp. Recherche et Developpement
> Departement d'Information Hospitalier
> CHU Henri Mondor 51, av. du Mal de Lattre de Tassigny 94010 CRETEIL
> tel : (00 33 1) 49 81 21 79 fax : (00 33 1) 49 81 27 08
> secr.: (00 33 1) 49 81 23 82 m.el.:harry.karadimas at hmn.ap-hop-paris.fr
> /
>
>
> stringtemplate-interest-request at antlr.org a écrit :
>> Send stringtemplate-interest mailing list submissions to
>> stringtemplate-interest at antlr.org
>>
>> To subscribe or unsubscribe via the World Wide Web, visit
>> http://www.antlr.org:8080/mailman/listinfo/stringtemplate-interest
>> or, via email, send a message with subject or body 'help' to
>> stringtemplate-interest-request at antlr.org
>>
>> You can reach the person managing the list at
>> stringtemplate-interest-owner at antlr.org
>>
>> When replying, please edit your Subject line so it is more specific
>> than "Re: Contents of stringtemplate-interest digest..."
>>
>>
>> Today's Topics:
>>
>> 1. Re: handling of arrays (John Snyders) (Terence Parr)
>> 2. Re: handling of arrays (John Snyders) (Terence Parr)
>> 3. Re: Porting StringTemplate (Kay Roepke)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Tue, 30 Jan 2007 12:14:43 -0800
>> From: Terence Parr <parrt at cs.usfca.edu>
>> Subject: Re: [stringtemplate-interest] handling of arrays (John
>> Snyders)
>> To: Nate <misc at n4te.com>
>> Cc: StringTemplate <stringtemplate-interest at antlr.org>
>> Message-ID: <E02F2DC0-7AE7-4B2B-A69A-49E19AD2CCE8 at cs.usfca.edu>
>> Content-Type: text/plain; charset=ISO-8859-1; delsp=yes; format=flowed
>>
>> crap. Ok, back to arrayiterator then.
>> Ter
>> On Jan 30, 2007, at 11:54 AM, Nate wrote:
>>
>>
>>> Unless you are using Java 5+, you'd have to use System.arrayCopy to
>>> copy the array to an Object array.
>>>
>>> -Nate
>>>
>>>
>>> Terence Parr wrote:
>>>
>>>> Awesome! Heh, it's exactly what we want I think.
>>>>
>>>> Wait, class cast issue:
>>>>
>>>> public static Object convertArrayToList(Object value) {
>>>> if ( value==null ) {
>>>> return null;
>>>> }
>>>> if ( value.getClass().isArray() ) {
>>>> return Arrays.asList((Object[])value); // CAST ISSUE!
>>>> }
>>>> return value;
>>>> }
>>>>
>>>> won't work as value is not Object[] most of the time...but how do
>>>> you get it to compile w/o the cast?
>>>>
>>>> Ter
>>>>
>>>> On Jan 30, 2007, at 9:13 AM, Harry Karadimas wrote:
>>>>
>>>>
>>>>
>>>>> Hi, I don't know if that relates to the previous post, but java
>>>>> *does* have something
>>>>> to encapsulate an array into a list, and that is the "asList"
>>>>> method of the java.util.Arrays
>>>>> class.
>>>>>
>>>>> Object[] myArray = ...
>>>>> List myList = Arrays.asList(myArray);
>>>>>
>>>>> Harry Karadimas
>>>>> ____________________________________________________________________
>>>>> __ Dr Harry Karadimas Medecin Ingenieur resp. Recherche et
>>>>> Developpement Departement d'Information Hospitalier CHU Henri
>>>>> Mondor 51, av. du Mal de Lattre de Tassigny 94010 CRETEIL tel :
>>>>> (00 33 1) 49 81 21 79 fax : (00 33 1) 49 81 27 08 secr.: (00 33
>>>>> 1) 49 81 23 82 m.el.:harry.karadimas at hmn.ap-hop-paris.fr
>>>>>
>>>>>
>>>>> stringtemplate-interest-request at antlr.org a ?crit :
>>>>>
>>>>>
>>>>>> Send stringtemplate-interest mailing list submissions to
>>>>>> stringtemplate-interest at antlr.org To subscribe or unsubscribe
>>>>>> via the World Wide Web, visit http://www.antlr.org:8080/
>>>>>> mailman/ listinfo/stringtemplate-interest or, via email, send a
>>>>>> message with subject or body 'help' to stringtemplate-interest-
>>>>>> request at antlr.org You can reach the person managing the list at
>>>>>> stringtemplate-interest-owner at antlr.org When replying, please
>>>>>> edit your Subject line so it is more specific than "Re:
>>>>>> Contents of stringtemplate-interest digest..." Today's Topics:
>>>>>> 1. Re: handling of arrays (John Snyders) 2. Re: inconsistency
>>>>>> with length function (Oliver Flege)
>>>>>> -------------------------------------------------------------------
>>>>>> -- - Message: 1 Date: Sun, 28 Jan 2007 21:44:26 -0500 From:
>>>>>> "John Snyders" <jjsnyders at rcn.com> Subject: Re:
>>>>>> [stringtemplate- interest] handling of arrays To: "Terence
>>>>>> Parr" <parrt at cs.usfca.edu>, "StringTemplate" <stringtemplate-
>>>>>> interest at antlr.org> Message-ID:
>>>>>> <PMEOJKDLMMHOHNEAMPBGGEJMCAAA.jjsnyders at rcn.com> Content-Type:
>>>>>> text/plain; charset="US-ASCII"
>>>>>>
>>>>>>
>>>>>>> -----Original Message----- From: stringtemplate-interest-
>>>>>>> bounces at antlr.org [mailto:stringtemplate-interest-
>>>>>>> bounces at antlr.org]On Behalf Of Terence Parr Sent: Saturday,
>>>>>>> January 27, 2007 6:38 PM To: StringTemplate Subject: Re:
>>>>>>> [stringtemplate-interest] handling of arrays On Jan 16, 2007,
>>>>>>> at 9:40 PM, John Snyders wrote:
>>>>>>>
>>>>>>>
>>>>>>>> I noticed in ASTExpr.java the method convertArrayToList.
>>>>>>>>
>>>>>>>>
>>>>>>> it is. just done to make things consistent...else have to
>>>>>>> check for arrays everyone. gross, eh?
>>>>>>>
>>>>>>>
>>>>>>>> It seems to me that this is wasteful. I have not looked at it
>>>>>>>> too deep but why not handle arrays like other collections and
>>>>>>>> wrap them in an ArrayIterator inside
>>>>>>>> convertAnythingIteratableToIterator.
>>>>>>>>
>>>>>>>>
>>>>>>> Interesting...ArrayIterator, eh? Does Sun have a standard one?
>>>>>>> I don't see it. Do you mean I should create one real quick?
>>>>>>>
>>>>>>>
>>>>>> There isn't one in the Java SDK (as far as I know) but jakarta
>>>>>> commons has one http://jakarta.apache.org/commons/collections/
>>>>>> api- release/org/apache/commons /collections/iterators/
>>>>>> ArrayIterator.html ST probably shouldn't rely on this so you
>>>>>> can create your own. It is straight forward. I created one
>>>>>> before I found the one in commons collections. I can give it to
>>>>>> you if you like (assuming I can find it). But again I didn't
>>>>>> think this through fully.
>>>>>>
>>>>>>
>>>>>>> Ter _______________________________________________
>>>>>>> stringtemplate-interest mailing list stringtemplate-
>>>>>>> interest at antlr.org http://www.antlr.org:8080/mailman/listinfo/
>>>>>>> stringtemplate-interest
>>>>>>>
>>>>>>>
>>>>>> ------------------------------ Message: 2 Date: Mon, 29 Jan
>>>>>> 2007 10:25:24 +0100 From: Oliver Flege <o.flege at market-
>>>>>> maker.de> Subject: Re: [stringtemplate-interest] inconsistency
>>>>>> with length function To: StringTemplate <stringtemplate-
>>>>>> interest at antlr.org> Message-ID: <45BDBD84.4040707 at market-
>>>>>> maker.de> Content-Type: text/ plain; charset=ISO-8859-1 Hi,
>>>>>> Terence Parr wrote:
>>>>>>
>>>>>>
>>>>>>>> I think that the length method in ASTExpr.java should be
>>>>>>>> changed as follows: From: } else if (attribute instanceof
>>>>>>>> List) { i = ((List)attribute).size(); } To: } else if
>>>>>>>> (attribute instanceof Collection) { i = ((List)attribute).size
>>>>>>>> (); }
>>>>>>>>
>>>>>>>>
>>>>>>> Howdy! OK, yep, good fix.
>>>>>>>
>>>>>>>
>>>>>> even better would be } else if (attribute instanceof
>>>>>> Collection) { i = ((Collection)attribute).size(); } :) Cheers,
>>>>>> Oliver ------------------------------
>>>>>> _______________________________________________ stringtemplate-
>>>>>> interest mailing list stringtemplate-interest at antlr.org http://
>>>>>> www.antlr.org:8080/mailman/listinfo/stringtemplate-interest End
>>>>>> of stringtemplate-interest Digest, Vol 22, Issue 14
>>>>>> *******************************************************
>>>>>>
>>>>>>
>>>>> <harry.karadimas.vcf>
>>>>> _______________________________________________
>>>>> stringtemplate-interest mailing list
>>>>> stringtemplate-interest at antlr.org
>>>>> http://www.antlr.org:8080/mailman/listinfo/stringtemplate-interest
>>>>>
>>>>>
>>>> _______________________________________________
>>>> stringtemplate-interest mailing list
>>>> stringtemplate-interest at antlr.org
>>>> http://www.antlr.org:8080/mailman/listinfo/stringtemplate-interest
>>>>
>>>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 2
>> Date: Tue, 30 Jan 2007 13:13:24 -0800
>> From: Terence Parr <parrt at cs.usfca.edu>
>> Subject: Re: [stringtemplate-interest] handling of arrays (John
>> Snyders)
>> To: StringTemplate <stringtemplate-interest at antlr.org>
>> Message-ID: <5DE29967-5C4B-4700-8D51-EDB9CF147D51 at cs.usfca.edu>
>> Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed
>>
>> Ok, i made an array wrapper and iterator. had to do both so a list
>> is not purely an iterator, which has sideeffects.
>>
>> /** Do a standard conversion of array attributes to a List. Wrap the
>> * array instead of copying like old version. Make an
>> * ArrayWrappedInList that knows to create an ArrayIterator.
>> */
>> public static Object convertArrayToList(Object value) {
>> if ( value==null ) {
>> return null;
>> }
>> if ( value.getClass().isArray() ) {
>> return new ArrayWrappedInList(value);
>> }
>> return value;
>> }
>>
>> ArrayWrappedInList creates ArrayIterator. These are two new classes.
>>
>> Pushed to depot.
>>
>> Ter
>>
>> On Jan 30, 2007, at 9:13 AM, Harry Karadimas wrote:
>>
>>
>>> Hi, I don't know if that relates to the previous post, but java
>>> *does* have something
>>> to encapsulate an array into a list, and that is the "asList"
>>> method of the java.util.Arrays
>>> class.
>>>
>>> Object[] myArray = ...
>>> List myList = Arrays.asList(myArray);
>>>
>>> Harry Karadimas ____
>>>
>>
>>
>> ------------------------------
>>
>> Message: 3
>> Date: Wed, 31 Jan 2007 02:21:11 +0100
>> From: Kay Roepke <kroepke at classdump.org>
>> Subject: Re: [stringtemplate-interest] Porting StringTemplate
>> To: Shane Witbeck <shane at digitalsanctum.com>
>> Cc: StringTemplate <stringtemplate-interest at antlr.org>
>> Message-ID: <6789A417-4627-450E-A443-BF753E93862F at classdump.org>
>> Content-Type: text/plain; charset=windows-1252; delsp=yes;
>> format=flowed
>>
>>
>> On Jan 28, 2007, at 1:04 AM, Shane Witbeck wrote:
>>
>>
>>> It seems like porting to ECMAScript would be better strategically
>>> since ActionScript is an extension of it and the amount of work out
>>> there being done in JavaScript (AJAX, etc.).
>>>
>>> Shane
>>>
>>> On 1/27/07, Terence Parr <parrt at cs.usfca.edu> wrote:
>>>
>>>> This would be very involved and a huge project. ANTLR doesn't
>>>> generate ActionScript so you'd need to parse everything by hand.
>>>>
>>>>
>>
>> Porting StringTemplate isn't exactly easy, esp. since it uses ANTLR
>> v2. My attempts
>> to do an Obj-C port haven't been exactly successful, mainly because
>> ANTLR v3 threw
>> up parsing ST :(
>>
>> I don't think that parsing ST by hand is a viable option, since it is
>> a bit involved
>> at times. I certainly wouldn't attempt it unless I was desperate...
>> In the long run, though, v3 should be able to handle ST easily and
>> that would make
>> it a lot easier (even if you'd need to write a new v3 target).
>>
>> As to the ECMAScript target, I'm not sure whether the current engines
>> are really fit to
>> do recursive descent parsing in. All the engines I have seen have
>> some real issues in
>> regard to memory, ie. tend to be slow molasses (but I admit it would
>> a cool thing to have
>> now and then).
>>
>> my 0.02?,
>>
>> -k
>>
>>
> _______________________________________________
> stringtemplate-interest mailing list
> stringtemplate-interest at antlr.org
> http://www.antlr.org:8080/mailman/listinfo/stringtemplate-interest
>
More information about the stringtemplate-interest
mailing list