Wow! Nice work Magesh.
A bit much for me to take in as that is quite a <load> of work ya did there
:)
I personally haven't had any need for this kind of functionality in any of
my build file scenarios, but I certainly can't argue with the use-cases that
others have provided.
I'm +1 on this (site unseen, no bandwidth to really give this a spin). But
I would like to have a suite of test cases in place for these before they
get moved into the main codebase. What happened to write-test-first
coding?! :) You surely had to test these out as you developed them, no?!
;)
Do you plan on modifying <copy> or the other tasks you mentioned to
incorporate this functionality? How will that play out with the current
<filter> capability, if at all?
Erik
----- Original Message -----
From: "Magesh Umasankar" <[EMAIL PROTECTED]>
To: "Ant Developers List" <[EMAIL PROTECTED]>
Sent: Wednesday, February 27, 2002 9:05 PM
Subject: [VOTE] Promotion of FilterReaders proposal to main development
tree.
> Hi,
>
> I would like to call upon a vote for the promotion of
> the FilterReaders proposal from the sandbox to the main
> development tree.
>
> Here is a summary of what this proposal is (as taken from the README):
>
>
============================================================================
> ===
>
> Usecase:
> ========
> * Usage of filtering has become a common pattern in
> Ant's tasks. Filtering is being performed one way or
> another in tasks like <copy>, <move>, <fixcrlf>,
> <loadfile>, etc.
>
> * There is no generic way to add custom filters
> currently to these tasks. User has to either extend
> the task to add custom filter processing or add
> more attributes as needed to the task itself.
>
> * If user is provided with a pluggable filtering
> mechanism, changes to built-in tasks can be mininized,
> while at the same time providing increased flexibility
> to the user.
>
> Design:
> ======
> * FilterChain is an ordered collection of 'AntFilterReader's and
> 'java.io.FilterReader's
>
> * Each AntFilterReader encloses the custom class representing
> the actual java.io.FilterReader and contains configuration
> parameters that may be used by the custom class if it
> implements the org.apache.tools.ant.types.Parameterizable
> interface.
>
> * For ease of use, Ant's core filter readers can
> be used with a filter-reader-specific syntax also.
> although the long form can also be used.
>
> * Custom filter readers can be created easily even
> without using any of Ant's API - all one needs to
> do to create a custom filter is to extend
> java.io.FilterReader.
>
> * If the extended class also implements Parameterizable,
> operation parameters can be made available to the
> custom filter.
>
> * Each FilterReader is piped through the other, if any, in
> the chain, in the order of declaration.
>
> Example:
> =======
>
> <loadfile srcFile="foo" property="bar">
> <filterchain>
> <filterreader
> classname="org.apache.tools.ant.filters.StripLineComments">
> <param type="comment" value="//"/>
> <param type="comment" value="REM "/>
> <param type="comment" value="--"/>
> </filterreader>
> <filterreader
> classname="org.apache.tools.ant.filters.StripLineBreaks"/>
> </filterchain>
> </loadfile>
>
> The above example loads the contents of the file foo,
> filters out the lines that begin with //, REM and --,
> removes line breaks and then stores the result in
> the property named bar.
>
> Since StripLineComments and StripLineBreaks are built-in
> Ant filter readers, the same can also be represented as:
>
> <loadfile srcFile="foo" property="bar">
> <filterchain>
> <striplinecomments>
> <comment value="//"/>
> <comment value="REM "/>
> <comment value="--"/>
> </striplinecomments>
> <striplinebreaks/>
> </filterchain>
> </loadfile>
>
>
============================================================================
> ===
>
> The following filterreaders have currently been added to
> the proposal based on the following use cases:
>
> HeadFilter:
> ==========
> A head task has been accepted for Ant2. This will make the need
> for an individual task to go away.
>
> LineContains:
> ============
> This may be used to get just those lines which contain
> specific strings. This may be useful in the context
> of the <loadproperties> task where only those keys that
> contain a specific string must be loaded.
>
> PrefixLines:
> ===========
> This may also be used while using <loadproperties>
> to perform transformation of the key before loading.
> Filters to add suffix to a key, value, etc. will also
> be useful, though they are not available currently.
> PrefixLines and StripLineComments combined with
> <loadproperties> provides the same output as <property>
> with the prefix attribute set.
>
> ReplaceTokens:
> =============
> This finds keys embedded within begintoken and endtoken
> and replaces them with user defined values. Rough
> equivalent of <filterset>, <filter>.
>
> StripJavaComments:
> =================
> This strips out from the data all comments embedded
> using Java's commenting syntax. I think Steve requested
> this...
>
> StripLineBreaks:
> ===============
> This strips line break characters. This obsoletes
> the need for the makeoneline attribute of <loadfile>
>
> StripLineComments:
> =================
> Jason van Zyl had requested a way to be able to
> strip out comments from a file while loading it up
> using <loadfile>. This need was the primary motivator
> of this proposal.
>
> TabsToSpaces:
> ============
> Tabs are converted into spaces by this filter reader.
>
> TailFilter:
> ==========
> A tail task has been accepted for Ant2. This will make the need
> for an individual task to go away.
>
>
> The following tasks have been modified/added:
>
> LoadFile:
> ========
> makeoneline attribute has been removed and task has been
> made <filterchain> aware.
>
> LoadProperties:
> ==============
> New task that is <filterchain> aware. This can be
> used in cases when transformations have to be done to
> the data before they are read in as Ant properties.
>
> Documentation:
> =============
> Alpha document is in proposal.
>
> Testcases:
> =========
> Currently none. Planning to add a few in the near future.
>
> Your votes/comments/reviews/questions on relevant portions please.
>
> Cheers,
> Magesh
>
>
>
>
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