[antlr-interest] TestRig: use with package-ized lexer/parser?

[Jim Idle]

I think that some of these issues will be alleviated once one of us can
make time to write the Maven plugins, as these can ensure that the correct
directory structures are created and so on.

Jim

-----Original Message-----
From: antlr-interest-bounces at antlr.org
[mailto:antlr-interest-bounces at antlr.org] On Behalf Of Graham Wideman
Sent: Tuesday, November 13, 2012 9:35 AM
To: antlr-interest at antlr.org
Subject: Re: [antlr-interest] TestRig: use with package-ized lexer/parser?

At 11/12/2012 10:53 AM, Terence Parr wrote:
>I assume you have tried TestRig pack.Grammar?   I don't remember if I
thought of this so it might not work but I can't see why not. Should be a
trivial string concatenation fix. I will look at the other things as well.

Well, yes, I did go down that path (so to speak) unsuccessfully, but as I
now learn, I missed a trick.

So, here are the details on how to exercise package-ized ANTLR grammars
with TestRig as currently designed.

1. Class directory structure must correspond to package
--------------------------------------------------------
If the grammar (mygrammar) specifies a package (let's say
com.abc.myparser), then you must arrange that the compiled class files
(mygrammarLexer.class and friends) wind up in a directory tree that
corresponds to the package. So something like (in NetBeans):

  [MyProject]/build/classes/com/abc/myparser/mygrammarLexer.class etc

[see note A]

2. cd to _root_ of classes
--------------------------
Before running TestRig (or grun) on this from the command line, you must
first cd to the _root_ of that class tree:
  [MyProject]/build/classes

... so that java runtime classloader can find the class in question from
dot (cwd) using the classname com.abc.myparser.mygrammarLexer .

3. Specify grammar name qualified by package
--------------------------------------------
In the TestRig (or grun) command line, you have to specify the grammar
name qualified by the package name, for example:

  grun com.abc.myparser.mygrammar startelement -gui otherargs

[See note B]

Other notes:
------------
A) This probably requires that, upstream, you have ANTLR generate the java
source files in a similarly appropriate source directory structure --
ANTLR itself doesn't create or require package-coordinated directories
when generating the lexer/parser code.  While ANTLR and javac can be used
with simple commands assuming default package, once non-default packages
become involved one probably needs a build system or IDE to automate the
coordination of packages and directories.

B) Of course, since you have to set the cwd to the classes root for
TestRig's benefit, you probably have to adjust the argument that specifies
the location of input files.

C) An IDE issue:  When working on a custom version of TestRig in NetBeans,
and attempting to run or debug it from the IDE, I still haven't found a
good way to add "current dir" to the runtime classpath.  You can add an
explicit dir to the Libraries list, but that's a poor substitute, so not a
final answer, IMO.  (This is only an issue if you're trying to work on
TestRig with its dynamic class loading, not a general problem with ANTLR
and packages.)

Hope that helps others.

-- Graham






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