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Re: [Jython-dev] Jython internal development docs
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From: Philip C. <Phil.Cannata@Sun.COM> - 2010-01-04 20:03:12
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Never mind, I think I'm on my way to figuring it out.
Thanks again for the help
phil
At 11:31 AM 1/4/2010, Philip Cannata wrote:
>At 05:40 PM 12/31/2009, Jim Baker wrote:
>>Here's my recommendation:
>> * Modify python.g to add support for the
>> select statement, as you've done with
>> query_stmt stuff you quote below. You don't
>> want to have the parser actually do things
>> like print, it's just not going to work too
>> well. And in particular, the parser has no
>> easy access to runtime values. You would have
>> to at least consider issues like PySystemState, etc., to find them.
>> * If you want to add AST
>> introspection/mutability, you probably need to
>> write an adapter in org.python.antlr.adapter.
>> (Frank would certainly know for certain on
>> this part.) This is certainly overkill for now.
>> * In org.python.compiler.CodeCompiler, add
>> a method to visit this query node. Something like visitQueryStatement.
>
>If I try to add something like
> @Override
> public Object visitQuery(Query node) throws Exception { . . .
>to CodeCompiler I need to have Query defined or I get
>
>compile:
> [javac] Compiling 526 source files to
> c:\MyJython\jython\jython\build\classes
> [javac]
> c:\MyJython\jython\jython\src\org\python\compiler\CodeCompiler.java:2286:
> cannot find symbol
> [javac] symbol : class Query
> [javac] location: class org.python.compiler.CodeCompiler
> [javac] public Object visitQuery(Query node) throws Exception {
>
>Where do I define the Query node? I tried adding
>Query.java to src\org\python\antlr\ast but that didn't do it.
>thanks
>phil
>
>> * This will be used to define the query
>> statement, which in Python is always a dynamic
>> construct. See visitClassDef for something
>> similar. You can add support to the Jython
>> runtime, or probably better just create an
>> appropriate class in Python. The easiest way
>> to do is do something like
>> code.invokestatic(... instantiate a
>> QueryStatement object with slots ...) - I'll
>> let you figure out the signature. One good
>> example of this melding of Python code into
>> Java code is seen in
>> org.python.core.PyBytecode, which loads up the
>> dis module to support the dissassembly of ops for debugging purposes.
>> * Write your QueryStatement class such that
>> its __repr__ special method prints out as desired.
>>
>>That should do it.
>>
>>- Jim
>>
>>On Wed, Dec 30, 2009 at 10:07 PM, Philip
>>Cannata <<mailto:Phi...@su...>Phi...@su...> wrote:
>>Frank and Marc, thanks for your time. Let me explain a little bit
>>what I'm trying to do. For teaching purposes, I like to teach my
>>students to modify the grammar first before proceeding to the AST
>>etc. So, with the small change to Python.g below I've gotten the
>>following to be recognized:
>>Â >>> a=111
>>Â >>> b=a+222
>>Â >>> SELECT * FROM emp WHERE x = b
>>SELECT Statement is: SELECT * Â FROM emp, WHERE x = b
>>but, I'd like to get it to print out:
>>SELECT Statement is: SELECT * Â FROM emp, WHERE x = 333
>>by getting the value of "b" which I believe has already been parsed
>>and turned into a real object and therefore has a value when I'm
>>parsing the SELECT line. (i.e., I need something in place of $e.text).
>>Here's the change to Python.g starting at line 568:
>>//small_stmt: (expr_stmt | print_stmt  | del_stmt | pass_stmt | flow_stmt |
>>// Â Â Â Â Â Â import_stmt | global_stmt | exec_stmt | assert_stmt)
>>small_stmt : expr_stmt
>>Â Â Â Â Â Â | print_stmt
>>Â Â Â Â Â Â | del_stmt
>>Â Â Â Â Â Â | pass_stmt
>>Â Â Â Â Â Â | flow_stmt
>>Â Â Â Â Â Â | import_stmt
>>Â Â Â Â Â Â | global_stmt
>>Â Â Â Â Â Â | exec_stmt
>>Â Â Â Â Â Â | assert_stmt
>>Â Â Â Â Â Â | query_stmt
>>Â Â Â Â Â Â ;
>>//query_stmt: SELECT * FROM person WHERE x = value
>>query_stmt
>>Â Â : SELECT STAR CAPSFROM n1 = NAME ( WHERE
>>n2 = NAME ASSIGN e = expr_stmt )?
>>Â Â Â Â { System.out.println("SELECT Statement is: SELECT * Â FROM "
>>+ $n1.text + ", WHERE " + $n2.text + " = " + $e.text); }
>>Â Â -> ^(SELECT<Pass>[$SELECT])
>>Â Â ;
>>At 03:35 PM 12/30/2009, Frank Wierzbicki wrote:
>> >On Wed, Dec 30, 2009 at 4:08 PM, Philip
>> Cannata <<mailto:Phi...@su...>Phi...@su...> wrote:
>> > > Yes, but if I put it in Python.g at line 639 as follows:
>> >Probably Python.g is not the place you want to be putting this, since
>> >the x in "x = a + b" is only a symbol from the viewpoint of parsing
>> >(which is all Python.g does). Â The way you get from source to
>> >something at runtime goes roughly:
>> >
>> >Source --- (parse) ---> AST --- (compile) ---> Java bytecodes ---
>> >(class loading) ---> real objects ready to run --- (interpreter) --->
>> >actual values like x = 333
>> >
>> >-Frank
>>
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>>
>>
>>--
>>Jim Baker
>><mailto:jb...@zy...>jb...@zy...
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