[antlr-interest] reuse() methos in 3.4 C runtime
Ruslan Zasukhin
ruslan_zasukhin at valentina-db.com
Tue Aug 30 00:01:05 PDT 2011
On 6/24/11 7:49 PM, "Jim Idle" <jimi at temporal-wave.com> wrote:
Hi Jim,
I do now third attempt switch from ANTLR2 to ANTLR3,
And reuse is very important for us, because we do parse SQL strings in the
DBMS servers ...
I am very happy to read it should work now again in 3.4!
But I have got question after this your letter.
You say that TreeParser cannot be reused. Then:
A) what do method reset() in the generated TreeParser?
can/should we use it? If yes when and for what?
B) Do you mean that on each loop we must free() Nodes and TreeParser
nodes ->free( nodes ); nodes = NULL;
treePsr ->free( treePsr ); treePsr = NULL;
And then create them again
nodes = antlr3CommonTreeNodeStreamNewTree(langAST.tree,
ANTLR3_SIZE_HINT);
treePsr = SqlTreeParser_v3New( nodes );
Or I can just do on each loop
treePsr->reset( treePsr );
Thank you in advance for explain
> Because the documentation is not yet up to date, here is an example of
> reusing the allocated memory in input streams and token streams:
>
>
>
> for (i=0; i<iterations; i++) {
>
>
>
> // Run the parser.
>
> //
>
> psr->start(psr);
>
>
>
> // --------------------------------------
>
> // Now reset everything for the next run.
>
> // Order of calls is important.
>
>
>
> // Input stream can now be reused
>
> //
>
> input->reuse(input, sourceCode, sourceLen, sourceName);
>
>
>
> // Reset the common token stream so that it will reuse its resources
>
> //
>
> tstream->reset(tstream);
>
>
>
> // Reset the lexer (new function generated by antlr now)
>
> //
>
> lxr->reset(lxr);
>
>
>
> // Reset the parser (new function generated by antlr now)
>
> //
>
> psr->reset(psr);
>
> }
>
>
>
> Note that tree parsers cannot reuse their allocations but this is rarely an
> issue. The input->reuse() will reuse any memory it has allocated, but
> requires that you handle the reading of the input files (or otherwise supply
> a pointer to them). The input files are assumed to be encoded in the way
> that the original input was created, for instance:
>
>
>
> input = antlr3FileStreamNew(fname, ANTLR3_ENC_8BIT);
>
>
>
> Then all reused input must be 8 bit encoded.
>
>
>
> Jim
>
> List: http://www.antlr.org/mailman/listinfo/antlr-interest
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>
--
Best regards,
Ruslan Zasukhin
VP Engineering and New Technology
Paradigma Software, Inc
Valentina - Joining Worlds of Information
http://www.paradigmasoft.com
[I feel the need: the need for speed]
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