[antlr-interest] Is there a safe and easy way to reuse LEXER and PARSER objects on C target?

[Jim Idle]

Ok - that is probably a bug. I guess nobody tried to do that before ;-). For now, you will have to recreate the parser each time until I can fix it.
 
Jim
 
From: Ronghui Yu [mailto:stoneyrh at gmail.com] 
Sent: Friday, December 11, 2009 5:01 AM
To: Jim Idle
Cc: antlr-interest
Subject: Re: [antlr-interest] Is there a safe and easy way to reuse LEXER and PARSER objects on C target?
 
Here is my pseudo code:
 
pLexer->pLexer->rec->reset(pLexer->pLexer->rec);
pInputStream->data = (pANTLR3_UINT8)GetText().c_str();
pInputStream->sizeBuf = (ANTLR3_UINT32)GetText().length();
pInputStream->reset(pInputStream);
pLexer->pLexer->setCharStream(pLexer->pLexer,pInputStream);
pTokenStream->free(pTokenStream);
pTokenStream = antlr3CommonTokenStreamSourceNew(TOKEN_SIZE_HINT, TOKENSOURCE(pLexer));
pTokenStream->discardOffChannelToks(pTokenStream,ANTLR3_FALSE);
pParser->pParser->setTokenStream(pParser->pParser,pTokenStream->tstream);
 
 
It works most of the time, but occasionally violation access occurs. It doesn't work if applied to a grammar file importing another grammar. For example, I have a a keywords.g file is imported to the main grammar. When setting the token stream on the main grammar, the token string of embedded parser does not get updated automatically.
 
On Fri, Dec 11, 2009 at 1:11 AM, Jim Idle <jimi at temporal-wave.com> wrote:
To be honest, I would think you can hardly measure the time taken to create them, but you have to call the reset() methods and set the character stream and the token stream. There were issues with that at one point but I think I have fixed them all now. You can see how to reuse the lexer by looking at the examples in the examples download. Specifically the Java parser example will help here.
 
Jim
 
From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-bounces at antlr.org] On Behalf Of Ronghui Yu
Sent: Thursday, December 10, 2009 8:21 AM
To: antlr-interest
Subject: [antlr-interest] Is there a safe and easy way to reuse LEXER and PARSER objects on C target?
 
Hi, All,
 
On my project, I have a parser for parsing different statements again and again. In order to save a little time on initialization, I would like to reuse the LEXER and PARSER objects created the first time, something like this:
 
if (bInitialized)
{
    reinitialize();
}
else
{
   initialize();
   bInitialized = true;
}
 
The problem now is how to write reinitialize() safely. I have no idea on which fields of LEXER or PARSER objects must be reset to which status. Then my current code works most of the time, but it encounters NULL pointer occasionally(I am sure the grammar file is good because if I don't reuse the LEXER and PARSER objects, everything goes fine).
 
Anybody could give me some ideas?
 
Thanks in advance.

-- 
===========================
Regards
Ronghui Yu


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Regards
Ronghui Yu


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