How to get yacc/bison and lex/flex to pause file scanning?

Im trying to parse a file using Bison/Yacc but i want to pause the parsing for a while. The reason i want to do this is that i want to process a huge file sequentially and simulate a java iterator using hasNext() and next() methods.

A trivial example would be, spl开发者_如何学编程itting a file by line using yacc so i could call:

while(myYaccObj.hasNext())
{
    std::string line = myYaccObj.next()
}

I cant find how to "pause" the file scanning. Is there a way to do that?

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The easiest way is just to do the pause directly in you action code. For example, you could have a rule:

rule:  whatever  { Pause(); }
;

This would call your Pause function which could pause and/or do whatever you want. When you want to continue parsing, simply have the Pause function return.

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In fact pausing for me means "keep the state and finish the yyparse" call. For example in my gramar I would do:

rule:
    SaveLine;
    Pause;

And then the control is returned to my code. I do what i have to do and then I call:

yyparse_resume();

and the parsing continues until another pause or EOF.