Ambiguity in Access Expressions
Monkey Forums/Monkey Programming/Ambiguity in Access Expressions
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| Hi! I would really like some input on a challenge I'm working on. My aim is to make a SyntaxPraser that can parse Monkey code. However I can't think my way out of how to solve that Monkey does not require parenthesis on function and method calls. Let us take an if-statement for an example: If expression statement expression can be replaced by a function call, ex MyFunction 20,10 statement can be replaced by a function call also, ex MyFunction 5,5 One trixy thing is that each parameter to the Function is in itself an expression, and can be a function call in turn. How do I parse this? I mean if THEN where required for one-liners, easy. If parenthesis where required on functions, easy. I don't think this compiles, but should it not in theory? If MyFunction MyFunction MyFunction 10 , 10 , MyFunction, 10 However this compiles: Field MyField:= new MyClass 10,10 I'm confused on how to boil this down to a LLParsable expression! Help! Which are the rules for when parenthesis are required? EDIT Can it be that this is an impossible problem to solve? That a complete parsing of Monkey is impossible if not assuming a certain code-standard?Though with my current grammar I can't even parse all of mojo correctly. |
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| If MyFunction MyFunction MyFunction 10 , 10 , MyFunction, 10 No, because the return value for MyFunction is being used. You can only call a function without parentheses if you're discarding the return value. Personally I think parentheses should be mandatory, as should the Then keyword. But this is coming from a background where languages actually have a rigid structure. :) If you can write a valid grammar for Monkey, you should be able to get an AST fairly simply. |
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| Can it be that this is an impossible problem to solve? If trans can correctly parse it, it's 100% possible. Bah... double post... |
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| welcome to the monkey parsing world! hehehe If you tokenize everything and cassify each token it's not that complicated. I would suggest you to take a look to the parser class in the trans module of the monkey parser. |
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| Hi, > However this compiles: > Field MyField:= new MyClass 10,10 It doesn't here! Perhaps a bug...? Brackets are only optional for 'statement' function calls (well, and for functions that don't take any parameters - but that's really a semantic issue as to the parser these just look like plain identifiers). To parse bracketless statement functions involves a bit of token 'look ahead' though, which may or may not be possible with an off-the-shelf parser. Please feel free to email me if you want to discuss any compiler issues in more detail without boring the pants off everyone here! |
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| Ops I didn't post my last reply, anyway here it goes again: Yeah I have a tokenized everything, got a class for almost every concept in Monkey, way over a 100 classes :) You can only call a function without parentheses if you're discarding the return value. Is it as simple as this? That would be awesome! @Mark, oh well my bad! Let me find one from the Monkey source instead.. Here we go: Function PlaySound( sound:Sound,channel=0,flags=0 ) If sound.sample device.PlaySample sound.sample,channel,flags End * As I have it now, my parser complains that after sound.sample it found a , that it did not expect Mark thanks for the offer! I will send you a mail and save the sanity of people here :) |
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