LAYOUT must allow empty match about parglare HOT 6 CLOSED

If LAYOUT is not provided ws setting is used.
If LAYOUT is provided it must match between each two adjacent tokens plus the beginning and end of the input. I've added a note in the docs.

Controlling word boundaries is in parglare handled with a special rule KEYWORD as the word boundary is not determined only by whitespaces. I think this mechanism should work in your case also.

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I found the WS and LAYOUT explanation in the documentation already (which is quite good, I might add). The confusion part there is that the WS setting is also non-empty, and it doesn't fail to match before the first token (just like my example doesn't fail if you take out the LAYOUT rule). I guess there is a default LAYOUT rule that allows empty matches.

I agree that KEYWORD is an alternative, and I have used that currently, and made LAYOUT allow empty matches. Thank you for confirming that is the desired solution here.

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Chars in ws setting are always optional and they are used if LAYOUT is not defined. This is relevant part of the implementation.

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Ah right, the code provides the optional matching rather than the pattern.

Looking at the code, I noticed the position is always incremented by 1. Does that mean my WS definition of WS : /[ \t]+/ ; is wrong, or at least non-efficient? That is, I match a sequence of whitespace at the line, rather than just 1 character. The code then repeats that process after moving forward 1 position, etc, until the end of the whitepsace is matched.

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No, your definition is perfectly fine. WS from your grammar is used in entirely different way. It has nothing to do with ws Parser param. You can call your rules in LAYOUT part of grammar anyway you like, only the entry rule must be called LAYOUT. Matching using grammar rules is done here using regex and string matches from terminal definitions. If the match succeeds the position is incremented by the length of the match, so your WS will greadilly consume all whitespaces ahead in one go.

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thank you for the explanation

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