Required space

Lezer
1

I have the following grammar:

@top Program { expression }

@skip { space }

expression { Identifier | Number | brackets<Op> | FunctionCall }

Plus { expression !plus ArithOp<"+"> expression }
And { expression !and LogicOp<"and"> expression }

Op {
  Plus |
  And
}

FunctionCall { Not }

Not { fn<"not"> "(" expression ")" }

fn<term> { @specialize[@name={term}]<Identifier, term> }

brackets<expression> { "(" expression ")" | expression }

@tokens {
  space { @whitespace+ }

  identifierChar { @asciiLetter }

  word { identifierChar (identifierChar | @digit)* }

  Identifier { word }

  Number { @digit+ }

  ArithOp<term> { term }

  LogicOp<term> { term }
}

which handles all the cases such as (1+1) or not(foo+bar) or foo + 1. But LogicOp parses 1and1 or fooandbar as a valid expression - it should not be allowed - any whitespace should be required before and after that LogicOp eg 1 and 1 or foo and bar. I tried to introduce requiredSpace token, but it can’t be compiled because it overlaps with @skip { space }. Is this somehow possible? Thank you

2

I expect that grammar would parse fooandbar as a single identifier. For letters directly after numbers, you could do something like introduce an invalid-number token that’s a number followed by letters, and giving it a higher precedence than normal number tokens.