How to exclude whitespace from location information?

[radekstatebox]

The usual way to ignore whitespace is by appending a whitespace rule to each terminal:

identifier = @$([a-z]+) _
_ = [ \t]*

However, now the location includes the whitespace:

Identifier = name:identifier { return { sourceSpan: location(), name } }

For the input a b, the location for the first identifier would be:

{
    start: { offset: 0, ... },
    end: { offset: 2, ... }, // 2 rather than 1
}

Is there a nice way to exclude the trailing whitespace from the location information? I could move the location() call to the definition of identifier like so:

identifier = @(name:$([a-z]+) { return { sourceSpan: location(), name } }) _

But that doesn’t really scale to more complicated productions (especially non-terminals).

[hildjj]

Your suggestion might be cleaner once #337 lands. Something like:

Trail_<R, n> = @(r:R { return { sourceSpan: location(), [n]: r } }) _
Identifier = Trail_<identifier, "name">

Except. You'd really like access to the rule name of R so you didn't also have to pass in "name". @quadristan I haven't fully internalized how templates work yet, do you have any insights?