Make skipcharsets non-allocating

It needed a little tweaking for constant-propagation to work.

Author: tecosaur

src/lexer.jl

@@ -760,7 +760,7 @@ julia> skipcharsets(strv, 1, 'a':'z', '0':'9', ' ', '.', '-')
 12
 ```
 """
-function skipcharsets(bytes::DenseVector{UInt8}, pos::Integer, charsets::Union{StepRange{Char}, Char}...; limit::Integer = length(bytes) % typeof(pos))
+function skipcharsets(bytes::DenseVector{UInt8}, pos::Integer, charsets::NTuple{N, Union{StepRange{Char}, Char}}; limit::Integer = length(bytes) % typeof(pos)) where {N}
     skipranges = map(c -> if c isa Char UInt8(c) else
                          UInt8(first(c)):UInt8(last(c)) end,
                      charsets)
@@ -773,6 +773,9 @@ function skipcharsets(bytes::DenseVector{UInt8}, pos::Integer, charsets::Union{S
     next
 end
 
+skipcharsets(bytes::DenseVector{UInt8}, pos::Integer, charsets::Union{StepRange{Char}, Char}...; limit::Integer = length(bytes) % typeof(pos)) =
+    skipcharsets(bytes, pos, Tuple(charsets); limit)
+
 """
     skipbalanced(bytes::DenseVector{UInt8}, pos::Integer, bpair::Pair{Char, Char},
                  quotes::NTuple{N, Char} = (), escapechar::Union{Char, Nothing} = nothing) -> Integer