expression = { SOI ~ ws? ~ or_expression ~ ws? ~ EOI }

or_expression = { and_expression ~ (ws+ ~ or_op ~ ws+ ~ and_expression)* }

and_expression = { with_expression ~ (ws+ ~ and_op ~ ws+ ~ with_expression)* }

with_expression = { primary ~ (ws+ ~ with_op ~ ws+ ~ exception_id)? }

primary = { 
    parenthesized_expression |
    license_ref |
    license_id
}

parenthesized_expression = { "(" ~ ws? ~ or_expression ~ ws? ~ ")" }

or_op = { ^"OR" }
and_op = { ^"AND" }
with_op = { ^"WITH" }

license_id = { 
    (ASCII_ALPHANUMERIC | "-" | "." | "+" | "_")+
}

license_ref = { 
    ("DocumentRef-" ~ license_id ~ ":" ~ "LicenseRef-" ~ license_id) |
    ("LicenseRef-" ~ license_id)
}

exception_id = { 
    (ASCII_ALPHANUMERIC | "-" | "." | "+" | "_")+ 
}

ws = _{ " " | "\t" | "\n" | "\r" }