WHITESPACE = _{ " " | "\t" }
char = { ASCII_ALPHANUMERIC | "." | "_" | "/" | "-" | "=" | ">" | "<" | "!" | "'" | "#" | "\"" }
text = @{ char+ | WHITESPACE | NEWLINE }
env_variable_char = { 'A'..'Z' | '0'..'9' }

macro_parameter = @{char+}
macro_name = @{char+}
macro_parameters = _{ ("," | macro_parameter)* }
spec_macro_without_parameters = _{"%{" ~ macro_name ~ "}" | "%" ~ macro_name}
spec_macro_with_parameters = _{"%{" ~ macro_name ~ "("~macro_parameters~")" ~ "}" | "%" ~ macro_name ~ "("~macro_parameters~")"}
spec_macro = { (spec_macro_with_parameters|spec_macro_without_parameters) }
spec_optional_macro = @{ "%{?" ~ char+ ~ "}" }
function = { "%(" ~ (spec_macro | spec_optional_macro | text)* ~ ")" }
text_with_macros = { function | spec_macro | spec_optional_macro }

file = {SOI ~ text* ~ (text | text_with_macros)+ ~ text* ~ EOI}

env_variable = @{"$" ~ (env_variable_char | "_")+}