- header-parsers #!optional ALISTparameter
- header-unparsers #!optional ALISTparameter
The parsers and unparsers used to read and write header values can be customized with these parameters.
These (un)parsers are indexed with as key the header name (a symbol) and the value being a procedure.
A header parser accepts the contents of the header (a string, without the leading header name and colon) and returns a list of vectors which represents the values of the header. For headers that are supposed to only have a single value, the last value in the list will be stored as the value (as determined by single-headers).
A header unparser accepts one argument: the header's contents (a vector). It should return a list of strings, each of which represents one line's worth of header contents (without the header name). For each entry, a header line will automatically be printed with the header name preceding it.
The parser driver will call update-header-contents! with the parser's result.