mimetype.pl -- Determine mime-type for a file

Simple library to guess the mime-type from the extension of a file. As various applications need to do this type of inferencing it seems worthwhile to place this functionality in an extensible library.

To be done

- Consider content handling (using the Unix file command)

- Allow parameters? (e.g. text/html; charset=UTF-8)

 file_mime_type(+FileName, -MimeType) is semidet

True when MimeType is the mime-type to be used for sending FileName. The default rules can be overridden and extended using the hook mime:mime_extension/2.

Arguments:

MimeType

- is a compound term of the form Type/SubType.

 mime:mime_extension(+Ext, -MimeType) is semidet[multifile]

Hook that is called by file_mime_type/2 before the default table is examined.

 default_mimetype(-MimeType) is semidet[private]

If the mime-type cannot be determined from the file extension, this predicate is used as fallback. It takes the value from the Prolog flag default_mimetype. To change the default, use e.g.,

:- set_prolog_flag(default_mimetype, text/plain).

The initial default mime-type is application/unknown. Use the value - to denote there is no default.

 ext_mimetype(+Extension, -MimeType) is semidet[private]

Built-in table of file-name extension to mime-type mappings.

To be done

- Update this list, e.g., from http://www.webmaster-toolkit.com/mime-types.shtml

 name_mimetype(+DownCaseFileName, -MimeType) is semidet[private]

Determine the mime-type of files based on the entire filename.

 text_mimetype(+MimeType) is semidet[private]

True when documents of MimeType are text documents and thus may need a charset specification.

 file_content_type(+File:atom, -ContentType:atom) is det

 file_content_type(+File:atom, ?MediaType, -ContentType:atom) is det

True if File should be served using ContentType: ContentType. It takes the following steps:

1. Determine the media type using file_mime_type/2, unless already specified using file_content_type/3.
2. Determine it is a text file using text_mimetype/1
3. Use the charset from the Prolog flag default_charset

The behavior is controlled by several hooks and a flag.

• mime:mime_extension/2 defines the media type
• text_mimetype/1 defines the media type is text
• mime:charset/3 derives the charset for a file with a given media type, if the media type is text according to text_mimetype/1.
• If text_mimetype/1 succeeds and mime:charset/3 fails, the flag default_charset defines the charset unless it is set to -. The flag set by default to UTF-8 if the Prolog flag encoding is set to utf8.

 mime:charset(+File, +MediaType, -Charset) is semidet[multifile]

Hook that determines the Charset for File that has media type MediaType. This hook allows overruling file_content_type/2.

See also

- text_mimetype/1.