-- about filter::
- This filter is given no arguments.
- The about text that is to be filtered is available on standard input and the
- filtered text is expected on standard output.
-- commit filter::
- This filter is given no arguments.
- The commit message text that is to be filtered is available on standard input
- and the filtered text is expected on standard output.
-- source filter::
- This filter is given a single parameter: the filename of the source file to
- filter. The filter can use the filename to determine (for example) the syntax
- highlighting mode.
- The contents of the source file that is to be filtered is available on
- standard input and the filtered contents is expected on standard output.
+By default, filters are separate processes that are executed each time they
+are needed. Alternative technologies may be used by prefixing the filter
+specification with the relevant string; available values are:
+
+'exec:'::
+ The default "one process per filter" mode.
+
+'lua:'::
+ Executes the script using a built-in Lua interpreter. The script is
+ loaded once per execution of cgit, and may be called multiple times
+ during cgit's lifetime, making it a good choice for repeated filters
+ such as the 'email filter'. It responds to three functions:
+
+ 'filter_open(argument1, argument2, argument3, ...)'::
+ This is called upon activation of the filter for a particular
+ set of data.
+ 'filter_write(buffer)'::
+ This is called whenever cgit writes data to the webpage.
+ 'filter_close()'::
+ This is called when the current filtering operation is
+ completed.
+
+ Additionally, cgit exposes to the Lua the following built-in functions:
+
+ 'html(str)'::
+ Writes 'str' to the webpage.
+ 'html_txt(str)'::
+ HTML escapes and writes 'str' to the webpage.
+ 'html_attr(str)'::
+ HTML escapes for an attribute and writes "str' to the webpage.
+ 'html_url_path(str)'::
+ URL escapes for a path and writes 'str' to the webpage.
+ 'html_url_arg(str)'::
+ URL escapes for an argument and writes 'str' to the webpage.
+
+
+Parameters are provided to filters as follows.
+
+about filter::
+ This filter is given a single parameter: the filename of the source
+ file to filter. The filter can use the filename to determine (for
+ example) the type of syntax to follow when formatting the readme file.
+ The about text that is to be filtered is available on standard input
+ and the filtered text is expected on standard output.
+
+commit filter::
+ This filter is given no arguments. The commit message text that is to
+ be filtered is available on standard input and the filtered text is
+ expected on standard output.
+
+email filter::
+ This filter is given two parameters: the email address of the relevent
+ author and a string indicating the originating page. The filter will
+ then receive the text string to format on standard input and is
+ expected to write to standard output the formatted text to be included
+ in the page.
+
+source filter::
+ This filter is given a single parameter: the filename of the source
+ file to filter. The filter can use the filename to determine (for
+ example) the syntax highlighting mode. The contents of the source
+ file that is to be filtered is available on standard input and the
+ filtered contents is expected on standard output.