Language plugins read and write a particular simulation language, and set up related commands. They determine the syntax used by gnucap.
This refers to SIMULATION languages, like “spice”, “spectre” or “verilog”, not NATURAL languages.
Language plugins need to #include the file: gnucap/lang_base.h. Others may be needed in some cases.
The base class LANGUAGE is defined in gnucap/u_lang.h which is included by gnucap/lang_base.h.
The “parse” and “print” functions go together. For every “parse” there must be a “print” that regenerates a string suitable for input to “parse” that is equivalent to the original.
As a generalization, to read a file the function parse_top_item is called in a loop:
for (;;) {
OPT::language->parse_top_item(file, Scope);
}
The loop exits when an exception is thrown, most likely Exception_End_Of_Input.
This function must be provided by the language plugin. A set of other functions must also be provided, as in this example:
As with all plugins, declare one static object of this new type, and INSTALL it in the DISPATCHER.
In addition to this, you will probably need to supply a few commands to recognize keywords at top level.
Details are described in the following “Implementation” section.