Synopsis parses source code into a variety of internal representations (IRs), which then are manipulated in various ways, before some output (such as a cross-referenced API documentation) is generated by an appropriate formatter.
At the core of Synopsis are a set of programing-language independent IRs which all parser frontends generate. These parsers use other IRs internally, which eventually get translated into the common representations.
For details about the AST, see the section called “The AST”
At this time, the C++ frontend's IRs are not yet accessible through python, though they eventually will be, making it possible to use Synopsis as a source-to-source compiler. To learn more about the evolving C & C++ parser and its IRs, see the Developer's Guide.