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Python S-Expression Object Model

There are many variants of S-Expression <https://en.wikipedia.org/wiki/S-expression>_. This module here only deals with the prefix notation, where the first element of an expression is expected to be an operator, which is referred to as the <key> in this module. The module provides a parser SexpParser that converts a python list-based expression into a python object model. Each expression in the list-based S-Expression representation is defined as a recursive list representation in the form of ::

[ <line number>, <key>, <value>... ]

where there may be none or multiple <values> of either an atom (i.e. plain string) or another list-based S-Expression. SexpParser assumes the <key> here is a plain string. The <line number> not being part of the conventional S-Expression is only here for debugging purpose

function parseSexp() can be used to convert plain text form S-Expression into the list-based representation

The class Sexp is the top class for objects representing a parsed expression.

If you only need a non-semantic-checking parser, you can use SexpParser as it is. For the usage of the object model produced by SexpParser, see the project here <http://github.com/realthunder/kicad_parser>_.

To construct a semantic checking parser, see the sample code here <test.py>. More details can be found in the code document here <sexp_parser.py>