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diff --git a/third_party/lisp/npg/README b/third_party/lisp/npg/README new file mode 100644 index 0000000000..a1661e744a --- /dev/null +++ b/third_party/lisp/npg/README @@ -0,0 +1,48 @@ + + NPG a Naive Parser Generator + for Common Lisp + + Copyright (C) 2003-2006, 2010 by Walter C. Pelissero + Copyright (C) 2021 by the TVL Authors + +Vendored into depot as it is a dependency of mime4cl and upstream has +become inactive. Upstream and depot version may diverge. + +Upstream Website: http://wcp.sdf-eu.org/software/#npg +Vendored Tarball: http://wcp.sdf-eu.org/software/npg-20150517T144652.tbz + +This library is free software; you can redistribute it and/or modify +it under the terms of the GNU Lesser General Public License as +published by the Free Software Foundation; either version 2.1 of the +License, or (at your option) any later version. This library is +distributed in the hope that it will be useful, but WITHOUT ANY +WARRANTY; without even the implied warranty of MERCHANTABILITY or +FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public +License for more details. You should have received a copy of the GNU +Lesser General Public License along with this library; if not, write +to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, +Boston, MA 02111-1307 USA + + +This library generates on the fly (no external representation of the +parser is produced) a recursive descent parser based on the grammar +rules you have fed it with. The parser object can then be used to +scan tokenised input. Although a facility to produce a lexical +analiser is not provided, to write such a library is fairly easy for +most languages. NPG parsers require your lexer to adhere to a certain +protocol to be able to communicate with them. Examples are provided +that explain these requirements. + +While quite possibly not producing the fastest parsers in town, it's +fairly simple and hopefully easy to debug. It accepts a lispy EBNF +grammar description of arbitrary complexity with the exception of +mutually left recursive rules (watch out, they produce undetected +infinite recursion) and produces a backtracking recursive descent +parser. Immediate left recursive rules are properly simplified, +though. + +Multiple concurrent parsers are supported. + +To compile, an ASDF and nix file are provided. + +See the examples directory for clues on how to use it. |