Parserlib

A c++17 recursive-descent parser library with the following features:

• ENBF-like syntax for writing grammar expressions.
• character, string, boolean, set, range terminals.
• recursive and left-recursive grammars.
• custom parsing functions, callbacks and nodes.
• multiple errors per parse.
• case sensitive/insensitive parsing.
• optional line/column counting.
• parsing utf-8 strings.
• translation of source to AST nodes.
• loading a file directly into memory.
• parsing streams.
• lexing/parsing.

Version 1.0.0.8

Quick Example

#include "parserlib.hpp"
using namespace parserlib;

int main() {
    const auto grammar = terminal("parserlib is") >> " my favorite library" >> -terminal('!');
    std::string source = "parserlib is my favorite library!";
    parse_context<std::string> pc(source);
    bool success = grammar.parse(pc);
}

Table Of Contents

1. EBNF-like syntax
2. Terminals
3. Recursive Grammars
4. The Parse Context
5. Custom Parse Functions/Callbacks/Parse Nodes
6. Error Handling
7. Line/Column counting
8. UTF-8 strings
9. AST Nodes
10. Lexing And Parsing
11. Parsing In-Memory Sources
12. Parsing Sources From Streams
13. Versions

Versions

• 1.0.0.8

  • Rewritten again from scratch, in order to deal with error handling in a much better way, to make everything noexcept for increased performance, to add new capabilities.

• 1.0.0.7

  • Rewritten from scratch, to improve quality of the API.

• 1.0.0.6

  • Added function-based parsing.

• 1.0.0.5

  • Added custom match functions in order to allow the resolution of ambiguities while parsing.
  • allowed terminal values to be of different type that the value of the source container, in order to allow the result of a parse (the ast nodes created by a parse) to be fed to another parse function.
  • added terminal parsing via functions.
  • added parsing via standalone functions.
  • added multiple error handling.

• 1.0.0.4

  • Rewrote the library:
    • all parser grammar classes are now inside a single template class class parser_engine<SourceT, MatchIdT>, for the following reasons:
      • compiler performance (MSVC 32-bit regularly crashed with out of memory error from the many template instantiations of previous versions).
      • library code organization; writing a grammar usually requires including all the grammar constructs, so it is reduntant to have separate files for each grammar-related class.
      • user code organization; whole grammars need to be specialized on source type.
    • coding style is closer to the standard: all identifiers are lower case, words are separated by underscores, idiomatic c++ is used whenever possible.
  • Rewrote the documentation, due to more functionality to be added in the future.

• 1.0.0.3

  • Reorganized the library in order to support compiler front ends into a separate namespace. The main library is now in namespace parserlib::core.
  • Added namespace parserlib::cfe which now contains the compiler-front-end functionality.
  • separated tokenization and parsing phases for compiler-front-ends.
  • Added relevant documentation and unit tests.

• 1.0.0.2

  • Rewrote the library from scratch in order to provide a better interface. Changes:

    • All the getter methods now start with 'get', in order to play better with Intellisense.
    • The ParseContext class is now configured over the Source type, with the default class being the class SourceString.
    • The class SourceString provides custom iterator which counts lines and columns, compatible with the std::string interface.
    • The functions terminal, terminalSet, terminalRange are changed to term, oneOf, oneIn.
    • Matches are now only hierarchical (as in operator >= of previous version).
    • The 'operator >= has been replaced with operator ->*, which is much more distinct than the former; no more typing accidentally '>>' where >= was intended.
    • The default match id type is no longer a string; it is an int.
    • Simplified the left recursion parsing implementation.

• 1.0.0.1

  • Added support for compiler front-end construction.

• 1.0.0.0

  • Initial release.

TODO

TODO list in the current version:

• review and improve the library documentation.