The Lingo library is a set of facilities that supports the construction of compilers, interpreters, and other language related tools. In particular, this library aims to provide reasonable implementations of common facilities that can be difficult and time-consuming to construct as part of a compiler implementation.

This library provides the following facilities:

• Memory management -- A set of factories that facilitates the allocation and cleanup of nodes. This includes an opt-in garbage collector that works using tree structures that mix collected and non-collected nodes.
• String representations -- A lightweight string view that supports zero-copy access to parsed text.
• String formatting -- Using C++ Format, tools for formatting strings.
• Source locations -- Facilities for efficiently representing locations in source code.
• Symbol table -- A facility for ensuring that each symbol in a parsed file is uniquely represented. This also allows additional information to be associated with those symbols.
• Token representation -- A lightweight and extensible representation of lexical tokens, integrated with the symbol table for ease of use.
• Error handling -- Tools for asserting logical conditions and control flow impossibilities.
• Diagnostics -- A set of facilities for emitting error and warning diagnostics.
• Node abstraction -- Generic data types and algorithms that support the definition of abstract syntax trees. Many of the other facilities in this library are designed on node concepts.
• Pretty printing -- A facility that supports the generation of formatted string output for languages built on the node concepts.
• Debug printing -- An extension of pretty printing that emits an s-expression representation of abstract syntax trees.
• Parsing and lexing facilities -- A set of generic algorithms that can be used to construct efficient lexers and parsers. These modules also define the concepts of character and token streams as well as the parsers and lexers that operate over them.

There are a number of features missing from this library. In particular:

• File management
• Application configuration (command-line parsing, etc.)
• Real number types
• Character and string literal support
• Unicode support for parsing and lexing
• Support for multithreaded environments
• Windows support

Also, note that many of the facilities could be further optimized. In particular, the garbage collector is fairly naive with respect to allocation policies, and the unique representation of source locations could be dramatically improved.

This library is designed to be included as a submodule in a larger project. For your compiler, add this submodule from your top-level source directory using the following command:

git submodule add https://github.com/asutton/lingo

The Lingo library also depends on a few external libraries:

• C++ Format -- This is included as the Git submodule 'cppformat'.
• GMP -- The GNU Multiple Precision Arithmetic Library (GMP) must be installed on your system.
• [iconv] (http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/iconv.h.html) -- The POSIX C header <iconv.h>, which contains the iconv() function, must be installed on your system. On some platforms, this is part of the system C library. On others, you can install GNU's libiconv.

The Lingo library is built using CMake (version 3.0 or later). Adding the cloned 'lingo' directory to your CMake project should be sufficient to make it build. The 'lingo' target produces a static library named 'liblingo'. This should be linked against your compiler implementations.