FE

A header-only C++ library for writing compiler/interpreter frontends.

What is FE?

FE provides a set of utilities that helps you writing your own compiler or interpreter frontend. FE is not a lexer or parser generator. Instead, it will give you the blueprint to easily hand-write your own lexer and parser.

Get Started Now!

Based on the toy language Let, either

• create a new repository from a template, or
• fork it.

Features

• [Arena](@ref fe::Arena) allocator for efficient memory management.
• Efficient [symbol pool](@ref fe::SymPool) that internalizes C and C++ strings into [symbols](@ref fe::Sym). Checking for equality/inequality is only a pointer comparisons!
• Keep track of [source code locations](@ref fe::Loc).
• Blueprint for a [lexer](@ref fe::Lexer) with [UTF-8](@ref fe::utf8) support.
• Blueprint for a [parser](@ref fe::Parser).
• Optional Abseil support.
• You need at least C++-20.

Building

FE optionally supports Abseil's excellent hash containers. In order to enable Abseil support, you have to define FE_ABSL. Otherwise, FE will fall back to the hash containers of the C++ standard library.

Option #1: Include FE as Submodule (Recommended)

1. Add FE as external submodule to your compiler project:

   • If your compiler project is already on GitHub, do this:

     git submodule add ../../leissa/fe external/fe

   • Otherwise:

     git submodule add [email protected]:leissa/fe.git external/fe

2. Integrate into your build system:

   • If you use CMake, add something like this to your CMakeLists.txt:

     set(FE_ABSL ON) # remove this line, if you don't want to use Abseil
     add_subdirectory(external/fe)
     
     target_link_libraries(my_compiler PUBLIC fe)

   • Otherwise:
     • Add external/fe/include as include directory.
     • Furthermore, add -DFE_ABSL to your CXXFLAGS, if you want to use Abseil.

Option #2: Directly include FE in your Source Tree

1. Copy over the headers from FE to your compiler project:

   git clone [email protected]:leissa/fe.git
   mkdir -p my_compiler/include/fe
   cp -r fe/include/fe/*.h my_compiler/include/fe

2. Integrate into your build system:

   Since your build system most likely already has my_compiler/include/ as an include directory, nothing more needs to be done. In addition, add -DFE_ABSL to your CXXFLAGS, if you want to use Abseil. In the case of CMake, add something like this to your CMakeLists.txt:

   target_compile_definitions(my_compiler PUBLIC FE_ABSL)

Other Projects using FE

• Let: A simple demo language that builds upon FE
• GraphTool: A small tool that reads a subset from Graphviz' DOT language and calculates several dominance-related properties
• SQL: Small and simple SQL parser
• Thorin2: The Higher-ORder INtermediate representation