Layout of an LLVM project
All LLVM projects follow the same idea of directory layout. To understand the idea, let's compare LLVM with GCC, the GNU Compiler Collection. GCC has provided mature compilers for decades for almost every system you can imagine. But, except for the compilers, there are no tools that take advantage of the code. The reason is that it is not designed for reuse. This is different with LLVM.
Every functionality has a clearly defined API and is put in a library of its own. The clang project has (among others) a library to lex a C/C++ source file into a token stream. The parser library turns this token stream into an abstract syntax tree (also backed by a library). Semantic analysis, code generation, and even the compiler driver are provided as a library. The well-known clang tool is only a small application linked against these libraries.
The advantage is obvious: when you want to build a tool that requires the abstract syntax tree (AST) of a C++ file...
