Toco
Toco is a small toy compiler using Flex (Lexer), Bison (Parser) and LLVM for generating the Assembly
Installation requirements
In order to build Toco you need Flex, Bison, LLVM and a recent C++ compiler. If you're on macOS you may use homebrew for installing all the dependencies:
$ brew install flex bison llvm
$ export PATH="/usr/local/Cellar/flex/2.6.3/bin:$PATH"
$ export PATH="/usr/local/Cellar/bison/3.0.4/bin:$PATH"
Basic compiler toolchain
Following are the different parts of Toco which will parse source code and transform it into a binary
+----------+ +----------+ +----------+
| Lexical | | Semantic | | Assembly |
| Analysis |--->| Parsing |--->| |
| (Flex) | | (Bison) | | (LLVM) |
+----------+ +----------+ +----------+
The lexer (compiler frontend) takes some source code (text) as input and generates a sequence of tokens (strings with an assigned and identified meaning, for instance identifiers, keywords, numbers, brackets etc.)
The semanting parsing part takes the sequence of tokens and generates an abstract syntax tree (AST). We will use Bison for this part.
Finally we traverse our previously generated AST and generate byte code / machine readable code for each node using LLVM.
Defining the grammar of Toco
As a first step, we will use the well known C-like syntax for Toco, since this is easy to parse and fairly simple. For instance, the following snippet will be valid code for Toco
int add_two_numbers(int a, int b) {
int res = a + b;
return res;
}