Troque para Português Brasileiro 🇧🇷.
Lexa is a parser created on top of flex and bison. Further, the Lexa grammar adopts its styles from programming languages like TypeScript, Pascal and Rust but also add its peculiarities.
Lexa parser project is a requirement for the Compilers course.
Lexa can be use to guide beginners in the use of flex and bison tools for making lexical and syntax analyzers, respectively.
Further, the interaction between the user and the program is easy, convenient and simple, such that, the program prints out the grammar rules that are valid and prints at the end of the execution if the input is valid with relation to the Lexa's grammar.
A lexical analyzer (or lexer) is one of the analyzers in the compiling process (generally, the first) in which a sequence of characters is taken as input and a sequence of token is given as output.
Further, it can be said that the sequence of tokens given as output is the input of the next step in the compiling process, in this case, the next step is the syntax analyzer or also called parser.
A syntax analyzer (or parser) is one of the analyzers in the compiling process (generally, the second) in which a sequence of tokens is taken as input and an abstract syntax tree is given as output. In some compiling process the result may be directly evaluated at the parser, such that, the abstract syntax tree is not necessarily produced.
Further, it can be said that the abstract syntax tree given as output is the input of the next step in the compiling process that is, generally, the semantic analyzer. In this project, a semantic analyzer is not implemented.
First things first, the parser must be compiled first. Therefore, we suggest to follow the next steps.
Install the gcc the C compiler executing the following line.
sudo apt install gcc
🔔 Note: If you already have the gcc installed, then you can jump to the next step.
Install the make easies the compilation of our simulator enabling compile the entire project using just one command.
sudo apt install make
🔔 Note: If you already have the make installed, then you can jump to the next step. Further, if you do not want to use make then you can jump the next step.
Execute the following line to compile the parser (using make)
make
🔔 Note: If you do not have the make installed, then you can jump to the next step. Otherwise, you can jump to the next section.
Execute the following line to compile the parser (without make)
bison --header=src/parser.h -o src/parser.c src/parser.y
flex -o src/scanner.c src/scanner.l
gcc -o lexa src/parser.c src/scanner.c
If you already followed the steps provided in the previous section, then you are ready to run our parser, for that run the following line.
./lexa {input}
in which is the input file name without the { and }.
After that, have fun!