Compiler front end generators.

Lexical analyzer generator

• Read Grammar file grammar.txt line by line, then substitute ranges.

  digit = 0 - 9 => digit = 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9

• Convert each range from infix to postfix.

  digit = 0 | 1 | 2 | 3 => digit = 0 1 | 2 | 3 |

• Convert each postfix to an equivalent NFA using Thompson's construction algorithm.

• Convert the generated NFA to DFA using Subset construction algorithm.

• Minimize the generated DFA using Hopcroft's algorithm.

• Read & tokenize source.txt file.

Parser generator

• Read java_cfg.txt

• Remove Left recursion if found.

• Perform Left factoring, only one is supported.

  A -> B D | B F => Supported

  A -> B | B D | B F => NOT supported

• Calculate First & Follow for each non terminal.

• Build the parse table with panic mode error recovery support.

• Parse tokens read from stdin.

Build and Run

• clone this repo

  git clone https://github.com/siamx/compiler-front-end

• Enter project directory

  cd compiler-front-end

• Build

  make

• Run

  ./lex | ./parse