Work in progress

What is this?

It's a personal project about my university studies on programming languages. It has the ambition to recreate some sort of compiler compiler like yacc-lex (also, I'm learning Go, I don't know why, should've gone with Rust? Let me know). Someday the set of tools will comprehend:

Lexical Analysis:
- Creation of NFA from regular expressions
- Creation of DFA from NFA (and its minimization)
- Lexical Analyzer
Grammars:
- Grammar parsing from file
  - command-line
- Nullable symbols
- First
- Follow
- Generators
- Reachable symbols
- Singular symbols
- Grammars simplification:
  - ε-productions
  - singular productions
  - useless symbols
  - left recursion (direct and indirect)
Syntax Analysis:
- Creation of PDA from Grammar
- Creation of DPDA from Grammar
- Parse Tree
  - Concrete
  - Abstract
- Top-Down parser LL(1)
- Bottom-Up parsers:
  - LR(0)
  - SLR(1)
  - LR(1)
  - LALR(1)

Parsing Grammar from file

You can parse a grammar by invoking the function Grammar.ParseGrammar("/path/to/grammar.g").
This function returns a Grammar (see below).

TODO: someday there will be a command-line for this

Any file .g should follow this syntax:

# This is a comment and can only be placed at the beginning of a line

# Blank lines and comments will be ignored.

Definitions of Terminals definitions which you can use later in the Grammar declaration.

Syntax for this is work in progress...

DEFINE:

name1 "def1"
name2 ("def2" name1)
...

# name2 will be "def1def2"

List of Rules of the Grammar.

White spaces separate the terms, while '|' separate the productions, so you can use every character you want except for ' ' and '|', which you'll need to escape.

Please, I beg you, don't use '#' as a NonTerminal, it'll be recognized as a comment, I didn't bother myself implementing the escaping

GRAMMAR:

  A_0 -> b_00 | ... | b_0k
  A_1 -> ...
  .
  .
  .
  A_i -> b_i0 | ... | b_ik

Anything other than that will throw a panic error at your face.

A Grammar is a type:

type Grammar struct {
  S  string              // initial symbol
  NT []string            // non terminals
  T  []string            // terminals
  R  map[string][]string // rules (A -> a_0 | ... | a_k is stored as Grammar.R[A] = [a_0 ... a_k])
}

Hamilnvt/Languages

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