README.md

shift-forth

DEMO

About

JavaScript Compiler library that takes input in Shift-AST format in SSA form and produces Forth program.

Examples

function add42 (a) {             // : add42 42 + exit ;
  return a + 42;
}

function square (x) {            // : square 0 pick * exit ;
  	return x * x;
}

function sub (a, b) {            // : sub
  return a - b;                  //     - exit
}                                // ;

                                 // variable g0
function mul_global (a) {        // : mul_global
  return a * g0;                 //     g0 @ * exit
}                                // ;

function add3_fast (a, b, c) {   // : add3_fast
  return b + c + a;              //     + + exit
}                                // ;

function add_var (a, b) {        // : add_var
  var x;
  x = a + b;                     //     +
  return x;                      //     exit
}                                // ;

function cmplx_re (a, b, c, d) { // : cmplx_re
  var re;                        //     3 pick 2 pick *
  re = a * c - b * d;            //     3 pick 2 pick * -
  return re;                     //     nip nip nip nip exit
}                                // ;

function cmplx_im (a, b, c, d) { // : cmplx_im
  var im;                        //     3 pick *
  im = a * d + b * c;            //     2 pick 2 pick * +
  return im;                     //     nip nip nip exit
}                                // ;

function foo (x0, y0) {          // : foo
  if (x0 < 100) {                //     over 100 < if
    do {                         //         begin
      x1 = ф(x0, x2);            //
      y1 = ф(y0, y2);            //
      x2 = x1 + 1;               //             swap 1 +
      y2 = y1 + x2;              //             swap over +
    } while (x2 < 100);          //         over 100 >= until
  }                              //     then
  x3 = ф(x0, x2);
  y3 = ф(y0, y2);
  return [x3, y3];               //     exit
}                                // ;

Status

Initial code.

Installation

npm install shift-forth

Usage

Require Parser, Scope analyzer, and Shift-Forth.

var parse = require('shift-parser').default,
    analyze = require('shift-scope').default,
    forth = require('shift-forth');

Parse JavaScript string, analyze scope, emit Forth string.

var source, tree, scope;

source = 'function sub (a, b) { return a - b; }';
tree = parse(source);  // Shift AST
forth.naming(tree);    // add names to noname AST nodes
scope = analyze(tree); // Scoped AST
forth.dfg(scope);      // add dependency graph
forth.emit(scope);     // add Forth definition to scoped AST
console.log(scope.forth);

// -> : sub - exit ;

The library uses: shift-traverse-js library for AST traversal.

License

MIT