@fork-bench/flexjs-open

flexjs-open is a home-made Flex utility. It's quite easy to use, and has small presets like _DIGITS_ or _LETTERS_ as well as _WORDS_ and _NUMBERS_.

Simple example : Polish math notation in JS :

``
const Flex = require('@fork-bench/flexjs-open');

var pile = [];

var input = '300 2 5 * -'
// In standard notation, it would be 300 - (2 * 5)
// See more on : https://en.wikipedia.org/wiki/Reverse_Polish_notation

// Tokens with their value
var tokens = {
"-": "operator",
"+": "operator",
"*": "operator",
"/": "operator"
};
// Equivalent in Flex :
// operator [\-\+\*\/]


// Import everything
const flex = new Flex(input, tokens, NUMBERS = true);

// On each NUMBER
flex.on('NUMBER', (token) => {
pile.push(parseInt(token.key));
});

// On each operator
flex.on('operator', (token) => {
var pileLength = pile.length;
var result = undefined;
switch (token.key) {
case '+':
result = pile[pileLength - 2] + pile[pileLength - 1];
break;
case '-':
result = pile[pileLength - 2] - pile[pileLength - 1];
break;
case '*':
result = pile[pileLength - 2] * pile[pileLength - 1];
break;
case '/':
result = pile[pileLength - 2] / pile[pileLength - 1];
break;
}
pile.pop();
pile.pop();
pile.push(result);

if (pile.length == 1) {
console.log(pile[0]);
}

});

// Run the tokenizer
flex.tokenize();
``