parser.js

export default parseString;

var NEUTRAL = 1;
var KEYWORD = 2;
var NUMBER = 3;
var QUOTED = 4;
var AFTERQUOTE = 5;
var ENDED = -1;
var whitespace = /\s/;
var latin = /[A-Za-z]/;
var keyword = /[A-Za-z84_]/;
var endThings = /[,\]]/;
var digets = /[\d\.E\-\+]/;
// const ignoredChar = /[\s_\-\/\(\)]/g;
function Parser(text) {
  if (typeof text !== 'string') {
    throw new Error('not a string');
  }
  this.text = text.trim();
  this.level = 0;
  this.place = 0;
  this.root = null;
  this.stack = [];
  this.currentObject = null;
  this.state = NEUTRAL;
}
Parser.prototype.readCharicter = function() {
  var char = this.text[this.place++];
  if (this.state !== QUOTED) {
    while (whitespace.test(char)) {
      if (this.place >= this.text.length) {
        return;
      }
      char = this.text[this.place++];
    }
  }
  switch (this.state) {
    case NEUTRAL:
      return this.neutral(char);
    case KEYWORD:
      return this.keyword(char)
    case QUOTED:
      return this.quoted(char);
    case AFTERQUOTE:
      return this.afterquote(char);
    case NUMBER:
      return this.number(char);
    case ENDED:
      return;
  }
};
Parser.prototype.afterquote = function(char) {
  if (char === '"') {
    this.word += '"';
    this.state = QUOTED;
    return;
  }
  if (endThings.test(char)) {
    this.word = this.word.trim();
    this.afterItem(char);
    return;
  }
  throw new Error('havn\'t handled "' +char + '" in afterquote yet, index ' + this.place);
};
Parser.prototype.afterItem = function(char) {
  if (char === ',') {
    if (this.word !== null) {
      this.currentObject.push(this.word);
    }
    this.word = null;
    this.state = NEUTRAL;
    return;
  }
  if (char === ']') {
    this.level--;
    if (this.word !== null) {
      this.currentObject.push(this.word);
      this.word = null;
    }
    this.state = NEUTRAL;
    this.currentObject = this.stack.pop();
    if (!this.currentObject) {
      this.state = ENDED;
    }

    return;
  }
};
Parser.prototype.number = function(char) {
  if (digets.test(char)) {
    this.word += char;
    return;
  }
  if (endThings.test(char)) {
    this.word = parseFloat(this.word);
    this.afterItem(char);
    return;
  }
  throw new Error('havn\'t handled "' +char + '" in number yet, index ' + this.place);
};
Parser.prototype.quoted = function(char) {
  if (char === '"') {
    this.state = AFTERQUOTE;
    return;
  }
  this.word += char;
  return;
};
Parser.prototype.keyword = function(char) {
  if (keyword.test(char)) {
    this.word += char;
    return;
  }
  if (char === '[') {
    var newObjects = [];
    newObjects.push(this.word);
    this.level++;
    if (this.root === null) {
      this.root = newObjects;
    } else {
      this.currentObject.push(newObjects);
    }
    this.stack.push(this.currentObject);
    this.currentObject = newObjects;
    this.state = NEUTRAL;
    return;
  }
  if (endThings.test(char)) {
    this.afterItem(char);
    return;
  }
  throw new Error('havn\'t handled "' +char + '" in keyword yet, index ' + this.place);
};
Parser.prototype.neutral = function(char) {
  if (latin.test(char)) {
    this.word = char;
    this.state = KEYWORD;
    return;
  }
  if (char === '"') {
    this.word = '';
    this.state = QUOTED;
    return;
  }
  if (digets.test(char)) {
    this.word = char;
    this.state = NUMBER;
    return;
  }
  if (endThings.test(char)) {
    this.afterItem(char);
    return;
  }
  throw new Error('havn\'t handled "' +char + '" in neutral yet, index ' + this.place);
};
Parser.prototype.output = function() {
  while (this.place < this.text.length) {
    this.readCharicter();
  }
  if (this.state === ENDED) {
    return this.root;
  }
  throw new Error('unable to parse string "' +this.text + '". State is ' + this.state);
};

function parseString(txt) {
  var parser = new Parser(txt);
  return parser.output();
}