trie_v2.js

var fs = require('fs'); // import for index_emails

function Trie() {
  this.head = {};
};

// want to make sure we have valid words
Trie.prototype.validate = function(word) { 
  if ((word === undefined) || (word === null) || (typeof word !== "string")) throw "invalid input";
}

// basic gist is to check if a node exists in a given sequence (prefix) and if it doesn't create a new one
Trie.prototype.add = function(word, value=null) {
  this.validate(word)
  var node = this.head;

  for (var i = 0; i < word.length; i++) { 
    if(!(word[i] in node)) {
      node[word[i]] = {};
    }
    node = node[word[i]]
  };

  node.word = word
  // this was added for the sake of having multiple non-word values for a single path in the trie
  if (value) {
    node.value = Array.isArray(node.value) ? [...node.value, value] : [value]
  }
};

// follow the trie from node to node to see if it has it
Trie.prototype.contains = function(word) {
  this.validate(word)
  var node = this.head;

  for (var i = 0; i < word.length; i++) { 
    if(!(word[i] in node)) {
      return false;
    }
    node = node[word[i]]
  };
  return node.word === word;
};

Trie.prototype.get = function(word) {
  this.validate(word)
  var node = this.head;

  for (var i = 0; i < word.length; i++) { 
    if(!(word[i] in node)) {
      return false;
    }
    node = node[word[i]]
  };
  return node.value;
};

// follow the trie from node to node to see if it has it
Trie.prototype.contains = function(word) {
  this.validate(word)
  var node = this.head;

  for (var i = 0; i < word.length; i++) { 
    if(!(word[i] in node)) {
      return false;
    }
    node = node[word[i]]
  };
  return node.word === word;
};

// doing this async would be preferable as it's currently blocking and would prevent it from doing anything else
Trie.prototype.index_emails = function(path) {
  var self = this
  fs.readdirSync(path).forEach(function(dirname) {
    var currentPath = path + '/' + dirname
    var isDir = fs.lstatSync(currentPath).isDirectory()
    // if a current dir level has both files and dirs we need to recurse accordingly
    if (isDir) {
      self.index_emails(currentPath)
    } else {
      var text = fs.readFileSync(currentPath, "utf-8");
      words = text.toLowerCase().split(' ')      
      words.forEach(function(word) {
        self.add(word, currentPath)
      })
    }
  })
  return self;
}

Trie.prototype.test = function(word, trie) {
  return trie.get(word)
}