walt-compiler/src/utils/trie.js

Alternative syntax for WebAssembly text format

// @flow
/**
 * A very basic trie with functional,recursive search
 */
const fsearch = node => {
  const next = (char: string) => {
    if (node && node.children[char]) {
      return fsearch(node.children[char]);
    }

    return null;
  };

  next.leaf = node.leaf;

  return next;
};

type Node = {
  char: string,
  children: { [string]: Node },
  leaf: boolean,
};

class Trie {
  root: Node;
  fsearch: any;

  constructor(words: Array<string>) {
    this.root = {
      char: '',
      children: {},
      leaf: false,
    };

    words.map(word => this.add(word));
    this.fsearch = fsearch(this.root);
  }

  add(word: string) {
    let current = this.root;
    let char = word.slice(0, 1);

    word = word.slice(1);

    while (typeof current.children[char] !== 'undefined' && char.length > 0) {
      current = current.children[char];
      char = word.slice(0, 1);
      word = word.slice(1);
    }

    while (char.length > 0) {
      const node = {
        char,
        children: {},
        leaf: false,
      };

      current.children[char] = node;
      current = node;
      char = word.slice(0, 1);
      word = word.slice(1);
    }

    current.leaf = true;
  }
}

module.exports = Trie;