convo/lib/parser.js

Easily create conversations (for more natural bots)

/**
 * Module dependencies
 */

var string_to_regexp = require('string-to-regexp')
var debug = require('debug')('convo:parse')
var TokenStream = require('token-stream')
var Lexer = require('./lexer')

/**
 * Export `parse`
 */

module.exports = Parser

/**
 * Initialize `parse`
 */

function Parser (tokens) {
  if (!(this instanceof Parser)) return new Parser(tokens)
  this.tokens = new TokenStream(tokens)
  return this.choices()
}

/**
 * Conversation
 */

Parser.prototype.choices = function() {
  var choices = []
  var choice = {}

  while (true) {
    switch(this.tokens.peek().type) {
      case 'string':
        choice.incoming = this.tokens.advance().val
        break
      case 'regexp':
        choice.incoming = string_to_regexp(this.tokens.advance().val)
        break
      case 'arrow':
        this.tokens.advance()
        choice.outgoing = this.outgoing()
        break
      case 'alias':
        choice.alias = this.tokens.advance().val
        break
      case 'newline':
        this.tokens.advance()
        Object.keys(choice).length && choices.push(choice)
        choice = {}
        break
      case 'indent':
        this.tokens.advance()
        choice.outgoing.choices = this.choices()
        Object.keys(choice).length && choices.push(choice)
        choice = {}
        break
      case 'outdent':
        this.tokens.advance()
        Object.keys(choice).length && choices.push(choice)
        return choices
      case 'eos':
        Object.keys(choice).length && choices.push(choice)
        return choices
      default:
        throw new Error('unrecognized token', this.token.advance().type)
    }
  }
}

/**
 * outgoing
 */

Parser.prototype.outgoing = function() {
  var outgoing = {}

  while (true) {
    switch (this.tokens.peek().type) {
      case 'alias':
        outgoing.id = this.tokens.advance().val
        break
      case 'string':
        outgoing.response = this.tokens.advance().val
        break
      case 'arrow':
        this.tokens.advance()
        break
      case 'uparrow':
        this.tokens.advance()
        outgoing.reset = true
        return outgoing
      case 'variable':
        outgoing.goto = this.tokens.advance().val
        break
      case 'indent':
      case 'newline':
        return outgoing
      case 'outdent':
      case 'eos':
        return outgoing
    }
  }
}