agbowo-parser

Motivation

I was (am) working on a mobile app for tracking my own spending. While there are a lot of apps out there that do this, what I needed was one that "just works". Other apps require you to input values, take pictures of your receipts, etc when using them (at least the ones I tried) and this is exhausting, gives room for "cheating" (not tracking a particular spending and thus "false positives" of your finances) and also sometimes you pay with your card online. So I decided: "I am going to write mine!" Not only would my app work great offline (no "3rd party API to user's account details and all that"), it's going to perfectly track my spending and I dont have to do almost anything! 🔥🔥🔥 😎

So I had the app up in no time (okay maybe not. took a while. I had to work) and then I hit a wall: "HOW DO I RETRIEVE ALL THE INFORMATION I NEED FROM THE SMS I RECEIVE?". I receive both SMS and E-mail notifications of every transaction! Thus, I decided to write a "parser". I couldnt continue so I stopped temporarily.

And if you have been seeing my github recently, I have been experimenting with lexers and parsers (and sweet WebAssembly!). Using a book, I even wrote a lexer for yorlang [WIP though...no schedule]. So it made sense!

So whats up?

Yeah this particular version is the very first version. Let me say: ITS NOT THE BEST CODE EVER. It basically was a way for me to put what I had in my head into code. I got something at the end and that was my aim. I am rewriting from scratch, the v2. With better ideas.

So easy on my code 🥺🙏

So please hang around. After this parser, the development of the app continues! 😎😎.

What does this then return?

Lets say you have this credit alert from GTBank (thats my bank):

Acct: 0175456083\nAmt: 2,000.00 CR \nDesc: -- --JAIZ BANK FAJUYI DUGBE IBADAN    OYNGSTAN9999002986\nAvail Bal: 129,696.51\n

the parser returns something like this:

[
  { LITERAL: 'ACCT', INDEX: 4, VALUE: '0175456083\n' },
  { LITERAL: 'AMT', INDEX: 20, VALUE: '' },
  { LITERAL: 'CR', INDEX: 33, VALUE: true },
  {
    LITERAL: 'DESC',
    INDEX: 39,
    VALUE: ': -- --JAIZ BANK FAJUYI DUGBE IBADAN    OYNGSTAN9999002986\n'
  },
  { LITERAL: 'BANK', INDEX: 55, VALUE: '' },
  { LITERAL: 'BAL', INDEX: 107, VALUE: '129,696.51' }
]

and tokens:

const TOKENS = {
  BANK: 'BANK',
  ACCTNO: 'ACCT',
  AMT: 'AMT',
  DESC: 'DESC',
  TRANSTYPECR: 'CR',
  TRANSTYPEDR: 'DR',
  BALANCE: 'BAL'
}

the INDEX is the ending position of the token. Note this is for GTBank. This might change for other banks.

So from the parser's output, we know that its a CR (credit) transaction, the AMT (amount) that left our account is: ₦2000. The DESC (description) is that its from JAIZ BANK at DUGBE IBADAN (therefore its from an ATM) and the BAL (balance left in accout) is ₦129, 696.51

Tada! 🎊🎉 we got what we wanted!!

Room for improvement though!