Add support for ledger plain text accounting format

[colindean]

I'd like to be able to parse ledger format. Ledger-CLI is an open source accounting tool that started the plaintext accounting ecosystem.

[colindean]

I've got a start on it in https://github.com/colindean/rouge/blob/colindean/ledger/lib/rouge/lexers/ledger.rb but I'm really struggling with the state machine. I can't seem to get it to recognize the commodity token that follows the amount in a transaction's line item. Then, I can't get it to start over again processing the next line item in a transaction. I've tried littering with :pop! to no avail.

You can see an (inexhaustive) example here. I've been using Rouge's built-in tester with http://localhost:9292/ledger.

[colindean]

I've got a start on it in https://github.com/colindean/rouge/blob/colindean/ledger/lib/rouge/lexers/ledger.rb but I'm really struggling with the state machine. I can't seem to get it to recognize the commodity token that follows the amount in a transaction's line item. Then, I can't get it to start over again processing the next line item in a transaction. I've tried littering with :pop! to no avail.

You can see an (inexhaustive) example here. I've been using Rouge's built-in tester with http://localhost:9292/ledger.