FIRST( ) / FOLLOW( ) — Grammar Worksheet

A browser-based tool that computes FIRST and FOLLOW sets for a context-free grammar, shows the derivation step by step, and can optionally build the LL(1) parsing table.

Running it

No build step, no server needed. Just open index.html in a browser.

first-follow-project/
├── index.html      # page structure
├── css/
│   └── style.css   # all styling
├── js/
│   └── app.js       # grammar parsing + FIRST/FOLLOW/LL(1) logic
└── README.md

Grammar input format

One production per line:

A -> alpha1 | alpha2

• Arrows: ->, →, or ::=
• Symbols separated by spaces
• Epsilon: ε, eps, epsilon, or λ
• Any symbol starting with a capital letter is treated as a non-terminal; everything else is a terminal.

What it computes

1. FIRST sets — via fixed-point iteration over all productions until no set changes.
2. FOLLOW sets — same fixed-point approach, seeded with $ on the start symbol.
3. LL(1) parsing table (optional, toggle in the results panel) — flags conflicting cells if the grammar isn't LL(1).

Every rule application is logged to the trace panel so you can follow (or double-check) the reasoning by hand.