Python Compiler IDE

A browser-based Python compiler that demonstrates all four classical compiler phases — Lexical Analysis, Syntax Analysis, Semantic Analysis, and Symbol Table — built with Flask and a modern glass-morphism UI.

Group Members: Farah · Mahnoor · Zaynab

---

Live Demo

View on Vercel —

---

What It Does

Write any Python code in the browser editor and run it through four compiler phases:

Phase	Page	What you see
Lexer	/lexer-page	Full token stream with type badges and line numbers
Parser	/parser-page	Pass/fail status + all recursive-descent parse steps
Semantic	/semantic-page	Errors (undefined variables) and warnings (redefined functions)
Symbol Table	/symbol-page	Every identifier — name, kind, type, scope, value, memory address

Use the Home page to run all 4 phases at once with tabbed results.

---

Screenshots

Home — Run All	Symbol Table Page
(add screenshot)	(add screenshot)

---

Project Structure

compiler_project/
├── app.py                   Flask entry point + REST API
├── requirements.txt
├── vercel.json              Vercel deployment config
│
├── lexer/
│   └── lexer.py             Regex tokenizer with INDENT/DEDENT generation
├── parser/
│   └── parser.py            Recursive-descent parser for Python grammar
├── semantic/
│   └── semantic.py          Scope tracker and error detector
├── symbol_table/
│   └── symbol_table.py      Identifier registry with inferred types
│
└── templates/
    ├── base.html            Shared layout, sidebar, CSS, shared JS
    ├── index.html           Home page — Run All with tabbed results
    ├── lexer.html           Phase 1 dedicated page
    ├── parser.html          Phase 2 dedicated page
    ├── semantic.html        Phase 3 dedicated page
    └── symbol_table.html    Phase 4 dedicated page

---

Run Locally

Python 3.9+ required

# 1. Clone
git clone https://github.com/YOUR_USERNAME/compiler_project.git
cd compiler_project

# 2. Install dependencies
pip install -r requirements.txt

# 3. Start server
python app.py

# 4. Open browser
# http://127.0.0.1:5000

---

API Reference

All endpoints accept POST with Content-Type: application/json.

Request body: { "code": "<python source code>" }

Endpoint	Returns
POST /api/lexer	{ tokens, errors, log }
POST /api/parser	{ success, errors, parse_steps }
POST /api/semantic	{ success, errors, warnings, log }
POST /api/symbol_table	{ entries, log, summary }
POST /api/analyze_all	All four results combined

Example — call the lexer:

curl -X POST http://127.0.0.1:5000/api/lexer \
  -H "Content-Type: application/json" \
  -d '{"code": "x = 10\nprint(x)"}'

---

Deploy to Vercel

Option 1 — Vercel CLI

npm install -g vercel
vercel

Follow the prompts. Your app goes live at a *.vercel.app URL.

Option 2 — GitHub Auto-Deploy

1. Push this repo to GitHub
2. Go to vercel.com → New Project → Import your repo
3. Vercel detects vercel.json automatically and deploys

Every future git push to main triggers a redeploy.

---

Tech Stack

Layer	Technology
Backend	Python 3, Flask
Frontend	Vanilla JS, HTML5, CSS3 (glass-morphism)
Fonts	Inter, JetBrains Mono
Icons	Font Awesome 6
Hosting	Vercel

---

Compiler Phases — Technical Detail

Lexer (lexer/lexer.py)

• Regex-based tokenizer using Python re named groups
• Token types: KEYWORD, BUILTIN, IDENTIFIER, INTEGER, FLOAT, STRING, OPERATOR, OP_AUG, SEPARATOR, COMMENT, INDENT, DEDENT, NEWLINE
• Generates INDENT/DEDENT tokens by tracking indentation stack — this is what makes it a real Python lexer
• Reports line numbers for every token and every error

Parser (parser/parser.py)

• Recursive-descent (top-down) parser
• Handles: assignments, if/elif/else, for-in, while, def with parameters and return type annotation (->), class
• Full expression hierarchy: or → and → not → comparison → arithmetic → term → factor → power → atom
• Handles attribute access (a.b), subscript (a[i]), and function calls (f(x, y)) via parse_atom_expr()

Semantic Analyzer (semantic/semantic.py)

• Tracks three scopes: global_vars, local_vars, functions
• Detects use-before-assignment for all identifiers
• Detects duplicate function definitions (warning, not error — Python allows this)
• Tracks import and from … import to whitelist module names
• Does NOT flag Python built-ins (print, range, len, etc.)

Symbol Table (symbol_table/symbol_table.py)

• SymbolTableEntry stores: name, kind, data_type, scope, value, address
• kind values: variable, function, class, parameter, module
• Type inference from assigned literal: int, float, str, bool, NoneType, unknown
• Addresses are sequential hex values starting at 0x03E8

---

Sample Code to Test

def factorial(n):
    result = 1
    for i in range(n):
        result = result * (i + 1)
    return result

count = 5
answer = factorial(count)
print(answer)

Paste this on the home page and click Run All to see all 4 phases at once.

---

Built with Python, Flask, and vanilla JS.