A simple yet powerful mathematics expressions interpreter made for the 42 software engineering school.
Prepare:
# Install python if necessary, the required version is 3.6+
brew install python
pip3 install virtualenv
virtualenv venv
Launch:
# Activate virtualenv
source venv/bin/activate
# With an argument
./computor_v1.py "x^2 = 4"
# Interactive mode
./computor_v1.py
Tests: ./tests.py
Bonuses:
- natural form input
- natural form output
- input error management
- parentheses handling:
(2 + 3) * x ^ (1+1) = 0 - division operator:
2/3 * x = x^2 / 10 - products and powers of polynomials:
(x + 5)^2 + (x - 5)^2 = 0
Launch:
# Activate virtualenv
source venv/bin/activate
# With an argument
./computor_v2.py "x^2 = 4"
# Interactive mode
./computor_v2.py
Tests: ./tests_v2.py
Bonuses:
- expression as argument
- products and powers of polynomials:
(x + 5)^2 + (x - 5)^2 = 0
The Computor uses the Top Down Operator Precedence parsing algorithm, also called Pratt parser.
It associates semantics with tokens instead of grammar rules, and uses a simple “binding power” mechanism to handle precedence levels. Traditional recursive-descent parsing is then used to handle odd or irregular portions of the syntax.
Top Down Operator Precedence by Vaughan R. Pratt (1973)
Top Down Operator Precedence by Douglas Crockford (2007)
Simple Top-Down Parsing in Python by Fredrik Lundh (2008)