animated-parse-tree 0.0.11

A simple parse tree utility package, with animated evaluations and configurable tree displays

Animated Parse Tree

Author	Ethan Tan
Date	11/12/2021
Language	Python (py)

Description

This package is meant to provide a high-level API for programmers to visualise parse trees. The eventual goal is to animate the tokenization (extracting symbols from a string), lexing (formatting the tokens), parsing (building the parse tree) and evaluation (reducing the parse tree).

Setup

It is extremely easy to integrate this package in your existing projects.

In the command line, run:

pip install animated_parse_tree

Sample Usage

From Command Line

Then in your terminal/shell, enter:

python -m animated_parse_tree

The output should look similar to the following:

Greetings...

                "This is a utility program which aims
                    to show the beauty of parse trees
                           in a fun and engaging way"

Don't be intimidated :)
It was designed to be easy to use, yet extensible.

                                               Enjoy!
?>

Enter 'help' to display the help menu or 'mode' to change your current mode

From Source Files

Then in your Python source file / Jupyter Notebook, insert:

from animated_parse_tree import ParseTree

# Instantiate Parse Tree Object
t = ParseTree()

# Read a Mathematical String Expression (separated by singular whitespace characters)
t.read('1 + 2 * 3')

# Retrieve the Result
print('<<< Equation >>>')
print(t.expression, '=', t.evaluate(), end='\n\n')

# Display the Parse Tree
print('<<< Parse Tree >>>')
print(str(t))

The output in the terminal will look something like this:

<<< Equation >>>
1 + 2 * 3 = 7

<<< Parse Tree >>>
 +
/  \
1  *
  / \
  2 3

Declaring Custom Operands/Operators

A Bundle is simply a list of Operands and/or Operators.

To extend functionality, one simply has to register their own custom operands/operators like so:

# Instantiate Parse Tree Object
t = ParseTree()

# Declaring Custom Operator
op = Operator(symbol='if', func=lambda a,b,c: b if a == 1 else c, priority=7, kind='pre', operands=3)

# Register the Custom Operator(s)
t.register(bundle=[op])

# Use it in Expressions
t.read('if(1, 8, -1)')
print(t.evaluate())

Current Support

• Operands
  • Integers
  • Floats
  • Constants (like pi, e, etc.)
• Operators
  • Unary
    • Pre-fix
    • Post-fix
  • Binary
    • Pre-fix
    • In-fix
  • Multi
    • Pre-fix
• Parentheses
  • Unlimited nesting permitted
  • Not encouraged for animation currently