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main.py
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main.py
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#!/usr/bin/env python3
# Simple app to convert Infix yo Postfix
# GitHub: htpps://github.com/Kourva/PostFix
# Imports
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.uix.textinput import TextInput
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.screenmanager import Screen, ScreenManager
from kivy.uix.actionbar import ActionBar, ActionView, ActionPrevious
# KV config
with open("main.kv", "r") as kv:
Builder.load_string(kv.read())
# Class to convert the expression
class Conversion:
# Constructor to initialize the class variables
def __init__(self, capacity):
self.top = -1
self.capacity = capacity
# This array is used a stack
self.array = []
# Precedence setting
self.output = []
self.precedence = {"+": 1, "-": 1, "*": 2, "/": 2, "^": 3}
# check if the stack is empty
def isEmpty(self):
return True if self.top == -1 else False
# Return the value of the top of the stack
def peek(self):
return self.array[-1]
# Pop the element from the stack
def pop(self):
if not self.isEmpty():
self.top -= 1
return self.array.pop()
else:
return "$"
# Push the element to the stack
def push(self, op):
self.top += 1
self.array.append(op)
# A utility function to check is the given character
# is operand
def isOperand(self, ch):
return ch.isalpha()
# Check if the precedence of operator is strictly
# less than top of stack or not
def notGreater(self, i):
try:
a = self.precedence[i]
b = self.precedence[self.peek()]
return True if a <= b else False
except KeyError:
return False
# The main function that
# converts given infix expression
# to postfix expression
def infixToPostfix(self, exp):
# Iterate over the expression for conversion
for i in exp:
# If the character is an operand,
# add it to output
if self.isOperand(i):
self.output.append(i)
# If the character is an '(', push it to stack
elif i == "(":
self.push(i)
# If the scanned character is an ')', pop and
# output from the stack until and '(' is found
elif i == ")":
while (not self.isEmpty()) and self.peek() != "(":
a = self.pop()
self.output.append(a)
if not self.isEmpty() and self.peek() != "(":
return -1
else:
self.pop()
# An operator is encountered
else:
while not self.isEmpty() and self.notGreater(i):
self.output.append(self.pop())
self.push(i)
# pop all the operator from the stack
while not self.isEmpty():
self.output.append(self.pop())
return "".join(self.output)
# StartMenu screen
class StartMenuScreen(Screen):
# Path to fonts
KremlinMenshevik = "KremlinMenshevikBold.ttf"
SourceCodePro = "SourceCodeProBold.ttf"
# Path to assets
background = "background.jpg"
# Encryption method
def convert(self, textinput, output):
exp = textinput.text
obj = Conversion(len(exp))
result = obj.infixToPostfix(exp)
output.text = f"[b][font=SourceCodeProBold.ttf]{result}[/font][/b]"
# Main class
class PostFix(App):
# Build method
def build(self):
# Root screen
root = ScreenManager()
# Main menu screen
self.StartMenuScreen = StartMenuScreen(name="StartMenu")
root.add_widget(self.StartMenuScreen)
# Set current screen to main menu and return root
root.current = "StartMenu"
return root
# Run App
PostFix().run()
# End of file