python

class Node():

def __init__(self, value):
pass

class PostScript():

def __init__(self):
pass
  
def push(self, value):
pass
  
def pop(self):
return None
  
def peek(self):
pass
  
def is_empty(self):
pass

def stack(self):
pass
  
def exch(self):
pass
  
def index(self):
pass
  
def clear(self):
pass
  
def dup(self):
pass
  
def equal(self):
pass
  
def depth(self):
pass
  
stack = PostScript()

def decode(command_list):
for object in command_list:
if object == '=':
stack.equal()
elif object == 'count':
stack.depth()
elif object == 'clear':
stack.clear()
elif object == 'dup':
stack.dup()
elif object == 'exch':
stack.exch()
elif object == 'index':
stack.index()
elif object == 'pop':
stack.pop()
elif object == 'stack':
stack.stack()
else:
stack.push(object)

command = input()
command_list = command.split()
decode(command_list)
  

For this assignment you are to implement a PostScript commandinterpreter using a Stack. You must implement the stack using asingly-linked list. Solutions that use a data structure other thana singly-linked list will received nocredit.

The interpreter must read and execute a string of PostScriptcommands based on the following definitions:
1. =
objn objn-1 … obj1 = : objn-1 … obj1
This command removes the topmost object form the stack andprints it.

1. count
   objn … obj1count : [depth of the stack] objn … obj1
   This command puts the depth of the stack on the top of thestack.
2. clear
   objn … obj1clear : [empty stack]
   This command removes all objects from the stack.
3. dup
   objn … obj1 = : objn objn … obj1
   This command adds a duplicate copy of the top object to the stack.
4. exch
   objn objn-1 … obj1 exch : objn-1 objn … obj1
   This command exchanges the position of the top two elements of thestack.
5. index
   objn … obj1 a index : objn … obja … obj1
   This command adds a copy of the ath object to the top thestack.
6. pop
   objn objn-1 … obj1 pop : objn-1 …. obj1
   This command removes the top element from the stack.
7. stack
   This command prints a copy of the entire stack, starting from thetop and working to the bottom..
   
   The input will be a series of data and commands separated by aspace. The data will go onto the stack. Commands do not go onto thestack. You must write at least one separate method for each of thecommands. You may reuse the standard Stack methods discussed inclass: push(), pop(), peek() and is_empty(). A template file hasbeen provided.