def arremstor_unit_test(self):
temp = ArrayStack()
for count in range(20):
temp.push(count+1)
for count in range(15):
temp.pop()
self.assertEqual(len(temp.items), 10)
def test_arraystack_popallthrowsempty(self):
stack = ArrayStack()
for i in range(100):
stack.push(i + 1)
for i in range(100):
stack.pop()
stack.pop()
def _is_palindrome(self, word):
stack1 = ArrayStack(word)
stack2 = ArrayStack(word[::-1])
for i in range(len(word)):
if stack1.pop() != stack2.pop():
return False
return True
class PFEvaluator(object):
def __init__(self, scanner):
self._expression_so_far = ""
self._operand_stack = ArrayStack()
self._scanner = scanner
def evaluate(self):
while self._scanner.has_next():
current_token = self._scanner.next()
self._expression_so_far += str(current_token) + " "
if current_token.get_type() == Token.INT: # 数字入栈
self._operand_stack.push(current_token)
elif current_token.is_operator(): # 操作符计算
if len(self._operand_stack) < 2: # 栈内数字小于2
raise AttributeError (\
"Too few operands on the stack")
t2 = self._operand_stack.pop()
t1 = self._operand_stack.pop()
result = \
Token(self._compute_value(current_token,
t1.get_value(),
t2.get_value()))
self._operand_stack.push(result)
else:
raise AttributeError("Unknown token type")
if len(self._operand_stack) > 1: # 计算完成后, 栈内深入数字大于2
raise AttributeError(\
"Too many operands on the stack")
result = self._operand_stack.pop()
return result.get_value()
def __str__(self):
result = "\n"
if self._expression_so_far == "":
result += \
"Portion of expression processed none\n"
else:
result += "Portion of expression processed: " + \
self._expression_so_far + "\n"
if self._operand_stack.isEmpty():
result += "Thre stack is empty"
else:
result += "Operands on the stack: " + \
str(self._operand_stack)
return result
def _compute_value(self, op, value1, value2):
result = 0
the_type = op.get_type()
if the_type == Token.PLUS:
result = value1 + value2
elif the_type == Token.MINUS:
result = value1 - value2
elif the_type == Token.MUL:
result = value1 * value2
elif the_type == Token.DIV:
result = value1 // value2
else:
raise AttributeError("Unknown operator")
return result
class PFEvaluator(object):
def __init__(self, scanner):
self._expressionSoFar = ""
self._operandStack = ArrayStack()
self._scanner = scanner
def evaluate(self):
while self._scanner.hasNext():
currentToken = self._scanner.next()
self._expressionSoFar += str(currentToken) + " "
if currentToken.getType() == Token.INT:
self._operandStack.push(currentToken)
elif currentToken.isOperator():
if len(self._operandStack) < 2:
raise Exception("Too few operands on the stack")
t2 = self._operandStack.pop()
t1 = self._operandStack.pop()
result = Token(self._computeValue(currentToken,
t1.getValue(),
t2.getValue()))
self._operandStack.push(result)
else:
raise Exception("Unknown token type")
if len(self._operandStack) > 1:
raise Exception("Too many operands on the stack")
result = self._operandStack.pop()
return result.getValue();
def __str__(self):
result = "\n"
if self._expressionSoFar == "":
result += "Portion of expression processed: none\n"
else:
result += "Portion of expression processed: " + \
self._expressionSoFar + "\n"
if self._operandStack.isEmpty():
result += "The stack is empty"
else:
result += "Operands on the stack : " + \
str(self._operandStack)
return result
def _computeValue(self, op, value1, value2):
result = 0;
theType = op.getType()
if theType == Token.PLUS:
result = value1 + value2;
elif theType == Token.MINUS:
result = value1 - value2;
elif theType == Token.MUL:
result = value1 * value2;
elif theType == Token.DIV:
result = value1 // value2;
elif theType == Token.EXP:
result = value1 ** value2;
else:
raise Exception("Unknown operator")
return result
def convert(self):
operatorStack = ArrayStack() #this will hold operators and grouping symbols
postfixExpression = "" #this will hold the final expression
while self.scanner.hasNext():
token_char = self.scanner.next()
if token_char.getType() == 4: #it's an integer
postfixExpression += str(token_char.getValue()) + " "
elif token_char.getValue() in ['(','[']: #left parenthesis
operatorStack.push(token_char)
elif token_char.isOperator(): #it's an operator
#pop off all the operators with equal or greater precedence
while len(operatorStack) != 0 and operatorStack.peek().getPrecedence() >= token_char.getPrecedence():
postfixExpression += str(operatorStack.pop().getValue()) + " "
#now we can push the new operator onto the stack
operatorStack.push(token_char)
elif token_char.getValue() in [')',']']: #right parenthesis
while len(operatorStack) != 0 and operatorStack.peek().getValue() not in ['(','[']: #find the matching one
postfixExpression += str(operatorStack.pop().getValue()) + " "
operatorStack.pop() #discard the left parenthesis
elif token_char.getType() == 0 and token_char.getValue() not in ['(',')','[',']']:
raise Exception("Error: unknown character.") #unknown character
#transfer over any remaining operators
while len(operatorStack) != 0:
postfixExpression += str(operatorStack.pop().getValue()) + " "
return postfixExpression
def convert(self):
"""Returns a list of tokens that represent the postfix
form. Assumes that the infix expression is syntactically correct"""
postfix = []
stack = ArrayStack()
while self._scanner.hasNext():
currentToken = self._scanner.next()
if currentToken.getType() == Token.INT:
postfix.append(currentToken)
elif currentToken.getType() == Token.LPAR:
stack.push(currentToken)
elif currentToken.getType() == Token.RPAR:
topOperator = stack.pop()
while topOperator.getType() != Token.LPAR:
postfix.append(topOperator)
topOperator = stack.pop()
else:
while not stack.isEmpty() and \
currentToken.getType() != Token.EXPO and \
stack.peek().getPrecedence() >= currentToken.getPrecedence():
postfix.append(stack.pop())
stack.push(currentToken)
while not stack.isEmpty():
postfix.append(stack.pop())
return postfix
def lipop_unit_test(self):
temp = ArrayStack()
for count in range(4):
temp.push(count+1)
temp.pop()
self.assertEqual(temp.peek(), 3)
temp.pop()
self.assertEqual(len(temp),2)
class PFEvaluator(object):
def __init__(self, scanner):
self._expressionSoFar = ""
self._operandStack = ArrayStack()
self._scanner = scanner
def evaluate(self):
while self._scanner.hasNext():
currentToken = self._scanner.next()
self._expressionSoFar += str(currentToken) + " "
if currentToken.getType() == Token.INT:
self._operandStack.push(currentToken)
elif currentToken.isOperator():
if len(self._operandStack) < 2:
raise AttributeError("Too few operands on the stack")
t2 = self._operandStack.pop()
t1 = self._operandStack.pop()
result = Token(self._computeValue(currentToken,
t1.getValue(),
t2.getValue()))
self._operandStack.push(result)
else:
raise AttributeError("Unknown token type")
if len(self._operandStack) > 1:
raise AttributeError("Too many operands on the stack")
result = self._operandStack.pop()
return result.getValue();
def __str__(self):
result = "\n"
if self._expressionSoFar == "":
result += "Portion of expression processed: none\n"
else:
result += "Portion of expression processed: " + \
self._expressionSoFar + "\n"
if self._operandStack.isEmpty():
result += "The stack is empty"
else:
result += "Operands on the stack : " + \
str(self._operandStack)
return result
def _computeValue(self, op, value1, value2):
result = 0;
theType = op.getType()
if theType == Token.PLUS:
result = value1 + value2;
elif theType == Token.MINUS:
result = value1 - value2;
elif theType == Token.MUL:
result = value1 * value2;
elif theType == Token.DIV:
result = value1 // value2;
else:
raise Exception("Unknown operator")
return result
class IFToPFConverter(object):
def __init__(self, scanner):
self._expressionSoFar = ""
self._operatorStack = ArrayStack()
self._scanner = scanner
def convert(self):
"""Returns a list of tokens that represent the postfix
form of sourceStr. Assumes that the infix expression
in sourceStr is syntactically correct"""
postfix = []
while self._scanner.hasNext():
currentToken = self._scanner.next()
self._expressionSoFar += str(currentToken) + " "
if currentToken.getType() == Token.UNKNOWN:
raise AttributeError("Unrecognized symbol")
if currentToken.getType() == Token.INT:
postfix.append(currentToken)
elif currentToken.getType() == Token.LPAR:
self._operatorStack.push(currentToken)
elif currentToken.getType() == Token.RPAR:
if self._operatorStack.isEmpty():
raise AttributeError("Too few operators")
topOperator = self._operatorStack.pop()
while topOperator.getType() != Token.LPAR:
postfix.append(topOperator)
if self._operatorStack.isEmpty():
raise AttributeError("Too few operators")
topOperator = self._operatorStack.pop()
else:
while not self._operatorStack.isEmpty() and \
currentToken.getType() != Token.EXPO and \
self._operatorStack.peek().getPrecedence() >= currentToken.getPrecedence():
postfix.append(self._operatorStack.pop())
self._operatorStack.push(currentToken)
while not self._operatorStack.isEmpty():
postfix.append(self._operatorStack.pop())
return postfix
def __str__(self):
result = "\n"
if self._expressionSoFar == "":
result += "Portion of expression processed: none\n"
else:
result += "Portion of expression processed: " + \
self._expressionSoFar + "\n"
if self._operatorStack.isEmpty():
result += "The stack is empty"
else:
result += "Operators on the stack : " + \
str(self._operatorStack)
return result
def conversionStatus(self):
return str(self)
class PFEvaluator(object):
def __init__(self, postfix):
self._expressionSoFar = ""
self._operandStack = ArrayStack()
self._postfix = postfix
def evaluate(self):
for currentToken in self._postfix:
self._expressionSoFar += str(currentToken) + " "
if currentToken.getType() == Token.INT:
self._operandStack.push(currentToken)
else:
t2 = self._operandStack.pop()
t1 = self._operandStack.pop()
result = Token(self._computeValue(currentToken,
t1.getValue(),
t2.getValue()))
self._operandStack.push(result)
result = self._operandStack.pop()
return result.getValue();
def __str__(self):
result = "\n"
if self._expressionSoFar == "":
result += "Portion of expression processed: none\n"
else:
result += "Portion of expression processed: " + \
self._expressionSoFar + "\n"
if self._operandStack.isEmpty():
result += "The stack is empty"
else:
result += "Operands on the stack : " + \
str(self._operandStack)
return result
def _computeValue(self, op, value1, value2):
result = 0;
theType = op.getType()
if theType == Token.PLUS:
result = value1 + value2;
elif theType == Token.MINUS:
result = value1 - value2;
elif theType == Token.MUL:
result = value1 * value2;
elif theType == Token.DIV:
if value2 == 0:
raise ZeroDivisionError("Attempt to divide by 0")
result = value1 // value2;
elif theType == Token.EXPO:
result = value1 ** value2;
else:
raise AttibuteError("Unknown operator")
return result
def check_brackets(s):
stack = ArrayStack()
for i in s:
if i == "(":
stack.push("(")
if i == ")":
if stack.isEmpty():
return False
stack.pop()
if stack.isEmpty():
return True
else:
return False
def checkBalance(st):
stck = ArrayStack()
for i in st:
if i == '[' or i == '{' or i == '(':
stck.push(i)
else:
if i == ']' or i == '}' or i == ')':
if stck.isEmpty() or stck.peek() != opposite(i):
return False
else:
stck.pop()
if stck.isEmpty():
return True
return False
def find_palindromes(self, file, file_name):
"""
method which finds palindroms.
"""
words_list = self.read_file(file)
stack = ArrayStack()
result = []
for word in words_list:
word_len = len(word)
if word_len == 1.0:
result.append(word)
else:
word_mid = word_len // 2
middle = word_len % 2
for i in range(word_len):
if i < word_mid:
stack.push(word[i])
elif middle == 1 and i == word_mid:
continue
else:
if stack.pop() != word[i]:
check = False
break
check = True
if check is True:
result.append(word)
self.write_to_file(result, file_name)
return result
def find_palindromes(self, input_file, output_file):
'''
Find palindromes using stack
'''
palindroms = []
self.input_file = input_file
self.output_file = output_file
words = self.read_file(self.input_file)
for word in words:
word_lst = list(word)
word_stack = ArrayStack()
flag = True
for letter in range(len(word_lst)-1, -1, -1):
word_stack.push(word[letter])
while not word_stack.isEmpty():
if word_stack.pop() != word_lst.pop():
flag = False
break
if flag:
palindroms.append("".join(word))
self.write_to_file(self.output_file, palindroms)
return palindroms
def find_palindromes(self, read_from: str, write_to: str) -> list:
"""
Finds all palindromes from the file and
write it into another one
Returns a list with palindromes
"""
words = self.read_file(read_from)
palindromes = list()
stack_with_words = ArrayStack()
reversed_word = ""
for word in words:
for char in word:
stack_with_words.push(char)
while not stack_with_words.isEmpty():
reversed_word += stack_with_words.pop()
if reversed_word == word:
palindromes.append(word)
reversed_word = ""
self.write_in_file(write_to, palindromes)
return palindromes
def is_matched_html(raw):
"""Return True if all HTML tags are properly matched;
False Otherwise."""
S = ArrayStack()
# find first '<' character
start = raw.find('<')
while start != -1:
# find next '>' character
end = raw.find('>', start + 1)
if end == -1:
return False
# strip away < >
tag = raw[start + 1:end]
# this is opening tag
if not tag.startswith('/'):
S.push(tag)
# this is closing tag
else:
if S.is_empty():
return False
if tag[1:] != S.pop():
return False
start = raw.find('<', end + 1)
# all tags matched
return S.is_empty()
def getOut(row, column, maze):
"""(row,column) is the position of the start symbol in the maze.
Returns True if the maze can be solved or False otherwise."""
# States are tuples of coordinates of cells in the grid.
stack = ArrayStack()
stack.push((row, column))
while not stack.isEmpty():
(row, column) = stack.pop()
if maze[row][column] == 'T':
return True
elif maze[row][column] != '.':
# Cell has not been visited, so mark it and push adjacent unvisited
# positions onto the stack
maze[row][column] = '.'
# Try NORTH
if row != 0 and not maze[row - 1][column] in ('*', '.'):
stack.push((row - 1, column))
# Try SOUTH
if row + 1 != maze.getHeight() and not maze[row + 1][column] in ('*', '.'):
stack.push((row + 1, column))
# Try EAST
if column + 1 != maze.getWidth() and not maze[row][column + 1] in ('*', '.'):
stack.push((row, column + 1))
# Try WEST
if column != 0 and not maze[row][column - 1] in ('*', '.'):
stack.push((row, column - 1))
return False
def test_stack():
S = ArrayStack()
S.push(5)
print(S.top())
S.push(6)
print(len(S))
print(S.pop())
print(S.is_empty())
print(S.data)
def isPalindrome(string):
"""Returns True if string is a palindrome
or False otherwise."""
stk = ArrayStack()
for ch in string:
stk.push(ch)
for ch in string:
if ch != stk.pop():
return False
return True
def stack_to_queue(stack):
'''Convert stack to queue, without changing given stack
peek of the stack is the first element in the queue'''
queue = ArrayQueue()
stack_copy = ArrayStack(stack)
while len(stack_copy) != 0:
queue.add(stack_copy.pop())
return queue
def infixToPostfix(exp):
stck = ArrayStack()
postfix = ""
for i in range(len(exp)):
if isOperand(exp[i]):
postfix += exp[i]
else:
if stck.isEmpty():
stck.push(exp[i])
else:
if prec(exp[i]) >= prec(stck.peek()):
stck.push(exp[i])
else:
while not stck.isEmpty() and prec(exp[i]) < prec(stck.peek()):
postfix += stck.pop()
stck.push(exp[i])
# print "Stack:", stck.printStack(), "Expression:", postfix
while not stck.isEmpty():
postfix += stck.pop()
return postfix
def infixToPostfix(exp):
stck = ArrayStack()
postfix = ""
for i in range(len(exp)):
if isOperand(exp[i]):
postfix += exp[i]
else:
if stck.isEmpty():
stck.push(exp[i])
else:
if prec(exp[i]) >= prec(stck.peek()):
stck.push(exp[i])
else:
while not stck.isEmpty() and prec(exp[i]) < prec(stck.peek()):
postfix += stck.pop()
stck.push(exp[i])
#print "Stack:", stck.printStack(), "Expression:", postfix
while not stck.isEmpty():
postfix += stck.pop()
return postfix
def check_palindrome(s):
s = str(s)
stack = ArrayStack()
even = 1 if len(s) % 2 else 0
half = len(s) // 2
for i in range(half):
stack.push(s[i])
ind = half + even
for i in range(half):
if stack.pop() != s[ind + i]:
return False
return True
def convert(self):
postfix = [] #Creating an empty list to store the postfix expression
storage = ArrayStack() #Creates a stack to store the operands when converting the expression.
while self._infix.hasNext():
current = self._infix.next()
if current.getType() == Token.INT:
postfix.append(current)
elif current.getType() == Token.LeftPar:
storage.push(current)
self._operand += 1
elif current.getType() == Token.RightPar:
self._operator += 1
topOpInSt = storage.pop()
while topOpInSt.getType() != Token.LeftPar:
postfix.append(topOpInSt)
topOpInSt = storage.pop()
elif current.getType() == Token.LeftBrac:
storage.push(current)
self._operand += 1
elif current.getType() == Token.RightBrac:
self._operator += 1
a = storage.pop()
while a.getType() != Token.LeftBrac:
postfix.append(a)
a = storage.pop()
else:
#The loop below tells the program to go through the array that is created so far, and as long as it is not empty and the precedence found in the Tokens.py file of the first item in the array is greater than or equal to the precedence of the current token the Scanner is on, the program continues.
while not storage.isEmpty() and storage.peek().getPrecedence() >= current.getPrecedence():
postfix.append(storage.pop())
storage.push(current)
if self._operand > self._operator or self._operator > self._operator:
return "Unbalanced Expression"
while not storage.isEmpty():
postfix.append(storage.pop())
return postfix
def queue_to_stack(queue):
'''
Conver queue to stack.
'''
queue_copy = deepcopy(queue)
stack = ArrayStack()
while queue_copy:
stack.push(queue_copy.pop())
result = ArrayStack()
while stack:
result.push(stack.pop())
return result
def stack_to_queue(stack):
"""
Converts stack to queue.
"""
temp_stack = ArrayStack()
result_queue = ArrayQueue()
while not stack.isEmpty():
elem = stack.pop()
result_queue.add(elem)
temp_stack.push(elem)
while not temp_stack.isEmpty():
stack.push(temp_stack.pop())
return result_queue
def stack_to_queue(stack):
"""
Return queue from stack (front of queue is peek of stack).
"""
copy_stack = ArrayStack()
queue = ArrayQueue()
for element in stack:
copy_stack.push(element)
while len(copy_stack) != 0:
queue.add(copy_stack.pop())
return queue
def queue_to_stack(queue):
"""
Convert queue to stack
"""
stack1 = ArrayStack()
stack2 = ArrayStack()
while len(queue) != 0:
num = queue.pop()
stack1.push(num)
while len(stack1) != 0:
num = stack1.pop()
stack2.push(num)
return stack2
def reverse_file(filename):
"""Overwrite a given file with contents line-by-line in reversed order"""
S = ArrayStack()
original = open(filename)
for line in original:
S.push(line.rstrip('\n')) # we will re-insert newlines while writing
original.close()
# now write the contents in LIFO order
output = open(filename, 'w')
while not S.is_empty():
output.write(S.pop() + '\n') # add trailing new line
output.close()
def palindrome_search(line):
"""
The function returns True if the word is a palindrome
"""
s = ArrayStack()
for letter in line:
s.push(letter)
reversed_line = ''
while not s.isEmpty():
reversed_line += s.pop()
if line == reversed_line:
return True
else:
return False
def is_match(expr):
"""Return True if all the delimiters are properly matched; False Otherwise;"""
lefty = '({['
righty = ')}]'
stack = ArrayStack()
for c in expression:
if c in lefty:
stack.push(c)
elif c in righty:
if stack.is_empty():
return False
if righty.index(c) != lefty.index(stack.pop()):
return False
return stack.is_empty()
def is_matched(expr):
"""Return True if all delimiters properly match (or closed); False otherwise"""
left_delimiters = "({["
right_delimiter = ")}]"
S = ArrayStack()
for c in expr:
if c in left_delimiters:
S.push(c)
elif c in right_delimiter:
if S.is_empty():
return False
if right_delimiter.index(c) != left_delimiters.index(S.pop()):
return False
return S.is_empty()
