Stack application: more kinds of bracket matching | python code

Method 1: Use more judgment sentences

class Stack:
    def __init__(self):
        self.items = []
    
    def isEmpty(self):
        return self.items == []
    
    def push(self, item):
        self.items.append(item)
    
    def pop(self):
        self.items.pop()
    
    def peek(self):
        return self.items[-1]
    
    def size(self):
        return len(self.items)

def parChecker(symbolString):
    s = Stack()
    balanced = True
    index = 0
    while index < len(symbolString) and balanced:
        symbol = symbolString[index]
        if symbol == "{":
            s.push(symbol)
            
        elif symbol == "[":
            s.push(symbol)
            
        elif symbol == "(":
            s.push(symbol)
            
        elif symbol == "}":
            if s.peek() == "{":
                s.pop()
            else:
                balanced = False
                
        elif symbol == "]":
            if s.peek() == "[":
                s.pop()
            else:
                balanced = False
        
        elif symbol == ")":
            if s.peek() == "(":
                s.pop()
            else:
                balanced = False
                     
        elif s.isEmpty():
                balanced = False

        index += 1
        
    if balanced and s.isEmpty():
        return True
    else:
        return False
    
print(parChecker("{[()()]}"))

Method 2: Use the index function to determine whether it matches through the position relationship

class Stack:
    def __init__(self):
        self.items = []
    
    def isEmpty(self):
        return self.items == []
    
    def push(self, item):
        self.items.append(item)
    
    def pop(self):
        self.items.pop()
    
    def peek(self):
        return self.items[-1]
    
    def size(self):
        return len(self.items)

def parChecker(symbolString):
    s = Stack()
    balanced = True
    index = 0
    while index < len(symbolString) and balanced:
        symbol = symbolString[index]
        if symbol in "([{":
            s.push(symbol)
        else:
            if s.isEmpty():
                balanced = False
            else:
                top = s.peek()                
                if matches(top,symbol) == True:
                    s.pop()                    
        index += 1
        
    if balanced and s.isEmpty():
        return True
    else:
        return False
    
def matches(left,right):
    lefts = "([{"
    rights = ")]}"
    return lefts.index(left) == rights.index(right) #index() 返回字符串的位置
    
    
print(parChecker("[{
    
    {()()}}]"))