design-in-memory-file-system.py

class FileNode(object):
    def __init__(self, name):
        self.isFolder = True
        self.childs = {}
        self.name = name
        self.data = ""

    def appendData(self, data):
        self.data += data

    def readAll(self):
        return self.data


class FileSystem(object):
    def __init__(self):
        self.root = FileNode("/")

    def ls(self, path):
        """
        :type path: str
        :rtype: List[str]
        """
        fd = self.lookup(path, False)
        if not fd:
            return []
        if not fd.isFolder:
            return [fd.name]
        files = []
        for file in fd.childs:
            files.append(file)
        files.sort()
        return files

    def lookup(self, path, isAutoCreate):
        path = path.split("/")
        p = self.root
        for name in path:
            if not name:
                continue
            if name not in p.childs:
                if isAutoCreate:
                    p.childs[name] = FileNode(name)
                else:
                    return None
            p = p.childs[name]
        return p

    def mkdir(self, path):
        """
        :type path: str
        :rtype: void
        """
        self.lookup(path, True)

    def addContentToFile(self, filePath, content):
        """
        :type filePath: str
        :type content: str
        :rtype: void
        """
        fd = self.lookup(filePath, True)
        fd.isFolder = False
        fd.appendData(content)

    def readContentFromFile(self, filePath):
        """
        :type filePath: str
        :rtype: str
        """
        fd = self.lookup(filePath, False)
        if fd:
            return fd.readAll()
        return ""

        


# Your FileSystem object will be instantiated and called as such:
# obj = FileSystem()
# param_1 = obj.ls(path)
# obj.mkdir(path)
# obj.addContentToFile(filePath,content)
# param_4 = obj.readContentFromFile(filePath)