悉尼大学INFO1113课业解析

悉尼大学 INFO1113 课业解析
题意：
使用 JAVA 通过动态数据类型去构建数据库
解析：
数据库中的所有条目都有一个唯一的键进行标识，条目和快照按照添加的顺序从 1 以此增加，快照需要以特定格式写入到可读文档中；数据库能够恢复快照，将当前数据重置为快照的状态。
同时数据库需要支持一些指令：
BYE 清空数据库并退出
HELP 显示提示信息
LIST KEYS 显示所有的 KEY 值
LIST ENTRIES 显示所有最近添加的条目
LIST SNAPSHOTS 显示数据库中所有的快照
GET < key > 显示输入 key 值的条目
DEL < key > 删除输入 key 值的条目
PURGE < key > 删除输入 key 值的条目并清楚快照
SET < key > <value …> 设置条目的值
PUSH < key > <value …> 将值置于前面
… …
涉及知识点：
文件读写、字符串处理
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INFO1113 Assignment 1
Due: September 22nd, 11:59PM AEST
This assignment is worth 6% of your final assessment
Task Description
In this assignment we will develop a key value store database called CrunchDB in the Java programming language using dynamic data structures. All entries to the database contain a unique key which
will map to a set of values. Each entry of the database is identified by a unique key string and contains
a dynamically sized list of integer values.
You are encouraged to ask questions on Ed using the assignments category. As with any assignment,
make sure that your work is your own, and you do not share your code or solutions with other students.
Working on your assignment
You can work on this assignment on your own computer or the lab machines. It is important that you
continually back up your assignment files onto your own machine, external drives, and in the cloud.
You are encouraged to submit your assignment on Ed while you are in the process of completing it.
By submitting you will obtain some feedback of your progress on the sample test cases provided.
Implementation details
Write a program in Java that implements CrunchDB as shown in the examples below. You can assume
that our test cases will contain only valid input commands and not cause any integer overflows. Keys
are case sensitive and do not contain spaces. Commands are case insensitive.
Entry values are indexed from 1. Snapshots are indexed from 1 and are unique for the lifetime of the
program. Keys, entries and snapshots are to be outputted in the order from most recently added to
least recently added. Snapshots can be archived in a human-readable text file, storing all entries in the
following form
< entry_key>|[< entries>,…]}
Example
a|1,2,3,4
b|3,4,5
c|9,6,1,2,0,3
Archived snapshots can be restored by CrunchDB, resetting the data to the archived snapshot’s state.
Your program can be contained in the provided scaffold of CrunchDB.java, Snapshot.java
and Entry.java. Do not modify any of the existing method signatures in these files. Your program
must produce no errors when built and run on the lab machines and Ed. Your program will read from
standard input and write to standard output.
Your program output must match the exact output format shown in the examples and on Ed. You
are encouraged to submit your assignment while you are working on it, so you can obtain some
feedback. You have been provided simple skeleton classes and hints on how to implement your
snapshot database.
In order to obtain full marks, your program will be checked against automatic test cases, manually
inspected by your tutors and you must submit a set of test cases that ensure you have implemented
functionality correctly.
Commands
Your program should implement the following commands, look at the examples to see how they work.
• If a < key> does not exist in the current state, output: no such key
• If a < snapshot> does not exist in the database, output: no such snapshot
• If an < index> does not exist in an entry, output: index out of range
BYE clear database and exit
HELP display this help message
LIST KEYS displays all keys in current state
LIST ENTRIES displays all entries in current state
LIST SNAPSHOTS displays all snapshots in the database
GET < key> displays entry values
DEL < key> deletes entry from current state
PURGE < key> deletes entry from current state and snapshots
SET < key> <value …> sets entry values
PUSH < key> <value …> pushes values to the front
APPEND < key> <value …> appends values to the back
PICK < key> < index> displays value at index
PLUCK < key> < index> displays and removes value at index
POP < key> displays and removes the front value
DROP < id> deletes snapshot
ROLLBACK < id> restores to snapshot and deletes newer snapshots
CHECKOUT < id> replaces current state with a copy of snapshot
SNAPSHOT saves the current state as a snapshot
ARCHIVE < id> < filename> saves snapshot to file
RESTORE < filename> loads and restores snapshot from file
MIN < key> displays minimum value
MAX < key> displays maximum value
SUM < key> displays sum of values
LEN < key> displays number of values
REV < key> reverses order of values
UNIQ < key> removes repeated adjacent values
SORT < key> sorts values in ascending order
DIFF < key> <key …> displays set difference of values in keys
INTER < key> <key …> displays set intersection of values in keys
UNION < key> <key …> displays set union of values in keys
CARTPROD < key> <key …> displays cartesian product of sets

BYE
bye
Examples (1)
LIST KEYS
no keys
LIST ENTRIES
no entries
LIST SNAPSHOTS
no snapshots
SET a 1
ok
GET a
[1]
POP a
1
GET a
[]
POP a
nil
PUSH a 2 1
ok
GET a
[1 2]
APPEND a 3 4
ok
GET a
[1 2 3 4]
DEL a
ok
DEL a
no such key
BYE
bye
Examples (2)
SET a 1
ok
SET b 2 3
ok
LIST KEYS
b
a
LIST ENTRIES
b [2 3]
a [1]
LIST SNAPSHOTS
no snapshots
PICK a 0
index out of range
PICK b 1
2
GET b
[2 3]
PLUCK b 2
3
GET b
[2]
DEL b
ok
GET b
no such key
PURGE b
ok
BYE
bye
Examples (3)
DROP 1
no such snapshot
ROLLBACK 1
no such snapshot
SET a 1 2
ok
SET b 3 4
ok
LIST ENTRIES
b [3 4]
a [1 2]
SNAPSHOT
saved as snapshot 1
SET c 5 6
ok
LIST ENTRIES
c [5 6]
b [3 4]
a [1 2]
SNAPSHOT
saved as snapshot 2
PURGE b
ok
ROLLBACK 1
ok
CHECKOUT 2
no such snapshot
LIST ENTRIES
a [1 2]
LIST SNAPSHOTS
1
BYE
bye
Examples (4)
SET a 1 4 2 3 4 2
ok
SNAPSHOT
saved as snapshot 1
MIN a
1
MAX a
4
SUM a
16
LEN a
6
REV a
ok
GET a
[2 4 3 2 4 1]
SORT a
ok
GET a
[1 2 2 3 4 4]
UNIQ a
ok
GET a
[1 2 3 4]
CHECKOUT 1
ok
LIST SNAPSHOTS
1
LIST ENTRIES
a [1 4 2 3 4 2]
BYE
bye
Examples (5)
SET a 1 2
ok
SET b 3 4
ok
ARCHIVE 1 example_file.txt
no such snapshot
SNAPSHOT
saved as snapshot 1
LIST ENTRIES
b [3 4]
a [1 2]
ARCHIVE 1 example_file.txt
ok
SET c 5 6
LIST SNAPSHOTS
1
LIST ENTRIES
c [5 6]
b [3 4]
a [1 2]
SNAPSHOT
saved as snapshot 2
LIST SNAPSHOTS
2
1
RESTORE example_file.txt
ok
LIST ENTRIES
b [3 4]
a [1 2]
LIST SNAPSHOTS
no snapshots
BYE
bye
Writing your own testcases
We have provided you with some test cases but these do not not test all the functionality described in
the assignment. It is important that you thoroughly test your code by writing your own test cases.
You should place all of your test cases in the tests/ directory. Ensure that each test case has the .in
input file along with a corresponding .out output file. We require that the names of your test cases are
descriptive so that you know what each is testing, e.g. get-set.in and sort-uniq.in and we
can accurately and quickly assess your test cases.
Submission Details
Final deliverable for the correctness and manual inspection will be due on the 22nd of September
2019.
You must submit your code and tests using the assignment page on Ed. To submit, simply place your
files and folders into the workspace, click run to check your program works and then click submit.
You are encouraged to submit multiple times, but only your last submission will be considered.
Marking
You will only be given valid inputs as part of the automatic test suite. Your program will be checked
for errors that a user can possibly make. In addition, we will mark your program against a substantial
collection of hidden test cases.
3 marks are assigned based on automatic tests for the correctness of your program. This component
will use hidden test cases that cover every aspect of the specification. Your program must match the
exact output in the examples and the test cases on Ed. Test cases will be released progressively, the
final set of public test cases will be released prior to 17th of September.
3 marks are assigned based on a manual inspection of the style (1 mark) and tests cases (2 marks).
Make sure that you carefully follow the assignment specifications and thoroughly test your code,
optimising for coverage and testing for a variety of input ranges.
Academic declaration
By submitting this assignment you declare the following:
I declare that I have read and understood the University of Sydney Student Plagiarism: Coursework Policy and Procedure, and except where specifically acknowledged, the work contained in this assignment/project is my own work, and has not been copied from other sources or been previously submitted for award or assessment.
I understand that failure to comply with the Student Plagiarism: Coursework Policy and Procedure can lead to severe penalties as outlined under Chapter 8 of the University of Sydney By-Law 1999 (as amended). These penalties may be imposed in cases where any significant portion of my submitted work has been copied without proper acknowledgment from other sources, including published works, the Internet, existing programs, the work of other students, or work previously submitted for other awards or assessments.
I realise that I may be asked to identify those portions of the work contributed by me and required to demonstrate my knowledge of the relevant material by answering oral questions or by undertaking supplementary work, either written or in the laboratory, in order to arrive at the final assessment mark.
I acknowledge that the School of Computer Science, in assessing this assignment, may reproduce it entirely, may provide a copy to another member of faculty, and/or communicate a copy of this assignment to a plagiarism checking service or in-house computer program, and that a copy of the assignment may be maintained by the service or the School of Computer Science for the purpose of future plagiarism checking.