代做program留学生程序、Java语言编程调试、代做Java程序设计

日期：2020-11-05 11:28

Regular Expression processor in Java

Overview: Create a Java program that will accept a regular expression and a filename for a text file. The

program will process the file, looking at every line to find matches for the regular expression and display

them.

Here is a resource for regular expressions: https://docs.python.org/3/howto/regex.html

Regular Expression Format

The following operators are required to be accepted:

+ - one or more of the following character (no groups)

* - zero or more of the following character (no groups)

[] – no negation, no character spans – the only format is explicit, for example [0123456789]

NOTE: You do not have to implement every possible regular expression. You can limit the program to

the three symbols above.

Input:

Your program should take two command line arguments. The first should be the regular exception, the

second should be the filename.

Output:

The output from your program should be formatted exactly like this:

Match found on line 10, starting at position 10 and ending at position 25: aaaaaaaaaaaaaa0

If the regular expression entered was a*[01]

And the input file contained at line 10:

Xxdsdsasdaaaaaaaaaaaaaaa0

Restrictions

Your program must implement its own regular expression functionality – you cannot use the built-in

regular expression mechanism, nor can you include one from a package or JAR file unless you created it

and included the source code in your submission. Therefore, you cannot use any pattern matching

methods in any programming language.

Testing

Please be sure to test your code thoroughly. Your code must work for all regular expressions and text

files as described above. While you MAY NOT share code in any way, I would encourage all of you to

write tests and share them with each other. You can write and test your test cases against sites like :

https://regex101.com/ or using Unix/Mac grep

Deliverables:

1) A state machine of your engine. Clearly identify each of the stages your parser can enter

2) A video recording (Either MP4 format or URL to a recording)

a. Scroll through the code

b. The code must be compiled

c. Cost must be test with at least 5 strings

3) A test plan on how you plan to test all of the regular expression options

a. Must include searching using each of the regular expression patterns

4) The test file you created to test your program

5) The Source code for your program

Some Design Hints

Break this down into two problems:

1) Build a list of states from the regular expression

2) Loop over the input lines, then over each character in each input line, checking the input against

the states.

I built a class to wrap String, adding the idea of which character is “current” and the ability to get the

current character and to peek at the next character. This made my code cleaner and easier to reason

about.

Rubric Poor OK Good Great

0 5 7 10

Video No video submitted Video Submitted but

it does not show code,

compilation, or

testing

Video Submitted, but

only shows two of the

three requirements

(Code, Compilation,

Testing)

Video is complete

Comments None/Excessive “What” not “Why”,

few

Some “what”

comments or missing

some

Anything not obvious

has reasoning

Variable/Function

naming

Single letters

everywhere

Lots of abbreviations Full words most of the

time

Full words, descriptive

0 5 13 20

Structure Global variables

everywhere,

indentation doesn’t

match braces {}, no

helper functions

Any 2 of:

Too many Global

variables

Indentation wrong

Missing helper

functions

Any 1 of:

Too many Global

variables

Indentation wrong

Missing helper

functions

Few/no Global

variables, indentation

correct, helper

functions

State Machine Doesn’t exist Some attempt at a

state machine

Mostly correct state

machine

State machine

“perfect”

0 10 20 30

Searching Doesn’t work at all Some searches work Minor search errors All searches perfect