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Instructions In this assignment, you will be required to scan, parse, and check the semantics of a le that encodes the state of a variation of Connect Four. The de nition of a properly formatted input le is given in Section 1.1. You will be submitting one .java le and two .g4…
In this assignment, you will be required to scan, parse, and check the semantics of a le that encodes the state of a variation of Connect Four. The de nition of a properly formatted input le is given in Section 1.1.
You will be submitting one .java le and two .g4 (ANTLR) les via web hand-in.
1.1 File Speci cation
An example of a properly formatted le is shown in Figure 1.
f | moves | /∗ | g | ||||||||||||
5 | 10 | 9 | 4 | 1 | 2 | 10 | 10 | 2 | 2 | 1 | 9 | 1 | 3 |
∗/
game | /∗ | ||||||
[ | |||||||
j | |||||||
j | |||||||
j | |||||||
j | |||||||
j | |||||||
j | |||||||
2 | 1 |
]
∗/
Figure 1: A properly formatted Connect Four (cnf) encoding
The assignment is made up of two parts: scanning the text of the input le and parsing the information contained in the input le.
1.2 Scanning
Construct a combined grammar in a .g4 le that ANTLR can use to scan a supplied Connect Four encoding. The logic in this le should be robust enough to identify tokens in the encoding and accurately process any correctly formatted encoding. The rules in your .g4 le will be augmented with actions that display information about the input le. An example of that output is speci ed in Section 2.
The purpose of the scanner is to extract tokens from the input and pass those along to the parser. For the Connect Four encoding, the types of tokens that you will need to consider are given in Table 1.
1
Type | Form |
Section Beginning | /* |
Section Ending | */ |
Section Title | game and moves |
Move Symbol | One or more Numerical Symbols |
Game Symbol | – or One or more Numerical Symbols |
Numerical Symbol | 0, 1, 2, 3, 4, 5, 6, 7, 8, or 9 |
Row Ending | | |
Game Beginning | [ |
Game Ending | ] |
Moves Beginning | { |
Moves Ending | } |
White Space (to be ignored) | spaces, tabs, newlines |
Table 1: Tokens to Consider
1.2.1 Invalid Encodings
For invalid Connect Four encodings, the output SYNTAX PROBLEM ON LINE L should display. L would be the line of input where the symbol was read. Your scanner should stop scanning the le after an unrecognized token is found.
1.3 Parsing
Construct a combined grammar in a .g4 le that ANTLR can use to parse a supplied Connect Four encoding. In addition to the rules for scanning, there are several parsing rules:
You may assume that each row has the same number of columns, and each column has the same number of rows.
The semantics of a properly formatted Connect Four encoding are:
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2.1 Scanner
Your .g4 le should produce output for both correctly formatted les and incorrectly formatted les. For the correctly formatted le in Figure 1, the output would have the form of the output presented in Figure 2
Moves Section
B eg in ni ng of Section
B eg in ni ng of List
Number : 5
Number : 10
…
Number : 1
Number : 3
End of List
End of Section
Game Section
B eg in ni ng of Section
Start of Game
Space : Empty
Space : Empty
…
Space : Empty
End of Row
Space : Empty
…
Space : Empty
End of Row
Space : Empty
…
Space : Empty
End of Row
Space : Empty
Space : Empty
Space : Empty
Number : 2
Space : Empty
Space : Empty
Space : Empty
Number : 1
Space : Empty
Space : Empty
End of Game
End of Section
End of File
Figure 2: Truncated Output of Scanner for File in Figure 1
For a correctly formatted le in Part 2, the output would be: p pieces have been played where p is the number of pieces in the Game . For the le in Figure 1, the output would be
2 pieces have been played.
2.1.1 Invalid Syntax & Semantics in Parsing
For invalid encodings in Part 2, the message SYNTAX PROBLEM ON LINE L should be displayed where L is the line number where the error occurred. For a semantic rule violation, the output
SEMANTIC PROBLEM P should be displayed, where P is the number of the rule (from List 1.3) that was
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violated, but parsing should continue.
Syntax errors in Part 2 should be reported in the syntaxError method of csce322assignment01partt02error.java.
The ANTLR le for the rst part of the assignment should be named csce322assignment01part01.g4. The ANTLR le for the second part of the assignment should be named csce322assignment01part02.g4. Both grammars should contain a start rule named connectFour. The Java le for the second part of the assignment should be named csce322assignment01part02error.java.
The webgrader is available for this assignment. You can test your submitted les before the deadline by submitting them on webhandin and going to http://cse.unl.edu/~cse322/grade, choosing the correct assignment and entering your cse.unl.edu credentials
The script should take approximately 2 minutes to run and produce a PDF.
4.1 The Use of diff
Because Part 1 of this assignment only depends on the symbols in the le, the order in which they are displayed should not be submission dependent. Therefore, diff will be used to compare the output of a particular submission against the output of the solution implementation. In Part 2, the output is sorted and the unique lines extracted, so the order and number of times a semantic error is reported will not a ect the di .
Component | Points | |
Part 1 | 35 | |
Part 2 | 65 | |
Total | 100 | |
6 External Resources
Overview (ANTLR 4 Runtime 4.7.2 API)
7 | Commands of Interest | |
alias | antlr4 = ‘ java – jar / path / to / antlr -4.7.2 – complete . jar ‘ | |
alias grun =’ java org . antlr . v4 . gui . TestRig ‘ | ||
export | C LA SS PA TH =”/ path / to / antlr -4.7.2 – complete . jar : $C L A S S P A T H “ | |
antlr4 | / path / to / c s c e 3 2 2 a s s i g n m e n t 0 1 p a r t 0 #. g4 | |
javac | -d / path / for /. c l a s s f i l e s / path / to / c s c e 3 2 2 a s s i g n m e n t 0 1 p a r t 0 #*. java | |
java | / path / of /. c l a s s f i l e s c s c e 3 2 2 a s s i g n m e n t 0 1 p a r t 0 2 d r i v e r / path / to / i np ut fi le | |
grun | c s c e 3 2 2 a s s i g n m e n t 0 1 p a r t 0 # c o n n e c t F o u r – gui | |
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grun c s c e 3 2 2 a s s i g n m e n t 0 1 p a r t 0 # grun c s c e 3 2 2 a s s i g n m e n t 0 1 p a r t 0 # grun c s c e 3 2 2 a s s i g n m e n t 0 1 p a r t 0 #
c o n n e c t F o u r – gui / path / to / i np ut fi le
c o n n e c t F o u r
c o n n e c t F o u r / path / to / i np ut fi le
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