CSE-PPL Assignment 1- Recognizer Solution

Contents
1 Specification 2
1.1 Phase 1: Lexer 3
1.2 Phase 2: Recognizer 3
2 Submission 4
3 Change Log 4


After completing this assignment, you will be able to
• define formally lexicon of a programming language.
• use ANTLR to implement a lexer for a programming language.
• define formally grammar of a programming language.
• use ANTLR to implement a recognizer for a programming language.
1 Specification
In this assignment, you are required to write a lexer and a recognizer for a program written in BKOOL. To complete this assignment, you need to:
• Install Python 3 if you have not installed it yet.
• Download initial.zip and unzip it.
• Download antlr-4.9.2-complete.jar from https://www.antlr.org/download.html, set the environment variable ANTLR_JAR to this file; install antlr4-python3-runtime (see instructions in section Python Targets of the above webpage) and follow the instructions in initial/README.txt to test the initial code.
• Remove all files in folders initial/src/main/bkool/utils, initial/src/main/bkool/astgen, initial/src/main/bkool/checker, initial/src/main/bkool/codegen.
• Delete files initial/src/test/ASTGenSuite.py, initial/src/test/CheckerSuite.py, and initial/src/test/CodeGenSuite.py
• Comment out five lines 11-15 and from line 103-end of file initial/src/test/TestUtils.py and test the initial code again with just three following tructions:
python run.py gen python run.py test LexerSuite python run.py test ParserSuite
• Change folder initial into assignment1 To complete this assignment, you need to:
• read carefully the specification of language
• Modify BKOOL.g4. in the initial code to describe formally BKOOL language.Please fill in your id in the header of this file.
• Add more test in LexerSuite and ParserSuite in the initial code.
This assignment is divided two phases: lexer phase and recognizer phase. These phases are assessed independently.
1.1 Phase 1: Lexer
In this phase, you are required to write a lexer for a program written in ANTLR. To complete this phase, you need to:
• Modify BKOOL.g4 to detect tokens in BKOOL language.
• Make 100 testcases for LexerSuite to test your code.
• For lexical errors, please print out as follows:
– "ErrorToken "+ <char>: when the lexer detects an unrecognized character
– "Unclosed string: "+<unclosed string>: when the lexer detects an unterminated string.
– "Illegal escape in string: "+<wrong string>: when the lexer detects an illegal escape in string. The wrong string is from the beginning of the string to the illegal escape.
• You can assume that there is only one error in each test case.
1.2 Phase 2: Recognizer
In this phase, you are required to write a recognizer for a program written in BKOOL. To complete this phase, you need to:
• Modify BKOOL.g4.
• Make 100 testcases for ParserSuite to test your code.
• You can assume that there is at most one error in each test case.
2 Submission
Run python run.py gen to generate the following files:
BKOOL.interp
BKOOLVisitor.py
BKOOLParser.py
BKOOLLexer.tokens
BKOOLLexer.py
BKOOLLexer.interp BKOOL.tokens in folder target or its subfolder. Submit these files together with BKOOL.g4, LexerSuite.py and ParserSuite.py (10 files). DO NOT COMPRESS THEM when submitting. Then click on Check button to check your submission. There are some simple testcases to check your submission which is marked later.
3 Change Log