CS 444/644 - Compiler Construction (Winter 2021) - Assignment 1

Scanning, Parsing, Weeding

The first assignment to implement lexical and syntactic analysis. The scanner splits up the input into tokens and catches lexical errors (inputs that cannot form valid tokens). The parser checks that the input list of tokens conforms to a syntax specified using a context-free grammar. The weeding stage detects simple errors that generally could have been checked by a context-free grammar, but this would make the grammar very complicated. It is recommended that your design follow the above three stages, though it is not required, as long as you somehow implement the lexical and syntactic specification of Joos 1W.

You must hand in to Marmoset a .zip archive containing your source code. The .zip file must contain a file called Makefile. Marmoset will run make on this Makefile to compile your compiler. The Makefile must generate an executable (binary or shell script) called joosc. When run with a single argument, a filename, joosc should process the given Joos 1W file, produce appropriate diagnostic messages on standard error, and exit with one of the following Unix return codes:

0: the input file is lexically/syntactically valid Joos 1W
42: the input file is not lexically/syntactically valid Joos 1W
any other value: your compiler crashed

The Marmoset tests for this assignment take several minutes to run. Do not submit more than one submission at a time to Marmoset. If Marmoset reports that your previous submission has not been tested yet, do not submit another one. Denial-of-service attacks on Marmoset will result in disciplinary action.

The following restrictions of the Joos 1W language must be checked (either in the parser or in the weeder):

All characters in the input program must be in the range of 7-bit ASCII (0 to 127).
A class cannot be both abstract and final.
A method has a body if and only if it is neither abstract nor native.
An abstract method cannot be static or final.
A static method cannot be final.
A native method must be static.
The type void may only be used as the return type of a method.
A formal parameter of a method must not have an initializer.
A class/interface must be declared in a .java file with the same base name as the class/interface.
An interface cannot contain fields or constructors.
An interface method cannot be static, final, or native.
An interface method cannot have a body.
Every class must contain at least one explicit constructor.
No field can be final.
No multidimensional array types or multidimensional array creation expressions are allowed.
A method or constructor must not contain explicit this() or super() calls.

This phase of the compiler should also determine the values of all literals in the program. For integer literals, it must check that the literal is within the range of a Java int. For character and string literals, it must expand any escape sequences in the literal.

Submit to Marmoset a PDF document of no more than five pages explaining the design of this phase of your compiler. The document should be organized to enable someone unfamiliar with your code to understand the structure of (this phase of) your compiler. In the document, discuss challenges that you encountered and how you tried to overcome them in your design and implementation. Also explain the testing that you did before submitting to Marmoset.

The document will be hand-marked, with 50% of the marks for organization, clarity, and style, and 50% of the marks for technical content.