willsewell / jaml_compiler Goto Github PK

RUNNING THE PROGRAM

The two entry points to the program are:

    - jamlcomp.py - This allows the program to be run.  It will either compile
                    the file, or print error information.

                    Usage: python jamlcomp.py <file> [<output directory>]
                    
                    If no <output directory> is specified, the output .class
                    files will be written to ./jaml_files/bin/<file_name>
    
    - test_runner.py - This allows all tests files to be run, and results
                       printed.
                       
                       Usage: python test_runner.py

Documentation generated from comments is available at: ./pydoc/

Some examples to run the program on are in: ./jaml_files/jaml/

INFORMAL JAML SPEC

The input files must conform to JaML's syntax and semantics' based on
Java 6. These key features are included:

    - All primitive types
    - Implicit type conversion of primitive types
    - Arrays
    - Support for classes (can be made abstract or final)
    - Inheritance and interface implementation
    - Polymorphism 
    - if, for and while statements
    - Assignment
    - Interfaces
    - Fields (can be made static void, and/or private)
    - Methods (can be made abstract and/or static and/or final and/or private)
    - Arithmetic operators: + (also for string concatenation) - * /
    - Unary operators: + - ++ -- !
    - Equality and relational operators: == != > >= < <=
    - Conditional operators: || &&
    - Calls to the super constructor with 'super()'
    - Reference to members of super with 'super.<member>'
    - Support for String, including concatenation - with +

Matrix features:

    - The 'matrix' keyword to declare a variable as a matrix type
    - A = |expr, expr| to initialise a matrix where expr denotes an expression
        that evaluates to an integer and specifies the dimension's length
    - A|expr, expr| indexes into a matrix where the expr evaluate to ints
    - C = A * B does matrix multiplication
    - C = A + B does addition
    - C = A - B does subtraction
    
Key Java features not included (although this is by no means exhaustive):

    - Packages (All files must be in the same directory)
    - Overloaded methods
    - Generic types
    - Casting
    - Methods and fields cannot be chained together, e.g.: x.y().z.w()
    - Only single constructors allowed
    - The 'this' keyword
    - Multi-threading
    - Switch statements
    - Exceptions
    - Bitwise operators
    - Fields cannot be updated directly in other objects;
        must be done through a method
    
Use of library classes is possible, but it is not as reliable. There are
also restrictions over what can be done in Java:

    - Library classes cannot be extended and interfaces cannot be implemented
    - Arguments of methods and constructors must be exactly the correct type
    - Method are not checked to see whether they are abstract
    - Using anything which requires syntax not available in JaML is unsupported
        (e.g. generic types)
    - Only members of the java.lang, java.util and java.io packages are
        included; this is because packages are not supported in JaML, so these
        packages are imported by implicitly
    - Polymorphic types not implemented e.g. String cannot be assigned to an
        Object.
    

There was no need for the 'public' modifier because there are no packages. All
fields and methods are implicitly 'protected', and can be made 'private'.
Because of this the 'main' method must have the signature:

static void main(String[] args)
    
It is hard to give a full specification of this language in such an informal
way. The full syntactic BNF specification is located in: ./docs/jaml.g.

How each included feature works can be found at:
http://docs.oracle.com/javase/specs/

KNOWN ISSUES

There is a bug in Jasmin where doubles become converted to floats with
static final field definition with assignment.

The variable declared in for loops is in the scope outside of the for loop
block