Code generation  20100629.

The evaluation criteria:

You may use and modify the test cases provided in the course web page. You may make up new test cases fitting your compiler. You can also introduce new features into your compiler.

You will need to implement three "library" routines:
	printInt( a+15 );
        printReal( b+c/3.14 );
        printString( "The size of the graph is" );

Each item below will earn 1 point.  A scaling formula will be used to translate your total points to a numerical score.

0.  (part 1) Filter out comments.
0.  (part 1) Use the longest-match rule in scanning.

1.   (part 3) check for duplicated declarations.
2.   variables of integer type.
3.   variables of real type.
4.   variables of simple array types, such as 
	array [ 23 .. 57 ] of integer
        array [ 12 .. 34 ] of real
5.   variables of multi-dimension arrays, such as 
	array [ 23 .. 57 ] of array [ 12 .. 34 ] of integer
        array [ 12 .. 34 ] of array [ 23 .. 57 ] of real

6.  Addition and subtraction operations.
7.  Multiplication and division operations.
8.  Comparision operations.
9.  Evaluate constant expressions in the compiler.
10.  assignment statements of simple types (integer and real)
11.  assignment of 1-dimensional arrays
12.  assignment of multi-dimensional arrays
13.  check out-of-bound array indices at compile time
14.  Generate code to check out-of-bound array indices at run time
15.  simple if statements
16.  simple while loops
17.  nested if statements 
18.  nested while loops
19.  arbitrary combination of assignment statements, if statements, and while loops

20.  subprograms (procedures and functions) without parameters and without return values
21.  recursive subprograms without parameters and without return values.
22.  subprograms with (integer and real) parameters and with (integer and real) return values
23.  recursive subprograms with (integer and real) parameters and with (integer and real) return values

25.  PrintInt, PrintReal, and PrintString.
26.  Check if a variable is initialized.
27.  There could be constant folding of various degrees of difficulty.
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