JavaSST Compiler

Generates a Java-Class file for a given JavaSST Program. This Project is part of a university course. JavaSST is a super-super-trivial subset of Java which was developed for education purposes.

Usage

JavaSSTCompiler inputFile [generateDotGraph]

The inputFile must be a valid path to a File containing JavaSST source code. If the second parameter generateDotGraph is set to true, an additional DOT file is created which contains a Graph describing the AST and symbol table.

Using the class file

java -noverify JavaClassFileUsingCompiled Class

The -noverify flag is used to circumvent the StackMap usage in higher Java versions.

Example

Given the following JavaSST Source code

class TestClass{
    final int c = 69;
    public int max(int x, int y){
        if(x>y){
            return x;
        }else{
            return y;
        }
    }
}

this compiler generates the following abstract syntax tree and symbol table: Red and green edges represent left and right child nodes respectively. Blue edges point towards conditions being used by if or while statements. Purple edges point to method declarations. Other edges represent references.

Based on this Graph a Java class file is generated. This class file contains the following ByteCode (ConstantPool not shown here):

  public int c;
    descriptor: I
    flags: (0x0001) ACC_PUBLIC

  public int max(int, int);
    descriptor: (II)I
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=5, args_size=3
         0: iconst_0
         1: iload         1
         3: iload         2
         5: if_icmpgt     12
         8: iconst_0
         9: goto          13
        12: iconst_1
        13: if_icmpne     22
        16: iload         2
        18: ireturn
        19: goto          25
        22: iload         1
        24: ireturn
        25: iconst_0
        26: ireturn

  public TestClass();
    descriptor: ()V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=1, args_size=1
         0: aload_0
         1: invokespecial #19                 // Method java/lang/Object."<init>":()V
         4: aload_0
         5: bipush        69
         7: putfield      #12                 // Field c:I
        10: return