ReactModifyVar.jrag

/*
 * ReactiveDominoJ is a practical implementation of an expand event system
 * supporting reactive programming.  This project is an implementation of its
 * compiler built on top of DominoJ and JastAddJ.
 * 
 * Copyright (c) 2013-, YungYu Zhuang. All rights reserved.
 *
 * The contents of this file are licensed under the modified BSD License
 * (please see the LICENSE file for the full text).
 */

/*
 * Collect the information about read fields and written fields in the preprocess.
 */

aspect ReactModifyVar {

    /*
     * every VarAccess has to
     * add itself to the field set for the method if it is a read field,
     * or add the method to the writer set for the field if it is a written field.
     */
    public void VarAccess.crossprocess() {

        if(!decl().hostType().compilationUnit().fromSource())    return;
        if(!(decl() instanceof FieldDeclaration))    return;
        FieldDeclaration decl = (FieldDeclaration)decl();
        if(decl.generated)    return;

        // get host method
        ASTNode p = getParent();
        while(!(p instanceof MethodDecl)) {
            p = p.getParent();
            if(p instanceof ClassDecl)    return;
        }
        MethodDecl md = (MethodDecl)p;

        // check if it written
        boolean isRead = true;
        p = getParent();
        while(!(p.getParent() instanceof Stmt)) {
            p = p.getParent();
        }
        if(p instanceof AssignExpr) {
            Expr e = ((AssignExpr)p).getDest();
            boolean isThis = true;
            if(e instanceof Dot) {
                e = ((Dot)e).extractLast();
                if(!(((Dot)e.getParent()).getLeft() instanceof ThisAccess)) {
                    isThis = false;
                }
            }
            if(e == this) {
                isRead = false;
                if(isThis) {
                    // only write accesses to fields on "this" object are tracked.
                    decl.addWriteMethod(md);
                } else {
                    //System.out.println("ignore write access: " + name() + " in method " + md.name());
                }
            }
        }
        if(isRead) {    // is read
            if(getParent() instanceof Dot && !(((Dot)getParent()).getLeft() instanceof ThisAccess)) {
                // only read accesses to fields on "this" object are tracked.
                //System.out.println("ignore read access: " + name() + " in method " + md.name());
                return;
            }
            md.addReadField(decl);
        }
    }
}