CS 784 Spring 2009 Final Exam: Static Fields, Attribute Grammars, Axiomatic Semantics, Exams of Programming Languages

Download CS 784 Spring 2009 Final Exam: Static Fields, Attribute Grammars, Axiomatic Semantics and more Exams Programming Languages in PDF only on Docsity! Wright State University Department of Computer Science and Engineering CS 784 Spring 2009 Prasad Final Exam (40 pts) 1 Interpreter for Object-Oriented Language (8 + 8 pts) Consider the interpreter for OOPL given in the files 5-3.scm and 5-4-4.scm. We explore introducing static fields into class definitions. Static fields associate some state with a class; all the instances of a class share this state. Static fields can appear in a method body. For example, one might write the following program and obtain as the result, the list (01): class c1 static next_serial_number field my_serial_number method get_serial_number () my_serial_number method initialize () begin set my_serial_number = next_serial_number; set next_serial_number = add1(next_serial_number); end let o1 = new c1() o2 = new c1() in list (send o1 get_serial_number(), send o2 get_serial_number()) Explain all the modifications to the interpreter code to incorporate the static fields shown in the grammar rule for class definition below, informally and clearly first, and formally in code later. Initialize each static field to 0, by default. (class-decl ("class" identifier "extends" identifier (arbno "static" identifier) (arbno "field" identifier) (arbno method-decl) ) a-class-decl) Specifically, locate all the changes to the original interpreter code on the accompanying interpreter code handout and/or locate changes/insertions using file name, page number, and line numbers. 1