SimpleLOOP-Compiler

The language SimpleLOOP is an object-oriented language and has some features of object-oriented language such as inheritance. In this language, there is a Main class in which an initialize method is implemented. The programs written in this language execute the commands inside this method when they are executed.

Sample Program in SimpleLOOP

class Person {
    private int id, age
    public initialize(int id, int age) {
        self.id = id
        self.age = age
    }
    public void showId()
    print(self.id)
}
class Employee < Person {
    private int salary
    private bool privileged
    public initialize(int id, int age, bool privileged, int salary) {
        self.id = id
        self.age = age
        self.privileged = privileged
        self.salary = salary
    }
    public void showSalary() {
        if !self.privileged
        print(self.salary)
        else
            print(0)
    }
}

class Main {
    public initialize() {
        Employee e
        e = Employee.new(10, 37, false, 300000)
        e.showSalary()
        e.showId()
    }
}

Phase 1 (Lexer)

• Grammar specification

Phase 2 (Name Analysis)

• Abstract Syntax Tree (AST)
• Errors
  • Redefinition of class <ClassName>
  • Redefinition of local variable <VariableName>
  • Redefinition of field <FieldName>
  • Redefinition of method <MethodName>
  • Name of method <MethodName> conflicts with a field's name
  • Redefinition of global variable <VariableName>
  • Name of local variable <VariableName> conflicts with a global variable’s name
  • Class <ClassName> is in an inheritance cycle

Phase 3 (Type-Checking)

• Errors
  • Variable <VariableName> is not declared
  • Class <ClassName> is not declared
  • There is no member named <VariableName> in class <ClassName>
  • Condition must be bool
  • Left side of the assignment must be a valid lvalue
  • Lvalue is required as the operand of <OperatorName>
  • Calling a non-callable
  • Unsupported type for print
  • ...

Phase 4 (Code Generation)

• Program translation to bytecode
• Generate .class files using jasmin assembler

Contributors

• Paria Khoshtab
• Parnian Fazel