Class Expr

  extended byavrora.syntax.ASTNode
      extended byavrora.syntax.Expr
Direct Known Subclasses:
Expr.BinOp, Expr.Func, Expr.RelativeAddress, Expr.Term, Expr.UnOp

public abstract class Expr
extends ASTNode

The Expr class represents an expression within the program that must be evaluated to a value. This could be an integer constant, a computable expression involving arithmetic operators, a variable, or an expression relative to the current position within the program.

Nested Class Summary
static class Expr.BinOp
          The BinOp class represents a simple binary arithmetic operator such as addition, multiplication, etc.
static class Expr.CharLiteral
          The CharLiteral class represents a character literal in the program that can be used as an integer value.
static class Expr.Constant
          The Constant class represents a integer literal (a constant) within the program.
static class Expr.Func
          The Func class represents a builtin function that is applied to an operand.
static class Expr.RelativeAddress
          The RelativeAddress class represents an expression that is derived from the addition (or subtraction) of a constant to the current byte address.
static class Expr.StringLiteral
          The StringLiteral class represents a string literal within the program.
static class Expr.Term
          The Term class is a superclass for all expressions that consist of a single lexical token.
static class Expr.UnOp
          The UnOp class represents an expression that is a single operand with a unary operation applied to it.
static class Expr.Variable
          The Variable class represents a variable reference within the program.
Constructor Summary
Method Summary
abstract  int evaluate(int currentByteAddress, Context c)
          The evaluate() method computes the value of the expression in this context and returns its value.
Methods inherited from class avrora.syntax.ASTNode
getLeftMostToken, getRightMostToken
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail


public Expr()
Method Detail


public abstract int evaluate(int currentByteAddress,
                             Context c)
The evaluate() method computes the value of the expression in this context and returns its value.

currentByteAddress - the current byte address within the program
c - the context in which to evaluate this expression
the value of the expression as a 32-bit integer