avrora.syntax
Class Expr

java.lang.Object
  avrora.syntax.ASTNode
      avrora.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

Expr()

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

Expr

public Expr()

Method Detail

evaluate

public abstract int evaluate(int currentByteAddress,
                             Context c)

The evaluate() method computes the value of the expression in this context and returns its value.

Parameters:

currentByteAddress - the current byte address within the program

c - the context in which to evaluate this expression

Returns:

the value of the expression as a 32-bit integer