slogo.expression

Class BinaryExpression

java.lang.Object

slogo.GrammarElement

slogo.expression.Expression

slogo.expression.BinaryExpression

Direct Known Subclasses:

Addition, Division, Multiplication, Subtraction

public abstract class BinaryExpression
extends Expression

The base class of any binary expression, e.g., a + b, a - b, or, in future use, a < b and so on. A binary expression has two subexpressions that can be evaluated via the methods leftValue and rightValue which, presumably, subclasses will call.

The current version is tied to arithmetic expressions via the the return type of leftValue and rightValue.

Field Summary

Fields

Modifier and Type	Field and Description
protected Expression	myLeft
protected Expression	myRight
protected java.lang.String	mySymbol

Fields inherited from class slogo.GrammarElement

gelementsToValue

Constructor Summary

Constructors

Constructor and Description
BinaryExpression(Expression lhs, Expression rhs) construct a binary expression from two subexpressions

Method Summary

Methods

Modifier and Type	Method and Description
double	leftValue(Context c)
double	rightValue(Context c)
java.lang.String	toString() Combine left/right subexpressions, return result using symbol as the combiner/juxtaposer for the subexpressions.

Methods inherited from class slogo.expression.Expression

evaluate, value

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

mySymbol

protected java.lang.String mySymbol

myLeft

protected Expression myLeft

myRight

protected Expression myRight

Constructor Detail

BinaryExpression

public BinaryExpression(Expression lhs,
                Expression rhs)

construct a binary expression from two subexpressions

Parameters:

lhs - is the left subexpression (left-hand side)

rhs - is the right subexpression (right-hand side)

Method Detail

leftValue

public double leftValue(Context c)

Returns:

the result of evaluating the left subexpression

rightValue

public double rightValue(Context c)

Returns:

the result of evaluating the right subexpression

toString

public java.lang.String toString()

Combine left/right subexpressions, return result using symbol as the combiner/juxtaposer for the subexpressions.

Overrides:

toString in class java.lang.Object

Returns:

a string representing this expression