dk.rode.thesis.interpreter
Class CompareExpression<E extends Comparable<? super E>>

java.lang.Object
  dk.rode.thesis.interpreter.AbstractExpression<E>
      dk.rode.thesis.interpreter.BinaryExpression<E,Boolean>
          dk.rode.thesis.interpreter.CompareExpression<E>

Type Parameters:

E - The type of value the evaluation of this expression produces.

All Implemented Interfaces:

Expression<Boolean>, NonTerminalExpression<Boolean>, Copyable<Expression<Boolean>>, StrictCopyable<Expression<Boolean>>

public class CompareExpression<E extends Comparable<? super E>>
extends BinaryExpression<E,Boolean>
implements NonTerminalExpression<Boolean>

A compare expression can compare two expressions evaluating to the same Comparable type as smaller than, smaller than or equal, equal, not equal, greater than, or equal or greater than.

Author:

Gunni Rode / rode.dk

See Also:

EqualExpression, AndExpression, OrExpression, NotExpression

Nested Class Summary

static class

CompareExpression.Comparison The comparison type to be performed by a compare expression.

Nested classes/interfaces inherited from interface dk.rode.thesis.interpreter.Expression

Expression.SymbolIdiom

Field Summary

CompareExpression.Comparison

comparison The type of comparison performed by this expression.

Fields inherited from class dk.rode.thesis.interpreter.BinaryExpression

first, second

Constructor Summary

CompareExpression(CompareExpression.Comparison comparison, Expression<? extends E> first, Class<E> type, E value)
Constructor.

CompareExpression(CompareExpression.Comparison comparison, Expression<? extends E> first, Class<E> type, String name)
Constructor.

CompareExpression(CompareExpression.Comparison comparison, Expression<? extends E> first, Expression<? extends E> second)
Constructor.

CompareExpression(CompareExpression<E> expression)
Copy constructor.

Method Summary

String	asSymbol(Context context) Returns x operator y, where x is the symbolic representation of the first expression operand, y of the the second, and operator is the operator used for the comparison.
CompareExpression<E>	copy() Copies this expression.
Boolean	evaluate(Context context) Evaluates this expression and returns the result.
String	name() The stand-alone symbol name for this expression.
String	toString() Returns the string representation of this expression.

Methods inherited from class dk.rode.thesis.interpreter.BinaryExpression

asSymbol, asSymbol, operands

Methods inherited from class dk.rode.thesis.interpreter.AbstractExpression

contains, equals, hashCode

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface dk.rode.thesis.interpreter.Expression

contains, operands

Field Detail

comparison

public final CompareExpression.Comparison comparison

The type of comparison performed by this expression.

Never null.

Constructor Detail

CompareExpression

public CompareExpression(CompareExpression.Comparison comparison,
                         Expression<? extends E> first,
                         Class<E> type,
                         E value)

Constructor.

The second expression used is a constant expression created based on type and value.

Parameters:

comparison - The comparison type; cannot be null.

first - The first expression operand; cannot be null.

type - The type of the constant expression to use as the second expression operand; cannot be null.

value - The value of the constant expression to use as the second expression operand; cannot be null.

Throws:

NullPointerException - If either argument is null.

CompareExpression

public CompareExpression(CompareExpression.Comparison comparison,
                         Expression<? extends E> first,
                         Class<E> type,
                         String name)

Constructor.

The second expression used is a variable expression created based on type and name.

Parameters:

comparison - The comparison type; cannot be null.

first - The first expression operand; cannot be null.

type - The type of the variable expression to use as the second expression operand; cannot be null.

name - The name of the variable expression to use as the second expression operand; cannot be null.

Throws:

NullPointerException - If either argument is null.

CompareExpression

public CompareExpression(CompareExpression.Comparison comparison,
                         Expression<? extends E> first,
                         Expression<? extends E> second)

Constructor.

Parameters:

comparison - The comparison type; cannot be null.

first - The first expression operand; cannot be null.

second - The second expression operand; cannot be null.

Throws:

NullPointerException - If either argument is null.

CompareExpression

public CompareExpression(CompareExpression<E> expression)

Copy constructor.

Parameters:

expression - The expression to copy; cannot be null.

Throws:

NullPointerException - If expression is null.

Method Detail

asSymbol

public String asSymbol(Context context)
                throws ExpressionException

Returns x operator y, where x is the symbolic representation of the first expression operand, y of the the second, and operator is the operator used for the comparison.

Specified by:

asSymbol in interface Expression<Boolean>

Parameters:

context - The context to use; never null.

Returns:

The symbolic representation; never null.

Throws:

ExpressionException - If the symbol cannot be generated.

See Also:

Expression.contains(Expression)

copy

public CompareExpression<E> copy()

Description copied from interface: Expression

Copies this expression.

Unlike Expression.asSymbol(Context), copying cannot handle cyclic expression references!

Specified by:

copy in interface Expression<Boolean>

Specified by:

copy in interface Copyable<Expression<Boolean>>

Returns:

A copy of this expression; never null.

evaluate

public Boolean evaluate(Context context)
                 throws ExpressionException

Description copied from interface: Expression

Evaluates this expression and returns the result.

There is no guarantee that the evaluation of this expression will terminate!

Specified by:

evaluate in interface Expression<Boolean>

Parameters:

context - The context to use; cannot be null.

Returns:

The result of the evaluation; never null.

Throws:

ExpressionException - If the evaluation fails.

name

public final String name()

Description copied from interface: Expression

The stand-alone symbol name for this expression.

Specified by:

name in interface Expression<Boolean>

Returns:

compare

toString

public String toString()

Description copied from class: AbstractExpression

Returns the string representation of this expression.

Specified by:

toString in interface Expression<Boolean>

Overrides:

toString in class BinaryExpression<E extends Comparable<? super E>,Boolean>

Returns:

The string representation; never null.