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Evaluating Software Design Patterns — the "Gang of Four" patterns implemented in Java 6 |
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java.lang.Object dk.rode.thesis.interpreter.AbstractExpression<E> dk.rode.thesis.interpreter.BinaryExpression<E,E> dk.rode.thesis.interpreter.ConditionalExpression<E>
E
- The type of value the evaluation of this expression
produces.@Participant(value="NonTerminalExpression") public class ConditionalExpression<E>
A conditional expression represents an if-then-else expression.
Nested Class Summary |
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Nested classes/interfaces inherited from interface dk.rode.thesis.interpreter.Expression |
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Expression.SymbolIdiom |
Field Summary | |
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private Expression<Boolean> |
condition
The condition in form of an expression that returns a Boolean value when evaluated. |
Fields inherited from class dk.rode.thesis.interpreter.BinaryExpression |
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first, second |
Constructor Summary | |
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ConditionalExpression(ConditionalExpression<E> expression)
Copy constructor. |
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ConditionalExpression(Expression<Boolean> condition,
Expression<? extends E> first,
Expression<? extends E> second)
Constructor. |
Method Summary | |
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String |
asSymbol(Context context)
Returns {@code (c ? |
boolean |
contains(Expression<?> expression)
Returns true if this expression is or contains the expression supplied as expression , false if not. |
ConditionalExpression<E> |
copy()
Copies this expression. |
E |
evaluate(Context context)
Evaluates this expression and returns the result. |
String |
name()
The stand-alone symbol name for this expression. |
List<Expression<?>> |
operands()
Returns the expression operands used by this expression, in order. |
String |
toString()
Returns the string representation of this expression. |
Methods inherited from class dk.rode.thesis.interpreter.BinaryExpression |
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asSymbol, asSymbol |
Methods inherited from class dk.rode.thesis.interpreter.AbstractExpression |
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equals, hashCode |
Methods inherited from class java.lang.Object |
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clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
Field Detail |
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private final Expression<Boolean> condition
Boolean
value when evaluated. Never null.
Constructor Detail |
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public ConditionalExpression(ConditionalExpression<E> expression)
expression
- The expression to copy; cannot be null.
NullPointerException
- If expression
is null.public ConditionalExpression(Expression<Boolean> condition, Expression<? extends E> first, Expression<? extends E> second)
condition
- The condition expression; cannot be null.first
- The first expression operand; cannot be null.second
- The second expression operand; cannot be null.
NullPointerException
- If either expression is null.Method Detail |
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public String asSymbol(Context context) throws ExpressionException
(c ? x : y)
, where c
is the symbolic
representation of the condition, x
of the first
expression operand, and y
of the the second.
asSymbol
in interface Expression<E>
context
- The context to use; never null.
ExpressionException
- If the symbol cannot be generated.Expression.contains(Expression)
public boolean contains(Expression<?> expression)
Expression
expression
, false if not. The test is performed using identity (==).
Unlike Expression.asSymbol(Context)
, querying for containment
cannot handle cyclic expression references!
contains
in interface Expression<E>
contains
in class AbstractExpression<E>
expression
- The expression to test; cannot be null.
expression
is this expression or
contained within this expression, false if not.Expression.asSymbol(Context)
,
Context.touch(Expression)
public ConditionalExpression<E> copy()
Expression
Unlike Expression.asSymbol(Context)
, copying
cannot handle cyclic expression references!
copy
in interface Expression<E>
copy
in interface Copyable<Expression<E>>
public E evaluate(Context context) throws ExpressionException
Expression
There is no guarantee that the evaluation of this expression will terminate!
evaluate
in interface Expression<E>
context
- The context to use; cannot be null.
ExpressionException
- If the evaluation fails.public final String name()
Expression
name
in interface Expression<E>
conditional
public List<Expression<?>> operands()
Expression
Modifying the returned list will not affect this expression.
operands
in interface Expression<E>
operands
in class BinaryExpression<E,E>
public String toString()
AbstractExpression
toString
in interface Expression<E>
toString
in class BinaryExpression<E,E>
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Gunni Rode / rode.dk | ||||||||
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