@@ -17,12 +17,7 @@ import figures.Group; | |||
import java.awt.Rectangle; | |||
aspect Answer4a { | |||
private Rectangle wholeCanvas = | |||
new Rectangle(FigureElement.MIN_VALUE, FigureElement.MIN_VALUE, | |||
FigureElement.MAX_VALUE - FigureElement.MIN_VALUE, | |||
FigureElement.MAX_VALUE - FigureElement.MIN_VALUE); | |||
Rectangle around(): execution(Rectangle Group.getBounds()) { | |||
return wholeCanvas; | |||
return FigureElement.MAX_BOUNDS; | |||
} | |||
} |
@@ -20,7 +20,8 @@ aspect Answer4b { | |||
private Rectangle Group.cache = null; | |||
Rectangle around(Group g): | |||
execution(Rectangle Group.getBounds()) && this(g) { | |||
execution(Rectangle Group.getBounds()) && this(g) | |||
{ | |||
if (g.cache == null) { | |||
g.cache = proceed(g); | |||
} |
@@ -20,7 +20,8 @@ aspect Answer4c { | |||
private Rectangle Group.cache = null; | |||
Rectangle around(Group g): | |||
execution(Rectangle Group.getBounds()) && this(g) { | |||
execution(Rectangle Group.getBounds()) && this(g) | |||
{ | |||
if (g.cache == null) { | |||
g.cache = proceed(g); | |||
} |
@@ -22,12 +22,14 @@ aspect Answer4d { | |||
private Group Point.enclosingGroup = null; | |||
before(Point p, Group g): | |||
execution(void add(FigureElement)) && args(p) && target(g) { | |||
execution(void add(FigureElement)) && args(p) && target(g) | |||
{ | |||
p.enclosingGroup = g; | |||
} | |||
Rectangle around(Group g): | |||
execution(Rectangle Group.getBounds()) && this(g) { | |||
execution(Rectangle Group.getBounds()) && this(g) | |||
{ | |||
if (g.cache == null) { | |||
g.cache = proceed(g); | |||
} |
@@ -22,12 +22,14 @@ aspect Answer4e { | |||
private Group FigureElement.enclosingGroup = null; | |||
before(FigureElement p, Group g): | |||
execution(void add(FigureElement)) && args(p) && target(g) { | |||
execution(void add(FigureElement)) && args(p) && target(g) | |||
{ | |||
p.enclosingGroup = g; | |||
} | |||
Rectangle around(Group g): | |||
execution(Rectangle Group.getBounds()) && this(g) { | |||
execution(Rectangle Group.getBounds()) && this(g) | |||
{ | |||
if (g.cache == null) { | |||
g.cache = proceed(g); | |||
} |
@@ -17,8 +17,8 @@ import java.awt.*; | |||
import java.awt.geom.*; | |||
public interface FigureElement { | |||
public static final int MIN_VALUE = 0; | |||
public static final int MAX_VALUE = 500; | |||
public static final Rectangle MAX_BOUNDS = | |||
new Rectangle(0, 0, 500, 500); | |||
public abstract void move(int dx, int dy); | |||
@@ -638,50 +638,32 @@ handle those points contained in Lines and Boxes only if time permits. | |||
<h3>a. Make a constant override</h3> | |||
<p> <strong>Problem:</strong> Pass <code>tests.Test4a</code>.</p> | |||
<p> <strong>Tools:</strong> <code>around</code>, | |||
<code>FigureElement.MAX_BOUNDS</code> | |||
</p> | |||
<p> <code>Group</code>'s <code>getBounds()</code> method could be | |||
understood to be a conservative approximation of the bounding box of a | |||
group. If that is true, then it would be a legal (and much faster) | |||
implementation of <code>getBounds()</code> to simply always return a | |||
rectangle consisting of the entire canvas, that is | |||
rectangle consisting of the entire canvas. The entire canvas is returned | |||
by the static method <code>FigureElement.MAX_BOUNDS</code>. | |||
</p> | |||
<blockquote><PRE> | |||
new Rectangle(FigureElement.MIN_VALUE, FigureElement.MIN_VALUE, | |||
FigureElement.MAX_VALUE - FigureElement.MIN_VALUE, | |||
FigureElement.MAX_VALUE - FigureElement.MIN_VALUE) | |||
</PRE></blockquote> | |||
<p> Write an aspect to implement this change. You can override | |||
<code>Group</code>'s <code>getBounds()</code> method entirely with | |||
around advice intercepting the method. | |||
</p> | |||
<p> Your code should pass the JUnit test case | |||
<code>tests.Test4a</code> with this change. | |||
</p> | |||
<h3>b. Make a constant cache</h3> | |||
<p> <strong>Answer: </strong> | |||
<p> <strong>Problem:</strong> Pass <code>tests.Test4b</code>. | |||
</p> | |||
<blockquote><PRE> | |||
package answers; | |||
import figures.*; | |||
import java.awt.Rectangle; | |||
aspect Answer4a { | |||
private Rectangle wholeCanvas = | |||
new Rectangle(FigureElement.MIN_VALUE, FigureElement.MIN_VALUE, | |||
FigureElement.MAX_VALUE - FigureElement.MIN_VALUE, | |||
FigureElement.MAX_VALUE - FigureElement.MIN_VALUE); | |||
Rectangle around(): execution(Rectangle Group.getBounds()) { | |||
return wholeCanvas; | |||
} | |||
} | |||
</PRE></blockquote> | |||
<h3>b. Make a constant cache</h3> | |||
<p> <strong>Tools:</strong> <code>private Rectangle Group.mumble;</code> | |||
</p> | |||
<p> Instead of making the (very) conservative approximation of | |||
<code>getBounds()</code> from part (a), write an aspect instead that | |||
@@ -693,25 +675,27 @@ call. </p> | |||
<p> <em>Hint: You can use an inter-type declaration to keep some | |||
state for every <code>Group</code> object.</em> </p> | |||
<p> Your code should pass the JUnit test case | |||
<code>tests.Test4b</code> with this change. | |||
</p> | |||
<h3>c. Invalidate, part 1</h3> | |||
<p> <strong>Problem:</strong> Pass <code>tests.Test4c</code>. | |||
</p> | |||
<p> <strong>Tools:</strong> <code>before</code> | |||
</p> | |||
<p> While caching in this way does save computation, it will lead to | |||
incorrect bounding boxes if a <code>Group</code> is ever moved. | |||
Change your aspect so that it invalidates the cache whenever the | |||
<code>move()</code> method of <code>Group</code> is called. | |||
</p> | |||
<p> Your code should pass the JUnit test case | |||
<code>tests.Test4c</code> with this change. | |||
</p> | |||
<h3>d. Invalidate, part 2</h3> | |||
<p> <strong>Problem:</strong> Pass <code>tests.Test4d</code>.</p> | |||
<p> <strong>Tools:</strong> <code>your solution to 3c</code></p> | |||
<p> Of course, part (c) didn't really solve the problem. What if a | |||
<code>Point</code> that is part of a <code>Group</code> moves? | |||
Whenever either of a Point's fields are set it should invalidate the | |||
@@ -720,12 +704,12 @@ modify your invalidation criteria in this way, but note that this is | |||
slightly different than the problem in 3c: Here you care about fields, | |||
where there you cared about method calls. </p> | |||
<p> Your code should pass the JUnit test case | |||
<code>tests.Test4d</code> with this change. | |||
</p> | |||
<h3>e. Invalidate, part 3</h3> | |||
<p> <strong>Problem:</strong> Pass <code>tests.Test4e</code>.</p> | |||
<p> <strong>Tools:</strong> <em>You're on you're own</em></p> | |||
<p> Did you really do part (d) correctly? Run the JUnit test | |||
<code>tests.Test4e</code> to see. If you pass, congratulations, now | |||
go help other people. Otherwise, you have fallen prey to our cruel |
@@ -18,6 +18,7 @@ import junit.framework.*; | |||
public class Test extends TestCase { | |||
public Test(String name) { super(name); } | |||
public Test() {} | |||
public static void main(String[] args) { | |||
junit.textui.TestRunner.run(Test.class); |
@@ -18,21 +18,11 @@ import java.awt.Rectangle; | |||
import junit.framework.*; | |||
public class Test4a extends Test { | |||
Rectangle wholeCanvas = | |||
new Rectangle(FigureElement.MIN_VALUE, FigureElement.MIN_VALUE, | |||
FigureElement.MAX_VALUE, FigureElement.MAX_VALUE); | |||
public Test4a(String name) { super(name); } | |||
public static void main(String[] args) { | |||
junit.textui.TestRunner.run(Test4a.class); | |||
} | |||
public void setUp() { | |||
super.setUp(); | |||
} | |||
public void testGroupBounds() { | |||
assertEquals(g.getBounds(), wholeCanvas); | |||
assertEquals(g.getBounds(), FigureElement.MAX_BOUNDS); | |||
} | |||
} |
@@ -18,17 +18,10 @@ import java.awt.Rectangle; | |||
import junit.framework.*; | |||
public class Test4b extends Test { | |||
public Test4b(String name) { super(name); } | |||
public static void main(String[] args) { | |||
junit.textui.TestRunner.run(Test4b.class); | |||
} | |||
public void setUp() { | |||
super.setUp(); | |||
} | |||
public void testBasicEquality() { | |||
assertTrue(g.getBounds() == g.getBounds()); | |||
} | |||
@@ -58,12 +51,9 @@ public class Test4b extends Test { | |||
public void testNotWholeCanvas() { | |||
assertTrue("bounds for this group should not be the whole canvas", | |||
g.getBounds().getWidth() < | |||
(FigureElement.MAX_VALUE - FigureElement.MIN_VALUE)); | |||
g.getBounds().getWidth() < FigureElement.MAX_BOUNDS.getWidth()); | |||
assertTrue("bounds for this group should not be the whole canvas", | |||
g.getBounds().getHeight() < | |||
(FigureElement.MAX_VALUE - FigureElement.MIN_VALUE)); | |||
g.getBounds().getHeight() < FigureElement.MAX_BOUNDS.getHeight()); | |||
} | |||
} | |||
@@ -18,17 +18,10 @@ import java.awt.Rectangle; | |||
import junit.framework.*; | |||
public class Test4c extends Test { | |||
public Test4c(String name) { super(name); } | |||
public static void main(String[] args) { | |||
junit.textui.TestRunner.run(Test4c.class); | |||
} | |||
public void setUp() { | |||
super.setUp(); | |||
} | |||
public void testBasicEquality() { | |||
assertTrue(g.getBounds() == g.getBounds()); | |||
} |
@@ -25,10 +25,6 @@ public class Test4d extends Test { | |||
junit.textui.TestRunner.run(Test4d.class); | |||
} | |||
public void setUp() { | |||
super.setUp(); | |||
} | |||
public void testBasicEquality() { | |||
assertTrue(g.getBounds() == g.getBounds()); | |||
} |
@@ -25,10 +25,6 @@ public class Test4e extends Test { | |||
junit.textui.TestRunner.run(Test4e.class); | |||
} | |||
public void setUp() { | |||
super.setUp(); | |||
} | |||
public void testBasicEquality() { | |||
assertTrue(g.getBounds() == g.getBounds()); | |||
} |