Difference between revisions of "Iterable Immutable List Assignment"

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=Exercise To Revisit=
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In this studio we will complete the <code>EmptyImmutableList</code> and <code>NonEmptyImmutableList</code> implementations from the [[ImmutableList_Assignment|ImmutableList exercise]].
 +
 +
==ImmutableList==
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The [https://www.cse.wustl.edu/~cosgroved/courses/cse425s/spring20/apidocs/immutable/list/core/ImmutableList.html ImmutableList] interface extends [https://docs.oracle.com/javase/8/docs/api/java/lang/Iterable.html Iterable] which has one method: [https://docs.oracle.com/javase/8/docs/api/java/lang/Iterable.html#iterator-- iterator()].
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<nowiki>public interface ImmutableList<E> extends Iterable<E> {
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E head();
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ImmutableList<E> tail();
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boolean isEmpty();
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}</nowiki>
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==Iterable==
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[https://docs.oracle.com/javase/8/docs/api/java/lang/Iterable.html interface java.lang.Iterable<T>]
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#[https://docs.oracle.com/javase/8/docs/api/java/lang/Iterable.html#iterator-- Iterator<T> iterator()]
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==Iterator==
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[https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html interface java.util.Iterator<T>]
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#[https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html#hasNext-- boolean hasNext()]
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#[https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html#next-- T next()]
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=Examples=
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==Using Iterable==
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<youtube>A-rTJTHq5B4</youtube>
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==Implementing Iterable: DOM NodeList==
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<youtube>4ycpqdJ4yb4</youtube>
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=Example=
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{{Example|IterableImmutableListExample|immutable.list.example}}
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 +
The code:
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<nowiki>ImmutableList<Integer> numbers = Lists.brackets(4, 66, 99);
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for (Integer i : numbers) {
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System.out.println(i);
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}</nowiki>
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 +
produces:
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<nowiki>4
 +
66
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99</nowiki>
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=Diagrams=
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==ImmutableList==
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<nowiki>ImList<Char> letters = Lists.brackets('A', 'B', 'C'); </nowiki>
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[[File:ImmutableList_letters.svg|600px]]
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==Initial Iterator State==
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<nowiki>ImList<Char> letters = Lists.brackets('A', 'B', 'C');
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Iterator<Char> iter = letters.iterator(); </nowiki>
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[[File:ImmutableList_iterator.svg|600px]]
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==Iterator State after next()==
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 +
<nowiki>ImList<Char> letters = Lists.brackets('A', 'B', 'C');
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Iterator<Char> iter = letters.iterator();
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if(iter.hasNext()) {
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    char a = iter.next();
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} </nowiki>
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[[File:ImmutableList_iterator_next.svg|600px]]
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==Iterator State after next() next()==
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<nowiki>ImList<Char> letters = Lists.brackets('A', 'B', 'C');
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Iterator<Char> iter = letters.iterator();
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if(iter.hasNext()) {
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    char a = iter.next();
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    if(iter.hasNext()) {
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        char b = iter.next();
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    }
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} </nowiki>
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 +
[[File:ImmutableList_iterator_next_next.svg|600px]]
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==Iterator State after next() next() next()==
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<nowiki>ImList<Char> letters = Lists.brackets('A', 'B', 'C');
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Iterator<Char> iter = letters.iterator();
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if(iter.hasNext()) {
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    char a = iter.next();
 +
    if(iter.hasNext()) {
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        char b = iter.next();
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        if(iter.hasNext()) {
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            char c = iter.next();
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        }
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    }
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} </nowiki>
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 +
[[File:ImmutableList_iterator_next_next_next.svg|600px]]
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=Code To Implement=
 
=Code To Implement=
==Lists==
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==enum EmptyImmutableList==
{{JavaToImplement|Lists|nil<br>cons<br>brackets|immutable.list.assignment}}
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{{JavaToImplement|EmptyImmutableList|iterator|immutable.list.assignment}}
===nil===
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===iterator()===
<nowiki>public static <E> ImmutableList<E> nil()</nowiki>
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return an [https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html Iterator] for the EmptyImmutableList.
  
Analogous to the [http://sml-family.org/Basis/list.html SML List] [http://sml-family.org/Basis/list.html#SIG:LIST.nil:TY nil constructor].
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Question to ask yourself: Does an iterator for an EmptyImmutableList ever have a next?
  
Note: often SML programs use empty brackets <code>[]</code> instead of <code>nil</code>.
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==class NonEmptyImmutableList==
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{{JavaToImplement|NonEmptyImmutableList|iterator|immutable.list.assignment}}
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===iterator()===
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return an [https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html Iterator] for this instance of NonEmptyImmutableList.
  
===cons===
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Note: If you are within an anonymous inner class, the way to get the outer class's this instance is to qualify it with the out class identifier. For example:
<nowiki>public static <E> ImmutableList<E> cons(E head, ImmutableList<E> tail)</nowiki>
 
===brackets===
 
  <nowiki>@SafeVarargs
 
public static <E> ImmutableList<E> brackets(E... elements)</nowiki>
 
  
==DefaultImmutableList==
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<nowiki>NonEmptyImmutableList.this</nowiki>
{{JavaToImplement|DefaultImmutableList|head<br>tail<br>isEmpty<br>iterator|immutable.list.assignment}}
 
===default constructor===
 
===head and tail constructor===
 
===head===
 
===tail===
 
===isEmpty===
 
===iterator===
 
  
 
=Test=
 
=Test=
{{TestSuite|ListsTestSuite|immutable.list.assignment}}
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{{TestSuite|IterableAssignmentTestSuite|immutable.list.util.exercise}}
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:{{TestSuite|ImmutableListIteratorMethodTestSuite|immutable.list.util.exercise}}

Latest revision as of 19:05, 24 April 2022

Exercise To Revisit

In this studio we will complete the EmptyImmutableList and NonEmptyImmutableList implementations from the ImmutableList exercise.

ImmutableList

The ImmutableList interface extends Iterable which has one method: iterator().

public interface ImmutableList<E> extends Iterable<E> {
	E head();
	ImmutableList<E> tail();
	boolean isEmpty();
}

Iterable

interface java.lang.Iterable<T>

  1. Iterator<T> iterator()

Iterator

interface java.util.Iterator<T>

  1. boolean hasNext()
  2. T next()

Examples

Using Iterable

Implementing Iterable: DOM NodeList

Example

class: IterableImmutableListExample.java Presentation icon-72a7cf.svg
package: immutable.list.example
source folder: src/main/java

The code:

ImmutableList<Integer> numbers = Lists.brackets(4, 66, 99);
for (Integer i : numbers) {
	System.out.println(i);
}

produces:

4
66
99

Diagrams

ImmutableList

ImList<Char> letters = Lists.brackets('A', 'B', 'C'); 

ImmutableList letters.svg

Initial Iterator State

ImList<Char> letters = Lists.brackets('A', 'B', 'C');
Iterator<Char> iter = letters.iterator(); 

ImmutableList iterator.svg

Iterator State after next()

ImList<Char> letters = Lists.brackets('A', 'B', 'C');
Iterator<Char> iter = letters.iterator();
if(iter.hasNext()) {
    char a = iter.next();
} 

ImmutableList iterator next.svg

Iterator State after next() next()

ImList<Char> letters = Lists.brackets('A', 'B', 'C');
Iterator<Char> iter = letters.iterator();
if(iter.hasNext()) {
    char a = iter.next();
    if(iter.hasNext()) {
        char b = iter.next();
    }
} 

ImmutableList iterator next next.svg

Iterator State after next() next() next()

ImList<Char> letters = Lists.brackets('A', 'B', 'C');
Iterator<Char> iter = letters.iterator();
if(iter.hasNext()) {
    char a = iter.next();
    if(iter.hasNext()) {
        char b = iter.next();
        if(iter.hasNext()) {
            char c = iter.next();
        }
    }
} 

ImmutableList iterator next next next.svg

Code To Implement

enum EmptyImmutableList

class: EmptyImmutableList.java Java.png
methods: iterator
package: immutable.list.assignment
source folder: src/main/java

iterator()

return an Iterator for the EmptyImmutableList.

Question to ask yourself: Does an iterator for an EmptyImmutableList ever have a next?

class NonEmptyImmutableList

class: NonEmptyImmutableList.java Java.png
methods: iterator
package: immutable.list.assignment
source folder: src/main/java

iterator()

return an Iterator for this instance of NonEmptyImmutableList.

Note: If you are within an anonymous inner class, the way to get the outer class's this instance is to qualify it with the out class identifier. For example:

NonEmptyImmutableList.this

Test

class: IterableAssignmentTestSuite.java Junit.png
package: immutable.list.util.exercise
source folder: src/test/java
class: ImmutableListIteratorMethodTestSuite.java Junit.png
package: immutable.list.util.exercise
source folder: src/test/java