April 30, 2004 1 ICE 1341 – Programming Languages (Lecture #18) In-Young Ko Programming Languages (ICE 1341) Lecture #18 Programming Languages (ICE 1341)

April 30, 2004 1 ICE 1341 – Programming Languages (Lecture #18) In-Young Ko

Programming LanguagesProgramming Languages(ICE 1341)(ICE 1341)

Lecture #18Lecture #18 April 30, 2004

In-Young Koiko .AT. icu.ac.kr

Information and Communications University (ICU)


Review of the Previous LecturesReview of the Previous Lectures

The Concept of AbstractionThe Concept of Abstraction Abstract Data TypesAbstract Data Types Design Issues for Abstract Data TypesDesign Issues for Abstract Data Types

Encapsulation MechanismsEncapsulation Mechanisms Support for Information HidingSupport for Information Hiding Primitive OperationsPrimitive Operations

Parameterized Abstract Data TypesParameterized Abstract Data Types Encapsulation ConstructsEncapsulation Constructs Naming EncapsulationsNaming Encapsulations


Software ReuseSoftware Reuse

How can we increase How can we increase software productivitysoftware productivity?? By improving By improving software reusabilitysoftware reusability

How can we improve software reusability?How can we improve software reusability? By supporting By supporting abstractionabstraction mechanisms mechanisms Abstract data types (ADTs)Abstract data types (ADTs) are the units to be are the units to be reusedreused

What are the problems with using ADTsWhat are the problems with using ADTs Needs Needs minor modificationsminor modifications (on both the data type and (on both the data type and

clients) for a new useclients) for a new use Needs a mechanism to Needs a mechanism to relate similar ADTsrelate similar ADTs that are that are

generated from one ADTgenerated from one ADT Any solutions? Any solutions? Inheritance mechanismInheritance mechanism


Examples of Examples of InheritanceInheritance

ListList

addadd(int, Object), (int, Object), getget(int): Object(int): Objectremoveremove(int), (int), clearclear()()sizesize(): int, (): int, containscontains(Object): boolean(Object): boolean

Linked ListLinked List

addadd(int, Object), (int, Object), getget(int): Object(int): Objectremoveremove(int), (int), clearclear()()sizesize(): int, (): int, containscontains(Object): boolean(Object): booleanaddFirstaddFirst(Object), (Object), addLastaddLast(Object)(Object)getFirstgetFirst(): Object, (): Object, getLastgetLast(): Object(): ObjectremoveFirstremoveFirst(), (), removeLastremoveLast()()

VectorVector

addadd(int, Object), (int, Object), getget(int): Object(int): Objectremoveremove(int), (int), clearclear()()sizesize(): int, (): int, containscontains(Object): boolean(Object): booleancapacitycapacity(): int, (): int, setSizesetSize(int)(int)

StackStack

emptyempty(): boolean, (): boolean, toptop(): Object(): Objectpushpush(Object), (Object), poppop(): Object(): Object


Object-Oriented Programming (OOP)Object-Oriented Programming (OOP)

A programming paradigm that centers around A programming paradigm that centers around ““objectsobjects,” which are ,” which are similar to real-world objectssimilar to real-world objects

Programmers see the execution of Programmers see the execution of a program a program as a collection of as a collection of dialoguing objectsdialoguing objects [Wikipedia] [Wikipedia]

OOP languages (OOPL) began in OOP languages (OOPL) began in 1960s1960s with with the the SimularSimular project, which project, which incorporated the incorporated the notions of notions of objects and inheritanceobjects and inheritance

OOPLs: Smalltalk, Ada 95, CLOS, Scheme, OOPLs: Smalltalk, Ada 95, CLOS, Scheme, Eiffel, C++, JavaEiffel, C++, Java


OOP DefinitionsOOP Definitions

CClasseslasses: Abstract data types: Abstract data types OObjectsbjects: Instances of a class: Instances of a class Subclass (Derived Class)Subclass (Derived Class): : A class that inherits A class that inherits

another classanother class SSuperclass uperclass (P(Parent arent CClasslass)):: The class from The class from

which another classwhich another classeses inherit inherit MethodsMethods: : Subprograms that define operations Subprograms that define operations

on objectson objects MMessagesessages: : Calls to methodsCalls to methods (Destination object (Destination object

+ Method name)+ Method name) MMessage essage PProtocol rotocol (M(Message essage IInterfacenterface)): : The The

entire collection of methods of an objectentire collection of methods of an object


Access Control and Overriden MethodsAccess Control and Overriden Methods

Inheritance can be complicated by Inheritance can be complicated by access access controlscontrols to encapsulated entities to encapsulated entities A class can A class can hide entities from its subclasseshide entities from its subclasses A class can A class can hide entities from its clientshide entities from its clients A class can also hide entities frA class can also hide entities fromom its clients while its clients while

allowing its subclasses to see themallowing its subclasses to see them ( (ProtectedProtected))

Besides inheriting methods as is, a class can Besides inheriting methods as is, a class can modify an inherited methodmodify an inherited method The new one The new one overridesoverrides the inherited one the inherited one The method in the parent is The method in the parent is overridenoverriden

* AW Lecture Notes


Examples of Examples of Overriden MethodsOverriden Methods

ListList

addadd(int, Object), (int, Object), getget(int): Object(int): Objectremoveremove(int), (int), clearclear()()sizesize(): int, (): int, containscontains(Object): boolean(Object): boolean

Linked ListLinked List

addadd(int, Object), (int, Object), getget(int): Object(int): Objectremoveremove(int), (int), clearclear()()sizesize(): int, (): int, containscontains(Object): boolean(Object): booleanaddFirstaddFirst(Object), (Object), addLastaddLast(Object)(Object)getFirstgetFirst(): Object, (): Object, getLastgetLast(): Object(): ObjectremoveFirstremoveFirst(), (), removeLastremoveLast()()

VectorVector

addadd(int, Object), (int, Object), getget(int): Object(int): Objectremoveremove(int), (int), clearclear()()sizesize(): int, (): int, containscontains(Object): boolean(Object): booleancapacitycapacity(): int, (): int, setSizesetSize(int)(int)

StackStack

emptyempty(): boolean, (): boolean, toptop(): Object(): Objectpushpush(Object), (Object), poppop(): Object(): Object

Methods that override Methods that override the ones in Listthe ones in List


Kinds of Methods and VariablesKinds of Methods and Variables

There are two kinds of variables in a class:There are two kinds of variables in a class: Class variablesClass variables – belong to a class (e.g., – belong to a class (e.g.,

static variables in Javastatic variables in Java)) Instance variablesInstance variables – belong to an instance– belong to an instance

There are two kinds of methods in a class:There are two kinds of methods in a class: Class methodsClass methods – accept messages to the – accept messages to the

classclass (e.g., (e.g., static methods in Javastatic methods in Java)) Instance methodsInstance methods – accept messages to – accept messages to

objectsobjects

* AW Lecture Notes


Abstract Classes and MethodsAbstract Classes and Methods

Abstract methodAbstract method: : one that does not one that does not include a definition include a definition (it only defines a (it only defines a protocol)protocol)

Abstract classAbstract class is is one that includes at one that includes at least one virtual least one virtual methodmethod

An abstract class An abstract class cannot be cannot be instantiatedinstantiated

public public interfaceinterface ListList { {public boolean add(Object);public boolean add(Object);public boolean remove(Object);public boolean remove(Object);public int size();public int size();public void clear();public void clear();……

}}public public abstract classabstract class AbstractListAbstractList

implements List {implements List {……// Partial implementation of List// Partial implementation of List……

}}public public classclass VectorVector extends extends

AbstractList {AbstractList {……

}} Java


Design Issues for OOPL (1)Design Issues for OOPL (1)

The Exclusivity of ObjectsThe Exclusivity of Objects Everything is an objectEverything is an object - - EElegancelegance and and uniformityuniformity, but , but

slow operations on simple objectsslow operations on simple objects (e.g., float) (e.g., float) Add objects to a complete typing systemAdd objects to a complete typing system – F – Fastast

operations on simple objectsoperations on simple objects, but , but results in a results in a confusing type systemconfusing type system (two kinds of entities (two kinds of entities, e.g., , e.g., IntegerInteger and and intint in Java in Java))

Are Subclasses Subtypes?Are Subclasses Subtypes? Does an “Does an “is-a” relationshipis-a” relationship hold between a parent hold between a parent

class object and an object of the subclass?class object and an object of the subclass? e.g., Ada – e.g., Ada – subtype Small_Int is Integer range 0..100;subtype Small_Int is Integer range 0..100;

* AW Lecture Notes



Type Checking and PolymorphismType Checking and Polymorphism PolymorphismPolymorphism may may requirerequire

dynamic type checkingdynamic type checking of of parameters and the return valueparameters and the return value

Dynamic type checking is Dynamic type checking is costly costly and delays error detectionand delays error detection

If overriding methods are If overriding methods are restricted to having the same restricted to having the same parameter types and return typeparameter types and return type, , the checking can be staticthe checking can be static

e.g., e.g., IntVector v = new IntVector();IntVector v = new IntVector();v.add(new Integer(20));v.add(new Integer(20));

class Vector {class Vector {void void add(Object item)add(Object item) { {

……} …} …

}}class IntegerVector class IntegerVector

extends Vector {extends Vector {void void add(Integer item)add(Integer item) { {

……} …} …

}}class IntVector extends class IntVector extends

IntegerVector {IntegerVector {void void add(int item)add(int item) { {

……} …} …

}} * AW Lecture Notes



Single Single vs.vs. Multiple Inheritance Multiple Inheritance Disadvantages of multiple inheritanceDisadvantages of multiple inheritance::

Language and implementation Language and implementation complexitycomplexity (in (in part due to part due to name collisionsname collisions))

Potential Potential inefficiencyinefficiency - - dynamic binding costs dynamic binding costs moremore with multiple inheritance with multiple inheritance

Allocation and Deallocation of ObjectsAllocation and Deallocation of Objects From where From where are objects allocated?are objects allocated? – In the – In the heap or heap or

stackstack area? area? Is deallocation Is deallocation explicit or implicitexplicit or implicit?? – e.g., Garbage – e.g., Garbage

collectorscollectors* AW Lecture Notes


Object-Oriented Processing of Object-Oriented Processing of XML DataXML Data


XML ProcessorsXML Processors

XML XML DocumentDocument

DatabasesDatabases

XML ParserXML Parser

DTD/ DTD/ XMLSchemaXMLSchema

XSL XSL DescriptionDescription

XSL ProcessorXSL Processor

XML Grammar XML Grammar (Structure) Validation(Structure) Validation

DOM ObjectsDOM Objects

HTML HTML PresentationPresentation

classclass

namename codecode studentsstudents

ProgProg. Lang. Lang ICE1341ICE1341 studentstudent studentstudent

namename bdaybday namename bdaybday

Y.K. KoY.K. Ko 820304820304 D.W. KimD.W. Kim 830512830512

classclass





Parsing EventsParsing Events

DOM APIDOM API SAX APISAX API


XML APIsXML APIs

SAX (Simple API for XML)SAX (Simple API for XML) – – XML-DEVXML-DEV Stream-based Access InterfaceStream-based Access Interface (Sequential Access) (Sequential Access) Notifies an application of a stream of Notifies an application of a stream of parsing eventsparsing events Needs a Needs a Content HandlerContent Handler to handle the parsing to handle the parsing

events (e.g., start and end of an element)events (e.g., start and end of an element) Appropriate to handle a large XML document Appropriate to handle a large XML document

DOM (Document Object Model)DOM (Document Object Model) – – W3CW3C Object-oriented Access Interface Object-oriented Access Interface (Random Access)(Random Access) Builds a Builds a tree of nodestree of nodes based on the structure and based on the structure and

information in an XML documentinformation in an XML document Types of nodes: Types of nodes: DocumentDocument, , ElementElement, , AttrAttr, …, …


DOM RepresentationDOM Representation

classclass





classclass





<class><class> <name><name>Prog. Lang.Prog. Lang.</name></name> <code><code>ICE1341ICE1341</code></code> <students><students>

<student <student id=“20037001”id=“20037001”>> <name><name>Y.K. KoY.K. Ko</name></name> <bday><bday>820304820304</bday></bday> </student></student> <student <student id=“20037002”id=“20037002”>> <name><name>D.W. KimD.W. Kim</name></name> <bday><bday>830512830512</bday></bday> </student></student>

</students></students></class></class>

XML DocumentXML Document DOM RepresentationDOM Representation

Document Document (Root Node)(Root Node)

Elements Elements (Child Nodes)(Child Nodes)

Node Values Node Values (Text Nodes)(Text Nodes)


Java API Hierarchy for DOMJava API Hierarchy for DOM

NodeNode

getChildNodesgetChildNodes(): NodeList(): NodeListgetAttributesgetAttributes(): NamedNodeMap(): NamedNodeMapgetNodeNamegetNodeName(): String(): StringgetNodeValuegetNodeValue(): String(): StringappendChildappendChild(Node)(Node)removeChildremoveChild(Node)(Node)setNodeValuesetNodeValue(String)(String)

AttrAttr

getNamegetName(): String(): StringgetValuegetValue(): String(): StringsetValuesetValue(String)(String)

CharacterDataCharacterData

getDatagetData(): String(): StringgetLengthgetLength(): int(): intsetDatasetData(String)(String)

DocumentDocument

createAttributecreateAttribute(String): Attr(String): AttrcreateElementcreateElement(String): Element(String): ElementcreateTextNodecreateTextNode(String): Text(String): TextgetDocumentElementgetDocumentElement(): Element(): ElementgetElementByTagNamegetElementByTagName(String): NodeList(String): NodeList

ElementElement

getAttributegetAttribute(String): String(String): StringgetTagNamegetTagName(): String(): String

TextText

splitTextsplitText(int): Text(int): Text

CommentComment


An Example of Creating DOM Objects An Example of Creating DOM Objects from an XML Filefrom an XML File

try {try { DocumentBuilderFactoryDocumentBuilderFactory docBuilderFactory = docBuilderFactory =

DocumentBuilderFactory.DocumentBuilderFactory.newInstancenewInstance();(); DocumentBuilderDocumentBuilder docBuilder docBuilder = = docBuilderFactory.docBuilderFactory.newDocumentBuildernewDocumentBuilder();(); DocumentDocument doc = doc =

docBuilder.docBuilder.parseparse(new File("(new File("sample.xmlsample.xml"));")); ElementElement rootEle = rootEle = doc.doc.getDocumentElementgetDocumentElement()();; NodeListNodeList children = rootEle. children = rootEle.getChildNodesgetChildNodes();(); for (int i = 0; i < children.for (int i = 0; i < children.getLengthgetLength(); i++) {(); i++) { NodeNode subEle = children. subEle = children.itemitem(i);(i); … … }}} catch(Exception e) { e.printStackTrace();} catch(Exception e) { e.printStackTrace(); }}


Related MaterialsRelated Materials

W3C Document Object ModelW3C Document Object Model ((www.w3.org/DOM/www.w3.org/DOM/))

A simple way to read an XML file in Java A simple way to read an XML file in Java ((www.developerfusion.com/show/2064/www.developerfusion.com/show/2064/))

Working with XML Working with XML ((java.sun.com/xml/jaxp/dist/1.0.1/docs/tutorial/index.htmljava.sun.com/xml/jaxp/dist/1.0.1/docs/tutorial/index.html))

Java Technology and XML FAQs Java Technology and XML FAQs ((java.sun.com/xml/faq.htmljava.sun.com/xml/faq.html))

Java API Manual Java API Manual ((java.sun.com/j2se/1.4.2/docs/api/java.sun.com/j2se/1.4.2/docs/api/))

See See org.w3c.domorg.w3c.dom and and javax.xml.parsersjavax.xml.parsers XML.org XML.org ((www.xml.orgwww.xml.org))


Final Project – Implementing a Cross Final Project – Implementing a Cross Compiler for the XML-based LanguageCompiler for the XML-based Language

1.1. Use Java’s DOM API to read your sample Use Java’s DOM API to read your sample programprogram written in your XML-based written in your XML-based programming languageprogramming language

2.2. Traverse through the nodes in the DOM Traverse through the nodes in the DOM representation of your sample program, and representation of your sample program, and convert them into another structured convert them into another structured programming languageprogramming language (e.g., Java, C, C++) (e.g., Java, C, C++)

3.3. Compile the resulting programCompile the resulting program with a compiler with a compiler for the target languagefor the target language

4.4. Run the programRun the program to validate that the program to validate that the program has been converted correctlyhas been converted correctly


Final Project – Report & PresentationFinal Project – Report & Presentation

Please submit a report that includes the following Please submit a report that includes the following by by May 28, 2004May 28, 2004 The The input XML programinput XML program (with more than 50 lines) (with more than 50 lines) The The resulting programresulting program in another language in another language Textual description about your Textual description about your cross compiler designcross compiler design Java source codeJava source code of your cross compiler of your cross compiler DiscussionsDiscussions

Explain about the language design decisions that made it easy Explain about the language design decisions that made it easy and efficient to implement the cross compiler and efficient to implement the cross compiler

Explain about the language design decisions that made it Explain about the language design decisions that made it difficult to implement the cross compilerdifficult to implement the cross compiler

Present your language and compiler designs at Present your language and compiler designs at the classes during the classes during the week of May 28ththe week of May 28th

Documents

April 30, 2004 1 ICE 1341 – Programming Languages (Lecture #18) In-Young Ko Programming Languages (ICE 1341) Lecture #18 Programming Languages (ICE 1341)