GENERATING JAVA CLASS SKELETON USING A

NATURAL LANGUAGE INTERFACE

Ender ÖZCAN, Şadi Evren ŞEKER, Zeynep İlknur KARADENİZ

Yeditepe University, Department of Computer Engineering

Artificial Intelligence Laboratory (AR+I)

26 Ağustos Yerleşkesi Kayışdağı/İstanbul

Turkey

Abstract. An intelligent natural language interface based on Turkish Language

is designed for creating Java class skeleton, listing the class and its members.

This interface is developed as a part of a project named as TUJA, a tool for

producing Java programs using Turkish sentences. Turkish sentences are

converted into instances of schemata, representing classes and their members.

Concept hierarchies are utilized for building the classes and their hierarchical

representation for Java class skeleton generation. In this paper, the details of the

design and the implementation are described and a sample run is provided.

1 Introduction

Programming languages are machine processible, precise and mostly unambiguous

with predefined syntax and semantics. Still, a novice programmer spends a lot of

effort in learning syntactic rules and at the same time developing general

programming skills. Even an experienced programmer may face the same problems,

if the programming language is a new one. On the other hand, natural languages are

more declarative, flexible, powerful and richer, being useful even for occasional

users. Also, the programmer may not know the language used in the resources, such

as books, to learn a new programming language.

There are visual tools for creating object oriented designs, furthermore, generating

Java/C++ skeletal programs, such as Rational Rose (an IBM product). Turkish to Java

(TUJA) is a natural language processing (NLP) application, designed with two modes

of operation, where each mode is to be implemented as a phase. First phase involves

in building an interface for creating a skeletal Java program, including all classes,

their attributes (data) and prototypes of member methods of each class. Second phase

involves in enlarging the functionality of the same interface to convert each skeletal

class into full Java programs by allowing users to express them in Turkish sentences.

In this paper, details of the first phase of TUJA projects are described. TUJA accepts

Turkish sentences, describing a class, a member method or a member attribute of a

class, using a conversational front end. Then the input is fed into an augmented

transition network (ATN) 1 for parsing and semantic analysis. At the end of this

process knowledge database is updated using the current command. Knowledge is

ÖZCAN E., Evren ¸SEKER ¸S. and Ä

rlknur KARADENÄ

rZ Z. (2004).

GENERATING JAVA CLASS SKELETON USING A NATURAL LANGUAGE INTERFACE.

In Proceedings of the 1st International Workshop on Natural Language Understanding and Cognitive Science, pages 126-134

DOI: 10.5220/0002683301260134

 SciTePress

represented using schemata. At any instant, the user can ask TUJA to produce the

Java skeletal code, saving it into a file. Architecture of TUJA is illustrated in Fig. 1.

Fig. 1. Framework of TUJA.

2 Natural Language Processing using Turkish

NLP consists of 5 layers: morphology, syntax, semantics, pragmatics and phonetics

(2, 10). Due to our scope and purposes we have limited our work in morphology and

especially in syntax and semantics layers.

Turkish is one of the most widely spoken languages in the world, distributed over a

large geographical region in Europe and Asia, as pointed in 6 based on United

Nations sources. Note that there are many Turkish dialects, such as the Azeri, the

Türkmen, the Tartar, the Uzbek, the Baskurti, the Nogay, the Kyrgyz, the Kazakh, the

Yakuti, the Cuvas. Turkish is similar to Mongolian, Manchu-Tungus, Korean

belonging to the same family of languages: the Altaic branch of the Ural-Altaic

family. There are 29 letters based on the Latin alphabet in Turkish, including 8

vowels. There is a vowel harmony in Turkish words. Words do not have gender. In

Turkish sentences adjectives precede nouns. It is unfortunate that there are a few

number of natural language applications (1, [3],[5], 7-[9]) based on Turkish language

due to its agglutinative nature.

The same suffix can be attached to different words in different ways. Sometimes, a

vowel or a consonant towards the end of a word may deform. For this reason,

morphological analysis in Turkish is not straightforward as shown in Table 1.

Table 1. Some deformation examples in Turkish words due to suffixes.

Word (Stem) + Suffixes

görünürlerde (in sight) (gör) + ün + ür + ler +de (görmek - to see)

ağaca (towards the tree) (ağaç) + a (tree)

ağlıyor (he/she/it is crying) (ağla) + yor (ağlamak – to cry)

Morpheme

Database

TUJA I

User Interface

Knowledge

Database

IS-A

Hierarchy

Java

Code

Generato

bute

ass

Hierarchy

User

ata

ATN Manager

127

There are seven morphological categories in Turkish: nouns, private nouns,

compound nouns, adjectives, verbs, adverbs and conjunctions. In Turkish, another

difficulty rises due to the syntax. Sentences with different syntaxes using the same

words are allowed in Turkish (free world-order), yielding a group of sentences with

the same meaning as illustrated in Table 2. The common property of all these three

sentences is a feature of Turkish language, that is, the verb appears at the end of the

sentences.

Table 2. Turkish sentences with different syntax having the same meaning.

Sentence (I gave the book to the child)

Çocuğa kitabı ben verdim

Çocuğa ben kitabı verdim

Ben çocuğa kitabı verdim

3 Morphology, Syntax and Semantics

It is assumed that Object Oriented Programming terminology is known. Morphology

of TUJA is inherited from a previous project, TUSA [6] based on PROLOG. The

sentences are categorized into four different groups: (a) Class Declaration Sentences,

(b) Attribute Declaration Sentences, (c) Method Declaration Sentences, (d) Relation

Declaration Sentences. All possible syntax types are supported to create an abstract

model representing the classes. An augmented transition network (ATN) is developed

for TUJA interface. HASA relationship is used for composing classes and ISA

relationship is used for building the class hierarchy. TUJA assumes that in general, a

noun in a sentence refers to a class, interface, or an attribute (primitive or an object),

and a verb refers to a method.

Class

diye

(so that)

ifi

olan

(called)

Nominalverb

ifi

Nou

bir

(a(n))

Nou

bir

(a(n))

•

nokta diye bir kavram

vardır. (there exists a

concept called point)

• şekil bir kuraldır.

(shape is a rule)

• liste soyut bir kavramdır.

(list is an abstract concept)

• liste diye soyut bir

kavram vardır. (there exists

an abstract concept called

list)

• bağlı liste soyut bir

kavramdır. (link list is an

abstract concept)

(a)

(b)

Fig. 2 (a) ATN, (b) some sample sentences for class declaration sentences.

128

3.1 Class Declaration Sentences

This group of sentences is used to create a new class or name an existing class as

shown in Fig. 2b. Note that declaration of abstract classes; Java interfaces are also

supported.

Part of the ATN for TUJA detects class declarations as illustrated in Fig. 2a.

Nominalverb component alone and combined with the Modifier component in the

ATN determines whether a class is abstract or not.

•

nokta x adlı korunan

tamsayıya sahiptir (point has

a protected integer named x)

• nokta y adlı korunan

tamsayıya sahiptir (point has

a protected integer named y)

• çember çap adlı korunan

çifte sahiptir (circle has a

protected double named

radius)

• liste kuralı yeni uzunluk adlı

tamsayıya sahiptir (list rule

has an integer named new

length)

• sıra soyut kavramı eski

uzunluk adlı tamsayıya

sahiptir (the abstract concept

named queue has an integer

named old length)

• her otomobil renge modele

markaya sahiptir (all

automobiles has color, model

and brand)

• bütün otomobil kavramları

rengi markası modeli ile

tanımlanabilir (all automobiles

can be defined by color, brand

and models

)

Noungroup(none)

Attribute

her

(every)

bütün

(all)

Nou

ifi

bütün

(all)

Noungroup

(-e)

Verb

ile

(with)

Verb

Nominalverb

her

(every)

Noungroup

(-den)

Noungroup

(-i or none)

(a)

(b)

Fig. 3 (a) ATN, (b) sample sentences for attribute (HASA relationship) declaration sentences.

129

3.2 Attribute Declaration Sentences

This group of sentences is used to define the attributes of an existing class or to define

a new class with specified attributes as shown Fig. 3. HAS relation represents the

inclusion relationship, determining the elements included by an object. In other

words, HAS relation is used to define the members of a class. Part of the ATN for

TUJA detects attribute declarations as shown in Fig. 3.

3. 3 Method Declaration Sentences

This group of sentences is used to define the methods of predefined classes or to

define a new class with specified member methods as shown in Fig. 4b. Part of the

ATN for TUJA determines method declarations as shown in Fig. 4a.

Fig. 4. (a) ATN, (b) sample sentences for method declaration sentences.

3.4 Hierarchy Declaration Sentences

Our knowledge about the world can be organized hierarchically using a naming

convention for each class including a set of objects with common properties. For

Noungroup

(-den

condition

)

Nou

Return

only

Both

Parameter

&Return

Both

Void

Parameter

only

Nou

Method

•

şekil kuralı çift döndüren alan

metoduna sahiptir (shape rule has an

area method, which returns double)

• şekil kuralı çift döndüren hacim

metoduna sahiptir (shape rule has a

volume method which returns double)

• insan ekmek yer (man eats bread)

• liste sıralanabilir (list can be sorted)

• liste eleman arar (list searches an

element)

• liste sona eleman ekler (list inserts an

element to the end)

• liste tamsayı döndüren yeni uzunluk

adlı uzunluk parametreli ölç korunan

metoduna sahiptir (list has a protected

size method, who returns an integer and

has a size parameter named new size)

• liste eleman döndüren başdan çıkar

genel metoduna sahiptir (list has a

remove from beginning method which

returns an element)

(a)

(b)

130

example, cows and horses represent two different set of objects, and mammals

contains both of them as a super class. Note that cows and horses carry the properties

of mammals. Similarly objects defined by a formal object oriented programming

language can be organized hierarchically, forming a class hierarchy, supporting

inheritance.

ISA hierarchy is used to represent inclusion relationship between classes. A class can

be defined to be a subset of two or more super classes (multiple inheritance). Since

the goal is generating JAVA class skeletal codes and JAVA does not support multiple

inheritance, such sentences are converted into JAVA class templates assuming that at

least one of them is a class and the rest are interfaces. Part of the ATN for TUJA

detects relation declarations as shown in Fig. 5a.

Fig. 5. (a) ATN, (b) sample sentences for hierarchy (ISA relationship) declaration sentences.

4 Knowledge Database

Knowledge database keeps all valuable data resulting from the object oriented design,

retrieved from sentences, necessary to generate the skeleton of each class. After

parsing and understanding a sentence, TUJA converts the input into an appropriate

instance of a schema or modifies an existing schema in the knowledge database.

PROLOG provides the advantage of keeping the instances in a relational database

form. There are three basic schemata, each generated by the corresponding ATN: (a)

Method Schema, (b) Attribute Schema, (c) Class/Interface Schema. Furthermore, ISA

hierarchy is embedded into the class schema.

Details of each schema are shown in Table 3. ISA hierarchy is supported using,

InheritedClass slot of the class schema, a pointer to the parent class. ClassSpecifier

slot keeps the access specifier of the related class (e.g. public, private, protected).

Nou

bir

(a(n))

her

(every)

Nominalverb

Birer

(one each)

bütün

(all)

Nou

Hierarch

•

her nokta bir şekildir

(every point is a shape)

• bütün çemberler bir

noktadır (all circles are

point)

• silindir bir çemberdir

(cylinder is a circle)

(a)

(b)

131

Table 3. Schemata details supported by TUJA.

class/interface( ClassName, InheritedClass, ListofAttributes, ListofMethods,

ListofImplementedIntefaces, ClassSpecifier )

attribute( AttributeName, AttributeType, AttributeSpecifier )

method( MethodName, ListofParameters, ListofReturnValues,MethodSpecifier )

4.1 Method Schema

Besides certain sentences, such as, “get X as input and return Y value”, there are

uncertainties for the verb in some sentences like “Routers send messages”. In this

specific example, it is obvious that the verb “send” gets “message” as a parameter. On

the other hand, there might be an input, such as, “Routers generate error message”,

where the verb of the sentence “generate” should return “error message” as an object.

In order to retrieve the prototype of a method fully, verbs in Turkish are categorized

as follows (Table 4):

− Consuming verbs identify methods requiring a list of parameters with no return

value

− Producing verbs identify methods requiring no parameters and returning a value

− Unaffecting verbs identify methods requiring no parameters with no return value

− Modifying verbs identify methods requiring a list of parameters and returning a

value

Table 4. Verb categories supported by TUJA to determine method parameters and return

values.

Verb Type Example Parameters Return

Consuming “İnsanlar ekmek yer”

(Human-beings eat bread)

Ekmek

(bread)

Void

Producing “At tay doğurur”

(A horse gives birth to a foal)

Void Tay

(foal)

Unaffecting “At hızlanır”

(The horse speeds up)

Void Void

Modifying “İnsan undan sudan ekmek pişirir”

(Man cooks bread from flour and water)

Un, su

(Flour, water)

Ekmek

(bread)

There is a special case for modifying verbs: “İnsan kuş avlar” (Man hunts for bird).

The question, “what is the result of the hunt?”, can be answered as “bird”, just as the

question, “what does man hunt for?”. Both return value and parameter of the method

are the same. ATN parses Turkish sentences, and if a sentence defines a method,

nouns are identified as a list of parameters or a list of return values of the related

method.

In Java, a method may have only one return value, but our sentence might contain

more than one return values. For example, “insan undan sudan ekmek börek pişirir”

(man cooks bread and pastry from flavor and water) consist of two return values;

132

bread and pastry. In such cases, TUJA produces two functions, one with return type of

bread, second with return type of pastry with different function names.

5 Code Generation

User can trigger the code generation at any time by using the “kodla”(code) command

at the prompt. TUJA code generator is a Prolog based predicate to java code

translator. Schemata, kept in the memory all the time, are processed and the code is

generated. This way of approach provides flexibility to handle any changes in the

declarations.

TUJA uses its defaults in the case of obscurities in access modifiers, getter/setter

methods and interface rules. TUJA generates all member methods as public and all

member attributes as private, generating public getter and setter methods for each

attribute during the code generation.

TUJA inherits all the member methods of an interface, generating each prototype

of the method as a member inside the class implementing it.

Following output is produced after feeding the input sentences in Figures 2b, 3b,

4b, 5b, formatted as bold. This example is the class skeleton of the Java codes

provided as a case study in 4:

class Point implements Shape{

protected int x;

public int getX(){return x;}

public void setX(int x){this.x=x;}

protected int y;

public int getY(){return y;}

public void setY(int y){this.y=y;}

public double volume(){}

public double area(){}

}

class Circle extends Point{

protected double radius;

public double getRadius(){return radius;}

public void setRadius(double radius){this.radius=radius;}

public double area(){}

}

class Cylinder extends Circle{

protected double heigth;

public double getHeigth(){return heigth;}

public void setHeigth(double heigth){this.heigth=heigth;}

public double volume(){}

public double area(){}

}

interface Shape{

public double volume(){}

public double area(){}

}

133

6 Conclusion

TUJA is a project for creating skeletal Java codes using our natural language, Turkish.

This project will be extended further allowing users to enter Turkish sentences,

producing the body of each member method. Yet, there are some issues to be attacked

before this next phase. For example, nested class declarations are not allowed. By the

time being, TUJA does not handle the cases, if an interface extends another.

Supporting punctuations and anaphora resolution will make TUJA to accept more

natural sentences.

At the best of our knowledge, this is the first time verbs are categorized for

retrieving possible parameters and return values from the sentences. TUJA is useful

for experienced programmers. Novice programmers should be familiar with at least

object oriented concepts. Since the code generator and knowledge database is

separate, TUJA can be easily modified to support other object oriented or object

based programming languages. Adapting the system to use a different natural

language requires more effort, necessitating modification of ATN Manager and

morpheme database components of TUJA.

7 Acknowledgement

Special thanks to Prof. Dr. A. C. Cem SAY from Boğaziçi University for providing

the morphological analyzer.

References

1. A. Cetinoglu, Prolog Based Natural Language Processing Infrastructure for

Turkish, M.Sc. Thesis, Bogazici University, 2001

2. M.A. Covington, Natural Language Programming for Prolog Programmers,

(Englewood Cliffs, NJ:Prentice-Hall, 1994)

3. O. N. Darcan, An intelligent database interface for Turkish, M.Sc. Thesis,

Bogazici University, Istanbul, 1991

4. H. M.Deitel, P. J. Deitel, Java: How To Program, 1998, 389-392

5. S. Demir, Improved treatment of word meaning in a Turkish conversational

agent, M.Sc. Thesis, Bogazici University, Istanbul, 2003.

6. M.U.Karakas, E. Inan, Current Status in Turkish Code Table Problem, Bilisim,

Bogazici University, Istanbul, 1996

7. K. Köymen, Prototype DMBS with a Turkish Query Language, University of

Petroleum and Minerals, Dhahran, Saudi Arabia, 1976

8. S.E. Seker, Türkçe Doğal Dil Arayüzlü Bir Kişisel Takvim Programının, Tasarım

ve Kodlamasi, TAINN 2003, Canakkale, Turkey.

9. S.E. Seker, A Personal Assistant with A Natural Language Interface in Turkish,

M.Sc. Thesis, Yeditepe University, Istanbul, 2003.

10. J. Weizenbaum, ELIZA: A Computer Program for the Study of Natural Language

Communication between Man and Machine, ACM Press, NY, USA, 1983, 23-28

11. W. A. Woods, Transition Network Grammars for Natural Language Analysis,

Harvard University, Cambridge, Massachusetts, 1970

134