Explain language processing activities with suitable diagrams?

Answer 1

Language processing activities arise to bridge the ideas of software designer with actual execution on the computer system. Due to the differences between the manners in which a software designer describes the ideas concerning the behavior of software and the manner in which these ideas are implemented in a computer system. The designer expresses the ideas in terms related to the application domain of the software. To implement these ideas, their description has to be interpreted in terms related to theexecution domain of the computer system. We use the term semantics to represent the rules of meaning of a domain, and the term semantic gap to represent the difference between the semantics of two domains. The fundamental language processing activities can be divided into those that bridge the specification gap and those that bridge the execution gap.

· Program Generation Activities

· Program Execution Activities

A program generation activity aims at automatic generation of a program. The source language is a specification language of an application domain and the target language is typically a procedure oriented PL. A program execution activity, organizes this execution of a program written in a PL on a computer system. Its source language could be a procedure-oriented language or a problem oriented language.

o Program Generation

The program generator is a software system which accepts the specification of a program to be generated, and generates a program in the target PL. We call this the program generator domain.The specification gap is now the gap between the application domain and the program generator domain. This gap is smaller than the gap between the application domain and the target PL domain.

Reduction in the specification gap increases the reliability of the generated program. Since the generator domain is close to the application domain, it is easy for the designer or programmer to write the specification of the program to be generated.

Fig. 1.3: Program generator domain

The harder task of bridging the gap to the PL domain is performed by the generator. This would be performed while implementing the generator. To test an application generated by using the generator, it is necessary to only verify the correctness of the specification input to the program generator. This is a much simpler task than ver­ifying correctness of the generated program. This task can be further simplified by providing a good diagnostic (i.e. error indication) capability in the program generator, which would detect inconsistencies in the specification.

It is more economical to develop a program generator than to develop a problem-oriented language. This is because a problem oriented language suffers a very large execution gap between the PL domain and the execution domain, whereas the program generator has a smaller semantic gap to the target PL domain, j which is the domain of a standard procedure oriented language. The execution gap between the target PL domain and the execution domain is bridged by the compiler or interpreter for the PL.

o Program Execution

Two popular models for program execution are

· Translation

· Interpretation

Program Translation

Program translation model bridges the execution gap by translating a program written in a PL, called the source program (SP), into an equivalent program in the machine or assembly language of the computer system, called the target program (TP).