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Compiler Design

Compiler Design. PROJECT PRESENTATION : COMPILER FOR OBJECTIVE C Group 10. Objective C: An Introduction. The Objective-C language is a strict superset of the standard C language, designed to give C full object-oriented programming capabilities.

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Compiler Design

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  1. Compiler Design PROJECT PRESENTATION : COMPILER FOR OBJECTIVE C Group 10

  2. Objective C: An Introduction The Objective-C language is a strict superset of the standard C language, designed to give C full object-oriented programming capabilities. The Objective-C model of object-oriented programming is based on sending messages to sovereign objects. An object with method "method" is said to "respond" to the message method. [objmethod:parameter]; Objective-C messages do not need to execute because they are dynamically bound.

  3. Non-C features : • Interfaces and implementations Objective-C requires the interface and implementation of a class be in separately declared code blocks. The interface is put in a header file The actual code is written in @implementation block. • Instantiation This is done by first allocating the memory for a new object and then by initializing it. MyObject * o = [[MyObjectalloc] init] • Protocols An informal protocol is a list of methods which a class can implement.

  4. Dynamic typing An interesting feature of the language is that an object can be sent a message that is not specified in its interface. • Forwarding If message is sent to an object which might not respond to it, it forwards the message on to an object which can respond to it. • Posing Objective-C permits a class to pose for another class within a program, i.e., all messages of the target class are received by the posing class. • Category Categories permit the programmer to add methods to a class and replace an existing method.

  5. History & Evolution • Hybrid between Smalltalk and C. • Created primarily by Brad Cox and Tom Love who began by modifying the C compiler to add some of the capabilities of Smalltalk. • The GNU Objective-C runtime which has been in use since 1993 is the one developed by Kresten Krab Thorup. • Most of Apple's present-day Cocoa API is based on OpenStep interface objects, and is the most significant Objective-C environment being used for active development.

  6. Why better than others? • Objective-C messages do not need to execute because they are dynamically bound. If message is not implemented the code will still compile and run, unlike statically typed languages like C++. • Delegating methods to other objects and remote invocation can be easily implemented using categories and message forwarding. • Instead of using an Enumerator object to iterate through a collection, Objective-C offers the fast enumeration syntax. • Since ObjC is C plus Objects, it's very compatible with C code bases.

  7. Categories allow addition of methods to classes after the class's initial definition. We can redefine an existing method's implementation. • Objective-C has a dynamic run-time. It allows crafting messages at run-time, dynamically creating classes, dynamically adding methods to existing classes, changing method implementations and so on. • ObjC has real, fast, runtime message sending. • #import appends a file only if it has not been already appended, unlike #include.

  8. Progress till now • Lexical Analysis : Completed Tool used : Lex • Syntax Analysis : Almost Completed Tool used : Yacc • Symbol Table : Hash table of an object with attributes -lexeme and token. The hash function we chose is: length(lexeme)%5 All the identifiers go in the SymbolTable and an identifier is inserted only if it is not already present in it. • We initially decided that C++ as our implementation language but now have to convert our Symbol Table implementation to C.

  9. End User commands • Objective-C code is to written in a .m file. • The compiler can be invoked by the following commands: $dawk –h? –d? –p? (-o <target>) <src.m>

  10. Future Plans • We have almost completed parser and testing would be complete before the deadline on 28th. • We have not yet skipped any language feature and we are aiming to keep it that way till the end. • We are not so keen on the optimization. • And we have a strong belief that sticking to future deadlines would ensure successful completion of our project.

  11. Thank You Harshal A. Waghmare Jeet Kumar Nandan Dubey Vishal Agrawal

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