Metaprogramming is a code that will run in compile time. Macro definition assembly language macro definitions can be predefined and placed in a macro library, or can be included inline with the. The output of the c preprocessor is then fed to the c compiler proper. The program form output by the macro preprocessor can be handed over to an assembler to obtain the target program. Macros allow you to generate code before the compilation. The book adds new material to cover the developments in compiler design and construction over the last. The macro prototype statement declares the name of a macro and the names and kinds of its parameters. It contains well written, well thought and well explained computer science and programming articles, quizzes and practicecompetitive programmingcompany interview questions. Preprocessors typically do macro substitutions, strip comments from compiler. It is called a macro processor because it allows you to define macros, which are brief abbreviations for longer constructs. Depending on the compiler, the preprocessor may be a separate program or it may be integrated into the compiler itself. This directive is a special purpose directive and is used to turn on or off some features. Aug 04, 2016 chapter 3b macro and macro preprocessor design of macro prepropcessor 1.
A macro short for macroinstruction, from greek long in computer science is a rule or. The c preprocessor is not part of the compiler, but is a separate step in the compilation process. But a macro is just a c preprocessor directive only known to the preprocessor itself. C programmingpreprocessor directives and macros wikibooks. Program that processes or analyzes the source code file before given to the compiler tasks performed by preprocessor. These preprocessor attempt to add capabilities to the language by certain amounts to build in macro.
By using a macro in the preceding code, we can demonstrate theres a new code generated from the max macro. The c preprocessor is a macro processor that is used automatically by the c compiler to transform your program before actual compilation. The c preprocessor gcc, the gnu compiler collection. Bestctraining is the leading online and class room training institute in hyderabad, well qualified microsoft training experts will train here. Macros improve expressiveness, concision, abstraction, and language. This macro expands to sequential integral values starting from 0. A macro prototype statement one or more model statements macro preprocessor statements the macro prototype statement declares the name of a macro and the names and kinds of its parameters. A preprocessor may include header files into the program. So far weve talked about declarative macros that expand out to be rust code based upon how they pattern match the rules defined by the macro.
In addition to simple macro replacement it allows evaluation of arbitrary python expressions and execution of python code making pyexpander turing complete. The preprocessor will parse the macro in compile time and bring the new code. This is the source file that was specified on the command line of the preprocessor or c compiler. Define compiler, interpreter, assembler, linker, loader. You should have some familiarity with antlr and the concept of topdown recursive descent parsers. Raja, cse, klu 4 compiler design introduction to compiler a compiler is a program that can read a program in one language the source language and translate it into an equivalent program in another language the target language. This document briefly describes what happens when you compiler and run a program. So below print statement will give us the same result. The gnu make utility in linux comes to your rescue by reading and interpreting a makefile. Apr 14, 2014 a preprocessor basically reads line by line from the input and replicates the line to the output. In other programming languages such as java, you need to use a code generator to fulfill this purpose. The command given above directs the compiler to include the header file standard inputoutput header file from c standard library in this program. Directives are used to make writing source code easier by making it more portable, for instance and to make the source code more understandable.
Chapter 3b macro and macro preprocessordesign of macro. C preprocessor macros work by simple textual substitution at the token, rather than the. The word limit in macro definition is called macro template and 3 is macro expansion. Only the preprocessor sees these directive lines since it deletes them from the code stream after processing them. A preprocessor may allow a user to define macros that are short hands for longer constructs. A preprocessor may include header files into the program text.
This book presents the subject of compiler design in a way thats. In simplistic terms, a c preprocessor is just a text substitution tool and they instruct compiler to do required preprocessing before actual compilation. It can also include macro processing, file inclusion and language extensions. However, the preprocessor operator defined section 4. In addition to the basic capability of building targets from dependents, gnu make includes many features that make it easy for you to express the dependencies and rules for building a target from its dependents. Jan 21, 2017 compiler design introduction lecture 1system programming compiler construction last moment tuitions. It is easy to design a twopass macro processor pass 1. The preprocessor provides a special keywords called preprocessor directives. With these macros, you can tailor your code to create flowdependent code. Macros are treated as a token substitution early in the compilation process. Safe, expressive macros for any language springerlink.
Sunita m dol aher, assistant professor, computer science and engineering department, walchand institute of technology, solapur, maharashtra. Macro definitions are typically located at the start of a program. This means that large or repeating sections of code can be abstracted into a preprocessor macro. Part of the lecture notes in computer science book series lncs, volume 73. Preprocessor news newspapers books scholar jstor february 20 learn how and when to remove this template message. Macros pass 1 and pass 2 flowchart in hindi youtube. A generalpurpose macro processor or general purpose preprocessor is a macro processor that is not tied to or integrated with a particular language or piece of software a macro processor is a program that copies a stream of text from one place to another, making a systematic set of replacements as it does so. Replaces trigraph sequences joins any line with the backslash character into single line divide program into set of tokens expand macroes remove comments and replace it by single space represent the escape sequence by. This preprocessor takes the description of the semantics of a language i. Sometimes they are standalone programs that can be used to process any kind of text. This macro directive can be used in two different ways. Cse304 compiler design notes kalasalingam university. Define compiler, interpreter, assembler, linker, loader, macro.
Typically, from high level source code to low level machine code or object code. Macro and macro preprocessor macro computer science. Macros in the pli language are written in a subset of pli itself. We will give examples regarding this application of macros. Please visit our youtube channel get more free videos. The c preprocessor is not the part of the compiler, but is a separate step in the compilation process. Synopsys made the unfortunate choice with their first design compiler to not implement a preprocessor, and instead created the dreaded pragma. It is called a macro processor because it allows you to definemacros, which are brief abbreviations for longer constructs. This macro expands to the name of the main input file, in the form of a c string constant. For example, this first declaration is a simple replacement macro after this macro any use of the word one in all caps will be replaced by the. Whenever this name is encountered by the compiler the compiler. Print this line will be converted to string by preprocessor. In compile time, the compiler modifies the code as follows.
The macros can be useful for specifying code fragments that only need to run in execution mode or in verification mode. A preprocessor basically reads line by line from the input and replicates the line to the output. What is the function of the preprocessor, compiler, loader. Preprocessor will ignore the spaces before or after the macro argument. The preprocessor interprets a subset of the full pli language to perform source file inclusion, conditional compilation, and macro expansion the preprocessor language has a plilike syntax with preprocessor statements and preprocessor procedures prefixed with a percent symbol %. Compiler design 10 a compiler can broadly be divided into two phases based on the way they compile. Macro definition ll calling a macro ll expansion of macro explained. Macros refers some specific set of instructions that can be used one after another in a same program. About the preprocessor linkedin learning, formerly. The macro preprocessor accepts an assembly program containing definitions and calls and translates it into an assembly program which does not contain any macro definitions and calls. It deals with macroprocessing, augmentation, file inclusion, language extension, etc. C has an integrated preprocessor that operates at the front end of its single pass algorithm. The instructions that the preprocessor parses are called directives and come in two forms. Language processors language processing activities, fundamental of language processing phases and passes of compiler and role of each analyzer.
The preprocessor is a part of the compiler which performs preliminary operations conditionally compiling code. Hence, the macro facility is a preprocessor, which interprets all macro calls into assembly. Pdf a study on language processing policies in compiler design. A preprocessor may allow a user to define macros that are short. Acm conference on programming language design and implementation.
This is a very important point to remember if you are going to use macros instead of functions. The c language standard defines macro expansion in a way that prevents infinite recursion. It does however, help us with providing specific control of compilation from within files, as well as provide macros that can help with code reuse and readability. Analysis phase known as the frontend of the compiler, the analysis phase of the compiler reads the source program, divides it into core parts, and then checks for lexical, grammar, and syntax errors. This type of preprocessor directive tells the compiler to include a file in the source code program.
Preprocessor directives direct the preprocessor on how it should process the source code, and compiler directives direct the compiler on how it should modify internal compiler options. However, one should not forget the fact that text replacement is carried out by the preprocessor, not the compiler. The preprocessor does not know anything about keywords. More details can be found in compilers, principles, techniques, and tools by aho, sethi, and ullman cse 401 book and appendix a of computer organization and design by patterson and hennesey cse 378 book. Is it possible for c preprocessor macros to contain.
This can be useful if you wish to hide a keyword such as const from an older compiler that does not understand it. Because macros are text substitutions, the compiler doesnt see the authors assumptions about. Generally, the preprocessor is actually a separate program that reads the original source file and writes out a new preprocessed source file that can then be. A preprocessor does not do any translation or generation of architecture specific code. The c preprocessor is a simple macro processora ctoc translatorthat conceptually processes the source text of a c program before the compiler proper reads the source program. You can tell the compiler to save the preprocessor output e or ep and then look. Compiler construction tools, parser generators, scanner generators, syntax. A macro is called by writing the macro name in the mnemonic field. The compiler knows everything about a function because it is part of the c grammar and it is parsed and being kept in the parse tree.
Macros are a piece of code in a program which is given some name. If the line is a preprocessing statement, then it performs the preprocessing directives. Variables or macros in the gnu make utility dummies. A macro processor is a program that copies a stream of text from one place to another, making a systematic set of replacements as it does so. Preprocessor directives compilation with gcc and gnu. A compiler is a computer program or a set of programs that transforms source code written in a programming language the source language into another computer language the target language. M4 and the htm4l macros work in a very similar way. Whenever this name is encountered by the compiler the compiler replaces the name with the actual piece of code. Understand the basic concept of compiler design, and its different phases which will be helpful to construct new tools like lex, yacc, etc. These pages lists various predefined compiler macros that can be used to identify standards, compilers, operating systems, hardware architectures, and even basic runtime libraries at compiletime. Compiler design introduction lecture 1system programming. Feb 27, 20 download java macro preprocessor for free.
All code discussed in this article is known to work on antlr2. A procedural macro is a plugin written in rust that is compiled and loaded by the compiler to produce arbitrary rust code as its output. A preprocessor, generally considered as a part of compiler, is a tool that produces input for compilers. They are available with the same meanings regardless of the machine or operating system on which you are using gnu c or gnu fortran. Macro processors are often embedded in other programs, such as assemblers and compilers. The pli preprocessor is the preprocessor for the pli computer programming language. Preprocessor programs provides preprocessors directives which tell the compiler to preprocess the source code before compiling.
The compiler proper consumes the clean output of the preprocessor. In computer science, a preprocessor is a program that processes its input data to produce. Unit i introduction language processing, structure of a compiler the evaluation of programming language, the science of building a compiler application of compiler technology. The c preprocessor, often known as cpp, is a macro processor that is used automatically by the c compiler to transform your program before compilation. Compiler a compiler is a computer program or a set of programs that transforms source code written in a programming language the source language into another computer language the target language. These preprocessor attempts to add capabilities to the language by certain amounts to build in macro 1.
Let us now learn about each of these directives in details. All macro invocation statements are expanded hthowever, a twopass macro processor would tld not allow the body of one macro instruction to contain dfiiti f thdefinitions of other macros see figure 4. Introduction to compilers and language design copyright. If the parameter of the string literal requires an escape sequence like before a double quote it will automatically be inserted by the preprocessor. The syntax of the preprocessor is different from the syntax of the rest of c program in several respects. The definition of a preprocessor macro, say x, is text that may contain other macros that are expanded in order to produce the final replacement for x.