Time-Sharing System
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Chapter # 9 LEX and YACC
Chapter # 9 LEX and YACC Dr. Shaukat Ali Department of Computer Science University of Peshawar Lex and Yacc Lex and yacc are a matched pair of tools. Lex breaks down files into sets of "tokens," roughly analogous to words. Yacc takes sets of tokens and assembles them into higher-level constructs, analogous to sentences. Lex's output is mostly designed to be fed into some kind of parser. Yacc is designed to work with the output of Lex. 2 Lex and Yacc Lex and yacc are tools for building programs. Their output is itself code – Which needs to be fed into a compiler – May be additional user code is added to use the code generated by lex and yacc 3 Lex : A lexical analyzer generator Lex is a program designed to generate scanners, also known as tokenizers, which recognize lexical patterns in text Lex is an acronym that stands for "lexical analyzer generator.“ The main purpose is to facilitate lexical analysis The processing of character sequences in source code to produce tokens for use as input to other programs such as parsers Another tool for lexical analyzer generation is Flex 4 Lex : A lexical analyzer generator lex.lex is an a input file written in a language which describes the generation of lexical analyzer. The lex compiler transforms lex.l to a C program known as lex.yy.c. lex.yy.c is compiled by the C compiler to a file called a.out. The output of C compiler is the working lexical analyzer which takes stream of input characters and produces a stream of tokens. -
Project1: Build a Small Scanner/Parser
Project1: Build A Small Scanner/Parser Introducing Lex, Yacc, and POET cs5363 1 Project1: Building A Scanner/Parser Parse a subset of the C language Support two types of atomic values: int float Support one type of compound values: arrays Support a basic set of language concepts Variable declarations (int, float, and array variables) Expressions (arithmetic and boolean operations) Statements (assignments, conditionals, and loops) You can choose a different but equivalent language Need to make your own test cases Options of implementation (links available at class web site) Manual in C/C++/Java (or whatever other lang.) Lex and Yacc (together with C/C++) POET: a scripting compiler writing language Or any other approach you choose --- must document how to download/use any tools involved cs5363 2 This is just starting… There will be two other sub-projects Type checking Check the types of expressions in the input program Optimization/analysis/translation Do something with the input code, output the result The starting project is important because it determines which language you can use for the other projects Lex+Yacc ===> can work only with C/C++ POET ==> work with POET Manual ==> stick to whatever language you pick This class: introduce Lex/Yacc/POET to you cs5363 3 Using Lex to build scanners lex.yy.c MyLex.l lex/flex lex.yy.c a.out gcc/cc Input stream a.out tokens Write a lex specification Save it in a file (MyLex.l) Compile the lex specification file by invoking lex/flex lex MyLex.l A lex.yy.c file is generated -
GNU M4, Version 1.4.7 a Powerful Macro Processor Edition 1.4.7, 23 September 2006
GNU M4, version 1.4.7 A powerful macro processor Edition 1.4.7, 23 September 2006 by Ren´eSeindal This manual is for GNU M4 (version 1.4.7, 23 September 2006), a package containing an implementation of the m4 macro language. Copyright c 1989, 1990, 1991, 1992, 1993, 1994, 2004, 2005, 2006 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License.” i Table of Contents 1 Introduction and preliminaries ................ 3 1.1 Introduction to m4 ............................................. 3 1.2 Historical references ............................................ 3 1.3 Invoking m4 .................................................... 4 1.4 Problems and bugs ............................................. 8 1.5 Using this manual .............................................. 8 2 Lexical and syntactic conventions ............ 11 2.1 Macro names ................................................. 11 2.2 Quoting input to m4........................................... 11 2.3 Comments in m4 input ........................................ 11 2.4 Other kinds of input tokens ................................... 12 2.5 How m4 copies input to output ................................ 12 3 How to invoke macros........................ -
UNIX Reference Card
UNlxt Reference Card distributed by Computing Information Service BELL LABORATORIES Murray Hill, N. J. 07974 compiled by Lorinda Cherry Second Edition March, 1979 TABLE OF CO~TEJIo"TS la. GENERAL UNIX COMMANDS adb general purpose debugger ...S. 21 ar archive & library maimainer. ..S as assembler. ..S at execute commands at designated time S awk pattern scanning & processing language S bas basic ...S basename strip filename affixes ...5 be arbitrary precision interactive language ... S calendar reminder service ... 5 cat concatenate & print...5 cb C program beautifier ...no arguments cc C compiler ...5 cd change working directory 5 chgrp change groupoid of files 6 . chmod change mode of files S chown change owner of files 6 cmp compare 2 files ...6 col filter reverse line feeds ...6 comm print" lines common to 2 files ...6 cp copy ...6 crypt encode/decode 6 date print or set date 6 de desk calculator 6 dd convert & copy a file ...6 deroff remove text formatting commands ...6 diff differential file comparator. ..6 dUO 3-way differential file comparison ...6 du summarize disk usage ...6 echo echo arguments ...7 ed text editor. ..7, 20 egrep full regular expression pattern search ...8 enroll enroll in secret mail...no arguments eqn typeset mathematics ...7. 29 expr evaluate arguments as expressions ...7 fT7 Fortran 77 compiler ... 7 factor factor a number ...7 false truth value ...no arguments fgrep search for a fixed pauern ...8 file determine file type ...7 find find files ...7 graph draw a graph ...7 grep search a file for a pattern ...8 join relational database operator. -
User Manual for Ox: an Attribute-Grammar Compiling System Based on Yacc, Lex, and C Kurt M
Computer Science Technical Reports Computer Science 12-1992 User Manual for Ox: An Attribute-Grammar Compiling System based on Yacc, Lex, and C Kurt M. Bischoff Iowa State University Follow this and additional works at: http://lib.dr.iastate.edu/cs_techreports Part of the Programming Languages and Compilers Commons Recommended Citation Bischoff, Kurt M., "User Manual for Ox: An Attribute-Grammar Compiling System based on Yacc, Lex, and C" (1992). Computer Science Technical Reports. 21. http://lib.dr.iastate.edu/cs_techreports/21 This Article is brought to you for free and open access by the Computer Science at Iowa State University Digital Repository. It has been accepted for inclusion in Computer Science Technical Reports by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. User Manual for Ox: An Attribute-Grammar Compiling System based on Yacc, Lex, and C Abstract Ox generalizes the function of Yacc in the way that attribute grammars generalize context-free grammars. Ordinary Yacc and Lex specifications may be augmented with definitions of synthesized and inherited attributes written in C syntax. From these specifications, Ox generates a program that builds and decorates attributed parse trees. Ox accepts a most general class of attribute grammars. The user may specify postdecoration traversals for easy ordering of side effects such as code generation. Ox handles the tedious and error-prone details of writing code for parse-tree management, so its use eases problems of security and maintainability associated with that aspect of translator development. The translators generated by Ox use internal memory management that is often much faster than the common technique of calling malloc once for each parse-tree node. -
GNU M4, Version 1.4.19 a Powerful Macro Processor Edition 1.4.19, 28 May 2021
GNU M4, version 1.4.19 A powerful macro processor Edition 1.4.19, 28 May 2021 by Ren´eSeindal, Fran¸coisPinard, Gary V. Vaughan, and Eric Blake ([email protected]) This manual (28 May 2021) is for GNU M4 (version 1.4.19), a package containing an implementation of the m4 macro language. Copyright c 1989{1994, 2004{2014, 2016{2017, 2020{2021 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled \GNU Free Documentation License." i Table of Contents 1 Introduction and preliminaries ::::::::::::::::: 3 1.1 Introduction to m4 :::::::::::::::::::::::::::::::::::::::::::::: 3 1.2 Historical references :::::::::::::::::::::::::::::::::::::::::::: 3 1.3 Problems and bugs ::::::::::::::::::::::::::::::::::::::::::::: 4 1.4 Using this manual :::::::::::::::::::::::::::::::::::::::::::::: 5 2 Invoking m4::::::::::::::::::::::::::::::::::::::: 7 2.1 Command line options for operation modes ::::::::::::::::::::: 7 2.2 Command line options for preprocessor features ::::::::::::::::: 8 2.3 Command line options for limits control ::::::::::::::::::::::: 10 2.4 Command line options for frozen state ::::::::::::::::::::::::: 11 2.5 Command line options for debugging :::::::::::::::::::::::::: 11 2.6 Specifying input files on the command line ::::::::::::::::::::: -
Programmer's Manual. the Documents Here Are Grouped
Programmer’s Manual. The documents here are grouped roughly into the areas of basics, editing, language tools, document preparation, and system maintenance. Further general information may be found in the Bell System Tech- nical Journal special issue on UNIX, July-August, 1978. Many of the documents cited within this volume as Bell Laboratories internal memoranda or Computing Science Technical Reports (CSTR) are also contained here. These documents contain occasional localisms, typically references to other operating systems like GCOS and IBM. In all cases, such references may be safely ignored by UNIX users. General Works 1.7th Edition UNIX — Summary. A concise summary of the facilities available on UNIX. 2.The UNIX Time-Sharing System. D. M. Ritchie and K. Thompson. The original UNIX paper, reprinted from CACM. Getting Started 3.UNIX for Beginners — Second Edition. B. W. Kernighan. An introduction to the most basic use of the system. 4.A Tutorial Introduction to the UNIX Text Editor. B. W. Kernighan. An easy way to get started with the editor. 5.Advanced Editing on UNIX. B. W. Kernighan. The next step. 6.An Introduction to the UNIX Shell. S. R. Bourne. An introduction to the capabilities of the command interpreter, the shell. 7.Learn — Computer Aided Instruction on UNIX. M. E. Lesk and B. W. Kernighan. Describes a computer-aided instruction program that walks new users through the basics of files, the edi- tor, and document preparation software. Document Preparation 8.Typing Documents on the UNIX System. M. E. Lesk. Describes the basic use of the formatting tools. Also describes ‘‘−ms’’, a standardized package of format- ting requests that can be used to lay out most documents (including those in this volume). -
Yacc a Tool for Syntactic Analysis
1 Yacc a tool for Syntactic Analysis CS 315 – Programming Languages Pinar Duygulu Bilkent University CS315 Programming Languages © Pinar Duygulu Lex and Yacc 2 1) Lexical Analysis: Lexical analyzer: scans the input stream and converts sequences of characters into tokens. Lex is a tool for writing lexical analyzers. 2) Syntactic Analysis (Parsing): Parser: reads tokens and assembles them into language constructs using the grammar rules of the language. Yacc is a tool for constructing parsers. Yet Another Compiler to Compiler Reads a specification file that codifies the grammar of a language and generates a parsing routine CS315 Programming Languages © Pinar Duygulu 3 Yacc • Yacc specification describes a Context Free Grammar (CFG), that can be used to generate a parser. Elements of a CFG: 1. Terminals: tokens and literal characters, 2. Variables (nonterminals): syntactical elements, 3. Production rules, and 4. Start rule. CS315 Programming Languages © Pinar Duygulu 4 Yacc Format of a production rule: symbol: definition {action} ; Example: A → Bc is written in yacc as a: b 'c'; CS315 Programming Languages © Pinar Duygulu 5 Yacc Format of a yacc specification file: declarations %% grammar rules and associated actions %% C programs CS315 Programming Languages © Pinar Duygulu 6 Declarations To define tokens and their characteristics %token: declare names of tokens %left: define left-associative operators %right: define right-associative operators %nonassoc: define operators that may not associate with themselves %type: declare the type of variables %union: declare multiple data types for semantic values %start: declare the start symbol (default is the first variable in rules) %prec: assign precedence to a rule %{ C declarations directly copied to the resulting C program %} (E.g., variables, types, macros…) CS315 Programming Languages © Pinar Duygulu 7 A simple yacc specification to accept L={ anbn | n>1}. -
Binpac: a Yacc for Writing Application Protocol Parsers
binpac: A yacc for Writing Application Protocol Parsers Ruoming Pang∗ Vern Paxson Google, Inc. International Computer Science Institute and New York, NY, USA Lawrence Berkeley National Laboratory [email protected] Berkeley, CA, USA [email protected] Robin Sommer Larry Peterson International Computer Science Institute Princeton University Berkeley, CA, USA Princeton, NJ, USA [email protected] [email protected] ABSTRACT Similarly, studies of Email traffic [21, 46], peer-to-peer applica- A key step in the semantic analysis of network traffic is to parse the tions [37], online gaming, and Internet attacks [29] require under- traffic stream according to the high-level protocols it contains. This standing application-level traffic semantics. However, it is tedious, process transforms raw bytes into structured, typed, and semanti- error-prone, and sometimes prohibitively time-consuming to build cally meaningful data fields that provide a high-level representation application-level analysis tools from scratch, due to the complexity of the traffic. However, constructing protocol parsers by hand is a of dealing with low-level traffic data. tedious and error-prone affair due to the complexity and sheer num- We can significantly simplify the process if we can leverage a ber of application protocols. common platform for various kinds of application-level traffic anal- This paper presents binpac, a declarative language and com- ysis. A key element of such a platform is application-protocol piler designed to simplify the task of constructing robust and effi- parsers that translate packet streams into high-level representations cient semantic analyzers for complex network protocols. We dis- of the traffic, on top of which we can then use measurement scripts cuss the design of the binpac language and a range of issues that manipulate semantically meaningful data elements such as in generating efficient parsers from high-level specifications. -
An Attribute- Grammar Compiling System Based on Yacc, Lex, and C Kurt M
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Digital Repository @ Iowa State University Computer Science Technical Reports Computer Science 12-1992 Design, Implementation, Use, and Evaluation of Ox: An Attribute- Grammar Compiling System based on Yacc, Lex, and C Kurt M. Bischoff Iowa State University Follow this and additional works at: http://lib.dr.iastate.edu/cs_techreports Part of the Programming Languages and Compilers Commons Recommended Citation Bischoff, Kurt M., "Design, Implementation, Use, and Evaluation of Ox: An Attribute- Grammar Compiling System based on Yacc, Lex, and C" (1992). Computer Science Technical Reports. 23. http://lib.dr.iastate.edu/cs_techreports/23 This Article is brought to you for free and open access by the Computer Science at Iowa State University Digital Repository. It has been accepted for inclusion in Computer Science Technical Reports by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Design, Implementation, Use, and Evaluation of Ox: An Attribute- Grammar Compiling System based on Yacc, Lex, and C Abstract Ox generalizes the function of Yacc in the way that attribute grammars generalize context-free grammars. Ordinary Yacc and Lex specifications may be augmented with definitions of synthesized and inherited attributes written in C syntax. From these specifications, Ox generates a program that builds and decorates attributed parse trees. Ox accepts a most general class of attribute grammars. The user may specify postdecoration traversals for easy ordering of side effects such as code generation. Ox handles the tedious and error-prone details of writing code for parse-tree management, so its use eases problems of security and maintainability associated with that aspect of translator development. -
Lex and Yacc
Lex and Yacc A Quick Tour HW8–Use Lex/Yacc to Turn this: Into this: <P> Here's a list: Here's a list: * This is item one of a list <UL> * This is item two. Lists should be <LI> This is item one of a list indented four spaces, with each item <LI>This is item two. Lists should be marked by a "*" two spaces left of indented four spaces, with each item four-space margin. Lists may contain marked by a "*" two spaces left of four- nested lists, like this: space margin. Lists may contain * Hi, I'm item one of an inner list. nested lists, like this:<UL><LI> Hi, I'm * Me two. item one of an inner list. <LI>Me two. * Item 3, inner. <LI> Item 3, inner. </UL><LI> Item 3, * Item 3, outer list. outer list.</UL> This is outside both lists; should be back This is outside both lists; should be to no indent. back to no indent. <P><P> Final suggestions: Final suggestions 2 if myVar == 6.02e23**2 then f( .. ! char stream LEX token stream if myVar == 6.02e23**2 then f( ! tokenstream YACC parse tree if-stmt == fun call var ** Arg 1 Arg 2 float-lit int-lit . ! 3 Lex / Yacc History Origin – early 1970’s at Bell Labs Many versions & many similar tools Lex, flex, jflex, posix, … Yacc, bison, byacc, CUP, posix, … Targets C, C++, C#, Python, Ruby, ML, … We’ll use jflex & byacc/j, targeting java (but for simplicity, I usually just say lex/yacc) 4 Uses “Front end” of many real compilers E.g., gcc “Little languages”: Many special purpose utilities evolve some clumsy, ad hoc, syntax Often easier, simpler, cleaner and more flexible to use lex/yacc or similar tools from the start 5 Lex: A Lexical Analyzer Generator Input: Regular exprs defining "tokens" my.flex Fragments of declarations & code Output: jflex A java program “yylex.java” Use: yylex.java Compile & link with your main() Calls to yylex() read chars & return successive tokens. -
Oral History of Brian Kernighan
Oral History of Brian Kernighan Interviewed by: John R. Mashey Recorded April 24, 2017 Princeton, NJ CHM Reference number: X8185.2017 © 2017 Computer History Museum Oral History of Brian Kernighan Mashey: Well, hello, Brian. It’s great to see you again. Been a long time. So we’re here at Princeton, with Brian Kernighan, and we want to go do a whole oral history with him. So why don’t we start at the beginning. As I recall, you’re Canadian. Kernighan: That is right. I was born in Toronto long ago, and spent my early years in the city of Toronto. Moved west to a small town, what was then a small town, when I was in the middle of high school, and then went to the University of Toronto for my undergraduate degree, and then came here to Princeton for graduate school. Mashey: And what was your undergraduate work in? Kernighan: It was in one of these catch-all courses called Engineering Physics. It was for people who were kind of interested in engineering and math and science and didn’t have a clue what they wanted to actually do. Mashey: <laughs> So how did you come to be down here? Kernighan: I think it was kind of an accident. It was relatively unusual for people from Canada to wind up in the United States for graduate school at that point, but I thought I would try something different and so I applied to six or seven different schools in the United States, got accepted at some of them, and then it was a question of balancing things like, “Well, they promised that they would get you out in a certain number of years and they promised that they would give you money,” but the question is whether, either that was true or not and I don’t know.