Compiler Construction 2011, Lecture 2
|
|
- Annabella Stokes
- 6 years ago
- Views:
Transcription
1 Drawing Hands M.C. Escher, 1948 Compiler Construction 2011, Lecture 2 Staff: Viktor Kuncak Lectures Etienne Kneuss and Philippe Suter {labs Eva Darulova and Giuliano Losa Exercises Regis Blanc assistant Yvette Gallay secretary
2 Reminder Register on: IS academia Moodle so you can get our s Our wonderful repository (reachable from course page) So please form the groups
3 i = 0 LF w h i l e i=0 while (i < 10) { a[i] = 7*i+3 i = i + 1 lexer i = 0 while ( i < 10 ) source code (e.g. Scala, Java,C) easy to write Compiler (scalac, gcc) parser type check assign while characters words trees i 0 assign + a[i] * 7 i machine code (e.g. x86, arm, JVM) efficient to execute < i 10 3 mov R1,#0 mov R2,#40 mov R3,#3 jmp +12 mov (a+r1),r3 add R1, R1, #4 add R3, R3, #7 cmp R1, R2 blt -16 Compiler Construction data-flow graphs optimizer code gen
4 Id3 = 0 while (id3 < 10) { println(,id3); id3 = id3 + 1 source code Compiler Construction i d 3 = 0 LF w lexer id3 = 0 while ( id3 < 10 ) Compiler (scalac, gcc) parser assign i 0 while assign + a[i] * 7 i < i 10 3 characters words (tokens) trees Lexer is specified using regular expressions. Groups characters into tokens and classifies them into token classes.
5 Today: Lexical Analysis. Summary: lexical analyzer maps a stream of characters into a stream of tokens while doing that, it typically needs only bounded memory we can specify tokens for a lexical analyzers using regular expressions it is not difficult to construct a lexical analyzer manually we give an example for manually constructed analyzers, we often use the first character to decide on token class; a notion first(l) = { a aw in L we follow the maximal munch rule: lexical analyzer should eagerly accept the longest token that it can recognize from the current point it is possible to automate the construction of lexical analyzers; the starting point is conversion of regular expressions to automata tools that automate this construction are part of compiler-compilers, such as JavaCC described in the Tiger book automated construction of lexical analyzers from regular expressions is an example of compilation for a domain-specific language
6 While Language Idea Small language used to illustrate key concepts Also used in your first lab interpreter later labs will use a more complex language we continue to use while in lectures while and if are the control statements no procedures, no exceptions the only variables are of int type no variable declarations, they are initially zero no objects, pointers, arrays
7 While Language Example Programs while (i < 100) { j = i + 1; while (j < 100) { println(,i); println(,,j); j = j + 1; i = i + 1; Nested loop x = 13; while (x > 1) { println("x=", x); if (x % 2 == 0) { x = x / 2; else { x = 3 * x + 1; Does the program terminate for every initial value of x? (Collatz conjecture - open)
8 Tokens (Words) of the While Language Ident ::= letter (letter digit)* integerconst ::= digit digit* stringconst ::= AnySymbolExceptQuote* keywords if else while println special symbols ( ) && < == + - * / %! - { ;, letter ::= a b c z A B C Z digit ::= regular expressions
9 Regular Expressions: Definition One way to denote (often infinite) languages Regular expression is an expression built from: empty language {ε, denoted just ε {a for a in Σ, denoted simply by a union, denoted or, sometimes + concatenation, as multiplication or nothing Kleene star * Identifiers: letter (letter digit)* (letter,digit are shorthands from before)
10 History: Kleene (from Wikipedia) Stephen Cole Kleene (January 5, 1909, Hartford, Connecticut, United States January 25, 1994, Madison, Wisconsin) was an American mathematician who helped lay the foundations for theoretical computer science. One of many distinguished students of Alonzo Church, Kleene, along with Alan Turing, Emil Post, and others, is best known as a founder of the branch of mathematical logic known as recursion theory. Kleene's work grounds the study of which functions are computable. A number of mathematical concepts are named after him: Kleene hierarchy, Kleene algebra, the Kleene star (Kleene closure), Kleene's recursion theorem and the Kleene fixpoint theorem. He also invented regular expressions, and was a leading American advocate of mathematical intuitionism.
11 Manually Constructing Lexers
12 Id3 = 0 while (id3 < 10) { println(,id3); id3 = id3 + 1 source code Compiler Construction i d 3 = 0 LF w lexer id3 = 0 while ( id3 < 10 ) Compiler (scalac, gcc) parser assign i 0 while assign + a[i] * 7 i < i 10 3 characters words (tokens) trees Lexer is specified using regular expressions. Groups characters into tokens and classifies them into token classes.
13 Lexer input and Output Stream of Char-s class CharStream(fileName : String){ val file = new BufferedReader( new FileReader(fileName)) var current : Char = ' ' var eof : Boolean = false def next = { if (eof) throw EndOfInput("reading" + file) val c = file.read() eof = (c == -1) current = c.asinstanceof[char] next i d 3 = 0 LF w lexer Stream of Token-s id3 = 0 while ( id3 < 10 ) class Lexer(ch : CharStream) { var current : Token def next : Unit = { lexer code here sealed abstract class Token case class ID(content : String) // id3 extends Token case class IntConst(value : Int) // 10 extends Token case class AssignEQ() = extends Token case class CompareEQ // == extends Token case class MUL() extends Token // * case class PLUS() extends Token // + case clas LEQ extends Token // <= case class OPAREN extends Token //( case class CPAREN extends Token //)... case class IF() extends Token // if case class WHILE() extends Token case class EOF() extends Token // End Of File
14 Identifiers and Keywords if (isletter) { b = new StringBuffer while (isletter isdigit) { b.append(ch.current) ch.next keywords.lookup(b.tostring) { case None => token=id(b.tostring) case Some(kw) => token=kw regular expression for identifiers: letter (letter digit)* Keywords look like identifiers, but are simply indicated as keywords in language definition A constant Map from strings to keyword tokens if not in map, then it is ordinary identifier
15 Integer Constants if (isdigit) { k = while (isdigit) { k = ch.next token = IntConst(k) regular expression for integers: digit digit* Keywords look like identifiers, but are simply indicated as keywords in language definition A constant Map from strings to keyword tokens if not in map, then it is ordinary identifier
16 Decision Tree to Map Symbols to Tokens ch.current match { case '(' => {current = OPAREN; ch.next; return case ')' => {current = CPAREN; ch.next; return case '+' => {current = PLUS; ch.next; return case '/' => {current = DIV; ch.next; return case '*' => {current = MUL; ch.next; return case '=' => { ch.next if (ch.current=='=') {ch.next; current = CompareEQ; return else {current = AssignEQ; return case '<' => { ch.next if (ch.current=='=') {ch.next; current = LEQ; return else {current = LESS; return
17 Skipping Comments if (ch.current='/') { ch.next if (ch.current='/') { while (!iseol &&!iseof) { ch.next Nested comments? /* foo /* bar */ baz */
18 Further Important Topics Longest Match Rule Combining pieces together computing first symbols for regular expressions Example of tiny lexical analyzer see wiki
19 Computing first symbols
20 Computing nullable expressions
21 Automating Construction of Lexers
22 Example in javacc TOKEN: { <IDENTIFIER: <LETTER> (<LETTER> <DIGIT> "_")* > <CONSTANT: <DIGIT> (<DIGIT>)* > <LETTER: ["a"-"z"] ["A"-"Z"]> <DIGIT: ["0"-"9"]> SKIP: { " " "\n" "\t"
23 Finite Automaton Kinds of finite automata: deterministic non-deterministic with epsilon transition with regular expressions on edges
24 Interpretation of Non-Determinism For a given string, some paths in automaton lead to accepting, some to rejecting states Does the automaton accept? yes, if there exists an accepting path Continued in next lecture
source code Compiler parser
Id3 = 0 while (id3 < 10) { println(,id3); id3 = id3 + 1 source code Compiler Construction i d 3 = 0 LF w lexer id3 = 0 while ( id3 < 10 ) Compiler (scalac, gcc) parser assign i 0 while assign + a[i] *
More informationCompiler Construction 2010 (6 credits)
http://lara.epfl.ch Drawing Hands M.C. Escher, 1948 Compiler Construction 2010 (6 credits) Staff: Viktor Kuncak Lectures Hossein Hojjat Exercises Philippe Suter {labs} Étienne Kneuss, Ali Sinan Köksal
More informationCompiler Construction
http://lara.epfl.ch/cc Drawing Hands M.C. Escher, 1948 Staff: Compiler Construction Viktor Kuncak Lectures Etienne Kneuss Labs Eva Darulova Exercises Yvette Gallay secretary Example: javac - from Java
More informationCompiler Construction
http://lara.epfl.ch/cc Drawing Hands M.C. Escher, 1948 Staff: Compiler Construction Viktor Kuncak Lectures Etienne Kneuss Labs Mikael Mayer Exercises Yvette Gallay secretary Example: javac - from Java
More informationLexical Analysis. Chapter 2
Lexical Analysis Chapter 2 1 Outline Informal sketch of lexical analysis Identifies tokens in input string Issues in lexical analysis Lookahead Ambiguities Specifying lexers Regular expressions Examples
More informationLexical Analysis. Lecture 2-4
Lexical Analysis Lecture 2-4 Notes by G. Necula, with additions by P. Hilfinger Prof. Hilfinger CS 164 Lecture 2 1 Administrivia Moving to 60 Evans on Wednesday HW1 available Pyth manual available on line.
More informationImplementation of Lexical Analysis
Implementation of Lexical Analysis Outline Specifying lexical structure using regular expressions Finite automata Deterministic Finite Automata (DFAs) Non-deterministic Finite Automata (NFAs) Implementation
More informationLexical Analysis. Lecture 3-4
Lexical Analysis Lecture 3-4 Notes by G. Necula, with additions by P. Hilfinger Prof. Hilfinger CS 164 Lecture 3-4 1 Administrivia I suggest you start looking at Python (see link on class home page). Please
More informationIntroduction to Lexical Analysis
Introduction to Lexical Analysis Outline Informal sketch of lexical analysis Identifies tokens in input string Issues in lexical analysis Lookahead Ambiguities Specifying lexical analyzers (lexers) Regular
More informationLexical Analysis. Introduction
Lexical Analysis Introduction Copyright 2015, Pedro C. Diniz, all rights reserved. Students enrolled in the Compilers class at the University of Southern California have explicit permission to make copies
More informationImplementation of Lexical Analysis
Implementation of Lexical Analysis Outline Specifying lexical structure using regular expressions Finite automata Deterministic Finite Automata (DFAs) Non-deterministic Finite Automata (NFAs) Implementation
More informationAutomating Construction of Lexers
Automating Construction of Lexers Regular Expression to Programs Not all regular expressions are simple. How can we write a lexer for (a*b aaa)? Tokenizing aaaab Vs aaaaaa Regular Expression Finite state
More informationRegular Expression Module-2
Regular Expression Module-2 Harivinod N, Dept of CSE, VCET Puttur 1 Introduction Let's now take a different approach to categorizing problems. Instead of focusing on the power of a computing device, let's
More informationInterpreter. Scanner. Parser. Tree Walker. read. request token. send token. send AST I/O. Console
Scanning 1 read Interpreter Scanner request token Parser send token Console I/O send AST Tree Walker 2 Scanner This process is known as: Scanning, lexing (lexical analysis), and tokenizing This is the
More informationAdministrivia. Lexical Analysis. Lecture 2-4. Outline. The Structure of a Compiler. Informal sketch of lexical analysis. Issues in lexical analysis
dministrivia Lexical nalysis Lecture 2-4 Notes by G. Necula, with additions by P. Hilfinger Moving to 6 Evans on Wednesday HW available Pyth manual available on line. Please log into your account and electronically
More informationOutline. 1 Scanning Tokens. 2 Regular Expresssions. 3 Finite State Automata
Outline 1 2 Regular Expresssions Lexical Analysis 3 Finite State Automata 4 Non-deterministic (NFA) Versus Deterministic Finite State Automata (DFA) 5 Regular Expresssions to NFA 6 NFA to DFA 7 8 JavaCC:
More informationCMSC 350: COMPILER DESIGN
Lecture 11 CMSC 350: COMPILER DESIGN see HW3 LLVMLITE SPECIFICATION Eisenberg CMSC 350: Compilers 2 Discussion: Defining a Language Premise: programming languages are purely formal objects We (as language
More information2010: Compilers REVIEW: REGULAR EXPRESSIONS HOW TO USE REGULAR EXPRESSIONS
2010: Compilers Lexical Analysis: Finite State Automata Dr. Licia Capra UCL/CS REVIEW: REGULAR EXPRESSIONS a Character in A Empty string R S Alternation (either R or S) RS Concatenation (R followed by
More informationImplementation of Lexical Analysis
Outline Implementation of Lexical nalysis Specifying lexical structure using regular expressions Finite automata Deterministic Finite utomata (DFs) Non-deterministic Finite utomata (NFs) Implementation
More informationLexical Analysis 1 / 52
Lexical Analysis 1 / 52 Outline 1 Scanning Tokens 2 Regular Expresssions 3 Finite State Automata 4 Non-deterministic (NFA) Versus Deterministic Finite State Automata (DFA) 5 Regular Expresssions to NFA
More informationCSEP 501 Compilers. Languages, Automata, Regular Expressions & Scanners Hal Perkins Winter /8/ Hal Perkins & UW CSE B-1
CSEP 501 Compilers Languages, Automata, Regular Expressions & Scanners Hal Perkins Winter 2008 1/8/2008 2002-08 Hal Perkins & UW CSE B-1 Agenda Basic concepts of formal grammars (review) Regular expressions
More informationCSc 453 Lexical Analysis (Scanning)
CSc 453 Lexical Analysis (Scanning) Saumya Debray The University of Arizona Tucson Overview source program lexical analyzer (scanner) tokens syntax analyzer (parser) symbol table manager Main task: to
More informationLexical Analysis. Implementation: Finite Automata
Lexical Analysis Implementation: Finite Automata Outline Specifying lexical structure using regular expressions Finite automata Deterministic Finite Automata (DFAs) Non-deterministic Finite Automata (NFAs)
More informationRegular Expressions. Agenda for Today. Grammar for a Tiny Language. Programming Language Specifications
Agenda for Today Regular Expressions CSE 413, Autumn 2005 Programming Languages Basic concepts of formal grammars Regular expressions Lexical specification of programming languages Using finite automata
More informationFinite Automata Theory and Formal Languages TMV027/DIT321 LP4 2016
Finite Automata Theory and Formal Languages TMV027/DIT321 LP4 2016 Lecture 15 Ana Bove May 23rd 2016 More on Turing machines; Summary of the course. Overview of today s lecture: Recap: PDA, TM Push-down
More informationTheory of Programming Languages COMP360
Theory of Programming Languages COMP360 Sometimes it is the people no one imagines anything of, who do the things that no one can imagine Alan Turing What can be computed? Before people even built computers,
More informationCOMP-421 Compiler Design. Presented by Dr Ioanna Dionysiou
COMP-421 Compiler Design Presented by Dr Ioanna Dionysiou Administrative! [ALSU03] Chapter 3 - Lexical Analysis Sections 3.1-3.4, 3.6-3.7! Reading for next time [ALSU03] Chapter 3 Copyright (c) 2010 Ioanna
More informationLexical Analysis. COMP 524, Spring 2014 Bryan Ward
Lexical Analysis COMP 524, Spring 2014 Bryan Ward Based in part on slides and notes by J. Erickson, S. Krishnan, B. Brandenburg, S. Olivier, A. Block and others The Big Picture Character Stream Scanner
More informationRegular Expressions. Regular Expressions. Regular Languages. Specifying Languages. Regular Expressions. Kleene Star Operation
Another means to describe languages accepted by Finite Automata. In some books, regular languages, by definition, are described using regular. Specifying Languages Recall: how do we specify languages?
More informationSyntactic Analysis. CS345H: Programming Languages. Lecture 3: Lexical Analysis. Outline. Lexical Analysis. What is a Token? Tokens
Syntactic Analysis CS45H: Programming Languages Lecture : Lexical Analysis Thomas Dillig Main Question: How to give structure to strings Analogy: Understanding an English sentence First, we separate a
More informationFormal Languages and Compilers Lecture VI: Lexical Analysis
Formal Languages and Compilers Lecture VI: Lexical Analysis Free University of Bozen-Bolzano Faculty of Computer Science POS Building, Room: 2.03 artale@inf.unibz.it http://www.inf.unibz.it/ artale/ Formal
More informationCompiler Construction LECTURE # 3
Compiler Construction LECTURE # 3 The Course Course Code: CS-4141 Course Title: Compiler Construction Instructor: JAWAD AHMAD Email Address: jawadahmad@uoslahore.edu.pk Web Address: http://csandituoslahore.weebly.com/cc.html
More informationLexical Analysis. Lecture 3. January 10, 2018
Lexical Analysis Lecture 3 January 10, 2018 Announcements PA1c due tonight at 11:50pm! Don t forget about PA1, the Cool implementation! Use Monday s lecture, the video guides and Cool examples if you re
More informationLexical Analysis. Dragon Book Chapter 3 Formal Languages Regular Expressions Finite Automata Theory Lexical Analysis using Automata
Lexical Analysis Dragon Book Chapter 3 Formal Languages Regular Expressions Finite Automata Theory Lexical Analysis using Automata Phase Ordering of Front-Ends Lexical analysis (lexer) Break input string
More informationCompiler Construction D7011E
Compiler Construction D7011E Lecture 2: Lexical analysis Viktor Leijon Slides largely by Johan Nordlander with material generously provided by Mark P. Jones. 1 Basics of Lexical Analysis: 2 Some definitions:
More informationIntroduction to Lexical Analysis
Introduction to Lexical Analysis Outline Informal sketch of lexical analysis Identifies tokens in input string Issues in lexical analysis Lookahead Ambiguities Specifying lexers Regular expressions Examples
More informationImplementation of Lexical Analysis
Implementation of Lexical Analysis Lecture 4 (Modified by Professor Vijay Ganesh) Tips on Building Large Systems KISS (Keep It Simple, Stupid!) Don t optimize prematurely Design systems that can be tested
More informationLecture 9 CIS 341: COMPILERS
Lecture 9 CIS 341: COMPILERS Announcements HW3: LLVM lite Available on the course web pages. Due: Monday, Feb. 26th at 11:59:59pm Only one group member needs to submit Three submissions per group START
More informationThe Language for Specifying Lexical Analyzer
The Language for Specifying Lexical Analyzer We shall now study how to build a lexical analyzer from a specification of tokens in the form of a list of regular expressions The discussion centers around
More informationLanguages and Strings. Chapter 2
Languages and Strings Chapter 2 Let's Look at Some Problems int alpha, beta; alpha = 3; beta = (2 + 5) / 10; (1) Lexical analysis: Scan the program and break it up into variable names, numbers, etc. (2)
More informationStructure of Programming Languages Lecture 3
Structure of Programming Languages Lecture 3 CSCI 6636 4536 Spring 2017 CSCI 6636 4536 Lecture 3... 1/25 Spring 2017 1 / 25 Outline 1 Finite Languages Deterministic Finite State Machines Lexical Analysis
More informationLecture 3: Lexical Analysis
Lecture 3: Lexical Analysis COMP 524 Programming Language Concepts tephen Olivier January 2, 29 Based on notes by A. Block, N. Fisher, F. Hernandez-Campos, J. Prins and D. totts Goal of Lecture Character
More informationCSCI312 Principles of Programming Languages!
CSCI312 Principles of Programming Languages!! Chapter 3 Regular Expression and Lexer Xu Liu Recap! Copyright 2006 The McGraw-Hill Companies, Inc. Clite: Lexical Syntax! Input: a stream of characters from
More informationMIT Specifying Languages with Regular Expressions and Context-Free Grammars
MIT 6.035 Specifying Languages with Regular essions and Context-Free Grammars Martin Rinard Laboratory for Computer Science Massachusetts Institute of Technology Language Definition Problem How to precisely
More informationFormal languages and computation models
Formal languages and computation models Guy Perrier Bibliography John E. Hopcroft, Rajeev Motwani, Jeffrey D. Ullman - Introduction to Automata Theory, Languages, and Computation - Addison Wesley, 2006.
More informationMATH Iris Loeb.
MATH 134 http://www.math.canterbury.ac.nz/math134/09/su1/c Iris Loeb I.Loeb@math.canterbury.ac.nz Office Hours: Thur 10.00-11.00, Room 703 (MSCS Building) The Limits of Formal Logic We now turn our attention
More informationCSE 413 Programming Languages & Implementation. Hal Perkins Autumn 2012 Grammars, Scanners & Regular Expressions
CSE 413 Programming Languages & Implementation Hal Perkins Autumn 2012 Grammars, Scanners & Regular Expressions 1 Agenda Overview of language recognizers Basic concepts of formal grammars Scanner Theory
More informationCode Generation Introduction
Code Generation Introduction i = 0 LF w h i l e i=0 while (i < 10) { a[i] = 7*i+3 i = i + 1 lexer i = 0 while ( i < 10 ) source code (e.g. Scala, Java,C) easy to write Compiler (scalac, gcc) parser type
More informationCS164: Programming Assignment 2 Dlex Lexer Generator and Decaf Lexer
CS164: Programming Assignment 2 Dlex Lexer Generator and Decaf Lexer Assigned: Thursday, September 16, 2004 Due: Tuesday, September 28, 2004, at 11:59pm September 16, 2004 1 Introduction Overview In this
More informationLexical Analysis - An Introduction. Lecture 4 Spring 2005 Department of Computer Science University of Alabama Joel Jones
Lexical Analysis - An Introduction Lecture 4 Spring 2005 Department of Computer Science University of Alabama Joel Jones Copyright 2003, Keith D. Cooper, Ken Kennedy & Linda Torczon, all rights reserved.
More informationLanguages, Automata, Regular Expressions & Scanners. Winter /8/ Hal Perkins & UW CSE B-1
CSE 401 Compilers Languages, Automata, Regular Expressions & Scanners Hal Perkins Winter 2010 1/8/2010 2002-10 Hal Perkins & UW CSE B-1 Agenda Quick review of basic concepts of formal grammars Regular
More informationWriting a Lexical Analyzer in Haskell (part II)
Writing a Lexical Analyzer in Haskell (part II) Today Regular languages and lexicographical analysis part II Some of the slides today are from Dr. Saumya Debray and Dr. Christian Colberg This week PA1:
More informationLexical Analysis. Note by Baris Aktemur: Our slides are adapted from Cooper and Torczon s slides that they prepared for COMP 412 at Rice.
Lexical Analysis Note by Baris Aktemur: Our slides are adapted from Cooper and Torczon s slides that they prepared for COMP 412 at Rice. Copyright 2010, Keith D. Cooper & Linda Torczon, all rights reserved.
More informationImplementation of Lexical Analysis
Written ssignments W assigned today Implementation of Lexical nalysis Lecture 4 Due in one week :59pm Electronic hand-in Prof. iken CS 43 Lecture 4 Prof. iken CS 43 Lecture 4 2 Tips on uilding Large Systems
More informationThe Front End. The purpose of the front end is to deal with the input language. Perform a membership test: code source language?
The Front End Source code Front End IR Back End Machine code Errors The purpose of the front end is to deal with the input language Perform a membership test: code source language? Is the program well-formed
More informationDr. D.M. Akbar Hussain
1 2 Compiler Construction F6S Lecture - 2 1 3 4 Compiler Construction F6S Lecture - 2 2 5 #include.. #include main() { char in; in = getch ( ); if ( isalpha (in) ) in = getch ( ); else error (); while
More informationCS 415 Midterm Exam Spring SOLUTION
CS 415 Midterm Exam Spring 2005 - SOLUTION Name Email Address Student ID # Pledge: This exam is closed note, closed book. Questions will be graded on quality of answer. Please supply the best answer you
More informationLexical Analysis. Lexical analysis is the first phase of compilation: The file is converted from ASCII to tokens. It must be fast!
Lexical Analysis Lexical analysis is the first phase of compilation: The file is converted from ASCII to tokens. It must be fast! Compiler Passes Analysis of input program (front-end) character stream
More informationCSE 413 Programming Languages & Implementation. Hal Perkins Winter 2019 Grammars, Scanners & Regular Expressions
CSE 413 Programming Languages & Implementation Hal Perkins Winter 2019 Grammars, Scanners & Regular Expressions 1 Agenda Overview of language recognizers Basic concepts of formal grammars Scanner Theory
More informationMIT Specifying Languages with Regular Expressions and Context-Free Grammars. Martin Rinard Massachusetts Institute of Technology
MIT 6.035 Specifying Languages with Regular essions and Context-Free Grammars Martin Rinard Massachusetts Institute of Technology Language Definition Problem How to precisely define language Layered structure
More informationCS412/413. Introduction to Compilers Tim Teitelbaum. Lecture 2: Lexical Analysis 23 Jan 08
CS412/413 Introduction to Compilers Tim Teitelbaum Lecture 2: Lexical Analysis 23 Jan 08 Outline Review compiler structure What is lexical analysis? Writing a lexer Specifying tokens: regular expressions
More informationFinite Automata. Dr. Nadeem Akhtar. Assistant Professor Department of Computer Science & IT The Islamia University of Bahawalpur
Finite Automata Dr. Nadeem Akhtar Assistant Professor Department of Computer Science & IT The Islamia University of Bahawalpur PhD Laboratory IRISA-UBS University of South Brittany European University
More informationAbout the Tutorial. Audience. Prerequisites. Copyright & Disclaimer. Compiler Design
i About the Tutorial A compiler translates the codes written in one language to some other language without changing the meaning of the program. It is also expected that a compiler should make the target
More informationCS308 Compiler Principles Lexical Analyzer Li Jiang
CS308 Lexical Analyzer Li Jiang Department of Computer Science and Engineering Shanghai Jiao Tong University Content: Outline Basic concepts: pattern, lexeme, and token. Operations on languages, and regular
More informationCS Lecture 2. The Front End. Lecture 2 Lexical Analysis
CS 1622 Lecture 2 Lexical Analysis CS 1622 Lecture 2 1 Lecture 2 Review of last lecture and finish up overview The first compiler phase: lexical analysis Reading: Chapter 2 in text (by 1/18) CS 1622 Lecture
More informationFinite State Automata are Limited. Let us use (context-free) grammars!
Finite State Automata are Limited Let us use (context-free) grammars! Context Free Grammar for a n b n S ::= - a grammar rule S ::= a S b - another grammar rule Example of a derivation S => asb => a asb
More informationToday. Assignments. Lecture Notes CPSC 326 (Spring 2019) Quiz 2. Lexer design. Syntax Analysis: Context-Free Grammars. HW2 (out, due Tues)
Today Quiz 2 Lexer design Syntax Analysis: Context-Free Grammars Assignments HW2 (out, due Tues) S. Bowers 1 of 15 Implementing a Lexer for MyPL (HW 2) Similar in spirit to HW 1 We ll create three classes:
More informationChapter 11 :: Functional Languages
Chapter 11 :: Functional Languages Programming Language Pragmatics Michael L. Scott Copyright 2016 Elsevier 1 Chapter11_Functional_Languages_4e - Tue November 21, 2017 Historical Origins The imperative
More informationConcepts. Lexical scanning Regular expressions DFAs and FSAs Lex. Lexical analysis in perspective
Concepts Lexical scanning Regular expressions DFAs and FSAs Lex CMSC 331, Some material 1998 by Addison Wesley Longman, Inc. 1 CMSC 331, Some material 1998 by Addison Wesley Longman, Inc. 2 Lexical analysis
More informationImplementation of Lexical Analysis
Written ssignments W assigned today Implementation of Lexical nalysis Lecture 4 Due in one week y 5pm Turn in In class In box outside 4 Gates Electronically Prof. iken CS 43 Lecture 4 Prof. iken CS 43
More informationCompiler Construction
Compiler Construction Thomas Noll Software Modeling and Verification Group RWTH Aachen University https://moves.rwth-aachen.de/teaching/ss-16/cc/ Conceptual Structure of a Compiler Source code x1 := y2
More informationLexical Analysis - 1. A. Overview A.a) Role of Lexical Analyzer
CMPSC 470 Lecture 02 Topics: Regular Expression Transition Diagram Lexical Analyzer Implementation A. Overview A.a) Role of Lexical Analyzer Lexical Analysis - 1 Lexical analyzer does: read input character
More information2. Syntax and Type Analysis
Content of Lecture Syntax and Type Analysis Lecture Compilers Summer Term 2011 Prof. Dr. Arnd Poetzsch-Heffter Software Technology Group TU Kaiserslautern Prof. Dr. Arnd Poetzsch-Heffter Syntax and Type
More informationChapter 4. Lexical analysis. Concepts. Lexical scanning Regular expressions DFAs and FSAs Lex. Lexical analysis in perspective
Chapter 4 Lexical analysis Lexical scanning Regular expressions DFAs and FSAs Lex Concepts CMSC 331, Some material 1998 by Addison Wesley Longman, Inc. 1 CMSC 331, Some material 1998 by Addison Wesley
More informationCompilers CS S-01 Compiler Basics & Lexical Analysis
Compilers CS414-2017S-01 Compiler Basics & Lexical Analysis David Galles Department of Computer Science University of San Francisco 01-0: Syllabus Office Hours Course Text Prerequisites Test Dates & Testing
More informationImplementation of Lexical Analysis. Lecture 4
Implementation of Lexical Analysis Lecture 4 1 Tips on Building Large Systems KISS (Keep It Simple, Stupid!) Don t optimize prematurely Design systems that can be tested It is easier to modify a working
More informationUNIT -2 LEXICAL ANALYSIS
OVER VIEW OF LEXICAL ANALYSIS UNIT -2 LEXICAL ANALYSIS o To identify the tokens we need some method of describing the possible tokens that can appear in the input stream. For this purpose we introduce
More informationLexical Analysis. Finite Automata
#1 Lexical Analysis Finite Automata Cool Demo? (Part 1 of 2) #2 Cunning Plan Informal Sketch of Lexical Analysis LA identifies tokens from input string lexer : (char list) (token list) Issues in Lexical
More informationCompilers CS S-01 Compiler Basics & Lexical Analysis
Compilers CS414-2005S-01 Compiler Basics & Lexical Analysis David Galles Department of Computer Science University of San Francisco 01-0: Syllabus Office Hours Course Text Prerequisites Test Dates & Testing
More informationFigure 2.1: Role of Lexical Analyzer
Chapter 2 Lexical Analysis Lexical analysis or scanning is the process which reads the stream of characters making up the source program from left-to-right and groups them into tokens. The lexical analyzer
More informationUniversity of Nevada, Las Vegas Computer Science 456/656 Fall 2016
University of Nevada, Las Vegas Computer Science 456/656 Fall 2016 The entire examination is 925 points. The real final will be much shorter. Name: No books, notes, scratch paper, or calculators. Use pen
More informationProgramming Languages (CS 550) Lecture 4 Summary Scanner and Parser Generators. Jeremy R. Johnson
Programming Languages (CS 550) Lecture 4 Summary Scanner and Parser Generators Jeremy R. Johnson 1 Theme We have now seen how to describe syntax using regular expressions and grammars and how to create
More informationUVa ID: NAME (print): CS 4501 LDI Midterm 1
CS 4501 LDI Midterm 1 Write your name and UVa ID on the exam. Pledge the exam before turning it in. There are nine (9) pages in this exam (including this one) and six (6) questions, each with multiple
More informationECS 120 Lesson 7 Regular Expressions, Pt. 1
ECS 120 Lesson 7 Regular Expressions, Pt. 1 Oliver Kreylos Friday, April 13th, 2001 1 Outline Thus far, we have been discussing one way to specify a (regular) language: Giving a machine that reads a word
More informationCS S-01 Compiler Basics & Lexical Analysis 1
CS414-2017S-01 Compiler Basics & Lexical Analysis 1 01-0: Syllabus Office Hours Course Text Prerequisites Test Dates & Testing Policies Projects Teams of up to 2 Grading Policies Questions? 01-1: Notes
More informationFunctional Languages. Hwansoo Han
Functional Languages Hwansoo Han Historical Origins Imperative and functional models Alan Turing, Alonzo Church, Stephen Kleene, Emil Post, etc. ~1930s Different formalizations of the notion of an algorithm
More informationAnnouncements! P1 part 1 due next Tuesday P1 part 2 due next Friday
Announcements! P1 part 1 due next Tuesday P1 part 2 due next Friday 1 Finite-state machines CS 536 Last time! A compiler is a recognizer of language S (Source) a translator from S to T (Target) a program
More informationIntroduction to Parsing. Lecture 8
Introduction to Parsing Lecture 8 Adapted from slides by G. Necula Outline Limitations of regular languages Parser overview Context-free grammars (CFG s) Derivations Languages and Automata Formal languages
More informationAppendix Set Notation and Concepts
Appendix Set Notation and Concepts In mathematics you don t understand things. You just get used to them. John von Neumann (1903 1957) This appendix is primarily a brief run-through of basic concepts from
More informationOutline CS4120/4121. Compilation in a Nutshell 1. Administration. Introduction to Compilers Andrew Myers. HW1 out later today due next Monday.
CS4120/4121 Introduction to Compilers Andrew Myers Lecture 2: Lexical Analysis 31 August 2009 Outline Administration Compilation in a nutshell (or two) What is lexical analysis? Writing a lexer Specifying
More informationSyntax and Type Analysis
Syntax and Type Analysis Lecture Compilers Summer Term 2011 Prof. Dr. Arnd Poetzsch-Heffter Software Technology Group TU Kaiserslautern Prof. Dr. Arnd Poetzsch-Heffter Syntax and Type Analysis 1 Content
More informationCSc 453 Compilers and Systems Software
CSc 453 Compilers and Systems Software 3 : Lexical Analysis I Christian Collberg Department of Computer Science University of Arizona collberg@gmail.com Copyright c 2009 Christian Collberg August 23, 2009
More informationCompiler phases. Non-tokens
Compiler phases Compiler Construction Scanning Lexical Analysis source code scanner tokens regular expressions lexical analysis Lennart Andersson parser context free grammar Revision 2011 01 21 parse tree
More informationCSC 467 Lecture 3: Regular Expressions
CSC 467 Lecture 3: Regular Expressions Recall How we build a lexer by hand o Use fgetc/mmap to read input o Use a big switch to match patterns Homework exercise static TokenKind identifier( TokenKind token
More informationFinite automata. We have looked at using Lex to build a scanner on the basis of regular expressions.
Finite automata We have looked at using Lex to build a scanner on the basis of regular expressions. Now we begin to consider the results from automata theory that make Lex possible. Recall: An alphabet
More information1. Lexical Analysis Phase
1. Lexical Analysis Phase The purpose of the lexical analyzer is to read the source program, one character at time, and to translate it into a sequence of primitive units called tokens. Keywords, identifiers,
More informationWARNING for Autumn 2004:
CSE 413 Programming Languages Autumn 2003 Max Points 50 Closed book, closed notes, no electronics. Do your own work! WARNING for Autumn 2004 Last year s exam did not cover Scheme and Java, but this year
More informationCompiler course. Chapter 3 Lexical Analysis
Compiler course Chapter 3 Lexical Analysis 1 A. A. Pourhaji Kazem, Spring 2009 Outline Role of lexical analyzer Specification of tokens Recognition of tokens Lexical analyzer generator Finite automata
More informationDVA337 HT17 - LECTURE 4. Languages and regular expressions
DVA337 HT17 - LECTURE 4 Languages and regular expressions 1 SO FAR 2 TODAY Formal definition of languages in terms of strings Operations on strings and languages Definition of regular expressions Meaning
More informationLexing, Parsing. Laure Gonnord sept Master 1, ENS de Lyon
Lexing, Parsing Laure Gonnord http://laure.gonnord.org/pro/teaching/capm1.html Laure.Gonnord@ens-lyon.fr Master 1, ENS de Lyon sept 2017 Analysis Phase source code lexical analysis sequence of lexems (tokens)
More information