Examples of attributes: values of evaluated subtrees, type information, source file coordinates,

Size: px
Start display at page:

Download "Examples of attributes: values of evaluated subtrees, type information, source file coordinates,"

Transcription

1 1

2 2

3 3

4 Attributes can be added to the grammar symbols, and program fragments can be added as semantic actions to the grammar, to form a syntax-directed translation scheme. Some attributes may be set by the lexical analysis, and some attributes may be computed in the semantic actions. Examples of attributes: values of evaluated subtrees, type information, source file coordinates, By injecting corresponding code fragments into the parser implementation, the semantic actions can be executed during the parse. This is known as a syntaxdirected translation. 4

5 Example from the book (Section 2.3): turn infix arithmetic expressions into postfix dittos. 5

6 Postfix notation for arithmetic expressions puts the operator at the end instead of in-between the operands (which is called infix notation). With postfix notation, no parentheses are needed. This is a good example since it postfix notation is similar to the stack machine code that you will generate in the first lab assignment. 6

7 The postfix notation of a single constant num is defined as just that constant. The postfix notation of an infix expression on the form (E) is defined as the postfix notation of E. The postfix notation of an infix expression on the form E 1 op E 2, where op is some binary operator, is defined as the postfix notation of E 1 followed by the postfix notation of E 2 followed by op. Note that this definition is not concerned with the precedence or associativity of operators. It assumes that the intended order in which the operators are applied is already reflected in the parse tree for the expression, and the same application order will be used in the resulting postfix expression. 7

8 8

9 Translation scheme based on the old expression grammar (we will take care of the left-recursion later). The code fragments should be executed by the parser as soon as the production has been identified. The semantic actions can also be put in the middle of production bodies. We assume that the scanner has attached an attribute value to the num tokens (the book uses a nonterminal). Note that attributes can be attached also to nonterminals, and the attributes may be changed by the semantic actions to propagate information to different parts of the parse tree. 9

10 The semantic actions can be seen as grammar symbols. If inserted as leaves in the parse tree, they are executed in the order given by a depthfirst, left-right traversal of the tree. 10

11 11

12 Since we treat the semantic actions as grammar symbols, they can be included in the left recursion elimination. Here the same translation scheme, with left recursion removed using the simple procedure shown before, is shown. Note that since the semantic actions now appear in the middle of the production bodies, they should be executed as soon as the parser has processed the symbols to the left in the body. However, this is a common mistake in the first lab assignment. Make sure e.g. the expression is translated as (3 2) 1 instead of as 3 (2 1)! 12

13 13

14 Syntax-directed definitions are similar to syntax-directed translation schemes, but more abstract or declarative. Extends the grammar in the following way: Attaches attributes to grammar symbols (terminals and nonterminals) Attaches semantic rules to productions that define the attributes. Contrary to semantic actions, no evaluation order is specified, but is instead implied by the definition. It is common to add subscripts to grammar symbols that occur several times in the same production, to be able to distinguish them in the semantic rules. The table shows a syntax-directed definition for the infix postfix translation. The operator means string concatenation. 14

15 15

16 16

17 Note that the lexical analysis should not assume that the input program is syntactically correct. For instance, the following regular expression used to distinguish the keyword if from identifiers starting with the letters if is problematic: if[ \t\n]*( The problem is that it assumes that the next token is a left parenthesis (which it will be if the program is syntactically correct, but this might not be the case). 17

18 The typesetting language TeX has support for configuring the lexical analysis. For example, it has support for changing which character should be used to start comments. Another example: if the macro \A expands to some and the macro \B expands to macro, then \csname\a\b\endcsname generates a call to the macro \somemacro. In this case, a token (a control sequence token) has been generated from the invocation of other macros. 18

19 19

20 20

21 21

22 22

23 The lexical analysis can also be implemented as a DFA. The DFA is invoked each time GetNextToken() is called. The tokens recognized by the DFA in this example are: < Less than <= Less than or equal > Greater than >= Greater than or equal = Equal <> Not equal The * at states 4 and 8 means that the current input position must be moved back one step. Optional exercise: Draw a DFA that recognizes the following tokens (from the language C): add Plus operator: + incr Increment operator: ++ sub Minus operator: - decr Decrement operator: -- arrow Struct member accessor: -> id Identifiers: [a-za-z_][a-za-z0-9_]* if The keyword if 23

24 This table encodes the DFA from the previous slide. Green cells mark success: the returning of a token. Red cells mark lexical error. In reality, other characters in the state 0 would be the start of some other lexemes, since it is not common that a language only contains relational operators. 24

25 With a keyword table, recognized identifiers can be checked against the keywords in the table to see if they should be returned as keyword tokens instead. Another strategy is to always test for keywords before identifiers, e.g. by constructing the DFA this way. 25

26 26

27 27

28 28

A Simple Syntax-Directed Translator

A Simple Syntax-Directed Translator Chapter 2 A Simple Syntax-Directed Translator 1-1 Introduction The analysis phase of a compiler breaks up a source program into constituent pieces and produces an internal representation for it, called

More information

A simple syntax-directed

A simple syntax-directed Syntax-directed is a grammaroriented compiling technique Programming languages: Syntax: what its programs look like? Semantic: what its programs mean? 1 A simple syntax-directed Lexical Syntax Character

More information

Context-Free Grammar. Concepts Introduced in Chapter 2. Parse Trees. Example Grammar and Derivation

Context-Free Grammar. Concepts Introduced in Chapter 2. Parse Trees. Example Grammar and Derivation Concepts Introduced in Chapter 2 A more detailed overview of the compilation process. Parsing Scanning Semantic Analysis Syntax-Directed Translation Intermediate Code Generation Context-Free Grammar A

More information

COMP-421 Compiler Design. Presented by Dr Ioanna Dionysiou

COMP-421 Compiler Design. Presented by Dr Ioanna Dionysiou COMP-421 Compiler Design Presented by Dr Ioanna Dionysiou Administrative! Any questions about the syllabus?! Course Material available at www.cs.unic.ac.cy/ioanna! Next time reading assignment [ALSU07]

More information

CSE 401 Midterm Exam 11/5/10

CSE 401 Midterm Exam 11/5/10 Name There are 5 questions worth a total of 100 points. Please budget your time so you get to all of the questions. Keep your answers brief and to the point. The exam is closed books, closed notes, closed

More information

A programming language requires two major definitions A simple one pass compiler

A programming language requires two major definitions A simple one pass compiler A programming language requires two major definitions A simple one pass compiler [Syntax: what the language looks like A context-free grammar written in BNF (Backus-Naur Form) usually suffices. [Semantics:

More information

2.2 Syntax Definition

2.2 Syntax Definition 42 CHAPTER 2. A SIMPLE SYNTAX-DIRECTED TRANSLATOR sequence of "three-address" instructions; a more complete example appears in Fig. 2.2. This form of intermediate code takes its name from instructions

More information

Structure of a compiler. More detailed overview of compiler front end. Today we ll take a quick look at typical parts of a compiler.

Structure of a compiler. More detailed overview of compiler front end. Today we ll take a quick look at typical parts of a compiler. More detailed overview of compiler front end Structure of a compiler Today we ll take a quick look at typical parts of a compiler. This is to give a feeling for the overall structure. source program lexical

More information

Principles of Programming Languages COMP251: Syntax and Grammars

Principles of Programming Languages COMP251: Syntax and Grammars Principles of Programming Languages COMP251: Syntax and Grammars Prof. Dekai Wu Department of Computer Science and Engineering The Hong Kong University of Science and Technology Hong Kong, China Fall 2007

More information

Building Compilers with Phoenix

Building Compilers with Phoenix Building Compilers with Phoenix Syntax-Directed Translation Structure of a Compiler Character Stream Intermediate Representation Lexical Analyzer Machine-Independent Optimizer token stream Intermediate

More information

COP 3402 Systems Software Top Down Parsing (Recursive Descent)

COP 3402 Systems Software Top Down Parsing (Recursive Descent) COP 3402 Systems Software Top Down Parsing (Recursive Descent) Top Down Parsing 1 Outline 1. Top down parsing and LL(k) parsing 2. Recursive descent parsing 3. Example of recursive descent parsing of arithmetic

More information

CPS 506 Comparative Programming Languages. Syntax Specification

CPS 506 Comparative Programming Languages. Syntax Specification CPS 506 Comparative Programming Languages Syntax Specification Compiling Process Steps Program Lexical Analysis Convert characters into a stream of tokens Lexical Analysis Syntactic Analysis Send tokens

More information

Part 5 Program Analysis Principles and Techniques

Part 5 Program Analysis Principles and Techniques 1 Part 5 Program Analysis Principles and Techniques Front end 2 source code scanner tokens parser il errors Responsibilities: Recognize legal programs Report errors Produce il Preliminary storage map Shape

More information

Chapter 3: Describing Syntax and Semantics. Introduction Formal methods of describing syntax (BNF)

Chapter 3: Describing Syntax and Semantics. Introduction Formal methods of describing syntax (BNF) Chapter 3: Describing Syntax and Semantics Introduction Formal methods of describing syntax (BNF) We can analyze syntax of a computer program on two levels: 1. Lexical level 2. Syntactic level Lexical

More information

This book is licensed under a Creative Commons Attribution 3.0 License

This book is licensed under a Creative Commons Attribution 3.0 License 6. Syntax Learning objectives: syntax and semantics syntax diagrams and EBNF describe context-free grammars terminal and nonterminal symbols productions definition of EBNF by itself parse tree grammars

More information

Formal Languages and Compilers Lecture VI: Lexical Analysis

Formal 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 information

CSE 311 Lecture 21: Context-Free Grammars. Emina Torlak and Kevin Zatloukal

CSE 311 Lecture 21: Context-Free Grammars. Emina Torlak and Kevin Zatloukal CSE 311 Lecture 21: Context-Free Grammars Emina Torlak and Kevin Zatloukal 1 Topics Regular expressions A brief review of Lecture 20. Context-free grammars Syntax, semantics, and examples. 2 Regular expressions

More information

Test I Solutions MASSACHUSETTS INSTITUTE OF TECHNOLOGY Spring Department of Electrical Engineering and Computer Science

Test I Solutions MASSACHUSETTS INSTITUTE OF TECHNOLOGY Spring Department of Electrical Engineering and Computer Science Department of Electrical Engineering and Computer Science MASSACHUSETTS INSTITUTE OF TECHNOLOGY 6.035 Spring 2013 Test I Solutions Mean 83 Median 87 Std. dev 13.8203 14 12 10 8 6 4 2 0 0 10 20 30 40 50

More information

Chapter 3: CONTEXT-FREE GRAMMARS AND PARSING Part 1

Chapter 3: CONTEXT-FREE GRAMMARS AND PARSING Part 1 Chapter 3: CONTEXT-FREE GRAMMARS AND PARSING Part 1 1. Introduction Parsing is the task of Syntax Analysis Determining the syntax, or structure, of a program. The syntax is defined by the grammar rules

More information

Parsing II Top-down parsing. Comp 412

Parsing II Top-down parsing. Comp 412 COMP 412 FALL 2018 Parsing II Top-down parsing Comp 412 source code IR Front End Optimizer Back End IR target code Copyright 2018, Keith D. Cooper & Linda Torczon, all rights reserved. Students enrolled

More information

Last time. What are compilers? Phases of a compiler. Scanner. Parser. Semantic Routines. Optimizer. Code Generation. Sunday, August 29, 2010

Last time. What are compilers? Phases of a compiler. Scanner. Parser. Semantic Routines. Optimizer. Code Generation. Sunday, August 29, 2010 Last time Source code Scanner Tokens Parser What are compilers? Phases of a compiler Syntax tree Semantic Routines IR Optimizer IR Code Generation Executable Extra: Front-end vs. Back-end Scanner + Parser

More information

Lexical analysis. Syntactical analysis. Semantical analysis. Intermediate code generation. Optimization. Code generation. Target specific optimization

Lexical analysis. Syntactical analysis. Semantical analysis. Intermediate code generation. Optimization. Code generation. Target specific optimization Second round: the scanner Lexical analysis Syntactical analysis Semantical analysis Intermediate code generation Optimization Code generation Target specific optimization Lexical analysis (Chapter 3) Why

More information

1 Lexical Considerations

1 Lexical Considerations Massachusetts Institute of Technology Department of Electrical Engineering and Computer Science 6.035, Spring 2013 Handout Decaf Language Thursday, Feb 7 The project for the course is to write a compiler

More information

Lexical Analysis. Introduction

Lexical 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 information

Introduction to Compiler Construction

Introduction to Compiler Construction Introduction to Compiler Construction ASU Textbook Chapter 1 Tsan-sheng Hsu tshsu@iis.sinica.edu.tw http://www.iis.sinica.edu.tw/~tshsu 1 What is a compiler? Definitions: A recognizer. A translator. source

More information

Left to right design 1

Left to right design 1 Left to right design 1 Left to right design The left to right design method suggests that the structure of the program should closely follow the structure of the input. The method is effective when the

More information

Program Analysis ( 软件源代码分析技术 ) ZHENG LI ( 李征 )

Program Analysis ( 软件源代码分析技术 ) ZHENG LI ( 李征 ) Program Analysis ( 软件源代码分析技术 ) ZHENG LI ( 李征 ) lizheng@mail.buct.edu.cn Lexical and Syntax Analysis Topic Covered Today Compilation Lexical Analysis Semantic Analysis Compilation Translating from high-level

More information

Stack Applications. Lecture 27 Sections Robb T. Koether. Hampden-Sydney College. Wed, Mar 29, 2017

Stack Applications. Lecture 27 Sections Robb T. Koether. Hampden-Sydney College. Wed, Mar 29, 2017 Stack Applications Lecture 27 Sections 18.7-18.8 Robb T. Koether Hampden-Sydney College Wed, Mar 29, 2017 Robb T. Koether Hampden-Sydney College) Stack Applications Wed, Mar 29, 2017 1 / 27 1 Function

More information

Compiler Design Aug 1996

Compiler Design Aug 1996 Aug 1996 Part A 1 a) What are the different phases of a compiler? Explain briefly with the help of a neat diagram. b) For the following Pascal keywords write the state diagram and also write program segments

More information

Briefly describe the purpose of the lexical and syntax analysis phases in a compiler.

Briefly describe the purpose of the lexical and syntax analysis phases in a compiler. Name: Midterm Exam PID: This is a closed-book exam; you may not use any tools besides a pen. You have 75 minutes to answer all questions. There are a total of 75 points available. Please write legibly;

More information

4. Semantic Processing and Attributed Grammars

4. Semantic Processing and Attributed Grammars 4. Semantic Processing and Attributed Grammars 1 Semantic Processing The parser checks only the syntactic correctness of a program Tasks of semantic processing Checking context conditions - Declaration

More information

Compiling Regular Expressions COMP360

Compiling Regular Expressions COMP360 Compiling Regular Expressions COMP360 Logic is the beginning of wisdom, not the end. Leonard Nimoy Compiler s Purpose The compiler converts the program source code into a form that can be executed by the

More information

COP 3402 Systems Software Syntax Analysis (Parser)

COP 3402 Systems Software Syntax Analysis (Parser) COP 3402 Systems Software Syntax Analysis (Parser) Syntax Analysis 1 Outline 1. Definition of Parsing 2. Context Free Grammars 3. Ambiguous/Unambiguous Grammars Syntax Analysis 2 Lexical and Syntax Analysis

More information

CSE au Final Exam Sample Solution

CSE au Final Exam Sample Solution CSE 413 12au Final Exam Sample Solution Question 1. (10 points) Regular expressions I. Describe the set of strings generated by each of the following regular expressions. For full credit, give a description

More information

Lecture Chapter 6 Recursion as a Problem Solving Technique

Lecture Chapter 6 Recursion as a Problem Solving Technique Lecture Chapter 6 Recursion as a Problem Solving Technique Backtracking 1. Select, i.e., guess, a path of steps that could possibly lead to a solution 2. If the path leads to a dead end then retrace steps

More information

More Assigned Reading and Exercises on Syntax (for Exam 2)

More Assigned Reading and Exercises on Syntax (for Exam 2) More Assigned Reading and Exercises on Syntax (for Exam 2) 1. Read sections 2.3 (Lexical Syntax) and 2.4 (Context-Free Grammars) on pp. 33 41 of Sethi. 2. Read section 2.6 (Variants of Grammars) on pp.

More information

Introduction to Compiler Construction

Introduction to Compiler Construction Introduction to Compiler Construction ASU Textbook Chapter 1 Tsan-sheng Hsu tshsu@iis.sinica.edu.tw http://www.iis.sinica.edu.tw/~tshsu 1 What is a compiler? Definitions: A recognizer. A translator. source

More information

Syntax Analysis Check syntax and construct abstract syntax tree

Syntax Analysis Check syntax and construct abstract syntax tree Syntax Analysis Check syntax and construct abstract syntax tree if == = ; b 0 a b Error reporting and recovery Model using context free grammars Recognize using Push down automata/table Driven Parsers

More information

ΕΠΛ323 - Θεωρία και Πρακτική Μεταγλωττιστών

ΕΠΛ323 - Θεωρία και Πρακτική Μεταγλωττιστών ΕΠΛ323 - Θεωρία και Πρακτική Μεταγλωττιστών Lecture 5a Syntax Analysis lias Athanasopoulos eliasathan@cs.ucy.ac.cy Syntax Analysis Συντακτική Ανάλυση Context-free Grammars (CFGs) Derivations Parse trees

More information

Introduction to Compiler Construction

Introduction to Compiler Construction Introduction to Compiler Construction ALSU Textbook Chapter 1.1 1.5 Tsan-sheng Hsu tshsu@iis.sinica.edu.tw http://www.iis.sinica.edu.tw/~tshsu 1 What is a compiler? Definitions: a recognizer ; a translator.

More information

MIT Specifying Languages with Regular Expressions and Context-Free Grammars. Martin Rinard Massachusetts Institute of Technology

MIT 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 information

MIT Specifying Languages with Regular Expressions and Context-Free Grammars

MIT 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 information

Lexical Scanning COMP360

Lexical Scanning COMP360 Lexical Scanning COMP360 Captain, we re being scanned. Spock Reading Read sections 2.1 3.2 in the textbook Regular Expression and FSA Assignment A new assignment has been posted on Blackboard It is due

More information

MidTerm Papers Solved MCQS with Reference (1 to 22 lectures)

MidTerm Papers Solved MCQS with Reference (1 to 22 lectures) CS606- Compiler Construction MidTerm Papers Solved MCQS with Reference (1 to 22 lectures) by Arslan Arshad (Zain) FEB 21,2016 0300-2462284 http://lmshelp.blogspot.com/ Arslan.arshad01@gmail.com AKMP01

More information

Some Applications of Stack. Spring Semester 2007 Programming and Data Structure 1

Some Applications of Stack. Spring Semester 2007 Programming and Data Structure 1 Some Applications of Stack Spring Semester 2007 Programming and Data Structure 1 Arithmetic Expressions Polish Notation Spring Semester 2007 Programming and Data Structure 2 What is Polish Notation? Conventionally,

More information

List of Figures. About the Authors. Acknowledgments

List of Figures. About the Authors. Acknowledgments List of Figures Preface About the Authors Acknowledgments xiii xvii xxiii xxv 1 Compilation 1 1.1 Compilers..................................... 1 1.1.1 Programming Languages......................... 1

More information

A lexical analyzer generator for Standard ML. Version 1.6.0, October 1994

A lexical analyzer generator for Standard ML. Version 1.6.0, October 1994 A lexical analyzer generator for Standard ML. Version 1.6.0, October 1994 Andrew W. Appel 1 James S. Mattson David R. Tarditi 2 1 Department of Computer Science, Princeton University 2 School of Computer

More information

More on Syntax. Agenda for the Day. Administrative Stuff. More on Syntax In-Class Exercise Using parse trees

More on Syntax. Agenda for the Day. Administrative Stuff. More on Syntax In-Class Exercise Using parse trees More on Syntax Judy Stafford Comp 80 Meeting February, 00 Agenda for the Day Administrative Stuff Moodle Classlist at without waiting list More on Syntax InClass Exercise Using parse trees Last time Syntax

More information

CSE P 501 Exam 11/17/05 Sample Solution

CSE P 501 Exam 11/17/05 Sample Solution 1. (8 points) Write a regular expression or set of regular expressions that generate the following sets of strings. You can use abbreviations (i.e., name = regular expression) if it helps to make your

More information

B The SLLGEN Parsing System

B The SLLGEN Parsing System B The SLLGEN Parsing System Programs are just strings of characters. In order to process a program, we need to group these characters into meaningful units. This grouping is usually divided into two stages:

More information

About the Tutorial. Audience. Prerequisites. Copyright & Disclaimer. Compiler Design

About 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 information

Front End. Hwansoo Han

Front End. Hwansoo Han Front nd Hwansoo Han Traditional Two-pass Compiler Source code Front nd IR Back nd Machine code rrors High level functions Recognize legal program, generate correct code (OS & linker can accept) Manage

More information

Semantic analysis and intermediate representations. Which methods / formalisms are used in the various phases during the analysis?

Semantic analysis and intermediate representations. Which methods / formalisms are used in the various phases during the analysis? Semantic analysis and intermediate representations Which methods / formalisms are used in the various phases during the analysis? The task of this phase is to check the "static semantics" and generate

More information

CS415 Compilers. Syntax Analysis. These slides are based on slides copyrighted by Keith Cooper, Ken Kennedy & Linda Torczon at Rice University

CS415 Compilers. Syntax Analysis. These slides are based on slides copyrighted by Keith Cooper, Ken Kennedy & Linda Torczon at Rice University CS415 Compilers Syntax Analysis These slides are based on slides copyrighted by Keith Cooper, Ken Kennedy & Linda Torczon at Rice University Limits of Regular Languages Advantages of Regular Expressions

More information

RYERSON POLYTECHNIC UNIVERSITY DEPARTMENT OF MATH, PHYSICS, AND COMPUTER SCIENCE CPS 710 FINAL EXAM FALL 96 INSTRUCTIONS

RYERSON POLYTECHNIC UNIVERSITY DEPARTMENT OF MATH, PHYSICS, AND COMPUTER SCIENCE CPS 710 FINAL EXAM FALL 96 INSTRUCTIONS RYERSON POLYTECHNIC UNIVERSITY DEPARTMENT OF MATH, PHYSICS, AND COMPUTER SCIENCE CPS 710 FINAL EXAM FALL 96 STUDENT ID: INSTRUCTIONS Please write your student ID on this page. Do not write it or your name

More information

CSE 401 Midterm Exam Sample Solution 2/11/15

CSE 401 Midterm Exam Sample Solution 2/11/15 Question 1. (10 points) Regular expression warmup. For regular expression questions, you must restrict yourself to the basic regular expression operations covered in class and on homework assignments:

More information

Parsing and Pattern Recognition

Parsing and Pattern Recognition Topics in IT 1 Parsing and Pattern Recognition Week 10 Lexical analysis College of Information Science and Engineering Ritsumeikan University 1 this week mid-term evaluation review lexical analysis its

More information

Time : 1 Hour Max Marks : 30

Time : 1 Hour Max Marks : 30 Total No. of Questions : 6 P4890 B.E/ Insem.- 74 B.E ( Computer Engg) PRINCIPLES OF MODERN COMPILER DESIGN (2012 Pattern) (Semester I) Time : 1 Hour Max Marks : 30 Q.1 a) Explain need of symbol table with

More information

CS 314 Principles of Programming Languages

CS 314 Principles of Programming Languages CS 314 Principles of Programming Languages Lecture 5: Syntax Analysis (Parsing) Zheng (Eddy) Zhang Rutgers University January 31, 2018 Class Information Homework 1 is being graded now. The sample solution

More information

Chapter 4. Syntax - the form or structure of the expressions, statements, and program units

Chapter 4. Syntax - the form or structure of the expressions, statements, and program units Syntax - the form or structure of the expressions, statements, and program units Semantics - the meaning of the expressions, statements, and program units Who must use language definitions? 1. Other language

More information

Syntax/semantics. Program <> program execution Compiler/interpreter Syntax Grammars Syntax diagrams Automata/State Machines Scanning/Parsing

Syntax/semantics. Program <> program execution Compiler/interpreter Syntax Grammars Syntax diagrams Automata/State Machines Scanning/Parsing Syntax/semantics Program program execution Compiler/interpreter Syntax Grammars Syntax diagrams Automata/State Machines Scanning/Parsing Meta-models 8/27/10 1 Program program execution Syntax Semantics

More information

An Introduction to Trees

An Introduction to Trees An Introduction to Trees Alice E. Fischer Spring 2017 Alice E. Fischer An Introduction to Trees... 1/34 Spring 2017 1 / 34 Outline 1 Trees the Abstraction Definitions 2 Expression Trees 3 Binary Search

More information

CSE 3302 Programming Languages Lecture 2: Syntax

CSE 3302 Programming Languages Lecture 2: Syntax CSE 3302 Programming Languages Lecture 2: Syntax (based on slides by Chengkai Li) Leonidas Fegaras University of Texas at Arlington CSE 3302 L2 Spring 2011 1 How do we define a PL? Specifying a PL: Syntax:

More information

Group A Assignment 3(2)

Group A Assignment 3(2) Group A Assignment 3(2) Att (2) Perm(3) Oral(5) Total(10) Sign Title of Assignment: Lexical analyzer using LEX. 3.1.1 Problem Definition: Lexical analyzer for sample language using LEX. 3.1.2 Perquisite:

More information

Theory and Compiling COMP360

Theory and Compiling COMP360 Theory and Compiling COMP360 It has been said that man is a rational animal. All my life I have been searching for evidence which could support this. Bertrand Russell Reading Read sections 2.1 3.2 in the

More information

Lexical Analysis. COMP 524, Spring 2014 Bryan Ward

Lexical 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 information

Theoretical Part. Chapter one:- - What are the Phases of compiler? Answer:

Theoretical Part. Chapter one:- - What are the Phases of compiler? Answer: Theoretical Part Chapter one:- - What are the Phases of compiler? Six phases Scanner Parser Semantic Analyzer Source code optimizer Code generator Target Code Optimizer Three auxiliary components Literal

More information

Code No: R Set No. 1

Code No: R Set No. 1 Code No: R05010106 Set No. 1 1. (a) Draw a Flowchart for the following The average score for 3 tests has to be greater than 80 for a candidate to qualify for the interview. Representing the conditional

More information

Consider a description of arithmetic. It includes two equations that define the structural types of digit and operator:

Consider a description of arithmetic. It includes two equations that define the structural types of digit and operator: Syntax A programming language consists of syntax, semantics, and pragmatics. We formalize syntax first, because only syntactically correct programs have semantics. A syntax definition of a language lists

More information

Specifying Syntax. An English Grammar. Components of a Grammar. Language Specification. Types of Grammars. 1. Terminal symbols or terminals, Σ

Specifying Syntax. An English Grammar. Components of a Grammar. Language Specification. Types of Grammars. 1. Terminal symbols or terminals, Σ Specifying Syntax Language Specification Components of a Grammar 1. Terminal symbols or terminals, Σ Syntax Form of phrases Physical arrangement of symbols 2. Nonterminal symbols or syntactic categories,

More information

Syntax and Grammars 1 / 21

Syntax and Grammars 1 / 21 Syntax and Grammars 1 / 21 Outline What is a language? Abstract syntax and grammars Abstract syntax vs. concrete syntax Encoding grammars as Haskell data types What is a language? 2 / 21 What is a language?

More information

Introduction to Syntax Directed Translation and Top-Down Parsers

Introduction to Syntax Directed Translation and Top-Down Parsers Introduction to Syntax Directed Translation and Top-Down Parsers 1 Attributes and Semantic Rules Let s associate attributes with grammar symbols, and semantic rules with productions. This gives us a syntax

More information

Compiler Code Generation COMP360

Compiler Code Generation COMP360 Compiler Code Generation COMP360 Students who acquire large debts putting themselves through school are unlikely to think about changing society. When you trap people in a system of debt, they can t afford

More information

COLLEGE OF ENGINEERING, NASHIK. LANGUAGE TRANSLATOR

COLLEGE OF ENGINEERING, NASHIK. LANGUAGE TRANSLATOR Pune Vidyarthi Griha s COLLEGE OF ENGINEERING, NASHIK. LANGUAGE TRANSLATOR By Prof. Anand N. Gharu (Assistant Professor) PVGCOE Computer Dept.. 22nd Jan 2018 CONTENTS :- 1. Role of lexical analysis 2.

More information

PRINCIPLES OF COMPILER DESIGN UNIT I INTRODUCTION TO COMPILERS

PRINCIPLES OF COMPILER DESIGN UNIT I INTRODUCTION TO COMPILERS Objective PRINCIPLES OF COMPILER DESIGN UNIT I INTRODUCTION TO COMPILERS Explain what is meant by compiler. Explain how the compiler works. Describe various analysis of the source program. Describe the

More information

CS 315 Programming Languages Syntax. Parser. (Alternatively hand-built) (Alternatively hand-built)

CS 315 Programming Languages Syntax. Parser. (Alternatively hand-built) (Alternatively hand-built) Programming languages must be precise Remember instructions This is unlike natural languages CS 315 Programming Languages Syntax Precision is required for syntax think of this as the format of the language

More information

Lexical 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. 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 information

Using an LALR(1) Parser Generator

Using an LALR(1) Parser Generator Using an LALR(1) Parser Generator Yacc is an LALR(1) parser generator Developed by S.C. Johnson and others at AT&T Bell Labs Yacc is an acronym for Yet another compiler compiler Yacc generates an integrated

More information

COMPILER DESIGN UNIT I LEXICAL ANALYSIS. Translator: It is a program that translates one language to another Language.

COMPILER DESIGN UNIT I LEXICAL ANALYSIS. Translator: It is a program that translates one language to another Language. UNIT I LEXICAL ANALYSIS Translator: It is a program that translates one language to another Language. Source Code Translator Target Code 1. INTRODUCTION TO LANGUAGE PROCESSING The Language Processing System

More information

1. INTRODUCTION TO LANGUAGE PROCESSING The Language Processing System can be represented as shown figure below.

1. INTRODUCTION TO LANGUAGE PROCESSING The Language Processing System can be represented as shown figure below. UNIT I Translator: It is a program that translates one language to another Language. Examples of translator are compiler, assembler, interpreter, linker, loader and preprocessor. Source Code Translator

More information

Introduction to Parsing. Lecture 5

Introduction to Parsing. Lecture 5 Introduction to Parsing Lecture 5 1 Outline Regular languages revisited Parser overview Context-free grammars (CFG s) Derivations Ambiguity 2 Languages and Automata Formal languages are very important

More information

Context-Free Grammars

Context-Free Grammars Context-Free Grammars Lecture 7 http://webwitch.dreamhost.com/grammar.girl/ Outline Scanner vs. parser Why regular expressions are not enough Grammars (context-free grammars) grammar rules derivations

More information

TDDD55 - Compilers and Interpreters Lesson 3

TDDD55 - Compilers and Interpreters Lesson 3 TDDD55 - Compilers and Interpreters Lesson 3 November 22 2011 Kristian Stavåker (kristian.stavaker@liu.se) Department of Computer and Information Science Linköping University LESSON SCHEDULE November 1,

More information

CSC 467 Lecture 3: Regular Expressions

CSC 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 information

Lexical and Syntax Analysis

Lexical and Syntax Analysis Lexical and Syntax Analysis In Text: Chapter 4 N. Meng, F. Poursardar Lexical and Syntactic Analysis Two steps to discover the syntactic structure of a program Lexical analysis (Scanner): to read the input

More information

Syntax-Directed Translation

Syntax-Directed Translation Syntax-Directed Translation What is syntax-directed translation? The compilation process is driven by the syntax. The semantic routines perform interpretation based on the syntax structure. Attaching attributes

More information

Section A. A grammar that produces more than one parse tree for some sentences is said to be ambiguous.

Section A. A grammar that produces more than one parse tree for some sentences is said to be ambiguous. Section A 1. What do you meant by parser and its types? A parser for grammar G is a program that takes as input a string w and produces as output either a parse tree for w, if w is a sentence of G, or

More information

PRINCIPLES OF COMPILER DESIGN UNIT I INTRODUCTION TO COMPILING

PRINCIPLES OF COMPILER DESIGN UNIT I INTRODUCTION TO COMPILING PRINCIPLES OF COMPILER DESIGN 2 MARKS UNIT I INTRODUCTION TO COMPILING 1. Define compiler? A compiler is a program that reads a program written in one language (source language) and translates it into

More information

CS 403: Scanning and Parsing

CS 403: Scanning and Parsing CS 403: Scanning and Parsing Stefan D. Bruda Fall 2017 THE COMPILATION PROCESS Character stream Scanner (lexical analysis) Token stream Parser (syntax analysis) Parse tree Semantic analysis Abstract syntax

More information

Compiler Lab. Introduction to tools Lex and Yacc

Compiler Lab. Introduction to tools Lex and Yacc Compiler Lab Introduction to tools Lex and Yacc Assignment1 Implement a simple calculator with tokens recognized using Lex/Flex and parsing and semantic actions done using Yacc/Bison. Calculator Input:

More information

CS321 Languages and Compiler Design I. Winter 2012 Lecture 4

CS321 Languages and Compiler Design I. Winter 2012 Lecture 4 CS321 Languages and Compiler Design I Winter 2012 Lecture 4 1 LEXICAL ANALYSIS Convert source file characters into token stream. Remove content-free characters (comments, whitespace,...) Detect lexical

More information

CSE 413 Final Exam. December 13, 2012

CSE 413 Final Exam. December 13, 2012 CSE 413 Final Exam December 13, 2012 Name The exam is closed book, closed notes, no electronic devices, signal flags, tin-can telephones, or other signaling or communications apparatus. Style and indenting

More information

Stating the obvious, people and computers do not speak the same language.

Stating the obvious, people and computers do not speak the same language. 3.4 SYSTEM SOFTWARE 3.4.3 TRANSLATION SOFTWARE INTRODUCTION Stating the obvious, people and computers do not speak the same language. People have to write programs in order to instruct a computer what

More information

March 13/2003 Jayakanth Srinivasan,

March 13/2003 Jayakanth Srinivasan, Statement Effort MergeSort(A, lower_bound, upper_bound) begin T(n) if (lower_bound < upper_bound) Θ(1) mid = (lower_bound + upper_bound)/ 2 Θ(1) MergeSort(A, lower_bound, mid) T(n/2) MergeSort(A, mid+1,

More information

SMURF Language Reference Manual Serial MUsic Represented as Functions

SMURF Language Reference Manual Serial MUsic Represented as Functions SMURF Language Reference Manual Serial MUsic Represented as Functions Richard Townsend, Lianne Lairmore, Lindsay Neubauer, Van Bui, Kuangya Zhai {rt2515, lel2143, lan2135, vb2363, kz2219}@columbia.edu

More information

LESSON 1. A C program is constructed as a sequence of characters. Among the characters that can be used in a program are:

LESSON 1. A C program is constructed as a sequence of characters. Among the characters that can be used in a program are: LESSON 1 FUNDAMENTALS OF C The purpose of this lesson is to explain the fundamental elements of the C programming language. C like other languages has all alphabet and rules for putting together words

More information

Compiler Design Concepts. Syntax Analysis

Compiler Design Concepts. Syntax Analysis Compiler Design Concepts Syntax Analysis Introduction First task is to break up the text into meaningful words called tokens. newval=oldval+12 id = id + num Token Stream Lexical Analysis Source Code (High

More information

UNIT -2 LEXICAL ANALYSIS

UNIT -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 information

Parsing. Roadmap. > Context-free grammars > Derivations and precedence > Top-down parsing > Left-recursion > Look-ahead > Table-driven parsing

Parsing. Roadmap. > Context-free grammars > Derivations and precedence > Top-down parsing > Left-recursion > Look-ahead > Table-driven parsing Roadmap > Context-free grammars > Derivations and precedence > Top-down parsing > Left-recursion > Look-ahead > Table-driven parsing The role of the parser > performs context-free syntax analysis > guides

More information

flex is not a bad tool to use for doing modest text transformations and for programs that collect statistics on input.

flex is not a bad tool to use for doing modest text transformations and for programs that collect statistics on input. flex is not a bad tool to use for doing modest text transformations and for programs that collect statistics on input. More often than not, though, you ll want to use flex to generate a scanner that divides

More information