Introduction to Compiler Construction in a Java World

Chapter 2

Lexical Analysis

2.1 Introduction

The first step in compiling a program is to break it into tokens. For example, given the j--

program

package pass ;

import java . lang . System ;

public class Factorial {

// Two m e t h o d s and a f ield

public static int f a ctorial ( int n) {

if ( n <= 0)

return 1;

else

return n * fac t o r i a l ( n - 1);

}

public static void m ain ( String [] args ) {

int x = n ;

System . out. println ( x + "! = " + fa c t o r i a l ( x ));

}

static int n = 5;

}

we want to produce the sequence of tokens package, pass, ;, import, java, ., lang, .,

System, ;, public, class, Factorial, {, public, static, int, factorial, (, int, n,),