Lexical Analyzer with parser

package parserPackage;

//A lexical analyzer system for simple expressions and assignment statements. //Author: Christian Watts //Class: CSCI 4200-DB, Fall 2017

import java.io.*;

public class Parse { static final int MAX_LEXEME_LENGTH = 100; static final int MAX_TOKEN_LENGTH = 100; static int charClass; static char[] lexeme = new char[MAX_LEXEME_LENGTH]; static char nextChar; static int lexLen; static int token; static int nextToken; static String nextLine; static FileReader file; static FileReader file2; static BufferedReader reader; static BufferedReader r2;

/*Character classes*/ static final int LETTER = 0; static final int DIGIT = 1; static final int UNKNOWN = 99;

/*Token codes*/ static String[] token_dict = new String[MAX_TOKEN_LENGTH]; static final int INT_LIT = 10; static final int IDENT = 11; static final int ASSIGN_OP = 20; static final int ADD_OP = 21; static final int SUB_OP = 22; static final int MULT_OP = 23; static final int DIV_OP = 24; static final int LEFT_PAREN = 25; static final int RIGHT_PAREN = 26; static final int END_OF_FILE = 98;

/********************************************************************/

/*Open the input data file and process its contents*/ public static void main(String[] args) throws FileNotFoundException {

token_dict[INT_LIT] = "INT_LIT\t"; token_dict[IDENT] = "IDENT\t"; token_dict[ASSIGN_OP] = "ASSIGN_OP"; token_dict[ADD_OP] = "ADD_OP\t"; token_dict[SUB_OP] = "SUB_OP\t"; token_dict[MULT_OP] = "MULT_OP\t"; token_dict[DIV_OP] = "DIV_OP\t"; token_dict[LEFT_PAREN] = "LEFT_PAREN"; token_dict[RIGHT_PAREN] = "RIGHT_PAREN"; token_dict[END_OF_FILE] = "END_OF_FILE";

file = new FileReader("src\\parserPackage\\front_in.txt"); file2 = new FileReader("src\\parserPackage\\front_in.txt");

reader = new BufferedReader(file); r2 = new BufferedReader(file2); if (file == null){ System.out.println("ERROR - cannot open front.in "); }else{ try { while(reader.ready()){ nextLine = r2.readLine(); System.out.println("Parsing the statement: " + nextLine + " "); getChar(); do{ lex(); }while(nextToken != END_OF_FILE); System.out.println(""); System.out.println("*************************************************************************"); System.out.println(""); } } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }

/********************************************************************/

/*lookup operators and parentheses and return their token value*/ static int lookup(char ch){

switch (ch) { case '(': addChar(); nextToken = LEFT_PAREN; break;

case ')': addChar(); nextToken = RIGHT_PAREN; break;

case '+': addChar(); nextToken = ADD_OP; break;

case '-': addChar(); nextToken = SUB_OP; break;

case '*': addChar(); nextToken = MULT_OP; break;

case '/': addChar(); nextToken = DIV_OP; break;

case '=': addChar(); nextToken = ASSIGN_OP; break;

default: lexeme[0] = 'E'; lexeme[1] = 'O'; lexeme[2] = 'F'; lexeme[3] = 0; lexLen = 4; nextToken = END_OF_FILE; break; } return nextToken; }

/********************************************************************/

/*adds next char to lexeme*/ static void addChar(){

if(lexLen <= (MAX_LEXEME_LENGTH-2)){ lexeme[lexLen++] = nextChar; lexeme[lexLen] = 0; }else{ System.out.println("ERROR - lexeme is too long "); } }

/********************************************************************/

/*get the next char of an input and determine its character class*/ static void getChar(){

char c = 0; try { c = (char)reader.read(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } nextChar = c; if((int)nextChar != 0){ if(isalpha(nextChar)){ charClass = LETTER; }else if(isdigit(nextChar)){ charClass = DIGIT; }else{ charClass = UNKNOWN;} }else{ charClass = END_OF_FILE; } }

/********************************************************************/

/*call getChar function until it returns a non-whitespace character*/ static void getNonBlank(){

while(isspace(nextChar)){ getChar(); } }

/********************************************************************/

/*a simple lexical analyzer for arithmetic expressions*/ static int lex(){

lexLen = 0; getNonBlank(); switch (charClass){

/*Parse identifiers */ case LETTER: addChar(); getChar(); while(charClass == LETTER || charClass == DIGIT){ addChar(); getChar(); } nextToken = IDENT; break;

/*Parse integer literals */ case DIGIT: addChar(); getChar(); while(charClass == DIGIT){ addChar(); getChar(); } nextToken = INT_LIT; break;

/*Parentheses and operators*/ case UNKNOWN: lookup(nextChar); getChar(); break;

/*End of the file*/ case END_OF_FILE: nextToken = END_OF_FILE;; lexeme[0] = 'E'; lexeme[1] = 'O'; lexeme[2] = 'F'; lexeme[3] = 0; lexLen = 4; break; }/*End of switch */ String s = new String(lexeme); s = s.substring(0,lexLen); System.out.printf("Next token is: %s\t\t Next lexeme is %s ", token_dict[nextToken], s); return nextToken; }/*End of function lex() */

/********************************************************************/

/*returns true if char is a letter*/ static boolean isalpha(char c){

int ascii = (int) c; if((ascii > 64 && ascii < 91) || (ascii > 96 && ascii < 123)){ return true; }else {return false;} }

/********************************************************************/

/*returns true if char is a digit*/ static boolean isdigit(char c){

int ascii = (int) c; if(ascii > 47 && ascii < 58){ return true; }else {return false;} }

/********************************************************************/

/*returns true if char is a space*/ static boolean isspace(char c){

int ascii = (int) c; if(ascii == 32){ return true; }else {return false;} }

/********************************************************************/

}

need the output to bo like this:

**************************************************** Parsing the statement: sumTotal = (sum + 47 ) / total Next token is: IDENT Next lexeme is sumTotal Enter Next token is: ASSIGN_OP Next lexeme is = Next token is: LEFT_PAREN Next lexeme is ( Enter Enter Enter Next token is: IDENT Next lexeme is sum Enter Enter Enter Next token is: ADD_OP Next lexeme is + Exit Exit Next token is: INT_LIT Next lexeme is 47 Enter Enter Next token is: RIGHT_PAREN Next lexeme is ) Exit Exit Exit Next token is: DIV_OP Next lexeme is / Exit Next token is: IDENT Next lexeme is total Enter Exit Exit Exit Exit