Java Programming: Below is the lexer, shank and token files along with the shank.txt file. The shank file is the main method file. The lexer must break up the input text stream into lexemes and return a token object for each one in the shank.txt file. Make sure to fix the errors in the lexer.java file and show the complete code for lexer.java.There must be no error in the code at all. Run the whole code and show the output which the shank.txt must be printed out in the terminal. Attached is the rubric. Lexer.java package mypack; import java.util.HashMap; import java.util.List; import mypack.Token.TokenType; public class Lexer { private static final int INTEGER_STATE = 1; private static final int DECIMAL_STATE = 2; private static final int IDENTIFIER_STATE = 3; private static final int SYMBOL_STATE = 4; private static final int ERROR_STATE = 5; private static final int STRING_STATE = 6; private static final int CHAR_STATE = 7; private static final int COMMENT_STATE = 8; private static final char EOF = (char) -1; private static String input; private static int index; private static char currentChar; private static int lineNumber = 1; private static int indentLevel = 0; private static int lastIndentLevel = 0; private static HashMap keywords = new HashMap() {{ put("while", TokenType.WHILE); put("if", TokenType.IF); put("else", TokenType.ELSE); put("print", TokenType.PRINT); }}; private static HashMap symbols = new HashMap() {{ put('+', TokenType.PLUS); put('-', TokenType.MINUS); put('*', TokenType.MULTIPLY); put('/', TokenType.DIVIDE); put('=', TokenType.EQUALS); put(':', TokenType.COLON); put(';', TokenType.SEMICOLON); put('(', TokenType.LEFT_PAREN); put(')', TokenType.RIGHT_PAREN); put('{', TokenType.LEFT_BRACE); put('}', TokenType.RIGHT_BRACE); put('<', TokenType.LESS_THAN); put('>', TokenType.GREATER_THAN); }}; public Lexer(String input) { Lexer.input = input; index = 0; currentChar = input.charAt(index); } private void nextChar() { index++; if (index >= input.length()) { currentChar = EOF; } else { currentChar = input.charAt(index); } } private void skipWhiteSpace() { while (Character.isWhitespace(currentChar)) { nextChar(); } } private int getIndentLevel() { int level = 0; int i = index; char c = input.charAt(i); while (c == ' ' || c == '\t') { if (c == '\t') { level += 1; } else if (c == ' ') { level += 1; } i++; if (i >= input.length()) { break; } } return level; } public List lex(String line) { List tokens = newArrayList(); Lexer lexer = new Lexer(line); while (currentChar != EOF) { if (Character.isWhitespace(currentChar)) { skipWhiteSpace(); continue; } if (currentChar == '#') { while (currentChar != '\n' && currentChar != EOF) { nextChar(); } skipWhiteSpace(); continue; } if (Character.isDigit(currentChar)) { int startPos = index; int state = INTEGER_STATE; String value = ""; } } Token.java package mypack; public class Token { public enum TokenType { WORD, WHILE, IF, ELSE, NUMBER, SYMBOL, PLUS, MINUS, MULTIPLY, DIVIDE, EQUALS, COLON, SEMICOLON, LEFT_PAREN, RIGHT_PAREN, LEFT_BRACE, RIGHT_BRACE, LESS_THAN, GREATER_THAN, PRINT } public TokenType tokenType; private String value; public Token(TokenType type, String val) { this.tokenType = type; this.value = val; } public TokenType getTokenType() { return this.tokenType; } public String toString() { return this.tokenType + ": " + this.value; } } Shank.java package mypack; import java.io.IOException; import java.nio.charset.Charset; import java.nio.charset.StandardCharsets; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; import java.util.List; public class Shank { public static void main(String[] args) { Path filePath = Paths.get("shank.txt"); Charset charset = StandardCharsets.UTF_8; if (args.length != 1) { System.out.println("Error: Exactly one argument is required."); System.exit(0); } String filename = args[0]; try { List lines = Files.readAllLines(Paths.get(filename)); for (String line : lines) { try { Lexer lexer = new Lexer(line); List tokens = lexer.lex(line); for (Token token : tokens) { System.out.println(token); } } catch (Exception e) { System.out.println("Exception: " + e.getMessage()); } } } catch (IOException e) { System.out.println("Error: Could not read file '" + filename + "'."); } } } Shank.txt Fibonoacci (Iterative) define add (num1,num2:integer var sum : integer) variable counter : integer Finonacci(N) int N = 10; while counter < N define start () variables num1,num2,num3 : integer add num1,num2,var num3 {num1 and num2 are added together to get num3} num1 = num2; num2 = num3; counter = counter + 1; GCD (Recursive) define add (int a,int b : gcd) if b = 0 sum = a sum gcd(b, a % b) GCD (Iterative) define add (inta, intb : gcd) if a = 0 sum = b if b = 0 sum = a while counter a != b if a > b a = a - b; else b = b - a; sum = a; variables a,b : integer a = 60 b = 96 subtract a,b

Java Programming: Below is the lexer, shank and token files along with the shank.txt file. The shank file is the main method file. The lexer must break up the input text stream into lexemes and return a token object for each one in the shank.txt file. Make sure to fix the errors in the lexer.java file and show the complete code for lexer.java.There must be no error in the code at all. Run the whole code and show the output which the shank.txt must be printed out in the terminal. Attached is the rubric. Lexer.java package mypack; import java.util.HashMap; import java.util.List; import mypack.Token.TokenType; public class Lexer { private static final int INTEGER_STATE = 1; private static final int DECIMAL_STATE = 2; private static final int IDENTIFIER_STATE = 3; private static final int SYMBOL_STATE = 4; private static final int ERROR_STATE = 5; private static final int STRING_STATE = 6; private static final int CHAR_STATE = 7; private static final int COMMENT_STATE = 8; private static final char EOF = (char) -1; private static String input; private static int index; private static char currentChar; private static int lineNumber = 1; private static int indentLevel = 0; private static int lastIndentLevel = 0; private static HashMap keywords = new HashMap() {{ put("while", TokenType.WHILE); put("if", TokenType.IF); put("else", TokenType.ELSE); put("print", TokenType.PRINT); }}; private static HashMap symbols = new HashMap() {{ put('+', TokenType.PLUS); put('-', TokenType.MINUS); put('*', TokenType.MULTIPLY); put('/', TokenType.DIVIDE); put('=', TokenType.EQUALS); put(':', TokenType.COLON); put(';', TokenType.SEMICOLON); put('(', TokenType.LEFT_PAREN); put(')', TokenType.RIGHT_PAREN); put('{', TokenType.LEFT_BRACE); put('}', TokenType.RIGHT_BRACE); put('<', TokenType.LESS_THAN); put('>', TokenType.GREATER_THAN); }}; public Lexer(String input) { Lexer.input = input; index = 0; currentChar = input.charAt(index); } private void nextChar() { index++; if (index >= input.length()) { currentChar = EOF; } else { currentChar = input.charAt(index); } } private void skipWhiteSpace() { while (Character.isWhitespace(currentChar)) { nextChar(); } } private int getIndentLevel() { int level = 0; int i = index; char c = input.charAt(i); while (c == ' ' || c == '\t') { if (c == '\t') { level += 1; } else if (c == ' ') { level += 1; } i++; if (i >= input.length()) { break; } } return level; } public List lex(String line) { List tokens = newArrayList(); Lexer lexer = new Lexer(line); while (currentChar != EOF) { if (Character.isWhitespace(currentChar)) { skipWhiteSpace(); continue; } if (currentChar == '#') { while (currentChar != '\n' && currentChar != EOF) { nextChar(); } skipWhiteSpace(); continue; } if (Character.isDigit(currentChar)) { int startPos = index; int state = INTEGER_STATE; String value = ""; } } Token.java package mypack; public class Token { public enum TokenType { WORD, WHILE, IF, ELSE, NUMBER, SYMBOL, PLUS, MINUS, MULTIPLY, DIVIDE, EQUALS, COLON, SEMICOLON, LEFT_PAREN, RIGHT_PAREN, LEFT_BRACE, RIGHT_BRACE, LESS_THAN, GREATER_THAN, PRINT } public TokenType tokenType; private String value; public Token(TokenType type, String val) { this.tokenType = type; this.value = val; } public TokenType getTokenType() { return this.tokenType; } public String toString() { return this.tokenType + ": " + this.value; } } Shank.java package mypack; import java.io.IOException; import java.nio.charset.Charset; import java.nio.charset.StandardCharsets; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; import java.util.List; public class Shank { public static void main(String[] args) { Path filePath = Paths.get("shank.txt"); Charset charset = StandardCharsets.UTF_8; if (args.length != 1) { System.out.println("Error: Exactly one argument is required."); System.exit(0); } String filename = args[0]; try { List lines = Files.readAllLines(Paths.get(filename)); for (String line : lines) { try { Lexer lexer = new Lexer(line); List tokens = lexer.lex(line); for (Token token : tokens) { System.out.println(token); } } catch (Exception e) { System.out.println("Exception: " + e.getMessage()); } } } catch (IOException e) { System.out.println("Error: Could not read file '" + filename + "'."); } } } Shank.txt Fibonoacci (Iterative) define add (num1,num2:integer var sum : integer) variable counter : integer Finonacci(N) int N = 10; while counter < N define start () variables num1,num2,num3 : integer add num1,num2,var num3 {num1 and num2 are added together to get num3} num1 = num2; num2 = num3; counter = counter + 1; GCD (Recursive) define add (int a,int b : gcd) if b = 0 sum = a sum gcd(b, a % b) GCD (Iterative) define add (inta, intb : gcd) if a = 0 sum = b if b = 0 sum = a while counter a != b if a > b a = a - b; else b = b - a; sum = a; variables a,b : integer a = 60 b = 96 subtract a,b

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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Question

Lexer.java

package mypack;

import java.util.HashMap;
import java.util.List;
import mypack.Token.TokenType;

public class Lexer {

private static final int INTEGER_STATE = 1;
private static final int DECIMAL_STATE = 2;
private static final int IDENTIFIER_STATE = 3;
private static final int SYMBOL_STATE = 4;
private static final int ERROR_STATE = 5;
private static final int STRING_STATE = 6;
private static final int CHAR_STATE = 7;
private static final int COMMENT_STATE = 8;

private static final char EOF = (char) -1;

private static String input;
private static int index;
private static char currentChar;
private static int lineNumber = 1;
private static int indentLevel = 0;
private static int lastIndentLevel = 0;

private static HashMap<String, TokenType> keywords = new HashMap<String, TokenType>() {{
put("while", TokenType.WHILE);
put("if", TokenType.IF);
put("else", TokenType.ELSE);
put("print", TokenType.PRINT);
}};

private static HashMap<Character, TokenType> symbols = new HashMap<Character, TokenType>() {{
put('+', TokenType.PLUS);
put('-', TokenType.MINUS);
put('*', TokenType.MULTIPLY);
put('/', TokenType.DIVIDE);
put('=', TokenType.EQUALS);
put(':', TokenType.COLON);
put(';', TokenType.SEMICOLON);
put('(', TokenType.LEFT_PAREN);
put(')', TokenType.RIGHT_PAREN);
put('{', TokenType.LEFT_BRACE);
put('}', TokenType.RIGHT_BRACE);
put('<', TokenType.LESS_THAN);
put('>', TokenType.GREATER_THAN);
}};

public Lexer(String input) {
Lexer.input = input;
index = 0;
currentChar = input.charAt(index);
}

private void nextChar() {
index++;
if (index >= input.length()) {
currentChar = EOF;
} else {
currentChar = input.charAt(index);
}
}

private void skipWhiteSpace() {
while (Character.isWhitespace(currentChar)) {
nextChar();
}
}

private int getIndentLevel() {
int level = 0;
int i = index;
char c = input.charAt(i);
while (c == ' ' || c == '\t') {
if (c == '\t') {
level += 1;
} else if (c == ' ') {
level += 1;
}
i++;
if (i >= input.length()) {
break;
}
}
return level;
}

public List<Token> lex(String line) {
List<Token> tokens = newArrayList<Token>();
Lexer lexer = new Lexer(line);
while (currentChar != EOF) {
if (Character.isWhitespace(currentChar)) {
skipWhiteSpace();
continue;
}
if (currentChar == '#') {
while (currentChar != '\n' && currentChar != EOF) {

nextChar();
}
skipWhiteSpace();
continue;
}
if (Character.isDigit(currentChar)) {
int startPos = index;
int state = INTEGER_STATE;
String value = "";

}
}

Token.java

package mypack;

public class Token {

public enum TokenType {
WORD, WHILE, IF, ELSE,
NUMBER,
SYMBOL, PLUS, MINUS, MULTIPLY, DIVIDE, EQUALS, COLON, SEMICOLON, LEFT_PAREN, RIGHT_PAREN, LEFT_BRACE, RIGHT_BRACE, LESS_THAN, GREATER_THAN, PRINT
}

public TokenType tokenType;
private String value;

public Token(TokenType type, String val) {
this.tokenType = type;
this.value = val;
}

public TokenType getTokenType() {
return this.tokenType;
}
public String toString() {
return this.tokenType + ": " + this.value;
}
}

Shank.java

package mypack;

import java.io.IOException;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.List;

public class Shank {
public static void main(String[] args) {
Path filePath = Paths.get("shank.txt");
Charset charset = StandardCharsets.UTF_8;

if (args.length != 1) {

System.out.println("Error: Exactly one argument is required.");
System.exit(0);
}

String filename = args[0];

try {

List<String> lines = Files.readAllLines(Paths.get(filename));

for (String line : lines) {
try {
Lexer lexer = new Lexer(line);
List<Token> tokens = lexer.lex(line);
for (Token token : tokens) {
System.out.println(token);
}
} catch (Exception e) {
System.out.println("Exception: " + e.getMessage());
}
}
} catch (IOException e) {
System.out.println("Error: Could not read file '" + filename + "'.");
}
}
}

Shank.txt

Fibonoacci (Iterative)

define add (num1,num2:integer var sum : integer)
variable counter : integer
Finonacci(N)
int N = 10;
while counter < N
define start ()
variables num1,num2,num3 : integer
add num1,num2,var num3
{num1 and num2 are added together to get num3}
num1 = num2;
num2 = num3;
counter = counter + 1;

GCD (Recursive)

define add (int a,int b : gcd)
if b = 0
sum = a
sum gcd(b, a % b)

GCD (Iterative)

define add (inta, intb : gcd)
if a = 0
sum = b
if b = 0
sum = a
while counter a != b
if a > b
a = a - b;
else
b = b - a;
sum = a;
variables a,b : integer
a = 60
b = 96
subtract a,b

Rubric
Comments
Variable/Function
naming
Keyword lexing
Punctuation lexing
String and
character literals
Invalid symbols
throw an exception
Comments
Indentation
Poor
None/Excessive (0)
Single letters everywhere
(0)
None(0)
None(0)
None (0)
None (0)
None (0)
None (0)
OK
"What" not "Why", few
(5)
Lots of abbreviations
(5)
A few and/or no hash
map (5)
A few punctuation
marks lex(5)
Exception thrown
and/or some cases
missing (5)
Good
Some "what" comments
or missing some (7)
Full words most of the
time (8)
At least 1/2 of the
keywords in the
hashmap and detected
(10)
Almost all lex but issues
with the multi-character
punctuation (10)
Custom exception
always thrown (10)
Single line handled (5)
Attempted (5)
Great
Anything not obvious has
reasoning (10)
Full words, descriptive (10)
Nearly all keywords in the
hashmap and appropriately
detected (15)
Almost all lex (15)
Lex correctly (10)
Custom exception thrown with
good ToString() (15)
Multi-line handled (10)
Handles all cases (15)

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