Java Programming: There are errors in the parser.java file. Make sure there are no error in the any of the files given. All the files must be working correctly without any error. Below are the lexer, parser, token, and shank files. The shank file is the main method file. Attached is rubric.

Lexer.java

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.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) { //TODO Auto-generated method stub return null; } }

Parser.java

package mypack;

import java.util.List; import java.util.Queue;

public class Parser { private Queue tokens;

public Parser(List tokens) { this.tokens = (Queue) tokens; }

private Token matchAndRemove(Token.TokenType type) { if (tokens.isEmpty() || tokens.peek().getType() != type) { return null; } return tokens.remove(); }

private void expectEndsOfLine() throws SyntaxErrorException { while (matchAndRemove(Token.TokenType.ENDOFLINE) != null); if (tokens.isEmpty()) { throw new SyntaxErrorException("Expected at least one ENDOFLINE token."); } }

private Token peek(int i) { if (tokens.size()

public Node parse() throws SyntaxErrorException { Node result = null; do { result = expression(); if (result != null) { System.out.println(result.toString()); expectEndsOfLine(); } } while (result != null); return null; }

private Node expression() { Node left = term(); if (left == null) { return null; } while (true) { Token op = matchAndRemove(Token.TokenType.PLUS, Token.TokenType.MINUS); if (op == null) { return left; } Node right = term(); if (right == null) { throw new SyntaxErrorException("Expected a term after " + op.getLexeme()); } left = new MathOpNode(op.getType(), left, right); } }

}

private Node term() { Node left = factor(); if (left == null) { return null; } while (true) { Token op = matchAndRemove(Token.TokenType.TIMES, Token.TokenType.DIVIDE, Token.TokenType.MOD); if (op == null) { return left; } Node right = factor(); if (right == null) { throw new SyntaxErrorException("Expected a factor after " + op.getLexeme()); } left = new MathOpNode(op.getType(), left, right); } }

private Node factor() { Token token = matchAndRemove(Token.TokenType.NUMBER, Token.TokenType.MINUS, Token.TokenType.LPAREN); if (token == null) { return null; } switch (token.getType()) { case NUMBER: return new IntegerNode(Integer.parseInt(token.getLexeme())); case MINUS: Node inner = factor(); if (inner == null) { throw new SyntaxErrorException("Expected a factor after -"); } return new MathOpNode(Token.TokenType.MINUS, new IntegerNode(0), inner); case LPAREN: Node expression = expression(); if (expression == null) { throw new SyntaxErrorException("Expected an expression after ("); } if (matchAndRemove(Token.TokenType.RPAREN) == null) { throw new SyntaxErrorException("Expected ) after expression"); } return expression; default: return null; // unreachable } }

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.file.Files; import java.nio.file.Paths; import java.util.List;

public class Shank { public static void main(String[] args) { 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 + "'."); } } }

\begin{tabular}{|l|l|l|l|l|} \hline Rubric & Poor & OK & Good & Great \\ \hline Comments & None/Excessive (0) & "What"not"Why",few(5) & Some"what"commentsormissingsome(7) & Anythingnotobvioushasreasoning(10) \\ \hline Variable/Functionnaming & Singleletterseverywhere(0) & Lotsofabbreviations(5) & Fullwordsmostofthetime(8) & Full words, descriptive (10) \\ \hline Node & None (0) & & & HasToString()andisabstract(5) \\ \hline IntegerNode & None(0) & & ExtendsNode,hasconstructorandprivatemember(5) \\ \hline FloatNode & None(0) & ExtendsNode,hasconstructorandprivatemember(5) \\ \hline \end{tabular} \begin{tabular}{|l|l|l|l|l|} \hline matchAndRemove & None (0) & & & returnsmatchingnextnodeornull(5) \\ \hline expectEndsOfLine & None (0) & & & Matchesmultipleendsoflineandthrowswhenitdoesnt(5) \\ \hline peek & None (0) & & Looksahead,returnsnullwhenitcant(5) \\ \hline parse & None(0) & & Loopsoverexpression()andexpectEndsOfLine()(5) & Loopsoverexpression()andexpectEndsOfLine()andprintsresults(10) \\ \hline expression & none (0) & callsterm,processes1+/(5) & callsterm,loopsover+/(10) \\ \hline term & none (0) & callsfactor,processes1or/or%(5) & callsfactor,loopsoveror/or%(10) \\ \hline factor & none (0) & handles2ofparens,negatives,integersandfloats(10) & handles3ofparens,negatives,integersandfloats(15) & handlesparens,negatives,integersandfloats(20) \\ \hline \end{tabular}