Java Programming: Below is parser.java and attached is circled all the methods that must be implemented in parser.java. Make sure to show a full working code & the screenshot of the output. 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... types) { if (tokens.isEmpty()) { return null; } Token token = tokens.peek(); for (Token.TokenType type : types) { if (token.getTokenType() == type) { tokens.remove(); return token; } } return null; } private void expectEndsOfLine() throws SyntaxErrorException { while (matchAndRemove(Token.TokenType.ENDOFLINE) != null); if (tokens.isEmpty()) { throw new SyntaxErrorException(); } } private Token peek(int i) { if (tokens.size() < i) { return null; } return (Token) tokens.toArray()[i-1]; } 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() throws SyntaxErrorException { 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(); } left = new MathOpNode(op.getTokenType(), left, right); } } private Node term() throws SyntaxErrorException { Node left = factor(); if (left == null) { return null; } while (true) { Token op = matchAndRemove(Token.TokenType.TIMES, Token.TokenType.DIVIDE, Token.TokenType.MODULUS); if (op == null) { return left; } Node right = factor(); if (right == null) { throw new SyntaxErrorException(); } left = new MathOpNode(op.getTokenType(), left, right); } } private Node factor() throws SyntaxErrorException { Token token = matchAndRemove(Token.TokenType.NUMBER, Token.TokenType.MINUS, Token.TokenType.LEFT_PAREN, Token.TokenType.IDENTIFIER); if (token == null) { return null; } switch (token.getTokenType()) { case NUMBER: return new IntegerNode(Integer.parseInt(token.getLexeme())); case MINUS: Node inner = factor(); if (inner == null) { throw new SyntaxErrorException(); } return new MathOpNode(Token.TokenType.MINUS, new IntegerNode(0), inner); case LEFT_PAREN: Node expression = expression(); if (expression == null) { throw new SyntaxErrorException(); } if (matchAndRemove(Token.TokenType.RIGHT_PAREN) == null) { throw new SyntaxErrorException(); } return expression; case IDENTIFIER: VariableReferenceNode varRefNode = new VariableReferenceNode(token.getLexeme()); if (matchAndRemove(Token.TokenType.LEFT_BRACE) != null) { Node indexExpr = expression(); if (indexExpr == null) { throw new SyntaxErrorException(); } varRefNode.setIndex(indexExpr); if (matchAndRemove(Token.TokenType.RIGHT_BRACE) == null) { throw new SyntaxErrorException(); } } return varRefNode; default: return null; }

Java Programming: Below is parser.java and attached is circled all the methods that must be implemented in parser.java. Make sure to show a full working code & the screenshot of the output. 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... types) { if (tokens.isEmpty()) { return null; } Token token = tokens.peek(); for (Token.TokenType type : types) { if (token.getTokenType() == type) { tokens.remove(); return token; } } return null; } private void expectEndsOfLine() throws SyntaxErrorException { while (matchAndRemove(Token.TokenType.ENDOFLINE) != null); if (tokens.isEmpty()) { throw new SyntaxErrorException(); } } private Token peek(int i) { if (tokens.size() < i) { return null; } return (Token) tokens.toArray()[i-1]; } 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() throws SyntaxErrorException { 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(); } left = new MathOpNode(op.getTokenType(), left, right); } } private Node term() throws SyntaxErrorException { Node left = factor(); if (left == null) { return null; } while (true) { Token op = matchAndRemove(Token.TokenType.TIMES, Token.TokenType.DIVIDE, Token.TokenType.MODULUS); if (op == null) { return left; } Node right = factor(); if (right == null) { throw new SyntaxErrorException(); } left = new MathOpNode(op.getTokenType(), left, right); } } private Node factor() throws SyntaxErrorException { Token token = matchAndRemove(Token.TokenType.NUMBER, Token.TokenType.MINUS, Token.TokenType.LEFT_PAREN, Token.TokenType.IDENTIFIER); if (token == null) { return null; } switch (token.getTokenType()) { case NUMBER: return new IntegerNode(Integer.parseInt(token.getLexeme())); case MINUS: Node inner = factor(); if (inner == null) { throw new SyntaxErrorException(); } return new MathOpNode(Token.TokenType.MINUS, new IntegerNode(0), inner); case LEFT_PAREN: Node expression = expression(); if (expression == null) { throw new SyntaxErrorException(); } if (matchAndRemove(Token.TokenType.RIGHT_PAREN) == null) { throw new SyntaxErrorException(); } return expression; case IDENTIFIER: VariableReferenceNode varRefNode = new VariableReferenceNode(token.getLexeme()); if (matchAndRemove(Token.TokenType.LEFT_BRACE) != null) { Node indexExpr = expression(); if (indexExpr == null) { throw new SyntaxErrorException(); } varRefNode.setIndex(indexExpr); if (matchAndRemove(Token.TokenType.RIGHT_BRACE) == null) { throw new SyntaxErrorException(); } } return varRefNode; default: return null; }

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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Related questions

Question

Java Programming: Below is parser.java and attached is circled all the methods that must be implemented in parser.java. Make sure to show a full working code & the screenshot of the output.

Parser.java

package mypack;

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

public class Parser {

private Queue<Token> tokens;

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

private Token matchAndRemove(Token.TokenType... types) {
if (tokens.isEmpty()) {
return null;
}

Token token = tokens.peek();
for (Token.TokenType type : types) {
if (token.getTokenType() == type) {
tokens.remove();
return token;
}
}
return null;
}

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


private Token peek(int i) {
if (tokens.size() < i) {
return null;
}
return (Token) tokens.toArray()[i-1];
}

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() throws SyntaxErrorException {
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();
}
left = new MathOpNode(op.getTokenType(), left, right);
}
}

private Node term() throws SyntaxErrorException {
Node left = factor();
if (left == null) {
return null;
}

while (true) {
Token op = matchAndRemove(Token.TokenType.TIMES, Token.TokenType.DIVIDE, Token.TokenType.MODULUS);
if (op == null) {
return left;
}

Node right = factor();
if (right == null) {
throw new SyntaxErrorException();
}
left = new MathOpNode(op.getTokenType(), left, right);
}
}

private Node factor() throws SyntaxErrorException {
Token token = matchAndRemove(Token.TokenType.NUMBER, Token.TokenType.MINUS, Token.TokenType.LEFT_PAREN, Token.TokenType.IDENTIFIER);
if (token == null) {
return null;
}

switch (token.getTokenType()) {
case NUMBER:
return new IntegerNode(Integer.parseInt(token.getLexeme()));
case MINUS:
Node inner = factor();
if (inner == null) {
throw new SyntaxErrorException();
}
return new MathOpNode(Token.TokenType.MINUS, new IntegerNode(0), inner);
case LEFT_PAREN:
Node expression = expression();
if (expression == null) {
throw new SyntaxErrorException();
}
if (matchAndRemove(Token.TokenType.RIGHT_PAREN) == null) {
throw new SyntaxErrorException();
}
return expression;

case IDENTIFIER:
VariableReferenceNode varRefNode = new VariableReferenceNode(token.getLexeme());
if (matchAndRemove(Token.TokenType.LEFT_BRACE) != null) {
Node indexExpr = expression();
if (indexExpr == null) {
throw new SyntaxErrorException();
}
varRefNode.setIndex(indexExpr);
if (matchAndRemove(Token.TokenType.RIGHT_BRACE) == null) {
throw new SyntaxErrorException();
}
}
return varRefNode;
default:
return null;
}
}
}

Rubric
Comments
Variable/Function
naming
IfNode
WhileNode
ForNode
RepeatNode
FunctionCallNode
ParameterNode
parseFor()
parseWhile()
parself()
parseFunctionCalls()
Ranges
Poor
None/Excessive
(0)
Single letters
everywhere (0)
None (0)
None (0)
None (0)
None (0)
None (0)
None (0)
None (0)
None (0)
None (0)
None (0)
None (0)
OK
"What" not
"Why", few (5)
Lots of
abbreviations (5)
Good
Some "what" comments
or missing some (7)
Full words most of the
time (8)
Parses simple for
statements correctly (5)
Parses simple while
statements correctly (5)
Parses simple if
statements correctly (5)
Parses simple function
calls correctly (5)
Implemented for
integers, strings (5)
Great
Anything not obvious has reasoning
(10)
Full words, descriptive (10)
Has constructor(s), ToString,
Conditions, Statements, Nextlf (5)
Has constructor(s), ToString,
Conditions, Statements(5)
Has constructor(s), ToString, from, to,
Statements(5)
Has constructor(s), ToString,
Conditions, Statements (5)
Has constructor(s), ToString, name,
collection of parameters(5)
Has VariableReferenceNode, Node,
constructor(s), ToString() (5)
Parses complex for statements
correctly (10)
Parses complex while statements
correctly (10)
Parses complex, chained if statements
correctly (10)
Parses complex function calls with
expressions and vars correctly (10)
Implemented for integers, strings,
reals (10)

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