Basic Error Handling
Added Scanner and Parsing Exceptions as well as keeping track of the source position.master
parent
242ca887f9
commit
f34ccd138d
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@ -3,6 +3,7 @@ package miniJava;
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import java.io.*;
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import miniJava.SyntacticAnalyzer.*;
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import miniJava.SyntacticAnalyzer.Errors.*;
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import miniJava.AbstractSyntaxTrees.*;
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import miniJava.AbstractSyntaxTrees.Package;
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@ -30,10 +31,16 @@ public class Compiler {
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System.exit(0);
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} catch(FileNotFoundException e) {
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System.exit(rc);
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System.out.println(e.getMessage());
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} catch(IOException e) {
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System.exit(rc);
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System.out.println(e.getMessage());
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}catch(ScanningException e) {
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System.out.println(e.getMessage());
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} catch(ParsingException e) {
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System.out.println(e.getMessage());
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}
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System.exit(rc);
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}
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}
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@ -0,0 +1,17 @@
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package miniJava.SyntacticAnalyzer.Errors;
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import miniJava.SyntacticAnalyzer.Token;
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public class ParsingException extends Exception {
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private static final long serialVersionUID = 1L;
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public ParsingException() {
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super("Unidentified parsing error!");
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}
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public ParsingException(Token t) {
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super("Parsing error with " + t.toString());
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}
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}
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@ -0,0 +1,11 @@
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package miniJava.SyntacticAnalyzer.Errors;
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public class ScanningException extends Exception {
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private static final long serialVersionUID = 1L;
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public ScanningException(int col, int line) {
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super("Scanning error at Column: " + col + ", Line: " + line);
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}
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}
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@ -1,9 +1,10 @@
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package miniJava.SyntacticAnalyzer;
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import java.io.*;
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import java.util.LinkedList;
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import miniJava.AbstractSyntaxTrees.*;
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import miniJava.AbstractSyntaxTrees.Package;
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import miniJava.SyntacticAnalyzer.Errors.*;
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public class Parser {
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@ -18,9 +19,9 @@ public class Parser {
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/**
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* Program ::= (ClassDeclaration)* eot
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* @return
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* @throws IOException
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* @throws ScanningException
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*/
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public Package parse() throws IOException {
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public Package parse() throws ParsingException, ScanningException {
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ClassDeclList decls = new ClassDeclList();
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while(peek(1).type == Token.TYPE.CLASS) {
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decls.add(parseClassDeclaration());
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@ -36,9 +37,9 @@ public class Parser {
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* (Declarators id (; | MethodDeclaration))*
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* }
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* @return
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* @throws IOException
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* @throws ScanningException
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*/
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private ClassDecl parseClassDeclaration() throws IOException {
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private ClassDecl parseClassDeclaration() throws ParsingException, ScanningException {
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// Class Header
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accept(Token.TYPE.CLASS);
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@ -72,9 +73,9 @@ public class Parser {
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/**
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* Declarators ::= (public | private)? static? Type
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* @return
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* @throws IOException
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* @throws ScanningException
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*/
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private Declarators parseDeclarators() throws IOException {
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private Declarators parseDeclarators() throws ParsingException, ScanningException {
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// Visibility
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boolean isPrivate = false;
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@ -103,9 +104,9 @@ public class Parser {
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* }
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* @param f describes the declaratory aspect of the method
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* @return
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* @throws IOException
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* @throws ScanningException
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*/
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private MethodDecl parseMethodDeclaration(FieldDecl f) throws IOException {
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private MethodDecl parseMethodDeclaration(FieldDecl f) throws ParsingException, ScanningException {
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// Method Header
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accept(Token.TYPE.LPAREN);
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@ -139,9 +140,9 @@ public class Parser {
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/**
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* Type ::= boolean | void | int ([])? | id ([])?
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* @return
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* @throws IOException
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* @throws ScanningException
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*/
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private Type parseType() throws IOException {
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private Type parseType() throws ParsingException, ScanningException {
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switch(peek(1).type) {
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@ -181,16 +182,16 @@ public class Parser {
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}
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default:
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throw new IOException();
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throw new ParsingException();
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}
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}
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/**
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* ParameterList ::= Type id (, Type id)*
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* @return
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* @throws IOException
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* @throws ScanningException
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*/
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private ParameterDeclList parseParameterList() throws IOException {
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private ParameterDeclList parseParameterList() throws ParsingException, ScanningException {
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ParameterDeclList decls = new ParameterDeclList();
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@ -213,9 +214,9 @@ public class Parser {
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/**
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* ArgumentList ::= Expression (, Expression)*
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* @return
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* @throws IOException
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* @throws ScanningException
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*/
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private ExprList parseArgumentList() throws IOException {
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private ExprList parseArgumentList() throws ParsingException, ScanningException {
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ExprList e = new ExprList();
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e.add(parseExpression());
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while(peek(1).type == Token.TYPE.COMMA) {
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@ -229,9 +230,9 @@ public class Parser {
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/**
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* Reference ::= BaseRef (. BaseRef)*
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* @return
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* @throws IOException
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* @throws ScanningException
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*/
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private Reference parseReference() throws IOException {
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private Reference parseReference() throws ParsingException, ScanningException {
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Reference r = parseBaseRef();
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while(peek(1).type == Token.TYPE.PERIOD) {
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accept(Token.TYPE.PERIOD);
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@ -253,9 +254,9 @@ public class Parser {
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/**
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* BaseRef ::= this | id ([ Expression])?
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* @return
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* @throws IOException
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* @throws ScanningException
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*/
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private Reference parseBaseRef() throws IOException {
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private Reference parseBaseRef() throws ParsingException, ScanningException {
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switch(peek(1).type) {
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case THIS:
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@ -289,9 +290,9 @@ public class Parser {
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* | if (Expression) Statement (else Statement)?
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* | while (Expression) Statement
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* @return
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* @throws IOException
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* @throws ScanningException
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*/
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private Statement parseStatement() throws IOException {
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private Statement parseStatement() throws ParsingException, ScanningException {
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switch(peek(1).type) {
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@ -391,9 +392,9 @@ public class Parser {
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* | num | true | false
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* | new (id() | int [ Expression ] | id [ Expression ] )
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* @return
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* @throws IOException
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* @throws ScanningException
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*/
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private Expression parseSingleExpression() throws IOException {
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private Expression parseSingleExpression() throws ParsingException, ScanningException {
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Expression e = null;
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switch(peek(1).type) {
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@ -430,7 +431,7 @@ public class Parser {
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Operator o = new Operator(accept(peek(1).type), null);
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e = new UnaryExpr(o, parseSingleExpression(), null);
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}
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else throw new IOException();
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else throw new ParsingException();
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break;
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}
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@ -487,7 +488,7 @@ public class Parser {
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}
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default:
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throw new IOException();
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throw new ParsingException();
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}
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return e;
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@ -497,9 +498,9 @@ public class Parser {
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* Disjunction & Initial Call:
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* Expression ::= Expression binop Expression
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* @return
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* @throws IOException
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* @throws ScanningException
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*/
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private Expression parseExpression() throws IOException {
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private Expression parseExpression() throws ParsingException, ScanningException {
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Expression e = parseCExpression();
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while(peek(1).spelling.equals("||")) {
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@ -513,9 +514,9 @@ public class Parser {
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/**
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* Conjunction
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* @return
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* @throws IOException
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* @throws ScanningException
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*/
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private Expression parseCExpression() throws IOException {
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private Expression parseCExpression() throws ParsingException, ScanningException {
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Expression e = parseEExpression();
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while(peek(1).spelling.equals("&&")) {
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@ -529,9 +530,9 @@ public class Parser {
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/**
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* Equality
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* @return
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* @throws IOException
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* @throws ScanningException
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*/
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private Expression parseEExpression() throws IOException {
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private Expression parseEExpression() throws ParsingException, ScanningException {
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Expression e = parseRExpression();
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while(peek(1).spelling.equals("==") || peek(1).spelling.equals("!=")) {
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@ -545,9 +546,9 @@ public class Parser {
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/**
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* Relational
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* @return
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* @throws IOException
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* @throws ScanningException
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*/
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private Expression parseRExpression() throws IOException {
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private Expression parseRExpression() throws ParsingException, ScanningException {
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Expression e = parseAExpression();
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while(peek(1).spelling.equals("<") || peek(1).spelling.equals("<=")
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@ -562,9 +563,9 @@ public class Parser {
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/**
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* Additive
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* @return
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* @throws IOException
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* @throws ScanningException
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*/
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private Expression parseAExpression() throws IOException {
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private Expression parseAExpression() throws ParsingException, ScanningException {
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Expression e = parseMExpression();
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while(peek(1).spelling.equals("+") || peek(1).spelling.equals("-")) {
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@ -578,9 +579,9 @@ public class Parser {
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/**
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* Multiplicative
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* @return
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* @throws IOException
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* @throws ScanningException
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*/
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private Expression parseMExpression() throws IOException {
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private Expression parseMExpression() throws ParsingException, ScanningException {
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Expression e = parseSingleExpression();
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while(peek(1).spelling.equals("*") || peek(1).spelling.equals("/")) {
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@ -594,9 +595,9 @@ public class Parser {
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/**
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* Sees what the next token is, caching the result.
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* @return
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* @throws IOException
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* @throws ScanningException
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*/
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private Token peek(int lookahead) throws IOException {
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private Token peek(int lookahead) throws ScanningException {
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// Cache tokens
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while(stream.size() < lookahead) {
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@ -610,12 +611,12 @@ public class Parser {
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/**
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* Consumes token or throws exception.
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* @throws IOException
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* @throws ScanningException
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*/
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private Token accept(Token.TYPE type) throws IOException {
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private Token accept(Token.TYPE type) throws ParsingException, ScanningException {
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Token next = peek(1);
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if(next.type == type) stream.poll();
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else throw new IOException();
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else throw new ParsingException(next);
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return next;
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}
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@ -2,8 +2,12 @@ package miniJava.SyntacticAnalyzer;
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import java.io.*;
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import miniJava.SyntacticAnalyzer.Errors.ScanningException;
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public class Scanner {
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private int col = 1;
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private int line = 1;
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private BufferedReader input;
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public Scanner(BufferedReader input) {
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@ -15,7 +19,7 @@ public class Scanner {
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* @return
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* @throws IOException
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*/
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public Token scan() throws IOException {
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public Token scan() throws ScanningException {
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String attr = "";
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Token token = null;
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@ -23,7 +27,7 @@ public class Scanner {
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while(token == null) {
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// Check for EOF
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int c = input.read();
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int c = read();
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if(c == -1) return new Token("", Token.TYPE.EOT);
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// Setup
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@ -37,18 +41,18 @@ public class Scanner {
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break;
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case '+':
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if(peek('+')) throw new IOException();
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if(peek('+')) throw new ScanningException(col, line);
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token = new Token(attr, Token.TYPE.BINOP);
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break;
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case '-':
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if(peek('-')) throw new IOException();
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if(peek('-')) throw new ScanningException(col, line);
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token = new Token(attr, Token.TYPE.BINOP);
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break;
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// Check for comment
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case '/':
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if(peek('*')) { input.read(); readComment(); attr = ""; }
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if(peek('*')) { read(); readComment(); attr = ""; }
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else if(peek('/')) { readLine(); attr = ""; }
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else token = new Token(attr, Token.TYPE.BINOP);
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break;
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@ -56,7 +60,7 @@ public class Scanner {
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// Check for c or c=
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case '>':
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case '<':
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if(peek('=')) attr += (char) input.read();
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if(peek('=')) attr += (char) read();
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token = new Token(attr, Token.TYPE.BINOP);
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break;
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@ -64,7 +68,7 @@ public class Scanner {
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case '!':
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if(!peek('=')) token = new Token(attr, Token.TYPE.UNOP);
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else {
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attr += (char) input.read();
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attr += (char) read();
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token = new Token(attr, Token.TYPE.BINOP);
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}
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break;
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@ -72,9 +76,9 @@ public class Scanner {
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// Check for && or ||
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case '&':
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case '|':
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if(!peek((char) c)) throw new IOException();
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if(!peek((char) c)) throw new ScanningException(col, line);
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else {
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attr += (char) input.read();
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attr += (char) read();
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token = new Token(attr, Token.TYPE.BINOP);
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}
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break;
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@ -83,7 +87,7 @@ public class Scanner {
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case '=':
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if(!peek('=')) token = new Token(attr, Token.TYPE.EQUALS);
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else {
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attr += (char) input.read();
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attr += (char) read();
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token = new Token(attr, Token.TYPE.BINOP);
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}
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break;
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@ -129,7 +133,7 @@ public class Scanner {
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// Identifier or Keyword
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if(isAlpha((char) c)) {
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for(char n = peek(); isAlpha(n) || isDigit(n) || n == '_';) {
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attr += (char) input.read();
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attr += (char) read();
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n = peek();
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}
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@ -143,7 +147,7 @@ public class Scanner {
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// Number
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else if(isDigit((char) c)) {
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for(char n = peek(); isDigit(n);) {
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attr += (char) input.read();
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attr += (char) read();
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n = peek();
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}
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@ -156,7 +160,7 @@ public class Scanner {
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}
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// Unrecognized Character
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else throw new IOException();
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else throw new ScanningException(col, line);;
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break;
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}
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@ -171,12 +175,16 @@ public class Scanner {
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* @return
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* @throws IOException
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*/
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private char peek() throws IOException {
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input.mark(1);
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int next = input.read();
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input.reset();
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private char peek() throws ScanningException {
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try {
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input.mark(1);
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int next = input.read();
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input.reset();
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return next == -1 ? '\0' : (char) next;
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return next == -1 ? '\0' : (char) next;
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} catch(IOException e) {
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throw new ScanningException(col, line);
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}
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}
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@ -186,12 +194,34 @@ public class Scanner {
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* @return
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* @throws IOException
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*/
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private boolean peek(char c) throws IOException {
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input.mark(1);
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int next = input.read();
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input.reset();
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private boolean peek(char c) throws ScanningException {
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try {
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input.mark(1);
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int next = input.read();
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input.reset();
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return c == next;
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return c == next;
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} catch(IOException e) {
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throw new ScanningException(col, line);
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}
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}
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/**
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* Alternative reading that keeps track of position.
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* @return
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* @throws IOException
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*/
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private int read() throws ScanningException {
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try {
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int next = input.read();
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if(next != '\n' && next != '\r') col += 1;
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else { col = 1; line += 1; }
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return next;
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} catch(IOException e) {
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throw new ScanningException(col, line);
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}
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}
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@ -199,15 +229,19 @@ public class Scanner {
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* Consumes input until an end of comment has been reached.
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* @throws IOException
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*/
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private void readComment() throws IOException {
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char prev = '\0', current = '\0';
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while(prev != '*' || current != '/') {
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private void readComment() throws ScanningException {
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try {
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char prev = '\0', current = '\0';
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while(prev != '*' || current != '/') {
|
||||
|
||||
prev = current;
|
||||
prev = current;
|
||||
|
||||
int next = input.read();
|
||||
if(next == -1) throw new IOException();
|
||||
else current = (char) next;
|
||||
int next = input.read();
|
||||
if(next == -1) throw new IOException();
|
||||
else current = (char) next;
|
||||
}
|
||||
} catch(IOException e) {
|
||||
throw new ScanningException(col, line);
|
||||
}
|
||||
}
|
||||
|
||||
|
@ -216,8 +250,12 @@ public class Scanner {
|
|||
* Consumes input until the end of line is reached
|
||||
* @throws IOException
|
||||
*/
|
||||
private void readLine() throws IOException {
|
||||
for(int n = 0; n != '\n' && n != '\r' && n != -1; n = input.read()) {}
|
||||
private void readLine() throws ScanningException {
|
||||
try {
|
||||
for(int n = 0; n != '\n' && n != '\r' && n != -1; n = input.read()) {}
|
||||
} catch(IOException e) {
|
||||
throw new ScanningException(col, line);
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
|
|
Loading…
Reference in New Issue