From e04b6e9243e80be4f83c72cab5fe6ab732df3cca Mon Sep 17 00:00:00 2001
From: Kraemerd <Dominic_Daniel.Kraemer@Student.Reutlingen-University.de>
Date: Mon, 9 Jan 2023 02:16:28 +0100
Subject: [PATCH] parser is now matching to the lexer.java pattern for decimals
---
expressions.txt | 2 +-
src/Application.java | 8 ++--
src/Lexer.java | 4 +-
src/Parser.java | 109 +++++++++++++++++++++----------------------
4 files changed, 59 insertions(+), 64 deletions(-)
diff --git a/expressions.txt b/expressions.txt
index 2b40cea..8fd2860 100644
--- a/expressions.txt
+++ b/expressions.txt
@@ -1 +1 @@
-40.2+3*x
\ No newline at end of file
+(5*2-(5^2)+3*(201.01-15))
\ No newline at end of file
diff --git a/src/Application.java b/src/Application.java
index f8ac1ee..a4c744f 100644
--- a/src/Application.java
+++ b/src/Application.java
@@ -12,10 +12,10 @@ public class Application {
List<String> expressions = new LinkedList<>();
//Reads the file "expressions.txt" and adds its values to a list
BufferedReader reader;
- String datapath = "expressions.txt";
+ String dataPath = "expressions.txt";
try {
System.out.println("Reading the file...\n");
- reader = new BufferedReader(new FileReader(datapath));
+ reader = new BufferedReader(new FileReader(dataPath));
String line = reader.readLine();
while(line != null) {
expressions.add(line);
@@ -39,8 +39,8 @@ public class Application {
}
Parser parser = new Parser();
try {
- parser.parse(tokens);
- System.out.println();
+ Parser.Expression exp = parser.parse(tokens);
+ System.out.println(exp.toString());
}
catch (ParserException e) {
System.out.println(e.getMessage());
diff --git a/src/Lexer.java b/src/Lexer.java
index 96295ae..c380695 100644
--- a/src/Lexer.java
+++ b/src/Lexer.java
@@ -43,14 +43,14 @@ public class Lexer {
//checks if a character is a digit, then creates a token with one or multiple numbers
//with TokenType=NUMBER
if(Character.isDigit(current)) {
- int endIndex = index+1;
+ int endIndex = index;
if(endIndex<input.length()) {
while(Character.isDigit(input.charAt(endIndex)) && endIndex<input.length()) {
endIndex += 1;
if(endIndex==input.length()) {
break;
}
- if(Character.compare(input.charAt(endIndex),'.')==0) {
+ if(input.charAt(endIndex) == '.') {
endIndex+=1;
}
}
diff --git a/src/Parser.java b/src/Parser.java
index ed584c4..e8f6331 100644
--- a/src/Parser.java
+++ b/src/Parser.java
@@ -3,10 +3,10 @@ import java.util.List;
public class Parser {
- private abstract class Expression {
- boolean capsuled;
- public Expression(boolean capsuled) {
- this.capsuled = capsuled;
+ public static class Expression {
+ @Override
+ public String toString() {
+ return "";
}
}
@@ -14,45 +14,60 @@ public class Parser {
Expression leftExpression;
String operator;
Expression rightExpression;
- public BinaryOperation(Expression leftExpression, String operator, Expression rightExpression, boolean capsuled) {
- super(capsuled);
+ Boolean capsuled;
+ public BinaryOperation(Expression leftExpression, String operator, Expression rightExpression, Boolean capsuled) {
this.leftExpression = leftExpression;
this.operator = operator;
this.rightExpression = rightExpression;
+ this.capsuled = capsuled;
+ }
+ @Override
+ public String toString() {
+ if(capsuled) {
+ return "("+ leftExpression.toString() + operator + rightExpression.toString() + ")";
+ }
+ return leftExpression.toString() + operator + rightExpression.toString();
}
}
private class Variable extends Expression {
String variableName;
public Variable(String i, Boolean capsuled) {
- super(capsuled);
this.variableName = i;
}
+ @Override
+ public String toString() {
+ return variableName;
+ }
}
private abstract class Value extends Expression {
- public Value(boolean capsuled) {
- super(capsuled);
- }
+
}
private class Number extends Value {
public String digits;
- public Number(String i, boolean capsuled) {
- super(capsuled);
+ public Number(String i) {
this.digits = i;
}
+ @Override
+ public String toString() {
+ return digits;
+ }
}
private class Decimal extends Value {
public Number beforeDot;
public Number afterDot;
- public Decimal(Number i1, Number i2, boolean capsuled) {
- super(capsuled);
+ public Decimal(Number i1, Number i2) {
this.beforeDot = i1;
this.afterDot = i2;
}
+ @Override
+ public String toString() {
+ return beforeDot.toString() + "." + afterDot.toString();
+ }
}
//starting method of the parser
@@ -193,64 +208,55 @@ public class Parser {
if (ts.get(0).getType() != Lexer.TokenType.NUMBER) {
return null;
}
- String data = ts.get(0).getData();
+ String data = ts.remove(0).getData();
if (data.isEmpty()) {
throw new ParserException("SyntaxError: empty token");
}
- Value value = null;
- if (ts.size()>1) {
- //if the next token is of TokenType.SPECIAL, check if it's a comma
- //if it is, create a decimal
- if(ts.get(1).getType() == Lexer.TokenType.SPECIAL) {
- if(parseComma(ts)) {
- value = parseDecimal(ts);
- }
- }
- }
- if(value==null) {
- value = parseNumber(ts.remove(0).getData());
+ if(data.contains(".")) {
+ return parseDecimal(data);
}
- return value;
+ return parseNumber(data, false);
}
//called by method parseValue(...)
//parses a decimal of a list of tokens & a string
- private Decimal parseDecimal(List<Lexer.Token> ts) throws ParserException {
- String data = ts.remove(0).getData();
+ private Decimal parseDecimal(String data) throws ParserException {
if(data.isEmpty()) {
throw new ParserException("SyntaxError: empty data");
}
- if(ts.size()==0) {
- throw new ParserException("SyntaxError: no tokens left to create Decimal");
- }
- Number beforeDot = (Number) parseNumber(data);
- ts.remove(0);
- data = ts.remove(0).getData();
- Number afterDot = (Number) parseNumber(data);
- return new Decimal(beforeDot, afterDot, false);
+ int dot = data.indexOf('.');
+ String number1 = data.substring(0,dot);
+ String number2 = data.substring(dot+1);
+ Number beforeDot = (Number) parseNumber(number1, true);
+ Number afterDot = (Number) parseNumber(number2, false);
+ return new Decimal(beforeDot, afterDot);
}
//called by method parseValue(...)
//parses a String into a number
- private Number parseNumber(String data) throws ParserException{
+ private Number parseNumber(String data, boolean afterDot) throws ParserException{
if (data.isEmpty()) {
throw new ParserException("RuntimeException: empty token");
}
if (data.startsWith("0") && data.length() == 1) {
- return new Number(data, false);
+ return new Number(data);
}
-
- parseDigitWithoutZero(data.substring(0,1));
- parseDigit(data.substring(1));
- return new Number(data, false);
+ if(afterDot) {
+ parseDigitWithoutZero(data.substring(0,1));
+ parseDigit(data.substring(1));
+ }
+ else {
+ parseDigit(data);
+ }
+ return new Number(data);
}
//called by method parseNumber(...)
//checks if a String only contains numbers(including zero) with parseCharacter(...)
private void parseDigit(String data) throws ParserException {
- for(int index=1; index<data.length(); index++) {
+ for(int index=0; index<data.length(); index++) {
String character = Character.toString(data.charAt(index));
if(!parseCharacter(character, "0123456789")) {
throw new ParserException("SyntaxError: unexpected character: " + character);
@@ -261,7 +267,7 @@ public class Parser {
//called by method parseNumber(...)
//checks if a String only contains numbers(excluding zero) with parseCharacter(...)
private void parseDigitWithoutZero(String data) throws ParserException {
- for(int index=1; index<data.length(); index++) {
+ for(int index=0; index<data.length(); index++) {
String character = Character.toString(data.charAt(index));
if(!parseCharacter(character, "123456789")) {
throw new ParserException("SyntaxError: unexpected character: " + character);
@@ -269,17 +275,6 @@ public class Parser {
}
}
- private boolean parseComma(List<Lexer.Token> ts) throws ParserException {
- String data = ts.get(1).getData();
- if(parseCharacter(data, ".")) {
- if(ts.get(2).getType()!= Lexer.TokenType.NUMBER) {
- throw new ParserException("SyntaxError: no number after comma");
- }
- return true;
- }
- return false;
- }
-
//called by methods parseOperator(...), parseDigit(...), parseDigitWithoutZero(...)
//checks if a certain string can be found in a string of allowed character
private boolean parseCharacter(String data, String allowedCharacters) throws ParserException {
--
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