diff --git a/expressions.txt b/expressions.txt
index 2b40ceaf50da3b0bfc6d612b6c9576e312e575a9..8fd2860c05d82f1195d3ce9a1e1827eb4a9a1419 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 f8ac1ee4a8efcb6326fb7f33612862193a4dc8fb..a4c744fcf4d30465f3709796e7ba4eae0af8acde 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 a65c71b0985fbd51f4fc9a793228e2bd2baf31a9..c3806955e133a727f09a745550f50d27c1aaa1a7 100644
--- a/src/Lexer.java
+++ b/src/Lexer.java
@@ -43,13 +43,16 @@ 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(input.charAt(endIndex) == '.') {
+ endIndex+=1;
+ }
}
}
Token token = new Token(TokenType.NUMBER, input.substring(index,endIndex));
diff --git a/src/Parser.java b/src/Parser.java
index fcc6fa333dc8dce123c0c474f149f5d35d9e0ee2..e8f6331d43ef4b14d1ccaeb6ea16547206150b75 100644
--- a/src/Parser.java
+++ b/src/Parser.java
@@ -1,29 +1,44 @@
import java.util.LinkedList;
import java.util.List;
-import java.util.Optional;
public class Parser {
- private abstract class Expression {
-
+ public static class Expression {
+ @Override
+ public String toString() {
+ return "";
+ }
}
private class BinaryOperation extends Expression {
Expression leftExpression;
String operator;
Expression rightExpression;
- public BinaryOperation(Expression leftExpression, String operator, Expression rightExpression) {
+ 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) {
+ public Variable(String i, Boolean capsuled) {
this.variableName = i;
}
+ @Override
+ public String toString() {
+ return variableName;
+ }
}
private abstract class Value extends Expression {
@@ -35,6 +50,10 @@ public class Parser {
public Number(String i) {
this.digits = i;
}
+ @Override
+ public String toString() {
+ return digits;
+ }
}
private class Decimal extends Value {
@@ -45,6 +64,10 @@ public class Parser {
this.beforeDot = i1;
this.afterDot = i2;
}
+ @Override
+ public String toString() {
+ return beforeDot.toString() + "." + afterDot.toString();
+ }
}
//starting method of the parser
@@ -58,7 +81,7 @@ public class Parser {
Expression ast = parseExpression(ts);
if(!ts.isEmpty()) {
- throw new ParserException("RuntimeError: " + ts.size() + " token(s) left");
+ throw new ParserException("SyntaxError: " + ts.size() + " token(s) left");
}
return ast;
}
@@ -69,22 +92,21 @@ public class Parser {
if(ts.isEmpty()) {
throw new ParserException("SyntaxError: empty token list");
}
- Expression ast;
- ast = parseBinaryOperation(ts);
- if(ast==null) {
- ast = parseVariable(ts);
+ Expression ast = parseBinaryOperation(ts);
if(ast==null) {
- ast = parseValue(ts);
- }
- if(ast==null) {
- throw new ParserException("SyntaxError: invalid character");
+ ast = parseVariable(ts);
+ if(ast==null) {
+ ast = parseValue(ts);
+ }
+ if(ast==null) {
+ throw new ParserException("SyntaxError: invalid character");
+ }
}
- }
return ast;
}
//checks if a String only contains an allowed operator with parseCharacter(...)
- private Boolean parseOperator(String operator) throws ParserException {
+ private boolean parseOperator(String operator) throws ParserException {
if(operator.length()>1) {
throw new ParserException("SyntaxError: invalid length for an operator: " + operator);
}
@@ -94,6 +116,35 @@ public class Parser {
return true;
}
+ private int parseBrackets(List<Lexer.Token> ts) throws ParserException{
+ if(parseCharacter(ts.get(0).getData(), "(")) {
+ int index;
+ int lBrackets = 0;
+ int rBrackets = 0;
+ boolean found = false;
+ for(index=1; index<ts.size(); index++) {
+ if(parseCharacter(ts.get(index).getData(), "(")) {
+ lBrackets += 1;
+ }
+ else if(parseCharacter(ts.get(index).getData(), ")")) {
+ rBrackets += 1;
+ if(rBrackets>lBrackets) {
+ found = true;
+ break;
+ }
+ }
+ }
+ if(!found) {
+ throw new ParserException("SyntaxError: brackets never got closed");
+ }
+ if(index==1) {
+ throw new ParserException("SyntaxError: no value inside brackets");
+ }
+ return index;
+ }
+ return -1;
+ }
+
private BinaryOperation parseBinaryOperation(List<Lexer.Token> ts) throws ParserException {
if(ts.isEmpty()) {
throw new ParserException("SyntaxError: empty token list");
@@ -101,52 +152,32 @@ public class Parser {
if(ts.size()==1) {
return null;
}
- int index;
- for(index=0; index<ts.size(); index++) {
- if(ts.get(index).getType()== Lexer.TokenType.SPECIAL) {
- if(!parseCharacter(ts.get(index).getData(), ".")) {
- break;
- }
- }
+ int index = 0;
+ int tokensInBracket = parseBrackets(ts);
+ boolean capsuled;
+ if(tokensInBracket+1==ts.size()) {
+ ts.remove(tokensInBracket);
+ ts.remove(0);
+ capsuled = true;
+ index = 1;
}
- if(index==ts.size()) {
- return null;
+ else if (tokensInBracket==-1) {
+ capsuled = false;
+ parseOperator(ts.get(1).getData());
+ index = 1;
+ }
+ else {
+ capsuled = false;
+ index = tokensInBracket+1;
}
- //0
- //1
- //2
- //3
- //4 * => index=4
-
- //5
- //6
- //7
List<Lexer.Token> leftList = new LinkedList<>();
- for(int i=0; i<index; i++) {
+ for(int iterator = 0; iterator<index; iterator++) {
leftList.add(ts.remove(0));
}
Expression leftExpression = parseExpression(leftList);
String operator = ts.remove(0).getData();
- parseOperator(operator);
- Expression rightExpression = parseExpression(ts);
-
- /*
- if(parseCharacter(ts.get(1).getData(), ".")) {
- return null;
- }
- BinaryOperation operation;
- if(ts.get(1).getType()!= Lexer.TokenType.SPECIAL) {
- throw new ParserException("SyntaxError: unexpected operator: " + ts.get(1).getData());
- }
- List<Lexer.Token> leftList = new LinkedList<>();
- leftList.add(ts.remove(0));
- Expression leftExpression = parseExpression(leftList);
- String operator = ts.remove(0).getData();
- parseOperator(operator);
Expression rightExpression = parseExpression(ts);
-
- */
- return new BinaryOperation(leftExpression, operator, rightExpression);
+ return new BinaryOperation(leftExpression, operator, rightExpression, capsuled);
}
private Variable parseVariable(List<Lexer.Token> ts) throws ParserException {
@@ -165,7 +196,7 @@ public class Parser {
if(!parseCharacter(data,"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz")) {
throw new ParserException("Invalid variable character: " + data);
}
- return new Variable(data);
+ return new Variable(data, false);
}
//called by method parseException(...)
@@ -177,47 +208,34 @@ 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(data.contains(".")) {
+ return parseDecimal(data);
}
- if(value==null) {
- value = parseNumber(ts.remove(0).getData());
- }
- 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);
+ 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");
}
@@ -225,16 +243,20 @@ public class Parser {
if (data.startsWith("0") && data.length() == 1) {
return new Number(data);
}
-
- parseDigitWithoutZero(data.substring(0,1));
- parseDigit(data.substring(1));
+ 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);
@@ -245,7 +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);
@@ -253,30 +275,9 @@ 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;
- }
-
- private Boolean parseBracket(List<Lexer.Token> ts) throws ParserException {
- String data = ts.get(0).getData();
- if(parseCharacter(data, "(")) {
- return true;
- }
- else {
- 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 {
+ private boolean parseCharacter(String data, String allowedCharacters) throws ParserException {
if(data.isEmpty()) {
throw new ParserException("RuntimeError: empty String");
}