From 42f8c59a58760c4e530d8eb27bd9f078d4578057 Mon Sep 17 00:00:00 2001
From: Kraemerd <Dominic_Daniel.Kraemer@Student.Reutlingen-University.de>
Date: Fri, 6 Jan 2023 05:43:52 +0100
Subject: [PATCH] implemented lexter in Lexter.java and fitting tests in
Application.java
---
src/Application.java | 13 ++++++++-
src/Lexer.java | 67 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 79 insertions(+), 1 deletion(-)
diff --git a/src/Application.java b/src/Application.java
index 00796fe..8f0b93c 100644
--- a/src/Application.java
+++ b/src/Application.java
@@ -1,3 +1,14 @@
-public class Application {
+import java.util.Arrays;
+import java.util.List;
+public class Application {
+ public static void main(String[] args) {
+ List<String> test = Arrays.asList("1 + x^2 - (31 * x)");
+ for (String value: test) {
+ List<Lexer.Token> tokens = Lexer.lex(value);
+ for(Lexer.Token singleToken: tokens) {
+ System.out.println(singleToken.toString());
+ }
+ }
+ }
}
diff --git a/src/Lexer.java b/src/Lexer.java
index 7b604e8..5cc07dd 100644
--- a/src/Lexer.java
+++ b/src/Lexer.java
@@ -1,3 +1,70 @@
+import java.util.LinkedList;
+import java.util.List;
+
public class Lexer {
+ public static enum TokenType {
+ NUMBER, VARIABLE, SPECIAL
+ }
+
+ public static class Token {
+ protected TokenType type;
+ protected String data;
+ public Token(TokenType type, String data) {
+ this.type = type;
+ this.data = data;
+ }
+
+ public TokenType getType() {
+ return type;
+ }
+
+ public String getData() {
+ return data;
+ }
+
+ @Override
+ public String toString() {
+ return String.format("type: %s, data: %s", type, data);
+ }
+ }
+
+ public static List<Token> lex(String input) {
+ List<Token> result = new LinkedList<Token>();
+ for(int index=0; index < input.length();) {
+
+ char current = input.charAt(index);
+ if(Character.isDigit(current)) {
+ int endIndex = index+1;
+ if(endIndex<input.length()) {
+ while(Character.isDigit(input.charAt(endIndex)) && endIndex<input.length()) {
+ endIndex += 1;
+ }
+ }
+ Token token = new Token(TokenType.NUMBER, input.substring(index,endIndex));
+ result.add(token);
+ index += endIndex - index;
+ }
+ else if(Character.isWhitespace(current)) {
+ index++;
+ }
+ else if(Character.isLetter(current)){
+ int endIndex = index+1;
+ if(endIndex<input.length()) {
+ while(Character.isLetter(input.charAt(endIndex)) && endIndex<input.length()) {
+ endIndex += 1;
+ }
+ }
+ Token token = new Token(TokenType.VARIABLE, input.substring(index,endIndex));
+ result.add(token);
+ index += endIndex - index;
+ }
+ else {
+ Token token = new Token(TokenType.SPECIAL, String.valueOf(current));
+ result.add(token);
+ index++;
+ }
+ }
+ return result;
+ }
}
--
GitLab