Start JSON exception handling

include/error_handling.hpp

@@ -1,7 +1,69 @@
 #pragma once
 
+#include <exception>
+#include <sstream>
+#include <format>
+
 namespace json
 {
+    class Exception : public std::exception {
+    private:
+        std::string whatstr;
+    public:
+        Exception(std::string base, std::string source, int index) {
+            //std::ostringstream s;
+            int counter = 0;
+            int line = 1;
+            int column = 0;
+            std::string lastline = "";
+            std::string whitespace = "";
+
+            for (auto c: source) {
+                if (counter == index) {
+                    break;
+                }
+
+                if (c == '\n') {
+                    line++;
+                    column = 0;
+                    lastline = "";
+                    whitespace = "";
+                } else if (c == '\t') {
+                    column++;
+                    lastline += "   ";
+                    whitespace += "   ";
+                } else {
+                    column++;
+                    lastline += c;
+                    whitespace += " ";
+                }
+                counter++;
+            }
+            while (counter < source.size()) {
+                auto c = source[counter];
+                if (c == '\n') {
+                    break;
+                }
+                lastline += c;
+                counter++;
+            }
+
+            // TODO: Migrate the below code bits to std::format
+
+            /*
+            s << base << " at line " << line << ", column " << column << std::endl;
+            s << lastline << std::endl;
+            s << whitespace << "^";*/
+            whatstr = std::format("{} at line {}, column {}\n{}\n{}^",
+                            base, line, column,
+                            lastline,
+                            whitespace);
+        };
+        virtual const char* what() const throw() {
+            return whatstr.c_str();
+        }
+    };
+
 	class file_error : public std::runtime_error
     {
 

src/lexer.cpp

@@ -2,6 +2,7 @@
 #include <json.hpp>
 #include <tuple>
 #include <vector>
+#include <error_handling.hpp>
 
 namespace json {
 	int lexers::lex_whitespace(std::string raw_json, int index)
@@ -43,7 +44,8 @@ namespace json {
 		// TODO: handle nested quotes
 		while (c = raw_json[index], c != '"') {
 			if (index == raw_json.length()) {
-				return {token, index, format_error("Unexpected EOF while lexing string", raw_json, index)};
+				//return {token, index, format_error("Unexpected EOF while lexing string", raw_json, index)};
+                throw Exception("Unexpected EOF while lexing string", raw_json, index);
 			}
 
 			token.value += c;