lib/file: Implement cut function.

src/lib/file.cpp

@@ -263,6 +263,32 @@ ErrorOr<uint8_t> File::cutByte(){
     return failure ? ErrorOr<uint8_t>(true, ErrorCodes::UNKNOWN) : ErrorOr<uint8_t>(byte);
 }
 
+ErrorOr<std::vector<uint8_t>> File::cut(uint64_t length){
+    bool failure = false;
+    std::vector<uint8_t> bytes;
+
+    try{
+        uint8_t* buffer = new uint8_t[this->size.value];
+        std::vector<uint8_t> readData;
+
+        this->fileStream.read(reinterpret_cast<char*>(buffer), this->size.value);
+        readData = std::vector<uint8_t>(buffer, buffer+this->size.value);
+
+        bytes = std::vector<uint8_t>(readData.begin() + this->cursorPosition, readData.begin() + (this->cursorPosition + length));
+        readData.erase(readData.begin() + this->cursorPosition, readData.begin() + (this->cursorPosition + length));
+
+        std::filesystem::resize_file(this->path, readData.size());
+        this->fileStream.seekg(0);
+        this->write(readData);
+        this->cursorPosition += length;
+        delete[] buffer;
+    }catch(std::exception& e){
+        failure = true;
+    }
+
+    return failure ? ErrorOr<std::vector<uint8_t>>(true, ErrorCodes::UNKNOWN) :ErrorOr<std::vector<uint8_t>>(bytes);
+}
+
 ErrorOr<File*> File::open(std::string path, char mode, uint64_t startPosition){
     if (!std::filesystem::exists(path) && (mode == 'r' || mode == 'm')) {
         return ErrorOr<File*>(true, ErrorCodes::FILE_NOT_FOUND, nullptr);

src/test/file.cpp

@@ -180,4 +180,18 @@ int main(){
     ASSERT(cutByte.value == '.');
     ASSERT(cutByteString == "Hallo, Hi THE CAKE IS A LIE, Ich bin Shwoomple");
     std::cout << "Passed cut byte test." << std::endl;
+
+    modifyFile->open();
+    modifyFile->cursorPosition = 9;
+    ErrorOr<std::vector<uint8_t>> cutBytes = modifyFile->cut(18);
+    modifyFile->close();
+
+    readFile->open();
+    readFile->cursorPosition = 0;
+    tiny_utf8::string cutBytesString = readFile->readString(readFile->size.value).value;
+    readFile->close();
+
+    ASSERT(cutBytes.value == std::vector<uint8_t>({' ', 'T', 'H', 'E', ' ', 'C', 'A', 'K', 'E', ' ', 'I', 'S', ' ','A', ' ', 'L', 'I', 'E'}))
+    ASSERT(cutBytesString == "Hallo, Hi, Ich bin Shwoomple");
+    std::cout << "Passed cut test." << std::endl;
 }