uart_read_line_sensor.h

#include "esphome.h"

class UartReadLineSensor : public Component, public UARTDevice, public TextSensor
{
public:
    UartReadLineSensor(UARTComponent *parent) : UARTDevice(parent) {}

    void setup() override
    {
        // nothing to do here
    }

    int readline(int readch, char *buffer, int len)
    {
        static int pos = 0;
        int rpos;

        if (readch > 0)
        {
            switch (readch)
            {
            case '\n': // Ignore new-lines
                break;
            case '\r': // Return on CR
                rpos = pos;
                pos = 0; // Reset position index ready for next time
                return rpos;
            default:
                if (pos < len - 1)
                {
                    buffer[pos++] = readch;
                    buffer[pos] = 0;
                }
            }
        }
        // No end of line has been found, so return -1.
        return -1;
    }

    void loop() override
    {
        const int max_line_length = 80;
        static char buffer[max_line_length];
        while (available())
        {
            if (readline(read(), buffer, max_line_length) > 0)
            {
                publish_state(buffer);
            }
        }
    }
};