据我所知，Bison声明的形式为
%type <type> nonterminal
有没有办法在不给它类型的情况下定义非终结符？
答案 0 :(得分：0)
#include <ros/ros.h>
#include <std_msgs/String.h>
#include "../include/heart_rate_monitor/wfdb.h"
#include <stdio.h>
#include <sstream>
#include <iostream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <deque>
static std::deque<std::string> queue_buffer;
static int entries_added_since_last_write = 0;
void write_data_to_file()
{
// open file
std::ofstream data_file("my_data_file.txt");
if (data_file.is_open())
{
for (int i = 0; i < queue_buffer.size(); ++i)
{
data_file << queue_buffer[i] << std::end;
}
}
else
{
std::cout << "Error - Cannot open file." << std::endl;
exit(1);
}
data_file.close();
}
void process_message(const std_msgs::String::ConstPtr& string_msg)
{
// if buffer has already 60 entries, throw away the oldest one
if (queue_buffer.size() == 60)
{
queue_buffer.pop_front();
}
// add the new data at the end
queue_buffer.push_back(string_msg.data);
// check if 10 elements have been added and write to file if so
entries_added_since_last_write++;
if (entries_added_since_last_write == 10
&& queue_buffer.size() == 60)
{
// write data to file and reset counter
write_data_to_file();
entries_added_since_last_write = 0;
}
}
int main(int argc, char **argv)
{
ros::init(argc, argv, "writer");
ros::NodeHandle n;
ros::Subscriber sub = n.subscribe("/HeartRateInterval", 1000, process_message);
ros::spin();
return 0;
}
实际上定义非终端 - 它设置了在其他位置定义的非终端的类型。某些版本的bison会为%type提供一个未定义的非终端警告，但其他版本只会忽略它。
您可以通过在左侧（%type之前）给出一个非终端规则来定义非终端。