Using the prompt class

The prompt class provides methods for reading lines of input from the user with line-editing and history support.

The prompt class supports configurable history files, history limits, and custom prompt strings. Lines read from the user are automatically added to the history, and the history can be flushed to a file so it persists across sessions.

The following example configures a history file and limits, sets a prompt string, reads lines from the user in a loop until ctrl-D is pressed, and then flushes the history to disk.

#include <rudiments/prompt.h>
#include <rudiments/charstring.h>
#include <rudiments/stdio.h>

int main(int argc, const char **argv) {

	prompt	p;


	// configure the history file and limits
	p.setHistoryFile("/tmp/.prompt_example_history");
	p.setMaxHistoryLines(100);
	p.setMaxHistoryQueue(10);

	// display the history configuration
	stdoutput.printf("history file: %s\n",p.getHistoryFile());
	stdoutput.printf("max history lines: %d\n",p.getMaxHistoryLines());
	stdoutput.printf("max history queue: %d\n",p.getMaxHistoryQueue());
	stdoutput.write('\n');


	// set the prompt and display it
	p.setPrompt("enter a command> ");
	stdoutput.printf("prompt: %s\n\n",p.getPrompt());


	// read lines until ctrl-D is pressed
	stdoutput.write("Type lines of input and press enter.\n");
	stdoutput.write("Press ctrl-D to exit.\n\n");
	for (;;) {

		// read a line
		char	*line=p.read();

		// NULL means ctrl-D was pressed
		if (!line) {
			stdoutput.write("done\n");
			break;
		}

		// an empty string means enter was hit by itself
		if (!line[0]) {
			stdoutput.write("(empty line)\n");
			delete[] line;
			continue;
		}

		// print the line
		stdoutput.printf("you entered: %s\n",line);

		// clean up
		delete[] line;
	}


	// flush history to the history file
	p.flushHistory();
}