The readline plugin provides a minimal API for reading user input from the keyboard. It can be configured (via compile-time options) to use GNU Readline, BSD Editline, or plain stdin as its input source. The programming interface is the same, however.

Getting the plugin

This plugin, due to its licensing (mixed-license with a GPL component), is stored as an add-on in a separate source tree. It's in the extra-plugins Subversion tree. Visit this page for instructions:

http://code.google.com/p/v8-juice/source/checkout

and check out the extra-plugins directory instead of trunk.

Building/installing

See the plugins page for build instructions.

Example usage

var my = {fn:"my.history"};
loadPlugin('v8-juice-readline',my);
if( my.readline.loadHistory(my.fn) ) {
    print("Loaded history file",my.fn);
} else {
    print("Couldn't load history file",my.fn);
}
var s;
while( undefined != (s = my.readline.read("Enter something (Ctrl-D quits): ")) )
{
    print("Result:",s);
}
print(""); // kludge: ensure a newline after Ctrl-D
print("Done!");
// history will be auto-saved at shutdown

That demonstrates all of the functions except for clearHistory(), which clears the history list, and saveHistory(), which saves the history. If saveHistory() is passed no filename then it uses the name which was passed to loadHistory().

Points of note:

• An application only has only one input terminal and therefore only one shared instance of readline.
• If loadHistory() is ever called then the history will be saved automatically at shutdown. If saveHistory() is ever called, the name set there will be used for auto-save.
• ACHTUNG: auto-save is not reliable because v8 does not guaranty that destructors are ever called. Thus one should use saveHistory() to explicitly save the history, either periodically (e.g. after reading each line) or after exiting the read loop. A try/catch block around the read loop is recommended so that history can be saved in the face of an exception.