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// A repl library that you can include in your own code to get a runtime
// interface to your program. Just require("/repl.js").
var sys = require('sys');
var buffered_cmd = '';
var trimmer = /^\s*(.+)\s*$/m;
var scopedVar = /^\s*var\s*([_\w\$]+)(.*)$/m;
var scopeFunc = /^\s*function\s*([_\w\$]+)/;
exports.scope = {};
exports.prompt = "node> ";
// Can overridden with custom print functions, such as `probe` or `eyes.js`
exports.writer = sys.p;
var stdin;
exports.start = function (prompt) {
if (prompt !== undefined) {
exports.prompt = prompt;
}
stdin = process.openStdin();
stdin.setEncoding('utf8');
stdin.addListener("data", readline);
displayPrompt();
}
/**
* The main REPL function. This is called everytime the user enters
* data on the command line.
*/
function readline (cmd) {
cmd = trimWhitespace(cmd);
// Check to see if a REPL keyword was used. If it returns true,
// display next prompt and return.
if (parseREPLKeyword(cmd) === true) {
return;
}
// The catchall for errors
try {
buffered_cmd += "\n" + cmd;
// This try is for determining if the command is complete, or should
// continue onto the next line.
try {
buffered_cmd = convertToScope(buffered_cmd);
// Scope the readline with exports.scope to provide "local" vars
with (exports.scope) {
var ret = eval(buffered_cmd);
if (ret !== undefined) {
exports.scope['_'] = ret;
exports.writer(ret);
}
}
buffered_cmd = '';
} catch (e) {
if (!(e instanceof SyntaxError)) throw e;
}
} catch (e) {
// On error: Print the error and clear the buffer
if (e.stack) {
sys.puts(e.stack);
} else {
sys.puts(e.toString());
}
buffered_cmd = '';
}
displayPrompt();
}
/**
* Used to display the prompt.
*/
function displayPrompt () {
sys.print(buffered_cmd.length ? '... ' : exports.prompt);
}
/**
* Used to parse and execute the Node REPL commands.
*
* @param {cmd} cmd The command entered to check
* @returns {Boolean} If true it means don't continue parsing the command
*/
function parseREPLKeyword (cmd) {
switch (cmd) {
case ".break":
buffered_cmd = '';
displayPrompt();
return true;
case ".clear":
sys.puts("Clearing Scope...");
buffered_cmd = '';
exports.scope = {};
displayPrompt();
return true;
case ".exit":
stdin.close();
return true;
case ".help":
sys.puts(".break\tSometimes you get stuck in a place you can't get out... This will get you out.");
sys.puts(".clear\tBreak, and also clear the local scope.");
sys.puts(".exit\tExit the prompt");
sys.puts(".help\tShow repl options");
displayPrompt();
return true;
}
return false;
}
/**
* Trims Whitespace from a line.
*
* @param {String} cmd The string to trim the whitespace from
* @returns {String} The trimmed string
*/
function trimWhitespace (cmd) {
var matches = trimmer.exec(cmd);
if (matches && matches.length == 2) {
return matches[1];
}
}
/**
* Converts commands that use var and function <name>() to use the
* local exports.scope when evaled. This provides a local scope
* on the REPL.
*
* @param {String} cmd The cmd to convert
* @returns {String} The converted command
*/
function convertToScope (cmd) {
var matches;
// Replaces: var foo = "bar"; with: exports.scope.foo = bar;
matches = scopedVar.exec(cmd);
if (matches && matches.length == 3) {
return "exports.scope." + matches[1] + matches[2];
}
// Replaces: function foo() {}; with: foo = function foo() {};
matches = scopeFunc.exec(buffered_cmd);
if (matches && matches.length == 2) {
return matches[1] + " = " + buffered_cmd;
}
return cmd;
}
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