Re: Web terminal for Lua http server
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- Subject: Re: Web terminal for Lua http server
- From: "jonsmirl@..." <jonsmirl@...>
- Date: 2013年6月11日 16:25:17 -0400
This is running in the node.js part -- isn't it calling the lua engine?
this['Lua'] = {
isInitialize: null,
state: null,
streamName: null,
reportError: function () {
_lua_settop(this.state, 0);
},
// Allocates a string on the heap.
allocateString: function(str) {
var arr = intArrayFromString(str);
return allocate(arr, 'i8', 0); // ALLOC_NORMAL
},
// Parses Lua code and loads it into the execution buffer. Returns true on
// success.
parse: function (command) {
// =x commands explicitly ask for the result.
if (command.match(/^=(?!=)/)) command = 'return ' + command.slice(1);
// Prepare the command, as an expression and a statement.
var commandPtr = this.allocateString(command);
var evalCommand = 'return ' + command;
var evalCommandPtr = this.allocateString(evalCommand);
// Try parsing the command, first as an expression, then if that fails, as a
// statement.
var parseFailed = _luaL_loadbuffer(
this.state, evalCommandPtr, evalCommand.length, this.streamName);
if (parseFailed) {
_lua_settop(this.state, -2) // Discard error message.
parseFailed = _luaL_loadbuffer(
this.state, commandPtr, command.length, this.streamName);
}
// Cleanup.
_free(commandPtr);
_free(evalCommandPtr);
return !parseFailed;
},
// Returns the string representation of the value at the top of the Lua stack.
popStack: function () {
var ret;
var type = _lua_type(this.state, -1);
switch (type) {
case -1: // LUA_TNONE
case 0: // LUA_TNIL
ret = null;
break;
case 1: // LUA_TBOOLEAN
var result = _lua_toboolean(this.state, -1);
ret = result ? 'true' : 'false';
break;
case 3: // LUA_TNUMBER
ret = _lua_tonumber(this.state, -1);
break;
case 4: // LUA_TSTRING
var ptr = _lua_tolstring(this.state, -1, 0);
var len = _lua_objlen(this.state, -1);
var buffer = [];
for (var i = 0; i < len; i++) {
buffer.push(String.fromCharCode(HEAP[ptr + i]));
}
ret = buffer.join('');
break;
default:
var ptr = _lua_typename(this.state, type);
var typename = Pointer_stringify(ptr);
var address = _lua_topointer(this.state, -1);
ret = typename + ': 0x' + address.toString(16);
}
_lua_settop(this.state, -2);
return ret;
},
// Initializes the Lua runtime with optional standard I/O callbacks. The input
// callback is asynchronous and takes a callback which should be passed a
// string. The output and error callbacks are synchronous and are passed
// character codes.
'initialize': function (input, output, error) {
if (this.isInitialize) throw new Error('Lua already initialized.');
FS.init(null, output, function (chr) { /* Ignore stderr. */ });
if (error) {
this.reportError = function(defaultMessage) {
var errorMessage = this.popStack();
if (!errorMessage.length) errorMessage = defaultMessage;
for (var i = 0; i < errorMessage.length; i++) {
error(errorMessage.charCodeAt(i));
}
_lua_settop(this.state, 0);
}
}
run();
this.streamName = this.allocateString('stdin');
this.state = _luaL_newstate();
_luaL_openlibs(this.state);
this.isInitialize = true;
},
// Checks whether a command is finished and does not require more input.
// Useful when running a REPL.
'isFinished': function (command) {
if (!this.isInitialize) throw new Error('Lua not initialized.');
var parseSuccess = this.parse(command);
if (!parseSuccess) this.popStack();
return parseSuccess;
},
// Evaluates Lua code and returns the result.
// 1. If an expression is passed, returns the representation of the value of
// this expression, or null if the value is nil.
// 2. If a statement or set of statements is passed, returns null.
// 3. If an error occurs, returns undefined.
'eval': function (command) {
if (!this.isInitialize) throw new Error('Lua not initialized.');
// Parse and load the command.
var parseSuccess = this.parse(command);
if (!parseSuccess) {
this.reportError('Unknown parsing error.');
}
// Execute the code.
var result = _lua_pcall(this.state, 0, 1, 0);
if (result == 0) { // LUA_OK
return _lua_gettop(this.state) > 0 ? this.popStack() : null;
} else { // LUA_ERR*
this.reportError('Unknown evaluation error.');
}
}
};
On Tue, Jun 11, 2013 at 4:11 PM, David Favro <lua@meta-dynamic.com> wrote:
> On 06/11/2013 03:45 PM, jonsmirl@gmail.com wrote:
>>
>> I believe repl.it is the Ace editor on the left:
>> http://ace.ajax.org/#nav=about
>>
>> tty.js on the right.
>> https://github.com/chjj/tty.js/
>>
>> And it is using an embedded Lua interpreter at the server.
>
>
> Nice stuff, to be sure -- but a little hard to find much info on their site;
> I got confused by their "About Us" page [1]:
>> All our interpreters are written in (or compiled to) JavaScript, and run >
>> completely on the user's device, regardless or whether it's a desktop,
>> laptop or phone.
>
> Which sure doesn't sound like it runs on the server.
>
> -- David
>
> [1]: http://repl.it/about
>
>
--
Jon Smirl
jonsmirl@gmail.com