BadVPN – Rev 1
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<!DOCTYPE html>
<html>
<head>
<title>NCD in Javascript</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
<script src="emncd.js"></script>
<script>
var cfunc_emncd_start = Module.cwrap('emncd_start', 'null', ['string']);
var cfunc_emncd_stop = Module.cwrap('emncd_stop', 'null', []);
function on_start ()
{
var code = document.getElementById('codetext').value;
var loglevel = 0;
for (i = 0; i <= 5; i++) {
if (document.getElementById('loglevel' + i).checked) {
loglevel = i;
}
}
cfunc_emncd_start(code, loglevel);
}
function on_stop ()
{
cfunc_emncd_stop();
}
function load_example (num)
{
document.getElementById('codetext').value = document.getElementById('example' + num).value;
}
</script>
This is a quick port of my <a href="http://code.google.com/p/badvpn/wiki/NCD">NCD programming language</a>
to Javascript using the <a href="https://github.com/kripken/emscripten">Emscripten</a> compiler.
<br />
Please open the Javascript console so you can see the output (Chrome: CTRL+Shift+J. Firefox: CTRL+Shift+K).
<br />
<textarea id="example1" style="display:none;">
process hello {
println("hello, world");
exit("0");
}
</textarea>
<textarea id="example2" style="display:none;">
process foo {
println("Starting up, please wait...");
rprintln("Goodbye World!");
sleep("500", "300"); # sleeps 500ms on init and 300ms on deinit
println("Hello World!");
rprintln("Shutting down, please wait...");
}
</textarea>
<textarea id="example3" style="display:none;">
process hello {
var("0") ctr;
blocker() blk;
blk->up();
blk->use();
num_modulo(ctr, "3") m_three;
num_modulo(ctr, "5") m_five;
num_equal(m_three, "0") d_three;
num_equal(m_five, "0") d_five;
and(d_three, d_five) d_three_five;
If (d_three_five) {
var("fizzbuzz") text;
} Elif (d_three) {
var("fizz") text;
} Elif (d_five) {
var("buzz") text;
} else {
var(ctr) text;
} branch;
println(branch.text);
num_add(ctr, "1") i;
num_modulo(i, "20") i;
ctr->set(i);
sleep("100", "0");
blk->downup();
}
</textarea>
<textarea id="example4" style="display:none;">
process main {
var({"0", "1", "3", "2", "2", "3", "1", "1", "6", "end"}) list;
value(["1":"one", "2":"two", "3":"three"]) map;
call("replace", {"_caller.list", "_caller.map"}) replace;
to_string(replace.result) str;
println(str);
exit("0");
}
template replace {
alias(_arg0) list;
alias(_arg1) map;
value({}) new_list;
Foreach (list As elem) {
map->try_get(elem) y;
If (y.exists) {
new_list->insert(new_list.length, y);
} Else {
new_list->insert(new_list.length, elem);
};
};
alias("new_list") result;
}
</textarea>
<textarea id="example5" style="display:none;">
process hello {
println("Hello, NCD in Javascript!");
println("Will now wait 2 seconds.");
rprintln("Goodbye.");
sleep("2000", "3000");
rprintln("Waiting 3 seconds before dying.");
call("func", {"FirstArg", "SecondArg"});
var({"one", "two", "three"}) list;
to_string(list) str;
println(str);
Foreach (list As elem) {
println("start ", elem);
rprintln("stop ", elem);
};
println("We're finished. Press \"Request termination\" to unwind us.");
rprintln("Terminating...");
}
template func {
println("func here, my args are: ", _arg0, " ", _arg1);
rprintln("func going away");
}
</textarea>
<textarea id="example6" style="display:none;">
process main {
# Turing machine specification.
var("B") blank;
var([
{"0", "0"}:{"0", "0", "right"},
{"0", "1"}:{"1", "x", "right"},
{"1", "1"}:{"1", "1", "right"},
{"1", "0"}:{"2", "0", "right"},
{"2", "0"}:{"2", "0", "right"},
{"2", "1"}:{"3", "1", "right"},
{"3", "1"}:{"3", "1", "right"},
{"3", "0"}:{"4", "1", "left"},
{"3", "B"}:{"4", "1", "left"},
{"4", "1"}:{"4", "1", "left"},
{"4", "0"}:{"5", "0", "left"},
{"5", "0"}:{"5", "0", "left"},
{"5", "1"}:{"6", "1", "left"},
{"5", "x"}:{"h", "x", "stay"},
{"6", "1"}:{"6", "1", "left"},
{"6", "x"}:{"0", "x", "right"},
{"6", "0"}:{"0", "0", "right"}
]) rules;
var("0") initial_state;
var({}) initial_tape_left;
var({
"1", "1", "1", "1", "0", "0", "1", "1", "1", "1"
}) initial_tape_right;
# Perform the computation, stopping when no rule matches.
call("turing", {blank, rules, initial_state, initial_tape_left, initial_tape_right}) results;
# Print results.
to_string(results.tape_left) tape_left;
to_string(results.tape_right) tape_right;
to_string({results.side, results.pos}) head_pos;
to_string(results.state) head_state;
println("Tape L: ", tape_left);
println("Tape R: ", tape_right);
println("Head position: ", head_pos);
println("Head state: ", head_state);
exit("0");
}
template turing {
alias("_arg0") blank;
value(_arg1) rules;
alias("_arg2") initial_state;
alias("_arg3") initial_tape_left;
alias("_arg4") initial_tape_right;
# Head state.
var(initial_state) state;
# Tape. Positions go like this: ... L2 L1 L0 R0 R1 R2 ...
value(initial_tape_left) tape_left;
value(initial_tape_right) tape_right;
# Make sure each side of the tape has at least one symbol so we can flip easily.
tape_left->insert(tape_left.length, blank);
tape_right->insert(tape_right.length, blank);
# Head position.
var("right") side;
var("0") pos;
# Enter loop.
blocker() loop_blk;
loop_blk->up();
loop_blk->use();
# Get symbol under head.
concat("tape_", side) tape_name;
alias(tape_name) cur_tape;
cur_tape->get(pos) symbol;
# Look for a matching rule.
rules->try_get({state, symbol}) rule;
If (rule.exists) {
# Extract directions from rule.
rule->get("0") new_state;
rule->get("1") new_symbol;
rule->get("2") move;
# Change head state.
state->set(new_state);
# Replace symbol under head.
cur_tape->remove(pos);
cur_tape->insert(pos, new_symbol);
# Branch based on how we move.
strcmp(move, side) is_outside;
strcmp(move, "stay") is_stay;
strcmp(pos, "0") is_zero;
If (is_outside) {
# Increment position.
num_add(pos, "1") new_pos;
pos->set(new_pos);
# If the new position is out of range, extend tape.
strcmp(pos, cur_tape.length) need_extend;
If (need_extend) {
cur_tape->insert(pos, blank);
};
} elif (is_stay) {
# Nop.
getargs();
} elif (is_zero) {
# Flip side, leave pos at zero.
side->set(move);
} else {
# Decrement position.
num_subtract(pos, "1") new_pos;
pos->set(new_pos);
};
# Continue loop.
loop_blk->downup();
};
}
</textarea>
Examples:
<button onclick="load_example(1)">Hello World</button>
<button onclick="load_example(2)">Sleep</button>
<button onclick="load_example(3)">FizzBuzz</button>
<button onclick="load_example(4)">Replace</button>
<button onclick="load_example(5)">Foreach, call</button>
<button onclick="load_example(6)">Turing Machine</button>
<br />
<textarea rows=30 cols=80 id="codetext">
process hello {
println("hello, world");
exit("0");
}
</textarea>
<br />
Loglevel:
<input type="radio" name="loglevel" id="loglevel0"> None
<input type="radio" name="loglevel" id="loglevel1"> Error
<input type="radio" name="loglevel" id="loglevel2" checked> Warning
<input type="radio" name="loglevel" id="loglevel3"> Notice
<input type="radio" name="loglevel" id="loglevel4"> Info
<input type="radio" name="loglevel" id="loglevel5"> Debug <br />
<button onclick="on_start()">Start NCD</button>
<button onclick="on_stop()">Request termination</button>
<br />
Note: if you get the interpreter stuck and unable to terminate, just refresh the page
</body>
</html>