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Implement Winding & Unwinding

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* module/language/js-il/runtime.js
  (wind, unwind): Implement.
  (callcc): Wind when invoking continuation.
This commit is contained in:
Ian Price 2017-06-28 15:03:03 +01:00
parent ff7fff920d
commit 479294fc05
1 changed files with 65 additions and 6 deletions
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71
module/language/js-il/runtime.js
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@ -380,7 +380,7 @@ var abort_to_prompt = function(self, k, prompt) {
kont = new scheme.Closure(f, 0);
};
unwind(idx);
unwind(scheme.dynstack, idx); // FIXME:
var handler = frame.handler;
args.unshift(kont);
@ -396,8 +396,17 @@ var call_with_values = function (self, k, producer, consumer) {
};
var callcc = function (self, k, closure) {
var dynstack = scheme.dynstack.slice();
var f = function (self, k2) {
var args = Array.prototype.slice.call(arguments, 2);
var i = shared_stack_length(dynstack, scheme.dynstack);
unwind(scheme.dynstack, i);
wind(dynstack, i);
scheme.dynstack = dynstack;
return k.apply(k,args);
};
return closure.fun(closure, k, new scheme.Closure(f, 0));
@ -461,8 +470,17 @@ scheme.primitives["fluid-ref"] = function (fluid) {
scheme.primitives["variable?"] = not_implemented_yet;
// Dynamic Wind
scheme.primitives["wind"] = not_implemented_yet;
scheme.primitives["unwind"] = not_implemented_yet;
scheme.primitives["wind"] = function(enter, leave) {
var frame = new scheme.frame.DynWind(enter, leave);
scheme.dynstack.unshift(frame);
};
scheme.primitives["unwind"] = function () {
var frame = scheme.dynstack.shift();
if (!(frame instanceof scheme.frame.DynWind)) {
throw "not a dynamic wind frame";
};
};
// Misc
scheme.primitives["prompt"] = function(escape_only, tag, handler){
@ -470,9 +488,45 @@ scheme.primitives["prompt"] = function(escape_only, tag, handler){
scheme.dynstack.unshift(frame);
};
var unwind = function (idx) {
// TODO: call winders
scheme.dynstack = scheme.dynstack.slice(idx+1);
var shared_stack_length = function (dynstack1, dynstack2) {
// Assumes that if it matches at i then it matches for all x<i,
// which will be fine given that we don't reuse frames
var size1 = dynstack1.length;
var size2 = dynstack2.length;
var last = Math.min(size1, size2);
var i = last-1;
for (; i >= 0; i--) {
if (dynstack1[i] === dynstack2[i]) {
break;
}
};
return i + 1;
};
var wind = function (dynstack, idx) {
for (var i = idx; i < dynstack.length; i++) {
var frame = dynstack[i];
if (frame instanceof scheme.frame.DynWind) {
// TODO: how to handle continuations and errors in this?
frame.wind.fun(frame.wind, scheme.initial_cont);
} else {
throw "unsupported frame type -- wind";
}
}
};
var unwind = function (dynstack, idx) {
for (var i = dynstack.length - 1; i >= idx; i--) {
var frame = dynstack[i];
if (frame instanceof scheme.frame.DynWind) {
// TODO: how to handle continuations and errors in this?
frame.unwind.fun(frame.unwind, scheme.initial_cont);
} else {
throw "unsupported frame type -- unwind";
}
}
};
var find_prompt = function(prompt) {
@ -509,6 +563,11 @@ scheme.frame.Fluid = function(fluid, old_value) {
this.old_value = old_value;
};
scheme.frame.DynWind = function(wind, unwind) {
this.wind = wind;
this.unwind = unwind;
};
// Module Cache
scheme.module_cache["guile"] = scheme.env;