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13484d7cca
whalesong/runtime.js
Danny Yoo 13484d7cca initial namespacing done
2011-04-02 17:53:43 -04:00

571 lines
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JavaScript
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if(this['plt'] === undefined) {
this['plt'] = {};
}
// All of the values here are namespaced under "plt.runtime".
(function() {
this['plt']['runtime'] = {};
var exports = this['plt']['runtime'];
var Machine = function() {
this.callsBeforeTrampoline = 100;
this.val = undefined;
this.proc = undefined;
this.env = [];
this.control = []; // Arrayof (U CallFrame PromptFrame)
this.running = false;
this.params = { currentDisplayer: function(v) {},
currentSuccessHandler: function(MACHINE) {},
currentErrorHandler: function(MACHINE, exn) {},
currentNamespace: {},
// These parameters control how often
// control yields back to the browser
// for response. The implementation is a
// simple PID controller.
//
// To tune this, adjust desiredYieldsPerSecond.
// Do no touch numBouncesBeforeYield or
// maxNumBouncesBeforeYield, because those
// are adjusted automatically by the
// recomputeMaxNumBouncesBeforeYield
// procedure.
desiredYieldsPerSecond: 5,
numBouncesBeforeYield: 2000, // self-adjusting
maxNumBouncesBeforeYield: 2000 // self-adjusting
};
this.primitives = Primitives;
};
// Control stack elements:
// A CallFrame represents a call stack frame.
var CallFrame = function(label, proc) {
this.label = label;
this.proc = proc;
};
// PromptFrame represents a prompt frame.
var PromptFrame = function(label, tag) {
this.label = label;
this.tag = tag; // ContinuationPromptTag
};
// Function types: a function is either a Primitive or a Closure.
// A Primitive is a function that's expected to return. It is not
// allowed to call into Closures. Its caller is expected to pop off
// its argument stack space.
//
//
// A Closure is a function that takes on more responsibilities: it is
// responsible for popping off stack space before it finishes, and it
// is also explicitly responsible for continuing the computation by
// popping off the control stack and doing the jump. Because of this,
// closures can do pretty much anything to the machine.
// A closure consists of its free variables as well as a label
// into its text segment.
var Closure = function(label, arity, closedVals, displayName) {
this.label = label; // (MACHINE -> void)
this.arity = arity; // number
this.closedVals = closedVals; // arrayof number
this.displayName = displayName; // string
};
// A continuation prompt tag labels a prompt frame.
var ContinuationPromptTag = function(name) {
this.name = name;
};
// There is a single, distinguished default continuation prompt tag
// that's used to wrap around toplevel prompts.
var DEFAULT_CONTINUATION_PROMPT_TAG =
new ContinuationPromptTag("default-continuation-prompt-tag");
var NULL = [];
var raise = function(e) { throw e; }
// testArgument: (X -> boolean) X number string string -> boolean
// Produces true if val is true, and otherwise raises an error.
var testArgument = function(expectedTypeName,
predicate,
val,
position,
callerName) {
if (predicate(val)) {
return true;
}
else {
raise(new Error(callerName + ": expected " + expectedTypeName
+ " as argument #" + position
+ " but received " + val + " instead"));
}
};
// captureControl implements the continuation-capturing part of
// call/cc. It grabs the control frames up to (but not including) the
// prompt tagged by the given tag.
var captureControl = function(MACHINE, skip, tag) {
var i;
for (i = MACHINE.control.length - 1 - skip; i >= 0; i--) {
if (MACHINE.control[i].tag === tag) {
return MACHINE.control.slice(i + 1,
MACHINE.control.length - skip);
}
}
raise(new Error("captureControl: unable to find tag " + tag));
};
// restoreControl clears the control stack (up to, but not including the
// prompt tagged by tag), and then appends the rest of the control frames.
// At the moment, the rest of the control frames is assumed to be in the
// top of the environment.
var restoreControl = function(MACHINE, tag) {
var i;
for (i = MACHINE.control.length - 1; i >= 0; i--) {
if (MACHINE.control[i].tag === tag) {
MACHINE.control =
MACHINE.control.slice(0, i+1).concat(
MACHINE.env[MACHINE.env.length - 1]);
return;
}
}
raise(new Error("restoreControl: unable to find tag " + tag));
}
var isNumber = function(x) { return typeof(x) === 'number'; };
// Primtitives are the set of primitive values. Not all primitives
// are coded here; several of them (including call/cc) are injected by
// the bootstrapping code.
var Primitives = (function() {
return {
'display': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
MACHINE.params.currentDisplayer(firstArg);
},
'newline': function(MACHINE, arity) {
MACHINE.params.currentDisplayer("\n");
},
'displayln': function(MACHINE, arity){
var firstArg = MACHINE.env[MACHINE.env.length-1];
MACHINE.params.currentDisplayer(firstArg);
MACHINE.params.currentDisplayer("\n");
},
'pi' : Math.PI,
'e' : Math.E,
'=': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
var secondArg = MACHINE.env[MACHINE.env.length-2];
testArgument('number', isNumber, firstArg, 0, '=');
testArgument('number', isNumber, secondArg, 1, '=');
return firstArg === secondArg;
},
'<': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
var secondArg = MACHINE.env[MACHINE.env.length-2];
testArgument('number', isNumber, firstArg, 0, '<');
testArgument('number', isNumber, secondArg, 1, '<');
return firstArg < secondArg;
},
'>': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
var secondArg = MACHINE.env[MACHINE.env.length-2];
testArgument('number', isNumber, firstArg, 0, '>');
testArgument('number', isNumber, secondArg, 1, '>');
return firstArg > secondArg;
},
'<=': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
var secondArg = MACHINE.env[MACHINE.env.length-2];
testArgument('number', isNumber, firstArg, 0, '<=');
testArgument('number', isNumber, secondArg, 1, '<=');
return firstArg <= secondArg;
},
'>=': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
var secondArg = MACHINE.env[MACHINE.env.length-2];
testArgument('number', isNumber, firstArg, 0, '>=');
testArgument('number', isNumber, secondArg, 1, '>=');
return firstArg >= secondArg;
},
'+': function(MACHINE, arity) {
var result = 0;
var i = 0;
for (i=0; i < arity; i++) {
testArgument(
'number',
isNumber,
MACHINE.env[MACHINE.env.length - 1 - i],
i,
'+');
result += MACHINE.env[MACHINE.env.length - 1 - i];
};
return result;
},
'*': function(MACHINE, arity) {
var result = 1;
var i = 0;
for (i=0; i < arity; i++) {
testArgument(
'number',
isNumber,
MACHINE.env[MACHINE.env.length - 1 - i],
i,
'*');
result *= MACHINE.env[MACHINE.env.length - 1 - i];
}
return result;
},
'-': function(MACHINE, arity) {
if (arity === 0) { raise(new Error()); }
if (arity === 1) {
testArgument('number',
isNumber,
MACHINE.env[MACHINE.env.length-1],
0,
'-');
return -(MACHINE.env[MACHINE.env.length-1]);
}
var result = MACHINE.env[MACHINE.env.length - 1];
for (var i = 1; i < arity; i++) {
testArgument('number',
isNumber,
MACHINE.env[MACHINE.env.length-1-i],
i,
'-');
result -= MACHINE.env[MACHINE.env.length - 1 - i];
}
return result;
},
'/': function(MACHINE, arity) {
if (arity === 0) { raise(new Error()); }
testArgument('number',
isNumber,
MACHINE.env[MACHINE.env.length - 1],
0,
'/');
var result = MACHINE.env[MACHINE.env.length - 1];
for (var i = 1; i < arity; i++) {
result /= MACHINE.env[MACHINE.env.length - 1 - i];
}
return result;
},
'cons': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
var secondArg = MACHINE.env[MACHINE.env.length-2];
return [firstArg, secondArg];
},
'list': function(MACHINE, arity) {
var result = NULL;
for (var i = 0; i < arity; i++) {
result = [MACHINE.env[MACHINE.env.length - (arity - i)],
result];
}
return result;
},
'car': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
return firstArg[0];
},
'cdr': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
return firstArg[1];
},
'pair?': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
return (typeof(firstArg) == 'object' &&
firstArg.length === 2);
},
'set-car!': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
var secondArg = MACHINE.env[MACHINE.env.length-2];
firstArg[0] = secondArg;
},
'set-cdr!': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
var secondArg = MACHINE.env[MACHINE.env.length-2];
firstArg[1] = secondArg;
},
'not': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
return (!firstArg);
},
'null' : NULL,
'null?': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
return firstArg === NULL;
},
'add1': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
return firstArg + 1;
},
'sub1': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
return firstArg - 1;
},
'zero?': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
return firstArg === 0;
},
'vector': function(MACHINE, arity) {
var i;
var result = [];
for (i = 0; i < arity; i++) {
result.push(MACHINE.env[MACHINE.env.length-1-i]);
}
return result;
},
'vector->list': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
var i;
var result = NULL;
for (i = 0; i < firstArg.length; i++) {
result = [firstArg[firstArg.length - 1 - i], result];
}
return result;
},
'list->vector': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
var result = [];
while (firstArg !== NULL) {
result.push(firstArg[0]);
firstArg = firstArg[1];
}
return result;
},
'vector-ref': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
var secondArg = MACHINE.env[MACHINE.env.length-2];
return firstArg[secondArg];
},
'vector-set!': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
var secondArg = MACHINE.env[MACHINE.env.length-2];
var thirdArg = MACHINE.env[MACHINE.env.length-3];
firstArg[secondArg] = thirdArg;
return null;
},
'symbol?': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
return typeof(firstArg) === 'string';
},
'symbol->string': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
return firstArg;
},
'string-append': function(MACHINE, arity) {
var buffer = [];
var i;
for (i = 0; i < arity; i++) {
buffer.push(MACHINE.env[MACHINE.env.length - 1 - i]);
}
return buffer.join('');
},
'string-length': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
return firstArg.length;
},
'box': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
var result = [firstArg];
return result;
},
'unbox': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
return firstArg[0];
},
'set-box!': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
var secondArg = MACHINE.env[MACHINE.env.length-2];
firstArg[0] = secondArg;
return;
},
'void': function(MACHINE, arity) {
return;
},
'eq?': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
var secondArg = MACHINE.env[MACHINE.env.length-2];
return firstArg === secondArg;
},
'equal?': function(MACHINE, arity) {
var firstArg = MACHINE.env[MACHINE.env.length-1];
var secondArg = MACHINE.env[MACHINE.env.length-2];
var lset = [firstArg], rset = [secondArg];
while (lset.length !== 0 && rset.length !== 0) {
var lhs = lset.pop();
var rhs = rset.pop();
if (lhs === rhs) {
continue;
} else if (typeof(lhs) === 'object' &&
typeof(rhs) === 'object' &&
typeof(lhs.length) === 'number' &&
typeof(rhs.length) === 'number' &&
lhs.length === rhs.length) {
lset.push.apply(lset, lhs);
rset.push.apply(rset, rhs);
} else {
return false;
}
}
return true;
}
};
})();
// recomputeGas: state number -> number
var recomputeMaxNumBouncesBeforeYield = function(MACHINE, observedDelay) {
// We'd like to see a delay of DESIRED_DELAY_BETWEEN_BOUNCES so
// that we get MACHINE.params.desiredYieldsPerSecond bounces per
// second.
var DESIRED_DELAY_BETWEEN_BOUNCES =
(1000 / MACHINE.params.desiredYieldsPerSecond);
var ALPHA = 256;
var delta = (ALPHA * ((DESIRED_DELAY_BETWEEN_BOUNCES -
observedDelay) /
DESIRED_DELAY_BETWEEN_BOUNCES));
MACHINE.params.maxNumBouncesBeforeYield =
Math.max(MACHINE.params.maxNumBouncesBeforeYield + delta,
1);
};
var trampoline = function(MACHINE, initialJump) {
var thunk = initialJump;
var startTime = (new Date()).valueOf();
MACHINE.callsBeforeTrampoline = 100;
MACHINE.params.numBouncesBeforeYield =
MACHINE.params.maxNumBouncesBeforeYield;
MACHINE.running = true;
while(thunk) {
try {
thunk(MACHINE);
break;
} catch (e) {
if (typeof(e) === 'function') {
thunk = e;
MACHINE.callsBeforeTrampoline = 100;
if (MACHINE.params.numBouncesBeforeYield-- < 0) {
recomputeMaxNumBouncesBeforeYield(
MACHINE,
(new Date()).valueOf() - startTime);
setTimeout(
function() {
trampoline(MACHINE, thunk);
},
0);
return;
}
} else {
MACHINE.running = false;
return MACHINE.params.currentErrorHandler(MACHINE, e);
}
}
}
MACHINE.running = false;
return MACHINE.params.currentSuccessHandler(MACHINE);
};
// Exports
exports.Machine = Machine;
exports.CallFrame = CallFrame;
exports.PromptFrame = PromptFrame;
exports.Closure = Closure;
exports.ContinuationPromptTag = ContinuationPromptTag;
exports.DEFAULT_CONTINUATION_PROMPT_TAG = DEFAULT_CONTINUATION_PROMPT_TAG;
exports.testArgument = testArgument;
exports.captureControl = captureControl;
exports.restoreControl = restoreControl;
exports.isNumber = isNumber;
exports.raise = raise;
exports.NULL = NULL;
exports.trampoline = trampoline;
}).call(this);
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