353 lines
11 KiB
JavaScript
353 lines
11 KiB
JavaScript
// Procedures
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// For historical reasons, this module is called 'functions' instead of 'procedures'.
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// This may change soon.
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(function(baselib) {
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var exports = {};
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baselib.functions = exports;
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// Procedure types: a procedure is either a Primitive or a Closure.
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// A Primitive is a function that's expected to return. It is not
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// allowed to call into Closures. Its caller is expected to pop off
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// its argument stack space.
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//
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// coerseToJavaScript: racket function -> JavaScript function
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// Given a closure or primitive, produces an
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// asynchronous JavaScript function.
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// The function will run on the provided MACHINE.
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//
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// It assumes that it must begin its own trampoline.
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var asJavaScriptFunction = function(v, MACHINE) {
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MACHINE = MACHINE || plt.runtime.currentMachine;
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if (isPrimitiveProcedure(v)) {
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return coersePrimitiveToJavaScript(v, MACHINE);
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} else if (isClosure(v)) {
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return coerseClosureToJavaScript(v, MACHINE);
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} else {
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plt.baselib.exceptions.raise(MACHINE,
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plt.baselib.exceptions.makeExnFail(
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plt.baselib.format.format(
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"Not a procedure: ~e",
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v)));
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}
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};
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var coersePrimitiveToJavaScript = function(v, MACHINE) {
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return function(succ, fail) {
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try {
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succ = succ || function(){};
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fail = fail || function(){};
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var args = [];
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for (var i = 2; i < arguments.length; i++) {
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args.push(arguments[i]);
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}
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// Check arity usage.
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if (! plt.baselib.arity.isArityMatching(v.arity, args.length)) {
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throw new Error("arity mismatch");
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}
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var result = v.apply(null, args);
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succ(result);
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} catch (e) {
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fail(e);
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}
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}
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};
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var coerseClosureToJavaScript = function(v, MACHINE) {
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var f = function(succ, fail) {
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succ = succ || function(){};
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fail = fail || function(){};
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var args = [], i;
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for (i = 2; i < arguments.length; i++) {
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args.push(arguments[i]);
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}
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// Check arity usage.
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if (! plt.baselib.arity.isArityMatching(v.arity, args.length)) {
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throw new Error("arity mismatch");
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}
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var oldVal = MACHINE.val;
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var oldArgcount = MACHINE.argcount;
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var oldProc = MACHINE.proc;
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var oldErrorHandler = MACHINE.params['currentErrorHandler'];
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var afterGoodInvoke = function(MACHINE) {
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plt.runtime.PAUSE(
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function(restart) {
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MACHINE.params['currentErrorHandler'] = oldErrorHandler;
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var returnValue = MACHINE.val;
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MACHINE.val = oldVal;
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MACHINE.argcount = oldArgcount;
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MACHINE.proc = oldProc;
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succ(returnValue);
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});
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};
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afterGoodInvoke.multipleValueReturn = function(MACHINE) {
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plt.runtime.PAUSE(
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function(restart) {
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MACHINE.params['currentErrorHandler'] = oldErrorHandler;
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var returnValues = [MACHINE.val];
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for (var i = 0; i < MACHINE.argcount - 1; i++) {
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returnValues.push(MACHINE.env.pop());
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}
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MACHINE.val = oldVal;
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MACHINE.argcount = oldArgcount;
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MACHINE.proc = oldProc;
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succ.apply(null, returnValues);
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});
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};
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setTimeout(
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function() {
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MACHINE.control.push(
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new plt.baselib.frames.CallFrame(afterGoodInvoke, null));
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MACHINE.argcount = args.length;
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for (var i = 0; i < args.length; i++) {
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MACHINE.env.push(args[i]);
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}
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MACHINE.proc = v;
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MACHINE.params['currentErrorHandler'] = function(MACHINE, e) {
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MACHINE.params['currentErrorHandler'] = oldErrorHandler;
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MACHINE.val = oldVal;
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MACHINE.argcount = oldArgcount;
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MACHINE.proc = oldProc;
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fail(e);
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};
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plt.runtime.trampoline(MACHINE, v.label);
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},
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0);
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};
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return f;
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};
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// internallCallDuringPause: call a Racket procedure and get its results.
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// The use assumes the machine is in a running-but-paused state.
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var internalCallDuringPause = function(MACHINE, proc, success, fail) {
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if (! plt.baselib.arity.isArityMatching(proc.arity, arguments.length - 4)) {
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return fail(plt.baselib.exceptions.makeExnFailContractArity("arity mismatch"));
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}
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if (isPrimitiveProcedure(proc)) {
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var oldArgcount = MACHINE.argcount;
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MACHINE.argcount = arguments.length - 4;
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for (var i = 0; i < arguments.length - 4; i++) {
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MACHINE.env.push(arguments[arguments.length - 1 - i]);
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}
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var result = proc.call(null, MACHINE);
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for (var i = 0; i < arguments.length - 4; i++) {
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MACHINE.env.pop();
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}
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success(result);
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} else if (isClosure(proc)) {
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var oldVal = MACHINE.val;
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var oldArgcount = MACHINE.argcount;
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var oldProc = MACHINE.proc;
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var oldErrorHandler = MACHINE.params['currentErrorHandler'];
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var afterGoodInvoke = function(MACHINE) {
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plt.runtime.PAUSE(function(restart) {
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MACHINE.params['currentErrorHandler'] = oldErrorHandler;
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var returnValue = MACHINE.val;
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MACHINE.val = oldVal;
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MACHINE.argcount = oldArgcount;
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MACHINE.proc = oldProc;
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success(returnValue);
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});
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};
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afterGoodInvoke.multipleValueReturn = function(MACHINE) {
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plt.runtime.PAUSE(function(restart) {
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MACHINE.params['currentErrorHandler'] = oldErrorHandler;
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var returnValues = [MACHINE.val];
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for (var i = 0; i < MACHINE.argcount - 1; i++) {
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returnValues.push(MACHINE.env.pop());
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}
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MACHINE.val = oldVal;
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MACHINE.argcount = oldArgcount;
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MACHINE.proc = oldProc;
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success.apply(null, returnValues);
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});
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};
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MACHINE.control.push(
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new plt.baselib.frames.CallFrame(afterGoodInvoke, null));
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MACHINE.argcount = arguments.length - 4;
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for (var i = 0; i < arguments.length - 4; i++) {
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MACHINE.env.push(arguments[arguments.length - 1 - i]);
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}
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MACHINE.proc = proc;
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MACHINE.params['currentErrorHandler'] = function(MACHINE, e) {
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MACHINE.params['currentErrorHandler'] = oldErrorHandler;
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MACHINE.val = oldVal;
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MACHINE.argcount = oldArgcount;
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MACHINE.proc = oldProc;
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fail(e);
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};
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plt.runtime.trampoline(MACHINE, proc.label);
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} else {
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fail(plt.baselib.exceptions.makeExnFail(
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plt.baselib.format.format(
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"Not a procedure: ~e",
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proc)));
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}
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};
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// A Closure is a function that takes on more responsibilities: it is
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// responsible for popping off stack space before it finishes, and it
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// is also explicitly responsible for continuing the computation by
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// popping off the control stack and doing the jump. Because of this,
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// closures can do pretty much anything to the machine.
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// A closure consists of its free variables as well as a label
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// into its text segment.
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var Closure = function(label, arity, closedVals, displayName) {
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this.label = label; // (MACHINE -> void)
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this.arity = arity; // number
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this.closedVals = closedVals; // arrayof number
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this.displayName = displayName; // string
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};
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// Finalize the return from a closure. This is a helper function
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// for those who implement Closures by hand.
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//
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// If used in the body of a Closure, it must be in tail
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// position. This finishes the closure call, and does the following:
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//
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// * Clears out the existing arguments off the stack frame
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// * Sets up the return value
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// * Jumps either to the single-value return point, or the multiple-value
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// return point.
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//
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// I'd personally love for this to be a macro and avoid the
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// extra function call here.
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var finalizeClosureCall = function(MACHINE) {
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MACHINE.callsBeforeTrampoline--;
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var frame, i, returnArgs = [].slice.call(arguments, 1);
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// clear out stack space
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// TODO: replace with a splice.
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for(i = 0; i < MACHINE.argcount; i++) {
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MACHINE.env.pop();
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}
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if (returnArgs.length === 1) {
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MACHINE.val = returnArgs[0];
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frame = MACHINE.control.pop();
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return frame.label(MACHINE);
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} else if (returnArgs.length === 0) {
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MACHINE.argcount = 0;
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frame = MACHINE.control.pop();
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return frame.label.multipleValueReturn(MACHINE);
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} else {
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MACHINE.argcount = returnArgs.length;
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MACHINE.val = returnArgs.shift();
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// TODO: replace with a splice.
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for(i = 0; i < MACHINE.argcount - 1; i++) {
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MACHINE.env.push(returnArgs.pop());
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}
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frame = MACHINE.control.pop();
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return frame.label.multipleValueReturn(MACHINE);
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}
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};
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var makePrimitiveProcedure = function(name, arity, f) {
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f.arity = arity;
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f.displayName = name;
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return f;
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};
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var makeClosure = function(name, arity, f, closureArgs) {
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if (! closureArgs) { closureArgs = []; }
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return new Closure(f,
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arity,
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closureArgs,
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name);
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};
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var isPrimitiveProcedure = function(x) {
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return typeof(x) === 'function';
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};
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var isClosure = function(x) {
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return x instanceof Closure;
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};
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var isProcedure = function(x) {
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return (typeof(x) === 'function' ||
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x instanceof Closure);
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};
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var renameProcedure = function(f, name) {
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if (isPrimitiveProcedure(f)) {
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return makePrimitiveProcedure(
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name,
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f.arity,
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function() {
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return f.apply(null, arguments);
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});
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} else {
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return new Closure(
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f.label,
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f.arity,
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f.closedVals,
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name);
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}
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};
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//////////////////////////////////////////////////////////////////////
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exports.Closure = Closure;
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exports.internalCallDuringPause = internalCallDuringPause;
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exports.finalizeClosureCall = finalizeClosureCall;
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exports.makePrimitiveProcedure = makePrimitiveProcedure;
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exports.makeClosure = makeClosure;
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exports.isPrimitiveProcedure = isPrimitiveProcedure;
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exports.isClosure = isClosure;
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exports.isProcedure = isProcedure;
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exports.renameProcedure = renameProcedure;
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exports.asJavaScriptFunction = asJavaScriptFunction;
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})(this['plt'].baselib); |