work around eager callback apis (in this case less.js)

tomyan · Jul 27, 2013 · 5d59f4a · 5d59f4a
1 parent 7636a28
commit 5d59f4a
Showing 1 changed file with 60 additions and 8 deletions.
diff --git a/lib/coro.js b/lib/coro.js
@@ -10,10 +10,15 @@ function currentCoro () {
 exports.resume = function () {
     var coro = currentCoro();
     return function (error) {
+        var result = error ? null : Array.prototype.slice.call(arguments, 1);
+        if (coros.length && coro === coros[coros.length - 1]) {
+            coro.save(error, result);
+            return;
+        }
         var val, err;
         coros.push(coro);
         try {
-            val = error ? coro.generator.throw(error) : coro.generator.next(Array.prototype.slice.call(arguments, 1));
+            val = error ? coro.generator.throw(error) : coro.generator.next(result);
         }
         catch (e) {
             err = e;
@@ -24,11 +29,15 @@ exports.resume = function () {
 
 exports.resumeFirst = function () {
     var coro = currentCoro();
-    return function (error, res) {
+    return function (error, result) {
+        if (coros.length && coro === coros[coros.length - 1]) {
+            coro.save(error, result);
+            return;
+        }
         var val, err;
         coros.push(coro);
         try {
-            val = error ? coro.generator.throw(error) : coro.generator.next(res);
+            val = error ? coro.generator.throw(error) : coro.generator.next(result);
         }
         catch (e) {
             err = e;
@@ -40,10 +49,15 @@ exports.resumeFirst = function () {
 exports.resumeNth = function (n) {
     var coro = currentCoro();
     return function (error) {
+        var result = error ? null : arguments[n];
+        if (coros.length && coro === coros[coros.length - 1]) {
+            coro.save(error, result);
+            return;
+        }
         var val, err;
         coros.push(coro);
         try {
-            val = error ? coro.generator.throw(error) : coro.generator.next(arguments[n]);
+            val = error ? coro.generator.throw(error) : coro.generator.next(result);
         }
         catch (e) {
             err = e;
@@ -55,10 +69,15 @@ exports.resumeNth = function (n) {
 exports.resumeNoThrow = function () {
     var coro = currentCoro();
     return function () {
+        var result = Array.prototype.slice.call(arguments, 0);
+        if (coros.length && coro === coros[coros.length - 1]) {
+            coro.save(null, result);
+            return;
+        }
         var val, err;
         coros.push(coro);
         try {
-            val = coro.generator.next(Array.prototype.slice.call(arguments, 0));
+            val = coro.generator.next(result);
         }
         catch (e) {
             err = e;
@@ -70,6 +89,10 @@ exports.resumeNoThrow = function () {
 exports.resumeNoThrowFirst = function () {
     var coro = currentCoro();
     return function (first) {
+        if (coros.length && coro === coros[coros.length - 1]) {
+            coro.save(null, first);
+            return;
+        }
         var val, err;
         coros.push(coro);
         try {
@@ -85,10 +108,15 @@ exports.resumeNoThrowFirst = function () {
 exports.resumeNoThrowNth = function (n) {
     var coro = currentCoro();
     return function () {
+        var result = arguments[n];
+        if (coros.length && coro === coros[coros.length - 1]) {
+            coro.save(null, result);
+            return;
+        }
         var val, err;
         coros.push(coro);
         try {
-            val = coro.generator.next(arguments[n]);
+            val = coro.generator.next(result);
         }
         catch (e) {
             err = e;
@@ -100,6 +128,10 @@ exports.resumeNoThrowNth = function (n) {
 exports.resumeThrow = function () {
     var coro = currentCoro();
     return function (error) {
+        if (coros.length && coro === coros[coros.length - 1]) {
+            coro.save(error);
+            return;
+        }
         var val, err;
         coros.push(coro);
         try {
@@ -119,13 +151,25 @@ var Coro = function (generator, deferred, callback) {
 };
 
 Coro.prototype.handle = function (err, result) {
+    var val, err;
     coros.pop();
-    if (err || result.done) {
-        this.handleResult(err, result);
+    if (err || this.savedError || result.done) {
+        this.handleResult(err || this.savedError, result);
     }
     else if (result.value && result.value.then) {
         this.handlePromise(result.value);
     }
+    else if (this.savedResult) {
+        coros.push(this);
+        try {
+            val = this.generator.next(this.savedResult);
+        }
+        catch (e) {
+            err = e;
+        }
+        this.savedResult = null;
+        this.handle(err, val);        
+    }
 };
 
 Coro.prototype.handleResult = function (err, result) {
@@ -168,6 +212,14 @@ Coro.prototype.handlePromise = function (promise) {
     );
 };
 
+Coro.prototype.save = function (error, result) {
+    if (this.savedResult || this.savedError) {
+        throw new Error('more than one coro callback called without yield');
+    }
+    this.savedError = error;
+    this.savedResult = result;
+};
+
 exports.run = function (makeGenerator, args, callback) {
 
     var deferred = callback ? null : p.defer(),