From b0578b6c94e174df0f4434c21ded2b76d2cff453 Mon Sep 17 00:00:00 2001
From: Forbes Lindesay <forbes@lindesay.co.uk>
Date: Mon, 7 Jan 2013 23:06:32 +0000
Subject: [PATCH] Handle synchronous exceptions better

---
 lib/consolidate.js | 315 +++++++++++++++++++--------------------------
 1 file changed, 131 insertions(+), 184 deletions(-)

diff --git a/lib/consolidate.js b/lib/consolidate.js
index 3f664ad..7421226 100644
--- a/lib/consolidate.js
+++ b/lib/consolidate.js
@@ -148,11 +148,38 @@ function fromStringRenderer(name) {
   };
 }
 
+/**
+ * Convert a function that may throw syncronous errors into a well behaved async
+ * function that calls it's callback exactly once.
+ * 
+ * @param {Function} fn
+ * @return {Function}
+ * @api private
+ */
+function handleErrors(fn) {
+  return function (str, options, cb) {
+    var finished = false;
+    function safeCB(err, res) {
+      if (!finished) {
+        finished = true;
+        cb(err, res);
+      } else if (err) {
+        throw err;
+      }
+    }
+    try {
+      fn(str, options, safeCB);
+    } catch (ex) {
+      safeCB(ex);
+    }
+  };
+}
+
 /**
  * Jade support.
  */
 
-exports.jade = function(path, options, fn){
+exports.jade = handleErrors(function(path, options, fn){
   var engine = requires.jade;
   if (!engine) {
     try {
@@ -162,13 +189,13 @@ exports.jade = function(path, options, fn){
     }
   }
   engine.renderFile(path, options, fn);
-};
+});
 
 /**
  * Jade string support.
  */
 
-exports.jade.render = function(str, options, fn){
+exports.jade.render = handleErrors(function(str, options, fn){
   var engine = requires.jade;
   if (!engine) {
     try {
@@ -178,7 +205,7 @@ exports.jade.render = function(str, options, fn){
     }
   }
   engine.render(str, options, fn);
-};
+});
 
 /**
  * Dust support.
@@ -190,7 +217,7 @@ exports.dust = fromStringRenderer('dust');
  * Dust string support.
  */
 
-exports.dust.render = function(str, options, fn){
+exports.dust.render = handleErrors(function(str, options, fn){
   var engine = requires.dust;
   if (!engine) {
     try {
@@ -215,13 +242,9 @@ exports.dust.render = function(str, options, fn){
     read(path, options, callback);
   };
 
-  try {
-    var tmpl = cache(options) || cache(options, engine.compileFn(str));
-    tmpl(options, fn);
-  } catch (err) {
-    fn(err);
-  }
-};
+  var tmpl = cache(options) || cache(options, engine.compileFn(str));
+  tmpl(options, fn);
+});
 
 /**
  * Swig support.
@@ -233,15 +256,11 @@ exports.swig = fromStringRenderer('swig');
  * Swig string support.
  */
 
-exports.swig.render = function(str, options, fn){
+exports.swig.render = handleErrors(function(str, options, fn){
   var engine = requires.swig || (requires.swig = require('swig'));
-  try {
-    var tmpl = cache(options) || cache(options, engine.compile(str, options));
-    fn(null, tmpl(options));
-  } catch (err) {
-    fn(err);
-  }
-};
+  var tmpl = cache(options) || cache(options, engine.compile(str, options));
+  fn(null, tmpl(options));
+});
 
 /**
  * Atpl support.
@@ -253,15 +272,11 @@ exports.atpl = fromStringRenderer('atpl');
  * Atpl string support.
  */
 
-exports.atpl.render = function(str, options, fn){
+exports.atpl.render = handleErrors(function(str, options, fn){
   var engine = requires.atpl || (requires.atpl = require('atpl'));
-  try {
-    var tmpl = cache(options) || cache(options, engine.compile(str, options));
-    fn(null, tmpl(options));
-  } catch (err) {
-    fn(err);
-  }
-};
+  var tmpl = cache(options) || cache(options, engine.compile(str, options));
+  fn(null, tmpl(options));
+});
 
 /**
  * Liquor support,
@@ -273,15 +288,11 @@ exports.liquor = fromStringRenderer('liquor');
  * Liquor string support.
  */
 
-exports.liquor.render = function(str, options, fn){
+exports.liquor.render = handleErrors(function(str, options, fn){
   var engine = requires.liquor || (requires.liquor = require('liquor'));
-  try {
-    var tmpl = cache(options) || cache(options, engine.compile(str, options));
-    fn(null, tmpl(options));
-  } catch (err) {
-    fn(err);
-  }
-};
+  var tmpl = cache(options) || cache(options, engine.compile(str, options));
+  fn(null, tmpl(options));
+});
 
 /**
  * EJS support.
@@ -293,15 +304,11 @@ exports.ejs = fromStringRenderer('ejs');
  * EJS string support.
  */
 
-exports.ejs.render = function(str, options, fn){
+exports.ejs.render = handleErrors(function(str, options, fn){
   var engine = requires.ejs || (requires.ejs = require('ejs'));
-  try {
-    var tmpl = cache(options) || cache(options, engine.compile(str, options));
-    fn(null, tmpl(options));
-  } catch (err) {
-    fn(err);
-  }
-};
+  var tmpl = cache(options) || cache(options, engine.compile(str, options));
+  fn(null, tmpl(options));
+});
 
 
 /**
@@ -314,14 +321,10 @@ exports.eco = fromStringRenderer('eco');
  * Eco string support.
  */
 
-exports.eco.render = function(str, options, fn){
+exports.eco.render = handleErrors(function(str, options, fn){
   var engine = requires.eco || (requires.eco = require('eco'));
-  try {
-    fn(null, engine.render(str, options));
-  } catch (err) {
-    fn(err);
-  }
-};
+  fn(null, engine.render(str, options));
+});
 
 /**
  * Jazz support.
@@ -333,17 +336,13 @@ exports.jazz = fromStringRenderer('jazz');
  * Jazz string support.
  */
 
-exports.jazz.render = function(str, options, fn){
+exports.jazz.render = handleErrors(function(str, options, fn){
   var engine = requires.jazz || (requires.jazz = require('jazz'));
-  try {
-    var tmpl = cache(options) || cache(options, engine.compile(str, options));
-    tmpl.eval(options, function(str){
-      fn(null, str);
-    });
-  } catch (err) {
-    fn(err);
-  }
-};
+  var tmpl = cache(options) || cache(options, engine.compile(str, options));
+  tmpl.eval(options, function(str){
+    fn(null, str);
+  });
+});
 
 /**
  * JQTPL support.
@@ -355,15 +354,11 @@ exports.jqtpl = fromStringRenderer('jqtpl');
  * JQTPL string support.
  */
 
-exports.jqtpl.render = function(str, options, fn){
+exports.jqtpl.render = handleErrors(function(str, options, fn){
   var engine = requires.jqtpl || (requires.jqtpl = require('jqtpl'));
-  try {
-    engine.template(str, str);
-    fn(null, engine.tmpl(str, options));
-  } catch (err) {
-    fn(err);
-  }
-};
+  engine.template(str, str);
+  fn(null, engine.tmpl(str, options));
+});
 
 /**
  * Haml support.
@@ -375,37 +370,29 @@ exports.haml = fromStringRenderer('haml');
  * Haml string support.
  */
 
-exports.haml.render = function(str, options, fn){
+exports.haml.render = handleErrors(function(str, options, fn){
   var engine = requires.hamljs || (requires.hamljs = require('hamljs'));
-  try {
-    options.locals = options;
-    fn(null, engine.render(str, options).trimLeft());
-  } catch (err) {
-    fn(err);
-  }
-};
+  options.locals = options;
+  fn(null, engine.render(str, options).trimLeft());
+});
 
 /**
  * Whiskers support.
  */
 
-exports.whiskers = function(path, options, fn){
+exports.whiskers = handleErrors(function(path, options, fn){
   var engine = requires.whiskers || (requires.whiskers = require('whiskers'));
   engine.__express(path, options, fn);
-};
+});
 
 /**
  * Whiskers string support.
  */
 
-exports.whiskers.render = function(str, options, fn){
+exports.whiskers.render = handleErrors(function(str, options, fn){
   var engine = requires.whiskers || (requires.whiskers = require('whiskers'));
-  try {
-    fn(null, engine.render(str, options));
-  } catch (err) {
-    fn(err);
-  }
-};
+  fn(null, engine.render(str, options));
+});
 
 /**
  * Coffee-HAML support.
@@ -417,15 +404,11 @@ exports['haml-coffee'] = fromStringRenderer('haml-coffee');
  * Coffee-HAML string support.
  */
 
-exports['haml-coffee'].render = function(str, options, fn){
+exports['haml-coffee'].render = handleErrors(function(str, options, fn){
   var engine = requires.HAMLCoffee || (requires.HAMLCoffee = require('haml-coffee'));
-  try {
-    var tmpl = cache(options) || cache(options, engine.compile(str, options));
-    fn(null, tmpl(options));
-  } catch (err) {
-    fn(err);
-  }
-};
+  var tmpl = cache(options) || cache(options, engine.compile(str, options));
+  fn(null, tmpl(options));
+});
 
 /**
  * Hogan support.
@@ -437,15 +420,11 @@ exports.hogan = fromStringRenderer('hogan');
  * Hogan string support.
  */
 
-exports.hogan.render = function(str, options, fn){
+exports.hogan.render = handleErrors(function(str, options, fn){
   var engine = requires.hogan || (requires.hogan = require('hogan.js'));
-  try {
-    var tmpl = cache(options) || cache(options, engine.compile(str, options));
-    fn(null, tmpl.render(options, options.partials));
-  } catch (err) {
-    fn(err);
-  }
-};
+  var tmpl = cache(options) || cache(options, engine.compile(str, options));
+  fn(null, tmpl.render(options, options.partials));
+});
 
 /**
  * Handlebars support.
@@ -457,18 +436,14 @@ exports.handlebars = fromStringRenderer('handlebars');
  * Handlebars string support.
  */
 
-exports.handlebars.render = function(str, options, fn) {
+exports.handlebars.render = handleErrors(function(str, options, fn) {
   var engine = requires.handlebars || (requires.handlebars = require('handlebars'));
-  try {
-    for (var partial in options.partials) {
-      engine.registerPartial(partial, options.partials[partial]);
-    }
-    var tmpl = cache(options) || cache(options, engine.compile(str, options));
-    fn(null, tmpl(options));
-  } catch (err) {
-    fn(err);
+  for (var partial in options.partials) {
+    engine.registerPartial(partial, options.partials[partial]);
   }
-}
+  var tmpl = cache(options) || cache(options, engine.compile(str, options));
+  fn(null, tmpl(options));
+});
 
 /**
  * Underscore support.
@@ -480,50 +455,38 @@ exports.underscore = fromStringRenderer('underscore');
  * Underscore string support.
  */
 
-exports.underscore.render = function(str, options, fn) {
+exports.underscore.render = handleErrors(function(str, options, fn) {
   var engine = requires.underscore || (requires.underscore = require('underscore'));
-  try {
-    var tmpl = cache(options) || cache(options, engine.template(str, null, options));
-    fn(null, tmpl(options).replace(/\n$/, ''));
-  } catch (err) {
-    fn(err);
-  }
-};
+  var tmpl = cache(options) || cache(options, engine.template(str, null, options));
+  fn(null, tmpl(options).replace(/\n$/, ''));
+});
 
 
 /**
  * QEJS support.
  */
 
-exports.qejs = function (path, options, fn) {
-  try {
-    var engine = requires.qejs || (requires.qejs = require('qejs'));
-    engine.renderFile(path, options).then(function (result) {
-        fn(null, result);
-    }, function (err) {
-        fn(err);
-    }).end();
-  } catch (err) {
-    fn(err);
-  }
-};
+exports.qejs = handleErrors(function (path, options, fn) {
+  var engine = requires.qejs || (requires.qejs = require('qejs'));
+  engine.renderFile(path, options).then(function (result) {
+      fn(null, result);
+  }, function (err) {
+      fn(err);
+  }).end();
+});
 
 /**
  * QEJS string support.
  */
 
-exports.qejs.render = function (str, options, fn) {
-  try {
-    var engine = requires.qejs || (requires.qejs = require('qejs'));
-    engine.render(str, options).then(function (result) {
-        fn(null, result);
-    }, function (err) {
-        fn(err);
-    }).end();
-  } catch (err) {
-    fn(err);
-  }
-};
+exports.qejs.render = handleErrors(function (str, options, fn) {
+  var engine = requires.qejs || (requires.qejs = require('qejs'));
+  engine.render(str, options).then(function (result) {
+      fn(null, result);
+  }, function (err) {
+      fn(err);
+  }).end();
+});
 
 
 /**
@@ -536,15 +499,11 @@ exports.walrus = fromStringRenderer('walrus');
  * Walrus string support.
  */
 
-exports.walrus.render = function (str, options, fn) {
+exports.walrus.render = handleErrors(function (str, options, fn) {
   var engine = requires.walrus || (requires.walrus = require('walrus'));
-  try {
-    var tmpl = cache(options) || cache(options, engine.parse(str));
-    fn(null, tmpl.compile(options));
-  } catch (err) {
-    fn(err);
-  }
-};
+  var tmpl = cache(options) || cache(options, engine.parse(str));
+  fn(null, tmpl.compile(options));
+});
 
 /**
  * Mustache support.
@@ -556,20 +515,16 @@ exports.mustache = fromStringRenderer('mustache');
  * Mustache string support.
  */
 
-exports.mustache.render = function(str, options, fn) {
+exports.mustache.render = handleErrors(function(str, options, fn) {
   var engine = requires.mustache || (requires.mustache = require('mustache'));
-  try {
-    fn(null, engine.to_html(str, options, options.partials));
-  } catch (err) {
-    fn(err);
-  }
-};
+  fn(null, engine.to_html(str, options, options.partials));
+});
 
 /**
  * Just support.
  */
 
-exports.just = function(path, options, fn){
+exports.just = handleErrors(function(path, options, fn){
   var engine = requires.just;
   if (!engine) {
     var JUST = require('just');
@@ -577,23 +532,23 @@ exports.just = function(path, options, fn){
   }
   engine.configure({ useCache: options.cache });
   engine.render(path, options, fn);
-};
+});
 
 /**
  * Just string support.
  */
 
-exports.just.render = function(str, options, fn){
+exports.just.render = handleErrors(function(str, options, fn){
   var JUST = require('just');
   var engine = new JUST({ root: { page: str }});
   engine.render('page', options, fn);
-};
+});
 
 /**
  * ECT support.
  */
 
-exports.ect = function(path, options, fn){
+exports.ect = handleErrors(function(path, options, fn){
   var engine = requires.ect;
   if (!engine) {
     var ECT = require('ect');
@@ -601,17 +556,17 @@ exports.ect = function(path, options, fn){
   }
   engine.configure({ cache: options.cache });
   engine.render(path, options, fn);
-};
+});
 
 /**
  * ECT string support.
  */
 
-exports.ect.render = function(str, options, fn){
+exports.ect.render = handleErrors(function(str, options, fn){
   var ECT = require('ect');
   var engine = new ECT({ root: { page: str }});
   engine.render('page', options, fn);
-};
+});
 
 /**
  * mote support.
@@ -623,34 +578,26 @@ exports.mote = fromStringRenderer('mote');
  * mote string support.
  */
 
-exports.mote.render = function(str, options, fn){
+exports.mote.render = handleErrors(function(str, options, fn){
   var engine = requires.mote || (requires.mote = require('mote'));
-  try {
-    var tmpl = cache(options) || cache(options, engine.compile(str));
-    fn(null, tmpl(options));
-  } catch (err) {
-    fn(err);
-  }
-};
+  var tmpl = cache(options) || cache(options, engine.compile(str));
+  fn(null, tmpl(options));
+});
 
 /**
  * Toffee support.
  */
 
-exports.toffee = function(path, options, fn){
+exports.toffee = handleErrors(function(path, options, fn){
   var toffee = requires.toffee || (requires.toffee = require('toffee'));
   toffee.__consolidate_engine_render(path, options, fn);
-};
+});
 
 /**
  * Toffee string support.
  */
 
-exports.toffee.render = function(str, options, fn) {
+exports.toffee.render = handleErrors(function(str, options, fn) {
   var engine = requires.toffee || (requires.toffee = require('toffee'));
-  try {
-  	engine.str_render(str, options,fn);
-  } catch (err) {
-    fn(err);
-  }
-}
+  engine.str_render(str, options,fn);
+});