Switch to callback-style in document-to-html for performance reasons

2 files changed, 44 insertions, 31 deletions

diff --git a/lib/document-to-html.js b/lib/document-to-html.js
index da1a69f..ab7dca4 100644
--- a/lib/document-to-html.js
+++ b/lib/document-to-html.js
@@ -1,4 +1,5 @@
 var q = require("q");
+var async = require("async");
 
 var htmlPaths = require("./html-paths");
 var HtmlGenerator = require("./html-generator").HtmlGenerator;
@@ -15,41 +16,41 @@ function DocumentConverter(options) {
     
     function convertToHtml(document) {
         var html = new HtmlGenerator();
-        return elementToHtml(document, html)
-            .then(function() {
-                html.closeAll();
-                
-                return {
-                    html: html.asString()
-                }; 
-            });
+        
+        return q.nfcall(elementToHtml, document, html).then(function() {
+            html.closeAll();
+            
+            return {
+                html: html.asString()
+            };
+        });
     }
     
-    function convertElements(elements, html) {
-        return forEachPromise(elements, function(element) {
-            return elementToHtml(element, html);
-        });
+    function convertElements(elements, html, callback) {
+        async.eachSeries(elements, function(element, callback) {
+            return elementToHtml(element, html, callback);
+        }, callback);
     }
 
-    function elementToHtml(element, html) {
+    function elementToHtml(element, html, callback) {
         var handler = elementConverters[element.type];
         if (handler) {
-            return q.when(handler(element, html));
+            handler(element, html, callback);
         } else {
-            return q.when();
+            callback();
         }
     }
     
-    function convertParagraph(element, html) {
+    function convertParagraph(element, html, callback) {
         html.satisfyPath(styleForParagraph(element));
-        return convertElements(element.children, html);
+        convertElements(element.children, html, callback);
     }
     
     function styleForParagraph(element) {
         return paragraphStyleMap[element.styleName] || defaultParagraphStyle;
     }
     
-    function convertRun(run, html) {
+    function convertRun(run, html, callback) {
         var runHtml = new HtmlGenerator();
         if (run.styleName) {
             var style = runStyleMap[run.styleName];
@@ -63,30 +64,40 @@ function DocumentConverter(options) {
         if (run.isItalic) {
             runHtml.open(htmlPaths.element("em"));
         }
-        return convertElements(run.children, runHtml)
-            .then(function() {
+        convertElements(run.children, runHtml, function(err) {
+            if (err) {
+                callback(err);
+            } else {
                 runHtml.closeAll();
                 html.append(runHtml);
-            });
+                callback();
+            }
+        });
     }
 
     var elementConverters = {
-        "document": function(document, html) {
-            return convertElements(document.children, html);
+        "document": function(document, html, callback) {
+            convertElements(document.children, html, callback);
         },
         "paragraph": convertParagraph,
         "run": convertRun,
-        "text": function(element, html) {
+        "text": function(element, html, callback) {
             html.text(element.value);
+            callback();
         },
-        "hyperlink": function(element, html) {
+        "hyperlink": function(element, html, callback) {
             html.open(htmlPaths.element("a", {href: element.href}));
-            return convertElements(element.children, html).then(function() {
-                html.close();
+            convertElements(element.children, html, function(err) {
+                if (err) {
+                    callback(err);
+                } else {
+                    html.close();
+                    callback();
+                }
             });
         },
-        "image": function(element, html) {
-            return element.read().then(function(imageBuffer) {
+        "image": function(element, html, callback) {
+            element.read().then(function(imageBuffer) {
                 // TODO: set alt attribute to wp:inline/wp:docPr/@descr
                 var src = "data:image/png;base64," + imageBuffer.toString("base64");
                 var attributes = {src: src};
@@ -94,7 +105,8 @@ function DocumentConverter(options) {
                     attributes.alt = element.altText;
                 }
                 html.selfClosing(htmlPaths.element("img", attributes));
-            });
+                callback();
+            }).fail(callback);
         }
     };
     return {
diff --git a/package.json b/package.json
index 8607b47..3b815f2 100644
--- a/package.json
+++ b/package.json
@@ -16,7 +16,8 @@
         "zipfile": "~0.3.4",
         "optimist": "~0.3.5",
         "connect": "~2.7.3",
-        "dustjs-linkedin": "~1.2.1"
+        "dustjs-linkedin": "~1.2.1",
+        "async": "0.2.6"
     },
     "devDependencies": {
         "mocha": "~1.8"