1 files changed, 45 insertions, 14 deletions

diff --git a/lib/output.js b/lib/output.js
index 801f7516..a3c6b4ab 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -70,6 +70,49 @@ function OutputStream(options) {
         keep_quoted_props: false
     }, true);
 
+    // Convert comment option to RegExp if neccessary and set up comments filter
+    if (typeof options.comments === "string" && /^\/.*\/[a-zA-Z]*$/.test(options.comments)) {
+        var regex_pos = options.comments.lastIndexOf("/");
+        options.comments = new RegExp(
+            options.comments.substr(1, regex_pos - 1),
+            options.comments.substr(regex_pos + 1)
+        );
+    }
+    if (options.comments instanceof RegExp) {
+        options.comments = (function(f) {
+            return function(comment) {
+                return comment.type == "comment5" || f.test(comment.value);
+            }
+        })(options.comments);
+    }
+    else if (typeof options.comments === "function") {
+        options.comments = (function(f) {
+            return function(comment) {
+                return comment.type == "comment5" || f(this, comment);
+            }
+        })(options.comments);
+    }
+    else if (options.comments === "some") {
+        options.comments = function(comment) {
+            var text = comment.value;
+            var type = comment.type;
+            if (type == "comment2") {
+                // multiline comment
+                return /@preserve|@license|@cc_on/i.test(text);
+            }
+        }
+    }
+    else if (options.comments){ // NOTE includes "all" option
+        options.comments = function() {
+            return true;
+        }
+    } else {
+        // Falsy case, so reject all comments, except shebangs
+        options.comments = function(comment) {
+            return comment.type == "comment5";
+        }
+    }
+
     var indentation = 0;
     var current_col = 0;
     var current_line = 1;
@@ -435,7 +478,7 @@ function OutputStream(options) {
 
     AST_Node.DEFMETHOD("add_comments", function(output){
         if (output._readonly) return;
-        var c = output.option("comments"), self = this;
+        var self = this;
         var start = self.start;
         if (start && !start._comments_dumped) {
             start._comments_dumped = true;
@@ -458,19 +501,7 @@ function OutputStream(options) {
                 }));
             }
 
-            if (!c) {
-                comments = comments.filter(function(comment) {
-                    return comment.type == "comment5";
-                });
-            } else if (c.test) {
-                comments = comments.filter(function(comment){
-                    return comment.type == "comment5" || c.test(comment.value);
-                });
-            } else if (typeof c == "function") {
-                comments = comments.filter(function(comment){
-                    return comment.type == "comment5" || c(self, comment);
-                });
-            }
+            comments = comments.filter(output.option("comments"), self);
 
             // Keep single line comments after nlb, after nlb
             if (!output.option("beautify") && comments.length > 0 &&