improve comment formatting logic (#4794)

1 files changed, 30 insertions, 51 deletions

diff --git a/lib/output.js b/lib/output.js
index e6b49804..fef57bce 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -347,6 +347,7 @@ function OutputStream(options) {
     };
 
     var indent = options.beautify ? function(half) {
+        if (need_newline_indented) print("\n");
         print(repeat_string(" ", half ? indentation - (options.indent_level >> 1) : indentation));
     } : noop;
 
@@ -450,6 +451,27 @@ function OutputStream(options) {
         return /^ *$/.test(OUTPUT.slice(index + 1));
     }
 
+    function pad_comment(token, force) {
+        if (need_newline_indented) return;
+        if (token.nlb && (force || !has_nlb())) {
+            need_newline_indented = true;
+        } else if (force) {
+            need_space = true;
+        }
+    }
+
+    function print_comment(comment) {
+        var value = comment.value.replace(/[@#]__PURE__/g, " ");
+        if (/^\s*$/.test(value) && !/^\s*$/.test(comment.value)) return false;
+        if (/comment[134]/.test(comment.type)) {
+            print("//" + value);
+            need_newline_indented = true;
+        } else if (comment.type == "comment2") {
+            print("/*" + value + "*/");
+        }
+        return true;
+    }
+
     function prepend_comments(node) {
         var self = this;
         var scan = node instanceof AST_Exit && node.value;
@@ -489,37 +511,12 @@ function OutputStream(options) {
         }
 
         comments = comments.filter(comment_filter, node);
-        if (comments.length == 0) return;
-        var last_nlb = has_nlb();
-        comments.forEach(function(c, i) {
-            if (!last_nlb) {
-                if (c.nlb) {
-                    print("\n");
-                    indent();
-                    last_nlb = true;
-                } else if (i > 0) {
-                    space();
-                }
-            }
-            var value = c.value.replace(/[@#]__PURE__/g, " ");
-            if (/^\s*$/.test(value)) return;
-            if (/comment[134]/.test(c.type)) {
-                print("//" + value + "\n");
-                indent();
-                last_nlb = true;
-            } else if (c.type == "comment2") {
-                print("/*" + value + "*/");
-                last_nlb = false;
-            }
+        var printed = false;
+        comments.forEach(function(comment, index) {
+            pad_comment(comment, index);
+            if (print_comment(comment)) printed = true;
         });
-        if (!last_nlb) {
-            if (node.start.nlb) {
-                print("\n");
-                indent();
-            } else {
-                space();
-            }
-        }
+        if (printed) pad_comment(node.start, true);
 
         function dump(node) {
             var token = node.start;
@@ -549,27 +546,9 @@ function OutputStream(options) {
         }))) return;
         comments._dumped = self;
         var insert = OUTPUT.length;
-        comments.filter(comment_filter, node).forEach(function(c, i) {
-            need_space = false;
-            if (need_newline_indented) {
-                print("\n");
-                indent();
-                need_newline_indented = false;
-            } else if (c.nlb && (i > 0 || !has_nlb())) {
-                print("\n");
-                indent();
-            } else if (i > 0 || !tail) {
-                space();
-            }
-            var value = c.value.replace(/[@#]__PURE__/g, " ");
-            if (/^\s*$/.test(value)) return;
-            if (/comment[134]/.test(c.type)) {
-                print("//" + value);
-                need_newline_indented = true;
-            } else if (c.type == "comment2") {
-                print("/*" + value + "*/");
-                need_space = true;
-            }
+        comments.filter(comment_filter, node).forEach(function(comment, index) {
+            pad_comment(comment, index || !tail);
+            print_comment(comment);
         });
         if (OUTPUT.length > insert) newline_insert = insert;
     }