1 files changed, 50 insertions, 19 deletions

diff --git a/lib/output.js b/lib/output.js
index 40800559..e9765f7c 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -189,12 +189,43 @@ function OutputStream(options) {
     var might_need_semicolon = false;
     var might_add_newline = 0;
     var last = "";
+    var mapping_token, mapping_name, mappings = options.source_map && [];
+
+    var do_add_mapping = mappings ? function() {
+        mappings.forEach(function(mapping) {
+            try {
+                options.source_map.add(
+                    mapping.token.file,
+                    mapping.line, mapping.col,
+                    mapping.token.line, mapping.token.col,
+                    !mapping.name && mapping.token.type == "name" ? mapping.token.value : mapping.name
+                );
+            } catch(ex) {
+                AST_Node.warn("Couldn't figure out mapping for {file}:{line},{col} → {cline},{ccol} [{name}]", {
+                    file: mapping.token.file,
+                    line: mapping.token.line,
+                    col: mapping.token.col,
+                    cline: mapping.line,
+                    ccol: mapping.col,
+                    name: mapping.name || ""
+                })
+            }
+        });
+        mappings = [];
+    } : noop;
 
     var ensure_line_len = options.max_line_len ? function() {
         if (current_col > options.max_line_len) {
             if (might_add_newline) {
                 var left = OUTPUT.slice(0, might_add_newline);
                 var right = OUTPUT.slice(might_add_newline);
+                if (mappings) {
+                    var delta = right.length - current_col;
+                    mappings.forEach(function(mapping) {
+                        mapping.line++;
+                        mapping.col += delta;
+                    });
+                }
                 OUTPUT = left + "\n" + right;
                 current_line++;
                 current_pos++;
@@ -204,7 +235,10 @@ function OutputStream(options) {
                 AST_Node.warn("Output exceeds {max_line_len} characters", options);
             }
         }
-        might_add_newline = 0;
+        if (might_add_newline) {
+            might_add_newline = 0;
+            do_add_mapping();
+        }
     } : noop;
 
     var requireSemicolonChars = makePredicate("( [ + * / - , .");
@@ -264,6 +298,18 @@ function OutputStream(options) {
             }
             might_need_space = false;
         }
+
+        if (mapping_token) {
+            mappings.push({
+                token: mapping_token,
+                name: mapping_name,
+                line: current_line,
+                col: current_col
+            });
+            mapping_token = false;
+            if (!might_add_newline) do_add_mapping();
+        }
+
         OUTPUT += str;
         current_pos += str.length;
         var a = str.split(/\r?\n/), n = a.length - 1;
@@ -358,24 +404,9 @@ function OutputStream(options) {
         space();
     };
 
-    var add_mapping = options.source_map ? function(token, name) {
-        try {
-            if (token) options.source_map.add(
-                token.file || "?",
-                current_line, current_col,
-                token.line, token.col,
-                (!name && token.type == "name") ? token.value : name
-            );
-        } catch(ex) {
-            AST_Node.warn("Couldn't figure out mapping for {file}:{line},{col} → {cline},{ccol} [{name}]", {
-                file: token.file,
-                line: token.line,
-                col: token.col,
-                cline: current_line,
-                ccol: current_col,
-                name: name || ""
-            })
-        }
+    var add_mapping = mappings ? function(token, name) {
+        mapping_token = token;
+        mapping_name = name;
     } : noop;
 
     function get() {