Revert "fix corner cases in preserve_line (#3212)"

This reverts commit 6a60eea.

And closes #85

README.md

@@ -948,8 +948,8 @@ can pass additional arguments that control the code output:
   adjust for this text.  Can be used to insert a comment containing
   licensing information, for example.
 
-- `preserve_line` (default `false`) -- pass `true` to retain line numbering on
-  a best effort basis.
+- `preserve_line` (default `false`) -- pass `true` to preserve lines, but it
+  only works if `beautify` is set to `false`.
 
 - `quote_keys` (default `false`) -- pass `true` to quote all keys in literal
   objects

lib/output.js

@@ -214,24 +214,16 @@ function OutputStream(options) {
     /* -----[ beautification/minification ]----- */
 
     var has_parens = false;
-    var line_end = 0;
-    var line_fixed = true;
     var might_need_space = false;
     var might_need_semicolon = false;
+    var might_add_newline = 0;
     var need_newline_indented = false;
     var need_space = false;
     var newline_insert = -1;
     var last = "";
     var mapping_token, mapping_name, mappings = options.source_map && [];
 
-    var adjust_mappings = mappings ? function(line, col) {
-        mappings.forEach(function(mapping) {
-            mapping.line += line;
-            mapping.col += col;
-        });
-    } : noop;
-
-    var flush_mappings = mappings ? function() {
+    var do_add_mapping = mappings ? function() {
         mappings.forEach(function(mapping) {
             try {
                 options.source_map.add(
@@ -254,30 +246,31 @@ function OutputStream(options) {
         mappings = [];
     } : noop;
 
-    function insert_newlines(count) {
-        var index = OUTPUT.lastIndexOf("\n");
-        if (line_end < index) line_end = index;
-        var left = OUTPUT.slice(0, line_end);
-        var right = OUTPUT.slice(line_end);
-        adjust_mappings(count, right.length - current_col);
-        current_line += count;
-        current_pos += count;
-        current_col = right.length;
-        OUTPUT = left;
-        while (count--) OUTPUT += "\n";
-        OUTPUT += right;
-    }
-
-    var fix_line = options.max_line_len ? function() {
-        if (line_fixed) {
+    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++;
+                current_col = right.length;
+            }
             if (current_col > options.max_line_len) {
                 AST_Node.warn("Output exceeds {max_line_len} characters", options);
             }
-            return;
         }
-        if (current_col > options.max_line_len) insert_newlines(1);
-        line_fixed = true;
-        flush_mappings();
+        if (might_add_newline) {
+            might_add_newline = 0;
+            do_add_mapping();
+        }
     } : noop;
 
     var requireSemicolonChars = makePredicate("( [ + * / - , . `");
@@ -310,7 +303,7 @@ function OutputStream(options) {
                     current_col++;
                     current_pos++;
                 } else {
-                    fix_line();
+                    ensure_line_len();
                     OUTPUT += "\n";
                     current_pos++;
                     current_line++;
@@ -328,6 +321,18 @@ function OutputStream(options) {
             }
         }
 
+        if (!options.beautify && options.preserve_line && stack[stack.length - 1]) {
+            var target_line = stack[stack.length - 1].start.line;
+            while (current_line < target_line) {
+                ensure_line_len();
+                OUTPUT += "\n";
+                current_pos++;
+                current_line++;
+                current_col = 0;
+                might_need_space = false;
+            }
+        }
+
         if (might_need_space) {
             if ((is_identifier_char(prev)
                     && (is_identifier_char(ch) || ch == "\\"))
@@ -349,7 +354,7 @@ function OutputStream(options) {
                 col: current_col
             });
             mapping_token = false;
-            if (line_fixed) flush_mappings();
+            if (!might_add_newline) do_add_mapping();
         }
 
         OUTPUT += str;
@@ -359,7 +364,7 @@ function OutputStream(options) {
         current_line += n;
         current_col += a[0].length;
         if (n > 0) {
-            fix_line();
+            ensure_line_len();
             current_col = a[n].length;
         }
         last = str;
@@ -390,12 +395,6 @@ function OutputStream(options) {
         return ret;
     } : function(col, cont) { return cont(); };
 
-    var may_add_newline = options.max_line_len || options.preserve_line ? function() {
-        fix_line();
-        line_end = OUTPUT.length;
-        line_fixed = false;
-    } : noop;
-
     var newline = options.beautify ? function() {
         if (newline_insert < 0) return print("\n");
         if (OUTPUT[newline_insert] != "\n") {
@@ -404,7 +403,10 @@ function OutputStream(options) {
             current_line++;
         }
         newline_insert++;
-    } : may_add_newline;
+    } : options.max_line_len ? function() {
+        ensure_line_len();
+        might_add_newline = OUTPUT.length;
+    } : noop;
 
     var semicolon = options.beautify ? function() {
         print(";");
@@ -466,7 +468,9 @@ function OutputStream(options) {
     } : noop;
 
     function get() {
-        if (!line_fixed) fix_line();
+        if (might_add_newline) {
+            ensure_line_len();
+        }
         return OUTPUT;
     }
 
@@ -637,14 +641,7 @@ function OutputStream(options) {
         col             : function() { return current_col; },
         pos             : function() { return current_pos; },
         push_node       : function(node) { stack.push(node); },
-        pop_node        : options.preserve_line ? function() {
-            var node = stack.pop();
-            if (node.start && node.start.line > current_line) {
-                insert_newlines(node.start.line - current_line);
-            }
-        } : function() {
-            stack.pop();
-        },
+        pop_node        : function() { return stack.pop(); },
         parent          : function(n) {
             return stack[stack.length - 2 - (n || 0)];
         }

lib/utils.js

@@ -170,7 +170,8 @@ var MAP = (function() {
 })();
 
 function push_uniq(array, el) {
-    if (array.indexOf(el) < 0) return array.push(el);
+    if (array.indexOf(el) < 0)
+        array.push(el);
 }
 
 function string_template(text, props) {