be more cautious when detecting indentation of mixed files

node_modules/ace/lib/ace/ext/whitespace.js

@@ -46,9 +46,10 @@ exports.$detectIndentation = function(lines, fallback) {
         if (!/^\s*[^*+\-\s]/.test(line))
             continue;
 
-        if (line[0] == "\t")
+        if (line[0] == "\t") {
             tabIndents++;
-
+            prevSpaces = -Number.MAX_VALUE;
+        } else {
             var spaces = line.match(/^ */)[0].length;
             if (spaces && line[spaces] != "\t") {
                 var diff = spaces - prevSpaces;
@@ -58,7 +59,7 @@ exports.$detectIndentation = function(lines, fallback) {
                 stats[spaces] = (stats[spaces] || 0) + 1;
             }
             prevSpaces = spaces;
-
+        }
         // ignore lines ending with backslash
         while (i < max && line[line.length - 1] == "\\")
             line = lines[i++];
@@ -81,7 +82,7 @@ exports.$detectIndentation = function(lines, fallback) {
             spaceIndents = score;
             score = stats[1] ? 0.9 : 0.8;
             if (!stats.length)
-                score = 0
+                score = 0;
         } else
             score /= spaceIndents;
 
@@ -95,9 +96,11 @@ exports.$detectIndentation = function(lines, fallback) {
     if (first.score && first.score > 1.4)
         var tabLength = first.length;
 
-    if (tabIndents > spaceIndents + 1)
+    if (tabIndents > spaceIndents + 1) {
+        if (tabLength == 1 || spaceIndents < tabIndents / 4 || first.score < 1.8)
+            tabLength = undefined;
         return {ch: "\t", length: tabLength};
-
+    }
     if (spaceIndents > tabIndents + 1)
         return {ch: " ", length: tabLength};
 };

node_modules/ace/lib/ace/ext/whitespace_test.js

@@ -32,6 +32,12 @@ module.exports = {
         s.insert({row: 0, column: 0}, "  ");
         indent = whitespace.$detectIndentation(s.doc.$lines);
         assert.equal(indent.ch, "\t");
+        assert.equal(indent.length, undefined);
+        s.doc.removeInLine(0, 0, 1);
+        
+        s.insert({row: 0, column: 0}, "x\n    y\n");
+        indent = whitespace.$detectIndentation(s.doc.$lines);
+        assert.equal(indent.ch, "\t");
         assert.equal(indent.length, 4);
         
         s.setValue("");